The effect of sex, height and time of day on the excretion of glycosaminoglycans and the consequences.

A diurnal rhythm in the excretion of glycosaminoglycan-derived uronic acid with an increased excretion during daytime has been found in adults. Due to this rhythm a 24-h excretion was established as the optimum measurement of glycosaminoglycan turnover in tissue. Neither the excretion of uronic acid nor the uronic acid/creatinine ratio in the morning urine could predict the 24-h excretion of glycosaminoglycans as estimated by a statistical model. This model may also be of general interest in similar clinical problems. Compared with males, females had a lower excretion of glycosaminoglycans. Part of this discrepancy reflected a sex-difference in height, which was shown to be positively correlated with the excretion. On the other hand, the uronic acid/creatinine ratio was not influenced by height or sex. Body mass, age and urine output did not influence the ratio or the excretion of uronic acid.