If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 2 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.
A 72-year-old woman comes to the physician because of a three-day history of mid-back pain. She denies any trauma to the back. Examination shows point tenderness over the T8 vertebra.
Laboratory studies show:
- Hemoglobin: 13 g/dL.
- Na+: 137 mEq/L.
- Cl–: 101 mEq/L.
- K+: 4.3 mEq/L.
- HCO3–: 25 mEq/L.
- Urea nitrogen (BUN): 21 mg/dL.
- Creatinine: 0.71 mg/dL.
- Albumin: 3.6 g/dL.
- Ca+: 9.0 mg/dL.
- Alkaline phosphatase: 50 U/L.
X-ray of the spine shows a compression fracture of the T8 vertebral body. Dual energy x-ray absorptiometry (DEXA) shows a bone mineral density T-score of -2.7.
Which of the following is the most likely diagnosis?
A. Metastatic disease.
B. Multiple myeloma.
C. Osteomalacia.
D. Osteopenia.
E. Osteoporosis.
The correct answer is E.
Kaplan Medical explains why
In this patient—a 72-year-old female with an acute, atraumatic thoracic vertebral compression fracture confirmed on X-ray, with a T-score of -2.7 on her DEXA scan—the most likely diagnosis is osteoporosis.
Why the other answers are wrong
Choices A and B: Multiple myeloma and metastatic disease should be included in the differential diagnosis when evaluating older adults with non-traumatic vertebral fractures. Findings in multiple myeloma include laboratory abnormalities, such as elevated serum calcium and creatinine levels, and constitutional symptoms such as weight loss.
