High concentration of sweat calcium, magnesium and phosphate in chronic renal failure

Sweat collected from the forearm of chronic renal failure and control patients, after iontophoretic stimulation with pilocarpine, was analyzed for Na, K, Cl, Mg, phosphate and urea. Concentrations of Ca, Mg and phosphate in sweat from chronic renal failure patients were significantly elevated (p less than 0.05) as compared to controls, while the concentrations of Na, K, and Cl were normal. The mean sweat rates and apparent skin conductivities were lower in uremics, but not significantly different from controls (0.05 less than p less than 0.10). Tentatively it is concluded that the increase of Ca, Mg and phosphate in uremic sweat is due to an increase in the secretion of these electrolytes in the secretory portion of the sweat gland, while the reabsorptive duct is normal.