Postabsorptive urine hydroxyproline (HYPRO) excretion ("spot" HYPRO test) was compared with the 24-hour urine excretion of HYPRO in 45 patients with breast cancer and nine normal subjects on a low-gelatin diet. A good correlation was observed between the results of these two tests in both groups. Patients with skeletal metastasis showed a higher spot HYPRO value than those without bone involvement and the number of lesions by bone scanning correlated with the values of spot HYPRO. In 20 of 22 patients with bone metastasis followed up for three to 19 months, spot HYPRO values correlated well with the evolution of bone disease. We conclude that the spot HYPRO test is a simple, inexpensive, and accurate method for the diagnosis and follow-up of patients with skeletal metastasis from breast cancer.
(Arch Intern Med 1981;141:1471-1473)