Urine hydroxyproline excretion--a marker of bone metastases in prostatic carcinoma.

24-hour urinary hydroxyproline excretion (THP), a marker of bone collagen metabolism, has been measured in 35 patients with carcinoma of the prostate. 21 patients had bone metastases diagnosed by bone scanning (99mTc MDP). All 9 patients with metastases studied before hormonal treatment and the majority of those on treatment had elevated levels. Patients with negative bone scans invariably had normal THP levels. Furthermore, THP reflected the presence of bone metastases more accurately than plasma alkaline or acid phosphatase. Serial THP levels altered predictably with symptomatic response to treatment. These results suggest that THP is more reliable than other markers of the presence and activity of bone metastases in response to treatment and may have been neglected in favour of more elaborate and costly X-ray and isotope investigations.