USMLE PRACTICE QUESTION #87
TOPIC: Foundations of Pathology
Today’s question will test your understanding of a commonly tested concept of foundational pathology.
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A 59-year-old female with a five-year history of rheumatoid factor-positive rheumatoid arthritis (RA) is seeing her primary care physician because of a two-week history of swelling in her eyes and feet. She has been taking ibuprofen and methotrexate for five years to manage her RA. Physical exam is positive for periorbital edema and 2+ pedal edema. Laboratory findings of importance are hemoglobin of 8.2mg/dL and urine protein of 3+; all other findings are within normal limits. She drinks one glass of wine per day and denies the use of tobacco products or recreational drugs. Which of the following is the most likely cause of the patient’s current symptoms?
A. Early-stage liver failure
B. AL amyloidosis
C. Reactive amyloidosis
D. Lupus nephritis
E. Medication adverse effect
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The MENTAL MODEL used to answer this question comes from our detailed test-taking skills masterclass (check it out if you want to elevate your skills). Here’s how to think through this question:
Step 1. Read the last line to get to the heart of the question: “Which of the following is the most likely cause of the patient’s current symptoms?”
Step 2: Is this a first-, second-, or third-order question?
Answer: 2nd order. 1st: Identify the problem, and 2nd: Identify the underlying cause of the problem.
Step 3: Read the vignette carefully and ask yourself: “What best explains this patient’s current findings?”
Step 4. Look at the answer choices and select the option most closely resembling your final thought from “Step 3” above.
GENERAL ANALYSIS
The 59-year-old female with a long-standing history of rheumatoid factor-positive rheumatoid arthritis presents with periorbital edema, pedal edema, anemia, and significant proteinuria (3+). These findings suggest nephrotic syndrome.
ANSWER CHOICES:
CHOICE A: Early-stage liver failure
Explanation: Early-stage liver failure can cause fluid retention and edema due to hypoalbuminemia from impaired liver function. The patient does not have signs or laboratory findings suggestive of liver disease (e.g., jaundice, elevated liver enzymes). Additionally, significant proteinuria is not a typical feature of liver failure.
CHOICE B: AL amyloidosis
Explanation: AL amyloidosis is caused by the deposition of immunoglobulin light chains and is associated with plasma cell dyscrasias such as multiple myeloma. This patient has no history or findings suggestive of plasma cell dyscrasia (e.g., bone pain, hypercalcemia). Her long-standing RA makes reactive (AA) amyloidosis more likely than AL amyloidosis.
CHOICE C: Reactive amyloidosis
Explanation: Reactive amyloidosis (AA amyloidosis) is a well-known complication of chronic inflammatory conditions such as rheumatoid arthritis. It results from the deposition of amyloid A protein in various organs, including the kidneys, leading to nephrotic syndrome. In this case, the patient’s long-standing RA and her presentation with nephrotic-range proteinuria, edema, and anemia are consistent with AA amyloidosis. Chronic inflammation in RA stimulates the overproduction of serum amyloid A (SAA), which can deposit in tissues and cause organ dysfunction, particularly in the kidneys.
CHOICE D: Lupus nephritis
Explanation: Lupus nephritis is a renal manifestation of systemic lupus erythematosus (SLE), characterized by immune complex deposition in the glomeruli. The patient has rheumatoid arthritis, not lupus. No clinical or serological findings suggest SLE.
CHOICE E: Medication adverse effect
Explanation: Methotrexate and NSAIDs can cause renal damage, but they are more commonly associated with acute kidney injury (AKI) or interstitial nephritis rather than nephrotic syndrome. While NSAIDs can contribute to kidney damage, the presence of significant proteinuria and edema suggests a more chronic process like amyloidosis rather than an acute drug-related nephropathy.
FINAL VERDICT…
The most likely cause of this patient’s symptoms is reactive amyloidosis (AA amyloidosis), secondary to her long-standing rheumatoid arthritis. This condition commonly affects the kidneys, leading to nephrotic syndrome characterized by significant proteinuria, hypoalbuminemia, and edema.
CORRECT ANSWER: C) Reactive amyloidosis
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That’s it for question 87!
See ya tomorrow 👋