Circadian rhythms and the urinary excretion of acid glycosaminoglycans in normal human adults.

Urine from normal human adults (11 males, 4 females) was collected for 24 hours in four-hour samples, commencing at 08.00 hours. The urine volume, and concentrations of chondroitin sulfate, heparan sulfate, cetylpyridinium turbidity, and creatinine were measured on every sample. Concentrations and total output of glycosaminoglycans were significantly higher in male urine than in female urine. Chondroitin sulfate total output/four hours showed a significant negative correlation with creatinine concentration in males, but not in females. A testicular hyaluronidase is implicated. No such correlation was observed for heparan sulfate. Glycosaminoglycans are filtered into the urine. Plasma clearances are very low. Heparan sulfate is excreted with a circadian rhythm, as is glycosaminoglycan assayed by cetyl pyridinium turbidity. Peak excretions are at 06.00 and 10.00 hours respectively. Chondroitin sulfate excretion is not rhythmic in the male, perhaps because hyaluronidase activity in the urine complicates the assay. A rhythm may be present in the female.