Estimation of hydroxylysine in urine and serum of patients with chronic uremia.

Free hydroxylysine and hydroxylysing glycosides were separated from urine and serum extracts on cation exchange resin and assayed spectrophotometrically. The method in conjunction with gel filtration in Bio-Gel P2 allowed to separate from urine also polypeptide hydroxylysine and hydroxylysine bound in small molecules of neutral or acidic character. Glycosylgalactosylhydroxylysineand galactosylhydroxylysine were separated by partition and/or ion exchange chromatography. Patients with chronic renal insufficiency had elevated serum levels and urinary excretion of hydroxylysine glycosides with increased excretion of hydroxylysine bound in polypeptides and in small molecules of neutral or acidic character. The excretion of free hydroxylysine was often within normal limits. When compared to values found in normal growing subjects and in adult patients with increased bone turnover and normal renin function the urinary excretion of hydroxylysine glycosides in chronic uremia was more markedly increased than excretion of hydroxyproline polypeptides and total hydroxyproline.