Hemolysis-induced acute renal failure in paroxysmal nocturnal hemoglobinuria.

Moshe Mittelman, MD, Department of Medicine B, Hasharon Hospital, Golda Medical Center, PO Box 121, Petah-Tikva 49372 (Israel) Dear Sir, Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired hematopoietic stem cell disorder characterized by chronic intra-vascular hemolysis and episodes of hemoglobinuria [1-3]. Acute renal failure (ARF) as a complication of PNH is uncommon and usually related to venous thrombosis [2, 3]. ARF due to acute tubular necrosis (ATN) during hemolysis or hemoglobinuria in PNH has been rarely reported [3, 4]. We describe a patient with PNH who developed such a complication and fully recovered on conservative treatment alone, without dialysis. A 59-year-old woman was admitted for evaluation of fatigue, back pain and 2 episodes of dark urine. Her physical examination was unremarkable. Hemoglobin level was 6.0 g/dl, hematocrit 21%, white blood cell count 3 × 10V1 (with normal differential count), platelet count 133 × 10V1, mean corpuscular volume 121 fl and reticulocyte count 3%. Serum bilirubin was 2.5 mg/dl (indirect 1.4 mg/dl) and lactic dehydrogenase (LDH) 2,000 U (normal < 150 U). Serum hapto-globin was 0. Serum urea, creatinine, iron, TIBC (transferrin), vitamin B12, folic acid, erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and hemoglobin electro-phoresis were normal. Coombs’ test was negative. Plasma hemoglobin level was 6.3 mg/ dl (normal < 1.5 mg/dl). Leukocyte alkaline phosphatase (LAP) score was 4 U (normal 30-100). The bone marrow (BM) was hypo-cellular with erythroid megaloblastosis. A urine sample for myoglobin was negative. Ham and sucrose tests (performed 3 days after admission) were negative. The patient received 3 U of packed RBC. Three days later, serum urea and creatinine levels rose to 300 and 11 mg/dl, respectively. Serum creatinine phosphokinase (CPK) was normal. Urine flow was 2,000 ml/day with no proteinuria. Urine reacted positively with orthotoluidine and its sediment showed no RBC or casts. Abdominal ultrasound was normal. Kidney biopsy showed focal tubu-lointerstitial changes, including interstitial edema, tubular cell necrosis and tubular regeneration, as well as acellular tubular (pro-teinacious) casts. Glomeruli were normal. These findings suggested pigment-induced ATN. Conservative treatment with intravenous fluids, NaHC03 and sodium polystyrene sul-fonate was initiated. The following days were characterized by disappearance of the back pain,