MKSAP: 53-year-old woman with swelling of the face, hands, and feet

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians. A 53-year-old woman is evaluated for a 3-month history of swelling of the face, hands, and feet. She has untreated hepatitis C virus infection. She takes lithium for bipolar disorder. She has no additional symptoms. On physical examination, temperature is normal, blood pressure is 134/93 mm Hg, pulse rate is 71/min, and respiration rate is 18/min. Bilateral periorbital edema and swelling of the hands and legs are noted. The remainder of the examination is unremarkable. Laboratory studies: Complete blood count Normal Albumin 1.6 g/dL (16 g/L) Blood urea nitrogen 28 mg/dL (10 mmol/L) Complement (C3 and C4) Normal Serum creatinine 1.5 mg/dL (133 µmol/L) Cryoglobulin Negative Serum protein electrophoresis Normal Rheumatoid factor Negative Hepatitis B surface antigen Negative Hepatitis C virus antibodies Positive with low RNA titer HIV antibodies Negative Antinuclear antibodies Negative Urinalysis 4+ protein; 4-7 erythrocytes/hpf; 4-7 leukocytes/hpf 24-Hour urine collection of protein 14 g/24 h Ultrasound shows normal-sized kidneys. Percutaneous kidney biopsy results show glomeruli of normal size and cellularity, with patent capillary lumina. Diffuse fusion of podocyte foot processes is noted on electron microscopy. Immunofluorescence studies show no immune deposits. Which of the following is the most likely cause of this patient’s...
Source: Kevin, M.D. - Medical Weblog - Category: Journals (General) Authors: Tags: Conditions Nephrology Source Type: blogs