A 20-year-old woman was referred for evaluation of persistent hematuria and proteinuria. She had a his- tory of fever and sore throat lasting 1 week that occurred 6 months earlier and were associated with abdominal pain and dark urine. She did not receive any antimicrobial agents. Significant findings on physical examination at that time included a BP of 140/90 mmHg and 2+ edema. Laboratory evaluation showed a serum creatinine value of 1.4 mg/dl, urinalysis with 2+ protein and 3+ blood, and a 24- hour urinary protein excretion of 680 mg. The C3 level was 46 mg/dl (reference range, 75–175 mg/dl) and the C4 level was 23 mg/dl (reference range, 14–40 mg/dl). A throat culture was negative for b-hemolytic strepto- cocci, and an antistreptolysin O titer was 200 IU/ml (upper limit of normal, 200 IU/ml). The serum albumin concentration was 3.6 g/dl.A renal biopsy was performed and showed a pattern of membranoproliferative GN on light mi- croscopy. No crescents were observed. Immunofluo- rescence microscopy showed bright (3+) mesangial and capillary wall C3 staining. Electron microscopy showed mesangial, intramembranous, and subendo- thelial deposits, as well as a few subepithelial hump-like deposits. Postinfectious GN and type III membrano- proliferative GN were diagnosed. The patient was treated symptomatically, but proteinuria and hematu- ria persisted. Current evaluation shows a hemoglobin level of 11.8 g/dl, a serum creatinine concentration of 1.3 mg/dl, urinalysis with 3+ blood and 3+ pro- tein, quantitative proteinuria of 2.2 g/24 hours, C3 concentration of 44 mg/dl, and C4 concentration of 22 mg/dl. To further evaluate this patient, you would now order: A. Antinuclear antibodies B.Hepatitis B and C serology C.Anti-deoxyribonuclease (DNase) antibody titers D. Serum C1q level E.Antibodies to complement-regulating proteins
Posted on: Sat, 15 Nov 2014 04:06:44 +0000
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