[Urinary and serum hydroxyproline in the diagnosis of bone metastases of prostatic cancer].

Of 31 patients with prostatic cancer, 21 have skeletal metastases proven by bone scintigraphy and/or radiology. The sensitivity and specificity of the following measurements are compared: total urinary hydroxyproline, urinary hydroxyproline/creatinine ratio, free serum hydroxyproline, alkaline and prostatic phosphatases and serum calcium. The hydroxyproline/creatinine ratio is the most sensitive measurement for the diagnosis of bone metastasis, while total urinary hydroxyproline excretion per 24 hours is the most specific. Free serum hydroxyproline has no particular significance for this diagnosis. The alkaline and acid phosphatases are elevated but are not specific. Serum calcium decreases when skeletal metastases are present.