Restoration of water diuresis in addisonian patients by expansion of the volume of extracellular fluid.

Abstract

Although the inability of patients with Addison's disease to excrete a water load is well known, the nature of this defect remains obscure. The effects of changing glomerular filtration rate (GFR) and solute excretion (UosmV) on water excretion in patients with adrenal insufficiency have recently been described (1). While an increase in these two variables leads to an increase in the excretion of water, the improvement is very small compared with that seen with carbohydrate-active steroids. In healthy persons expansion of the volume of extracellular fluid may increase the rate of excretion of solute-free water (CH2o) (2, 3). In patients with Addison's disease, when replacement therapy is stopped, the increase in urinary sodium excretion leads to a depletion of body fluids, and continues despite this depletion. It is possible that depletion of the volume of extracellular fluid (ECF) could limit the rate at which water is excreted. These experiments were designed to explore the effects of contraction and expansion of the volume of ECF on water excretion in adrenal insufficiency.