Membranoproliferative Glomerulonephritis Presenting with Hypokalemia

Ilgar Taşdemir, MD, Department of Nephrology, Faculty of Medicine, Hacettepe University, Hacettepe, Ankara (Turkey) Dear 7⁄8ir, The association of tubulointerstitial structural or functional disorders with glomerular diseases has been a well-known phenomenon [1–3]. The immunopathogenet-ic mechanisms that cause glomerulonephritis may also induce tubulointerstitial nephritis (TIN) or TIN may be a nonspecific reaction of kidney to a variety of etiopatho-genetic factors, including severe glomerular disease [4]. Here, we present a patient with membranoproliferative glomerulonephritis (MPGN) whose renal disease was dominated by rhabdomyolysis caused by hypokalemia. Case Report A 19-year-old male farmer was admitted for evaluation of severe hypokalemia. He was well until 4 months earlier when weakness, polyuria and nocturia first began. He had no history of use of diuretic, laxative, licorice, carbenoxolone or any other drug. Neither excessive vomiting, diarrhea nor similar disease in his family was present. His blood pressure was 170/105 mm Hg. Physical examination revealed mild lethargy, pretibial edema and generalized muscle tenderness. Laboratory values at the beginning were as follows. The hemoglobin was 10.4 g/dl (104 g/l), the blood urea nitrogen 62 mg/dl (22.3 mmol/l), serum creatinine 5.1 mg/dl (452 μmol/l), potassium 1.1 mEq/1 (1.1 mmol/l), calcium 8.7 mg/dl (2.1 mmol/l), phosphorus 7.4 mg/dl (2.5 mmol/l), albumin 2.8 g/dl (28 g/l), globulin 3.0 g/dl (30 g/l). Serum alanine aminotransferase was 205 U/l (3.4 mmol/s/1), aspartate aminotransferase 316 U/l (5.3 mmol/s/1), lactic dehy-drogenase 867 U/l (14.7 μmol/s/1) and creatine kinase 28,764 U/l (489 mmol/s/1). Arterial blood pH was 7.38, PaCo: 32.3 mm Hg, Paθ2 85.8 mm Hg, and bicarbonate 18.6 mmol/l. Plasma osmolality was 320 mosm/kg. In urinalysis, the pH was 5.5, density 1,009, osmolality 200 mosm/kg, sodium 0– 17 mEq/day (0–17 mmol/day), potassium 24–63 mEq/day (24–63 mmol/day), calcium 255 mg/day (6.1 mmol/day), and phosphorus 287 mg/day (9.7 mmol/day). Urine volume varied between 1,200 and 2,100 ml per day. Daily urinary protein excretion was calculated as 1.8 g. Creatinine clearance was 10.7 ml/min. Electrocardiogram showed prominent U waves in precordial derivations. Plasma aldosterone levels were 35.7 pg/ml (1.00 nmol/l) in supine (normal value: 10–160 pg/ml or 0.28–4.52 nmol/l) and 31.6 pg/ml (0.89 nmol/l) in upright position (normal value: 40–310 pg/ml or 1.12–8.75 nmol/l). Plasma renin activities were 0.48