Assessment of the nephron segments involved in post-obstructive diuresis in man, using lithium clearance.

The phenomena of post-obstructive diuresis and natriuresis have been studied using the lithium clearance technique in 10 patients with high pressure chronic retention. Following relief of obstruction there was a significant increase in both sodium and water excretion. There was a coincident reduction in the fractions of sodium and water reabsorbed in both proximal and distal nephron segments. This study demonstrates for the first time that following relief of chronic obstructive uropathy in man, changes in sodium and water excretion are due to altered handling in both proximal and distal nephron segments.