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DIP Episode 306 - USMLE Step 2CK Rapid Review Series 54

BiochemistryMedium4 - HighHas Q&A

Step 2Step 3MedicineUSMLEStep 2Step 3

Topic

Hypercalcemia workup and management; Malignancy associations (SCLC, Multiple Myeloma); Immunodeficiency syndromes; Calcium metabolism disorders.

Key Takeaway

The differential diagnosis of hypercalcemia must differentiate between PTH-related peptide mediated elevation (e.g., SCLC), osteoclast activation via IL-6/RANKL pathways (e.g., Multiple Myeloma), and excessive Vitamin D synthesis (e.g., Stägehosis).

Runtime: 38.1 min

Published: 2021-04-16

Completed audio: Yes

Completed notes: Yes

Anki made: Yes

Section: RAPID REVIEW SERIES

Open Notion notes Episode source

Episode Notes

Source / episode info

Episode: 306
Title: Divine Intervention Episode 306 – USMLE Step 2 CK Rapid Review Series 54.
Published: 2021-04-16
Source: Episode page

One-liner

This episode provides a high-yield review of hypercalcemia mechanisms in malignancy (SCLC via PT HrP; MM via IL-6/RANKL; Stägehosis via Vitamin D excess), the step-wise management protocol for acute hypercalcemia, and key concepts regarding B-cell immunodeficiency.

High-yield summary

Acute Hypercalcemia Management: Always start with IV Normal Saline (NS) to correct volume depletion. If refractory, proceed to IV Bisphosphonates (e.g., pamidronate). Third line is Calcitonin.
SCLC Mechanism: Parathyroid hormone related peptide (PT HrP) acts on the calcium sensing receptor (CaSR), mimicking PTH and causing hypercalcemia. Look for cavitary lung lesions.
Multiple Myeloma (MM) Mechanism: Hypercalcemia results from increased osteoclast activity, mediated by cytokines like IL-6, which upregulates RANKL binding to the RANK receptor on osteoclasts. This is independent of PT HrP.
Stägehosis Mechanism: Granulomatous inflammation leads to high local production of 1--hydroxylase, converting inactive Vitamin D (25-OHD) to active Calcitriol (1,25-dihydroxyvitamin D), causing hypercalcemia.
Immunodeficiency: Pan-hypogammaglobulinemia (low IgG, IgA, IgM, etc.) in a young child with recurrent infections suggests B-cell impairment (e.g., X-linked Agammaglobulinemia).

Learning objectives

Differentiate the mechanisms causing hypercalcemia associated with SCLC, Multiple Myeloma, and Stägehosis.
Outline the three sequential steps for managing acute symptomatic hypercalcemia (NS -> Bisphosphonate -> Calcitonin).
Recognize the clinical signs of B-cell immunodeficiency based on hypogammaglobulinemia.
Understand that PT HrP is a peptide hormone mimicking PTH, distinct from true parathyroid overproduction.
Correlate granulomatous inflammation with excessive Vitamin D activation in Stägehosis.

Board exam buzzwords

Condition	Key Finding	Association	Board Exam Tip
Hypercalcemia of Malignancy (HHM)	Elevated PT HrP	SCLC, Squamous Cell Carcinoma	Always check for PT HrP first; it is the most common cause.
Multiple Myeloma	High turnover bone disease; hypercalcemia	IL-6 -> RANKL -> Osteoclast activation	Hypercalcemia here is independent of PTH/PT HrP axis.
Stägehosis	Granulomas; high 1--hydroxylase activity	Excessive Calcitriol (1,25-(OH)₂D₃) synthesis	Think "Vitamin D excess" when granulomatous disease causes hypercalcemia.
Acute Hypercalcemia Management	Symptomatic symptoms (e.g., confusion, kidney injury)	IV Normal Saline -> Bisphosphonate -> Calcitonin	Remember the sequence: NS first, then phosphate binders/bisphosphonates.

Rapid review table

Topic	Key Point	Context	Exam Relevance
Hypercalcemia	Initial step is volume expansion with IV Normal Saline (NS).	All causes of hypercalcemia; corrects associated dehydration and kidney injury.	Must be the first step in management, regardless of etiology.
SCLC/PT HrP	PT HrP mimics PTH action on CaSR.	Cavitary lung lesions + Hypercalcemia.	Distinguishes HHM from primary hyperparathyroidism (PHPT).
Multiple Myeloma	Osteoclast activation via IL-6 and RANKL signaling.	Bone lytic lesions, high turnover bone disease.	Key mechanism is cytokine-driven osteolysis, not PTH/PT HrP driven.
Stägehosis	Granulomas induce 1--hydroxylase activity.	Chronic granulomatous diseases (e.g., sarcoidosis).	Leads to secondary hyperparathyroidism and hypercalcemia due to Vitamin D excess.

Board-speak -> diagnosis

Board-speak / Vignette phrase	Diagnosis / Concept	Why it fits
A patient presents with a cavitary lung lesion and hypercalcemia, with elevated PT HrP levels.	Squamous Cell Lung Cancer (SCLC)	SCL Cs often secrete PT HrP, leading to humoral hypercalcemia of malignancy (HHM).
Multiple myeloma presenting with bone pain and hypercalcemia, but PTH is suppressed and PT HrP is normal.	Multiple Myeloma	Hypercalcemia here is due to cytokine-mediated osteoclast activation (IL-6/RANKL), not PTH or PT HrP excess.
A patient with chronic granulomatous disease presents with hypercalcemia.	Stägehosis	Granulomas stimulate 1--hydroxylase, leading to excessive calcitriol synthesis and subsequent calcium absorption.
Initial management of symptomatic hypercalcemia involves administering IV Normal Saline.	Acute Hypercalcemia Management (Step 1)	Volume depletion is a key component; NS corrects this first before addressing the underlying cause.
A patient with metastatic thyroid cancer develops prolonged QT interval and signs of hypocalcemia upon blood pressure cuff inflation.	Medullary Thyroid Cancer (MTC) / Severe Hypercalcemia	MTC can secrete calcitonin, leading to acute hypercalcemia; severe calcium shifts affect cardiac repolarization (QT prolongation).
A young boy with recurrent bacterial infections shows low levels of IgG, IgA, and IgM.	B-cell Immunodeficiency (e.g., XLA)	Indicates a failure in plasma cell maturation or antibody production, suggesting an impairment in the humoral immune response.

Differential diagnosis / distinguishing features

B-cell Immunodeficiency

Key Features	Distinguishing Findings	Next Step
Pan-hypogammaglobulinemia (Low IgG, IgA, IgM)	Recurrent bacterial infections in infancy/childhood.	Confirm diagnosis and initiate IVIG replacement therapy.

Management pearls

Acute Hypercalcemia: Always assume volume depletion is present; start with NS to restore euvolemia.
Bisphosphonates (e.g., Pamidronate): These drugs are phosphate analogs that bind bone mineral, making calcium unavailable for excretion by the kidneys. They take 2–3 days to achieve maximum effect.
Calcitonin: Acts rapidly by inhibiting osteoclast activity and promoting renal calcium excretion. It is useful as a third-line agent or in acute settings where rapid control is needed.
Symptomatic Hypercalcemia: Requires aggressive management (NS -> Bisphosphonate -> Calcitonin) to prevent nephrocalcinosis, cardiac arrhythmias, and encephalopathy.

Don't miss

🚨

PT HrP is a peptide hormone that acts on the Calcium Sensing Receptor (CaSR), not true parathyroid hormone.

🚨

The hypercalcemia in Multiple Myeloma is driven by cytokines (IL-6) stimulating osteoclasts via RANKL, bypassing normal calcium regulation pathways.

🚨

Stägehosis represents an overproduction of active Vitamin D due to local enzyme induction within granulomas.

🚨

IV Normal Saline is the cornerstone of initial management because it corrects volume depletion and helps mobilize calcium from bone.

Integration & clinical reasoning

Calcium Homeostasis: The body maintains tight control via PTH (stimulates 1-\alpha-hydroxylase, increases renal Ca reabsorption) and Calcitriol (increases gut absorption). Hypercalcemia disrupts this balance by overstimulating osteoclasts or increasing intestinal absorption.
Malignancy & Bone: Many cancers metastasize to bone, causing hypercalcemia. The mechanism dictates the treatment: PT HrP -> treat source; MM -> inhibit osteoclast activity (bisphosphonates).
Immunology Link: B-cell deficiencies impair antibody production, leading to recurrent infections and requiring replacement therapy (IVIG), which is a key concept in pediatric infectious disease.

Concept connections / cross-references

No explicit cross-references.

High-yield association table

Condition	Association	Mechanism	Clinical Significance
SCLC	Hypercalcemia; Cavitary lung lesions	Secretion of PT HrP, mimicking PTH action.	Requires immediate workup to rule out HHM and initiate calcium management.
Multiple Myeloma	Bone lytic metastases; Hypercalcemia	IL-6 stimulates RANKL -> excessive osteoclast activity.	Bisphosphonates are the primary treatment for hypercalcemic crisis.
Stägehosis	Granulomatous inflammation (e.g., sarcoidosis)	Local induction of 1--hydroxylase, leading to excess Calcitriol.	Hypercalcemia is a direct result of Vitamin D toxicity/excess.
B-cell Deficiency	Recurrent bacterial infections; Hypogammaglobulinemia	Failure in plasma cell maturation and antibody production.	Requires prophylactic IVIG replacement therapy.

Key terms glossary

Term	Definition	Context	Example
PT HrP	Parathyroid hormone related peptide. A polypeptide that mimics PTH action.	Hypercalcemic malignancy (SCLC).	Elevated levels strongly suggest humoral hypercalcemia of malignancy.
RANKL/RANK	Receptor Activator of Nuclear Factor Kappa-B Ligand / Receptor. Key signaling axis for osteoclast differentiation.	Multiple Myeloma, bone resorption.	High RANKL activity drives excessive osteoclast formation and calcium release.
Calcitriol (1,25-(OH)₂D₃)	The active form of Vitamin D.	Stägehosis; Gut absorption of Ca/P.	Excess Calcitriol synthesis causes hypercalcemia in granulomatous disease.
Hypogammaglobulinemia	Low levels of serum immunoglobulins (IgG, IgA, IgM).	B-cell deficiency syndromes (e.g., XLA).	Indicates impaired humoral immunity and risk of recurrent infections.

Study optimization

Topic	Study Approach	Priority	Resources
Hypercalcemia Mechanisms	Create a flow chart comparing SCLC, MM, and Stägehosis mechanisms (PT HrP vs IL-6/RANKL vs Calcitriol).	High. Must know the why behind the hypercalcemia.	Review board vignettes focusing on differential diagnosis.
Acute Hypercalcemia Management	Memorize the three sequential steps: NS -> Bisphosphonate -> Calcitonin.	Critical. This is a high-yield, step-wise protocol question.	Practice questions and flowcharts.
Immunodeficiency	Focus on recognizing the pattern of hypogammaglobulinemia in infancy/childhood.	Medium. Important for pediatric board questions.	Review genetics and primary immunodeficiencies (e.g., XLA).

Question pattern recognition

Pattern: Cavitary lung lesion + Hypercalcemia: Points to SCLC, suggesting PT HrP as the mechanism. Next step is confirming elevated PT HrP.
Pattern: Bone lytic lesions + Hypercalcemia + Low PTH/PT HrP: Strongly suggests Multiple Myeloma due to cytokine-mediated osteoclast activation (IL-6/RANKL).
Pattern: Granulomas + Hypercalcemia: Points to Stägehosis, indicating excessive Vitamin D synthesis. Treatment involves addressing the granulomatous cause and potentially calcitriol antagonists.

Test yourself

Common mistakes to avoid

🚫

Mistake 1: Confusing PT HrP and PTH. Remember that PT HrP is a peptide hormone, not true parathyroid hormone, but it acts on the same receptor (CaSR) to raise calcium.

🚫

Mistake 2: Mismanaging Acute Hypercalcemia. Never forget the sequence: NS -> Bisphosphonate -> Calcitonin. Skipping NS or giving calcitonin first can delay effective treatment.

🚫

Mistake 3: Assuming all hypercalcemic malignancies are PT HrP driven. Remember that MM uses a cytokine pathway (IL-6/RANKL) and Stägehosis uses Vitamin D excess, making the differential diagnosis crucial.

Common traps

⚠️

Trap 1: The question might list high PTH levels in a patient with SCLC. This is a trap; PTH should be suppressed because the hypercalcemia itself suppresses parathyroid release.

⚠️

Trap 2: When managing acute hypercalcemia, giving IV phosphate binders (like Sevelamer) alone is insufficient; volume expansion and bisphosphonates are required for effective calcium removal.

⚠️

Trap 3: Assuming that all granulomatous diseases cause hypercalcemia. While Stägehosis is the classic example, other causes of Vitamin D excess must be considered if calcitriol levels are high.

Original transcript with highlights

Okay, welcome. My name is Divine. This is episode 306 of the Divine Intervention Podcast. In this podcast, I'll be continuing the Rapid Review series for the US Emily Step 2 CK exam. This is going to be Series 54. It's going to be short, it's going to be sweet, it's going to be very high yield. And at the end, I'll talk about a quick life lesson. And again, just as a reminder, the course is coming up soon. For those of you that are preparing for Step 2 CK Step 3, I do have a 20-hour comprehensive review course that's taking place between the 20th of this month and the first of me. So it's four days, it's five hours each day. It's from 11 a.m. to 11 a.m. to 4 p.m. Pacific Standard Time. So that's 2 p.m. to 7 p.m. Eastern Standard Time on each of those days. It's a Wednesday, Thursday, Friday and Saturday. And the goal of the course is to go over Pete's surgery, internal medicine, OB-GYN, Neuro, Psych, Bio-Stats, Ethics. The new changes that we're made with regards to Step 2 CK Step 3 from November of 2020. So those things on professionalism, healthcare systems, errors and all those things, quality and safety. And then the final thing will be going over at those Step 1 things that your friends at the Mbimini will care about a lot on Step 2 CK. In fact, I'm going to be sprinkling that all throughout the course of all four days. And there will be time allotted for people to ask questions and have those questions answered, which is always nice.

And again, you'll be able to take some very good detailed notes as we go along. Also, I have, so the day before that's a Tuesday, that's the 27th of this month. We have the Mbimini Testicking Strategies class. That's from 2 to 4 p.m. Pacific Standard Time. It's right around 5 to 7.30 p.m. Eastern Standard Time. And during that course, we'll be going over just a ton of just very, very high yield ways of taking Mbimini exams. So we'll have Mbimini style questions. And then using those questions, I will teach you a very logical approach for reading questions, for paying attention to what is most important in question steps, and for picking out the right answer. And we'll visit topics like, oh, if you're not sure of this thing that they are testing, if you don't even know the information being presented, how can you answer it correctly? We'll talk about timing, talk about taking breaks during exams, we'll talk about all those things. Again, many people have taken this course, found it to be extremely helpful. So if you're interested, just shoot me an email through the website, and I'll give you some more information on costs and stuff like that. The course is a held via Zoom, a held via Zoom. So let's jump right into it. So what if they give you a question about a 33 year old female and they tell you that she's brought to the hospital because for the last two days, she has been having an altered mental status, having shortness of breath. Right.

She has been having to drink a lot of water and she has been peeing a lot. Right. And then they see on physical exam, she has skin tinting, she has decreased capillary refill. And then they show you a chest x-ray and you see like a white circular opacity that is, and you know, that has like air fluid levels and it's very close to the media's style. What are you thinking about? Well, I really hope that you're thinking about this person having hypercalfs email of malignancy. So whenever you see a person having all these and again, they may be nice and give you like the person's calcium being elevated. Right. What if you notice this situation I just described, especially the long image and finding is essentially a person that has, again, you see the nodular thing has air fluid levels. That's a cavity, right. Whenever you see a person having a cavitary lesion malignancy, especially one that is centrally in the lungs, I would really hope you're thinking about scrimal cell lung cancer. Right. So this person has hypercalfs email of malignancy. And remember, people get hypercalfs email in malignancy through many different mechanisms. Right. I will talk about the treatment in a bit, but in scrimal cell lung cancer, as we know, those people have PT HRP, parthid, who want related peptide that goes ahead and essentially works like PTH. So that causes those people to have hypercalfs email. A second one, right.

If we think about multiple my Loma, multiple my Loma is not associated with PT HRP or NBM exams. It's associated with interlooking one, right. Those plasma cells that constitute malignancy, be producing interlooking one. And that interlooking one is a very powerful activity of osteoclasts. In fact, it makes you have more interact. It increases the expression of rank ligand and rank. Right. So rank ligand can then bind to that rank receptor, now, activate osteoclasts. That will cause the presence bond to leach away. Right. So the person will get hypercalfs email. In fact, one nifty question your friends at the NBM could give you is a person that has multiple my Loma or should be true of their levels of PTH. I hope you're telling me that it's low, right. You can essentially use that to assess your ability to see if you actually know the mechanism behind the hypercalfs email in multiple my Loma. Right. Because again, you're getting that hypercalfs email through a separate non-PTHRP pathway. Right. It's interlooking one that's doing all the action. So the thing that happens is the presence calcium will go up. Right. So as a negative feedback, right. Those calcium sensors that will be like, okay, we see there's a lot of calcium. So you'll suppress the presence in dodging of PTH. Right. You'll suppress the presence in dodging of PTH. Right. And remember, people that have staquidosis. Right. Why do they have hypercalfs email?

Well, people that have staquidosis, they'll have hypercalfs email. Right. Because remember, in staquidosis, we see those non-KCD granulomas. Well, by definition, a granuloma should have those giant cells around those epithelioid microfeges. Well, the epithelioid microfeges that surround the granuloma in in a staquidosis, those things produce the express one alpha hydroxylase in high amounts. Right. So those high amounts of one alpha hydroxylase, they would cause you to make convert calcium dial, which is 25 hydroxy vitamin D to calcium trial, which is 125 dihydroxy vitamin D. And that's going to cause the individual to make a ton of vitamin D. And as we know, vitamin D, it increases the absorption of calcium and phosphate in the gut. Right. So that's going to cause hypercalfs email. Right. So if a person has symptomatic hypercalfs email like this, what is the first thing you're supposed to do on an ambient exam? Always, always start with IV normal ceiling. Right. Always start with normal ceiling. Remember, normal ceiling is also the same thing as 0.9% ceiling. Right. So you start with IV normal ceiling. If that's not helping, right. You'll second thing you're going to do on an exam. And you may be like, well, where we're doing this normal ceiling business? Again, remember, when a person is hypercalfsemic, it actually distorts the signaling cascade of EDH, especially the one that goes through the visual pressing V to receptor.

Essentially, hypercalfsemia causes like diabetes and sypedas, like an effrogenic diabetes and sypedas. Right. So you need to bring the calcium under control to fix that problem. Right. So those people actually like super volume depleted as it is in the case that I just described. Right. So you want to give them IV normal ceiling. Right. And then after that, if that doesn't work, right, you're going to go ahead and introduce an IVB phosphinate. Right. And IVB phosphates to those folks. And then if that's still not working, a third-line thing you can go into is giving them calcium toning. Remember, calcium toning tones down your blood calcium levels. Right. Calcy toning tones down your blood calcium levels. In fact, I can imagine your friends at the end of the week, they give you a question about a person that has a neck mass. And then they show you an e-cigil. You notice that the QT interval is prolonged. And the person has like, you know, for some drastic signs, positive. I hope you think the mom made a thyroid cancer in those circumstances. Right. Because essentially the thing that's happening in that patient is the medallary thyroid cancer. Remember, it's a cancer of the C cells. Right. And the meat calcium toning. So they can bring down the present blood calcium. Right. And that can prolong the QT interval on an e-cigil. Right. And that can cause them to have that true source sign where if you're tight in a blood pressure cough, you'll have a couple of pidospasins. Right.

And if you do the joystick sign, right, where you tap the cheek and they have like fish or muscle spasins, right. Those are quality signs of hypocalcemia. Right. So when a person has a acute hypercalcemia, you can give calcium toning as a third line agent. Right. So again, whenever a person has a acute hypercalcemia, symptomatic hypercalcemia, right. It's always your first step in management. So let me know quality that could hypercalcemia. Let me call it symptomatic hypercalcemia. Right. What's going to be your first step in management? You're going to give no more ceiling. Right. What's going to be your second step in management? You're going to give an IV Bs phosphine. It's going to be a third step in management. You're going to give calcium toning. Right. That's very high. You'll to know for purposes of NV Me examples. Right. And then one thing that your friends at the NV Me care about. Right. So your friends at the NV Me actually care about you knowing you immunodeficiency diseases with respect to the particular kind of cell that is impaired. Right. This is something that unfortunately is not emphasized in many resources. And it's something that many people just cannot gloss over. But then it ends up being like eminently important on these USML exams. Right. For example, if a person has, if they give you a question about a boy, right. Six months old. He starts having all these recurrent infections, recurring bacterial infections.

What is like the first thing you should think about? Right. In fact, they may be nice and give you like immunoglobulin levels. And you notice that, oh, wow, IgM is low, IgG is low, IgA is low, IgE is low. Everything is low. Right.

If you see that, I really hope you're thinking about Brutons, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, Ig IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM,

IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM, IgM

Practice questions — USMLE style

Question 1 — Endocrinology/Critical Care

A 58-year-old male is admitted to the emergency department with acute onset of altered mental status, polyuria, and polydipsia. Laboratory studies reveal a total serum calcium level of 16 mg/dL (normal range: 8.5–10.5 mg/dL). The patient is hypotensive and shows signs of dehydration. The initial management plan for symptomatic hypercalcemia includes aggressive hydration with intravenous normal saline. If the patient's symptoms persist despite adequate volume resuscitation, what is the next most appropriate pharmacological intervention?

A) Intravenous calcium gluconate
B) IV bisphosphonate (e.g., zoledronic acid)
C) Calcitonin
D) PTH analog replacement therapy

Answer: B. The management of symptomatic hypercalcemia follows a stepwise approach. Step 1 is volume expansion with IV normal saline to correct dehydration and improve renal clearance. If this fails, the next step is administering an IV bisphosphonate (like zoledronic acid), which inhibits osteoclast activity and reduces bone resorption. Calcitonin (C) is typically reserved as a third-line agent or for rapid symptom control, while calcium gluconate (A) would worsen hypercalcemia.

Question 2 — Pathology/Endocrinology

A 70-year-old woman presents with chronic symptoms of elevated serum calcium and bone pain. Imaging reveals multiple lytic bone lesions. Laboratory testing shows a significantly elevated parathyroid hormone related peptide (PT HrP) level, but the patient's intact PTH levels are undetectable. Which underlying malignancy is most likely responsible for this hypercalcemia?

A) Multiple Myeloma
B) Sarcoidosis
C) Squamous Cell Lung Cancer
D) Medullary Thyroid Carcinoma

Answer: C. The clinical picture of hypercalcemia driven by elevated PT HrP, especially in the context of a cavitary lung lesion (as described in the transcript), is highly characteristic of squamous cell lung cancer. Multiple myeloma causes hypercalcemia via increased RANKL/RANK signaling from plasma cells, leading to bone breakdown, but it does not typically involve high PT HrP. Sarcoidosis elevates calcium through Vitamin D activation by granulomas, and Medullary Thyroid Carcinoma secretes calcitonin, which generally lowers calcium levels.

Question 3 — Immunology

A 4-year-old boy is brought to the clinic by his parents due to recurrent bacterial infections (e.g., pneumonia, otitis media) over the past year. Physical examination and laboratory workup reveal a markedly low serum level of IgG, IgA, and IgE, while the IgM levels are normal or mildly elevated. Which diagnosis best explains this constellation of findings?

A) Common Variable Immunodeficiency (CVID)
B) X-linked Agammaglobulinemia (XLA)
C) Selective IgA Deficiency
D) Chronic Granulomatous Disease (CGD)

Answer: A. The pattern of low IgG, IgA, and IgE with relatively preserved IgM is highly suggestive of Common Variable Immunodeficiency (CVID). While X-linked Agammaglobulinemia (XLA) presents with a near-total absence of all immunoglobulins (including IgM), CVID is characterized by hypogammaglobulinemia affecting multiple classes. The clinical presentation of recurrent bacterial infections points to humoral immunity failure, which is the hallmark of these primary antibody deficiencies.

Question 4 — Rheumatology/Pathophysiology

A patient with sarcoidosis develops hypercalcemia due to granulomatous inflammation in the lungs and lymph nodes. This condition leads to excessive production of an enzyme that converts calcidiol (25-hydroxyvitamin D) into calcitriol (1,25-dihydroxyvitamin D). Which specific enzymatic process is responsible for this pathological elevation of active Vitamin D?

A) Conversion of 25-OH vitamin D to 1-$\alpha$-hydroxylase activity
B) Action of PT HrP on the renal tubules
C) Increased osteoclast activity mediated by RANKL
D) Secretion of calcitonin from C cells

Answer: A. Sarcoidosis causes hypercalcemia because the epithelioid macrophages surrounding the non-caseating granulomas express high amounts of 1-$\alpha$-hydroxylase. This enzyme is responsible for converting inactive Vitamin D (25-hydroxyvitamin D) into its active, potent form, calcitriol (1,25-dihydroxyvitamin D). This excess vitamin D then dramatically increases intestinal absorption of calcium and phosphate, leading to hypercalcemia.

Quick fire review

What is the first-line treatment for acute symptomatic hypercalcemia?

IV Normal Saline (0.9% NaCl).

Which specific pulmonary finding suggests considering squamous cell carcinoma in the context of hypercalcemia?

A cavitary lesion with air-fluid levels, especially centrally located.

What is the key difference in PTH levels between Multiple Myeloma and primary hyperparathyroidism causing hypercalcemia?

In multiple myeloma, PTH levels are typically low because the calcium elevation is due to a non-PTH related mechanism (IL-6/RANKL).

Which two granulomatous conditions can lead to hypercalcemia via increased calcitriol production?

Stacculosis and Sjögren's syndrome.

What class of drug acts by inhibiting osteoclasts, making it a second-line treatment for severe hypercalcemia?

Bisphosphonates (IV).

What is the third-line agent used to directly lower blood calcium levels in refractory hypercalcemia?

Calcium toning.

Mechanism of Hypercalcemia in Multiple Myeloma

Increased RANKL expression by plasma cells activates osteoclasts, leading to bone demineralization (non-PTH related).

PTH level expected in a patient with Multiple Myeloma and hypercalcemia?

Low. The calcium elevation is independent of PTH regulation.

Pathophysiology linking Sjögren's Syndrome/Stacculosis to Hypercalcemia

Epithelioid macrophages produce high amounts of 1-$\alpha$-hydroxylase, converting inactive Vitamin D (25-OH) to active calcitriol (1,25-dihydroxy).

First step in managing symptomatic hypercalcemia?

IV Normal Saline.

What is the clinical sign indicating hypocalcemia that can be tested on an exam?

Tapping the cheek causing muscle spasms (Chvostek's sign) or tingling/spasms upon blood pressure cuff release (Trousseau's sign).

Which type of cancer often secretes PT HrP, leading to hypercalcemia?

Squamous cell lung carcinoma.

Quick recall / Anki-style questions