Urinary hydroxyproline excretion as a marker of bone metastasis in prostatic cancer.

In 25 patients with prostatic cancer and 26 patients with benign prostatic hypertrophy, urinary hydroxyproline excretion as estimated by the method described by Cleary and Saunders. The patients were kept on a diet free of gelatin. Urinary creatinine was measured in all patients and serum acid phosphatase, prostatic acid phosphatase, alkaline phosphatase and calcium were measured in patients with prostatic cancer. Urinary hydroxyproline excretion and the hydroxyproline/creatinine ratio were both elevated in patients who had prostate cancer with bone metastasis when compared to values in patients who had benign prostatic hypertrophy or prostatic cancer without bone metastasis. These two were more sensitive indicators of bone metastasis than serum acid phosphatase, prostatic acid phosphatase, alkaline phosphatase and calcium. These results suggest that urinary hydroxyproline is a valuable index of bone metastasis in prostatic cancer.