Paraplegia, proteinuria, and renal failure

CASE PRESENTATION A 62-year-old African-American male with a history of paraplegia following surgery for removal of a spinal tumor 30 years earlier presented to the Emergency Department with worsening shortness of breath. He was found to have congestive heart failure, which responded well to diuresis, and renal failure with a creatinine concentration of 6.6. mg/dl (583 μmol/l). On further questioning, the patient reported a history of renal dysfunction and hypertension. The patient had a creatinine concentration of 1.4 mg/dl (124 μmol/l) 10 months before and of 3.0 mg/dl (265 μmol/l) 4 months before. Kidney biopsy had been recommended but was refused by the patient. Past medical history was significant for a severe decubitus ulcer of the hip complicated by osteomyelitis and requiring hospitalization, debridement, and long-term treatment with antibiotics via an indwelling Hickman catheter, which was discontinued 1 year before. The patient had intact bladder function and a history of recurrent cystitis, but no pyelonephritis. The patient's only prescription medication on admission was metoprolol tartrate 75 mg twice per day. There was no family history of renal disease. The patient also had a history of significant tobacco use (1.5 packs per day of cigarettes for 40 years).Physical examination revealed a well-developed male, with a blood pressure of 155/75 mmHg, no active decubitus ulcers, and no evidence of jugular venous distention. Examination of the lungs revealed diminished breath sounds at the bases and scattered rhonchi. The heart was regular in rate and rhythm with no murmurs, rubs, or gallops. The lower extremities exhibited muscular atrophy. No lower extremity edema was evident.Laboratory data were as follows: hematocrit, 34% (normal range, 42-52%); white blood count, 7.7 × 10 ⁹/l (normal range, 4.0-10.5 × 10⁹/l); platelet count 418 × 10⁹/l(normal range, 150-500 × 10⁹/l); blood urea nitrogen, 48 mg/dl (17.1 mmol/l) (normal range, 9-20 mg/dl (3.2-7.1 mmol/l)); 24-h urine protein, 2840 mg; aspartate aminotransferase, 22 U/l (normal range, 10-40 U/l); alanine aminotransferase, 14 U/l (normal range, 10-45 U/l); and serum albumin, 1.7 g/dl (17 g/l) (normal range, 3.5-5.0 g/dl (35-50 g/l)). Urinalysis revealed 4+ proteinuria and a bland sediment. Hepatitis C antibody was positive. All other serologies were negative or normal, including hepatitis B surface antigen, antinuclear antibody, antineutrophilic cytoplasmic antibody, and C3 and C4 complement levels.A chest radiograph showed small bilateral pleural effusions. An echocardiogram revealed mild left ventricular hypertrophy but no evidence of infiltrative disease. A renal sonogram showed normal-sized kidneys, with a 2.3 cm mass at the lower pole of the left kidney that was suspicious for malignancy. A renal biopsy was performed.