Urinary hydroxyproline excretion in acromegaly.

The urinary hydroxyproline excretion of 8 acromegalics kept on a collagen free diet has been studied. Urinary hydroxyproline showed a circadian rhythm with maximum excretion rates at night and early morning and minimum excretion rates in the late afternoon and evening. When mean values are compared, there is a significant correlation between fasting GH-levels and 24 h urinary hydroxyproline excretion (Rs = 0.74 and between GH and fasting hydroxyproline:creatinine ratios (Rs = 0.76). No significant correlation could be demonstrated between collagen content of bone biopsies and GH-levels or urinary hydroxyproline excretion. It is suggested that a practical assessment of disease activity in acromegaly can be achieved through a simplified hydroxyproline assay.