Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 62-year-old man is evaluated for a 2-month history of progressive fatigue, dyspnea on exertion, anorexia, and nausea. He has no other medical problems and takes no medications.

On physical examination, temperature is normal, blood pressure is 157/88 mm Hg, pulse rate is 86/min, and respiration rate is 22/min. BMI is 31. The conjunctivae are pale. On cardiopulmonary examination, the point of maximal impulse is displaced laterally. There is dullness to percussion at both lung bases. Abdominal examination reveals no organomegaly. There is bilateral lower-extremity edema. Neurologic examination reveals mild asterixis.

Laboratory studies:

Hemoglobin	7.2 g/dL (72 g/L)
Total protein	9.8 g/dL (98 g/L)
Calcium	10.2 mg/dL (2.5 mmol/L)
Phosphorus	6.8 mg/dL (2.2 mmol/L)
Serum parathyroid hormone	92 pg/mL (92 ng/L)
Blood urea nitrogen	98 mg/dL (35.0 mmol/L)
Serum creatinine	9.8 mg/dL (866.3 µmol/L)
Urinalysis	2+ protein
Urine protein-creatinine ratio	5 mg/mg

Serum and urine protein electrophoreses are positive for a monoclonal IgG κ spike. On kidney ultrasound, both kidneys are 13.5 cm and there is increased bilateral echogenicity. There is no evidence of obstruction. Chest radiograph shows cardiomegaly and bilateral pleural effusions.

Which of the following is the most appropriate next step in this patient’s management?

A) Chemotherapy
B) Hemodialysis and plasmapheresis
C) Hemodialysis, plasmapheresis, and chemotherapy
D) Plasma exchange and chemotherapy

MKSAP Answer and Critique

The correct answer is C) Hemodialysis, plasmapheresis, and chemotherapy. This item is available to MKSAP 15 subscribers as item 44 in the Nephrology section.

This patient has multiple myeloma, which is characterized by kidney failure, anemia, proteinuria, and a monoclonal protein in the plasma and urine. This patient’s bilaterally enlarged kidneys also are consistent with multiple myeloma. The most appropriate next step is hemodialysis, plasmapheresis, and chemotherapy.

The most common cause of kidney failure in multiple myeloma is myeloma kidney, which manifests as chronic kidney failure that results from tubular injury and intratubular cast formation and obstruction. This patient’s light chain excretion is characteristic of myeloma cast nephropathy. Initial management in patients with myeloma cast nephropathy should include volume expansion, alkalinization of the urine, discontinuation of nephrotoxic agents, and avoidance of radiocontrast agents. In this patient with evidence of fluid overload and no hypercalcemia, volume expansion is not necessary and may be hazardous.

The goal of therapy for patients with myeloma kidney is to remove the light chains as quickly as possible by decreasing their production with chemotherapy and enhancing their removal with plasmapheresis. Dialysis also is appropriate for patients with symptomatic uremia. The 2-month mortality rate of patients with multiple myeloma who undergo dialysis is 30%, but those who survive have a median life expectancy of 2 years. Hemodialysis or peritoneal dialysis can be performed, but the same catheter used for plasmapheresis can be used for hemodialysis.

Finally, approximately 10% of patients with myeloma kidney who undergo plasmapheresis recover kidney function and do not require chronic dialysis. Furthermore, this intervention is associated with minimal side effects.

Key Point

• Chemotherapy and plasmapheresis are indicated for patients with myeloma kidney and may be accompanied by dialysis in those with symptomatic uremia.

Learn more about ACP’s MKSAP 16.

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