Renal artery stenosis and diurnal rhythm of water and sodium excretion under conditions of restricted fluid intake.

The diurnal rhythm of urinary excretion of water and sodium is inverted in patients with arterial hypertension and concomitant renal arterial stenosis. Fluid withdrawal for 36 hours normalizes the rhythm of water and sodium excretion. The authors' findings support the assumption that the changes in the diurnal rhythm of urinary excretion of water and sodium in such patients depend on their state of hydration.