Renal Tubular Function in Systemic Lupus Erythematosus

Renal function is commonly assessed by measurement of glomerular filtration rate (GFR). However, defects in tubular function may still exist in the presence of a normal GFR. In 12 patients with systemic lupus erythematosus (SLE), 6 of whom had previously been shown to have renal impairment, glomerular and tubular function were studied separately. In 4 patients, all parameters of renal function tested were normal. Impaired tubular function was found in 8 of the 12 patients, including 5 with normal GFR. Defects were noted in the ability to acidify urine in 7 patients and tubular reabsorption of phosphate was reduced in 2. A poor correlation was noted between the presence of renal tubular acidosis and the serum y-globulin level. The pathogenesis of the defect in urinary acidification in SLE and its prognostic significance are discussed.S. Afr. Med. J., 47, 132 (1973)