Urinary hydroxyproline excretion in carcinoma of the prostate. A comparison of 4 different modes of assessment and its role as a marker.

Urinary hydroxyproline (HP) excretion has been estimated without prior dietary restriction in 33 patients with carcinoma of the prostate and expressed as either 24-h HP output or as the hydroxyproline/creatinine (HP/Cr) ratio in 24-h urine sample, an early morning urine sample or a spot urine sample. The early morning urine hydroxyproline/creatinine ratio (EMU HP/Cr) appears to be the most accurate and avoids the disadvantages of formal dietary restriction and prolonged urine collection. The rest is useful in monitoring the responses to treatment of a patient with bony metastatic disease and relapse of a patient when his tumour ceases to be hormone sensitive. Furthermore, changes in EMU HP/Cr occur earlier than changes in other clinical or investigative variables, giving the test predictive value.