Chronic lead poisoning: a "forgotten" cause of renal disease

Chronic lead nephropathy occurs as a result of years of lead exposure. Nowadays, with the induction of high standards for industrial hygiene, symptomatic lead intoxication has become extremely rare. We report a case of chronic lead nephropathy in a 59-year-old man who worked in a battery-recycling unit and was diagnosed with plumbism during a regular health screening few years ago. The diagnosis was suggested by the following findings: serum creatinine 160 microg/L, creatinine clearance 46 ml/min, daily urine protein excretion 0.1 g, uric acid 9.7 mg/dl, blood lead 9.2 microg/dl, and a urinary excretion of 850 microg lead/72 h after a mobilisation test by a Na2-Ca-EDTA chelating agent. Renal ultrasound showed bilateral borderline small kidneys. The kidney biopsy revealed moderate focal atrophy, loss of proximal tubules, and prominent interstitial fibrosis. The patient was prescribed angiotensin-converting-enzyme inhibitors to slow the progression of renal insufficiency and control the blood pressure. Hyperuricemia was also treated and controlled. During the regular follow-up, renal function remained stable with no proteinuria. A high index of suspicion for lead intoxication in chronic kidney disease patients should be practiced, especially in patients with hyperuricemia. Chelation of lead urinary excretion is helpful in the diagnosis of this disease.