Functional renal involvement in normotensive patients with progressive systemic sclerosis: impaired sodium excretion during isotonic saline infusion.

An intravenous infusion of 2,000 ml isotonic saline was performed in 8 normotensive, normoreninemic patients with progressive systemic sclerosis. None of them had clinical evidence of renal disease. Total and proximal fractional excretion of sodium was reduced when compared with that of 8 normal subjects. No correlation was found with para-aminohippurate (PAH) clearance values. Two years after this study was done, 4 patients developed arterial hypertension; interestingly, plasma renin activity remained within the normal range. Reduced sodium excretion is suggested as having a pathogenetic role in the hypertension of progressive systemic sclerosis.