The Effect of Potassium Loading on Sodium Excretion and Plasma Renin Activity in Addisonian Man

plasma renin activity (PRA). This study was designed to study the role of increased aldosterone production in the mediation of such a response. Five patients with adrenal insufficiency were placed on a diet of 60 meq potassium and 100-150 meq of sodium while receiving a constant amount of cortisone acetate and Florinef. Upright PRA was determined each day for 2-3 days in the control period and then for 3-4 days after potassium intake had been increased to 200-300 meq/day. Potassium loading induced a natriuresis. Hence, pa-tients were either sodium replaced (six studies in four patients) or allowed to become sodium depleted (three patients). Potassium loading without replacement was associated with a decrease in weight, negative sodium balance, hyperkalemia, and a positive potassium bal-ance. PRA rose during the experimental period. Potas-sium loading with sodium replacement was associated with little change in weight or sodium balance. Hyper-kalemia and positive potassium balance were present to the same degree as found in the studies without so-dium replacement. When all PRA values are considered (both morning and evening values) there was no sig-nificant change with potassium loading (+ 1.31 ng/ml per h; range + 6.9 to- 2.0). We conclude that hyper-kalemia or a positive potassium balance did not sup-press PRA in Addisonian man in these studies when so-dium balance was maintained, nor did it prevent a rise in PRA when sodium balance was negative