99mTc-MDP retention in osteoporosis: relationship to other indices of bone cell activity and response to calcium and vitamin D therapy.

Serum calcium, albumin, phosphorus, and alkaline phosphatase, urinary creatinine and retention of 99mTc-methylene bisphosphonate (99mTc-MDP) were measured in 61 subjects with osteoporosis and the values compared with those obtained in normal subjects. 99mTc-MDP retention was inversely related with urinary creatinine output in normal subjects. In osteoporotic subjects urinary creatinine output was lower and 99mTc-MDP retention higher even when urinary creatinine output was taken into account. Other measurements were similar. In 21 subjects these measurements together with urinary hydroxyproline were performed before and after treatment with calcium and vitamin D. 99mTc-MDP and alkaline phosphatase fell; urinary hydroxyproline was unchanged. A single 24 h urine measurement after 99mTc-MDP injection is a valuable method of predicting whether calcium and vitamin D therapy will be useful in a particular case of osteoporosis.