Abnormalities of Renal Physiology in Systemic Sclerosis

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Abstract
Objective. To evaluate the prognostic value of measurements of renal plasma flow and circulating vasoactive hormones in patients with systemic sclerosis (SSc). Methods. Renal plasma flow (para-aminohippurate [PAH] clearance) and levels of selected circulating hormones (plasma renin activity [PRA] and serum aldosterone and catecholamines) were assessed in 57 SSc patients under the following conditions: at rest, in response to cold, while in upright position, and in response to sodium depletion. Survival was assessed 10.7 years after testing (20 patients had died). Results. Both unstimulated and stimulated PRA clearance rates were frequently elevated. Resting PAH clearances were usually abnormally low. PAH clearances and levels of aldosterone and catecholamines did not change during cold stimulation. Supine PRA levels following acute sodium depletion correlated with survival (P < 0.008). Conclusion. The frequent finding of elevated PRA and reduced PAH values reflects clinically the high frequency of renovascular disease noted histopathologically in SSc. Isolated decreases in PAH and elevations in PRA, however, did not predict renal crisis. Changes in PAH clearances were not demonstrable during cold stimulation. An abnormally high supine PRA after sodium depletion correlated with improved survival.