An independent, community-dwelling 71-year-old male schedules a clinic appointment due to … — USMLE Step 2 CK

An independent, community-dwelling 71-year-old male schedules a clinic appointment due to persistent lumbar back pain that began spontaneously 6 weeks ago. The pain is described as a deep ache that does not improve with rest or ibuprofen. Over the past month, he has also experienced unusual fatigue and new-onset constipation. He has a history of mild essential hypertension controlled with amlodipine. Vital signs are within normal limits. Physical examination reveals point tenderness over the L4 spinous process.

Laboratory results are as follows:

Laboratory Test	Result	Reference Range
Hemoglobin	9.6 g/dL	13.5–17.5 g/dL
Mean corpuscular volume	89 fL	80–100 fL
Leukocytes	5,800/mm³	4,500–11,000/mm³
Platelets	142,000/mm³	150,000–400,000/mm³
Creatinine	2.1 mg/dL	0.6–1.2 mg/dL
Calcium	11.4 mg/dL	8.4–10.2 mg/dL
Alkaline phosphatase	95 U/L	40–120 U/L

Which of the following is the most appropriate initial diagnostic step to evaluate this patient's condition?

Serum protein electrophoresisCevap
B
Radionuclide bone scan
C
Intact parathyroid hormone level
D
Bone marrow aspiration and biopsy
E
Prostate-specific antigen measurement

Cevap

Serum protein electrophoresis

This patient's presentation of hypercalcemia, acute renal insufficiency, normocytic anemia, and new-onset bone pain is classic for multiple myeloma. These hallmark clinical manifestations are frequently summarized by the acronym CRAB (Calcium elevation, Renal failure, Anemia, and Bone lesions). The hypercalcemia is responsible for his new-onset constipation. When multiple myeloma is suspected, the initial diagnostic approach focuses on identifying a monoclonal immunoglobulin (M-protein) or free light chains in the blood or urine. Therefore, the most appropriate initial, noninvasive diagnostic step is serum protein electrophoresis (SPEP), often performed concurrently with urine protein electrophoresis (UPEP) and a serum free light chain assay.

Adım Adım Çözüm

Analyze the patient's clinical symptoms

An elderly male presents with severe bone pain, generalized fatigue, and new-onset constipation.

Identifying the clinical syndrome points toward a systemic illness rather than mechanical back pain.

Interpret the laboratory findings

The labs show normocytic anemia, acute kidney injury (elevated creatinine), hypercalcemia, and importantly, a normal alkaline phosphatase level.

These findings directly align with the CRAB criteria for multiple myeloma.

Synthesize symptoms and labs to form a diagnosis

The hypercalcemia explains the constipation; marrow infiltration explains the anemia; osteoclast activation explains the bone pain without corresponding osteoblast activity (keeping alkaline phosphatase normal).

Multiple myeloma is the most likely unifying diagnosis.

Determine the appropriate initial diagnostic step

Serum protein electrophoresis (along with urine protein electrophoresis and free light chains) is indicated.

Initial evaluation requires detecting a monoclonal paraprotein noninvasively before proceeding to definitive invasive testing like a bone marrow biopsy.

Anahtar Kavram

The initial evaluation of suspected multiple myeloma (presenting with the CRAB criteria: hyperCalcemia, Renal failure, Anemia, and Bone pain) relies on detecting a monoclonal paraprotein using serum and urine protein electrophoresis.

Tahmini Süre:1m 15s

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

Bu konudan daha fazla soru