Renal abnormalities in patients with sickle cell-beta thalassemia.

We examined renal abnormalities in Greek patients with sickle-cell beta thalassemia (S-beta thal). A total of 17 patients aged 16-59 years suffering from S-beta thal and 17 age- and sex-matched healthy controls were studied. In all individuals we carried out a detailed study of renal function including electrolytes in serum and urine, concentrating or diluting ability, urine acidification ability, glomerular filtration rate (GFR), and hormones [such as plasma renin activity (PRA), serum aldosterone, and erythropoietin (EPO)]. Though the GFR did not differ significantly in patients and controls, half the patients had either supranormal or subnormal values. Serum potassium and uric acid were significantly higher in patients than controls. Serum phosphorus was similar in both groups, though patients with S-beta thal had significantly lower phosphate excretion indices. All patients were unable to maximally concentrate the urine, and seven also had limited ability to maximally dilute it. Five patients had incomplete distal renal tubular acidosis. Four had mild proteinuria, and six had microalbuminuria. Serum EPO and aldosterone were higher in S-beta thal patients than controls, but there was no difference in PRA between the two groups. There was a strong correlation between hemoglobin concentration and EPO levels, which was strongest in patients with GFR < 50 ml/min. We conclude that patients with S-beta thal, like sickle-cell anemia patients, present multiple abnormalities of renal function.