Relevance of urinary excretion of alcian blue-glycosaminoglycans complexes and hydroxyproline to disease activity in rheumatoid arthritis.

Urinary excretion of glycosaminoglycans (GAG) and hydroxyproline was studied in 42 adult patients with rheumatoid arthritis (RA). A significant increase of GAG and hydroxyproline was found in RA patients compared to normal controls. RA patients fulfilling the criteria of disease activity were found to have urinary excretion of GAG and hydroxyproline higher than of RA patients not fulfilling these criteria. No significant correlation however was observed between urinary GAG and hydroxyproline. GAG and hydroxyproline excretion might be the expression of cartilage destruction and bone involvement and both may be related to the activity of the rheumatoid process.

Relevance of hydroxyproline excretion to bone metastasis in breast cancer.

In 181 consecutive patients with breast cancer, urinary hydroxyproline excretion has been critically evaluated in conjunction with clinical, biochemical, radiological and scintigraphic parameters. The urinary hydroxyproline/creatinine ratio is a sensitive index of the presence of bone metastases. Urinary hydroxyproline excretion is a reliable method of selecting those patients whose elevated serum alkaline phosphatase is secondary to bone disease rather than liver idsease. The estimation of hydroxyproline excretion furthermore gives information on the activity of bone metastasis, and its response to treatment, which cannot be given by radiological or scintigraphic methods. It is doubtful whether urinary hydroxyproline estimation will help to detect bone metastases before they are apparent on scintigrams. When the bone scan is doubtful, as often occurs in older subjects, hydroxyproline excretion has been found to be helpful in classifying the patient. When scintigraphy is not available, an elevation of hydroxyproline excretion, together with an elevation of Ca/cr ratio or alkaline phosphatase activity, may pre-date by several months the radiological demonstration of osseous metastases.