Free and peptide hydroxyproline in chronic uremia

Plasma levels, urinary excretion and renal clearance rates of free and peptide hydroxyproline were estimated in normal subjects, patients with chronic uremia, and in representative cases of generalised bone disease and chronic pyelonephritis without glomerular insufficiency. Chronic uremia was accompanied by an elevation of plasma levels and urinary excretion of free hydroxyproline, whereas the excretion of hydroxyproline peptides was decreased despite increased plasma levels. The changes of free hydroxyproline appeared to be related to the degree of glomerular insufficiency.