An evaluation of serum osteocalcin in Paget's disease of bone and its response to diphosphonate treatment.

We found that serum bone gamma-carboxyglutamic acid-containing protein (BGP) (osteocalcin) had lower sensitivity and specificity for measurement of disease activity in Paget's disease of bone than other biochemical measures of disease activity. The administration of diphosphonates induced suppression of urinary hydroxyproline excretion and a subsequent decrease in alkaline phosphatase values, but no consistent change in BGP values. Serum BGP measurements have limited value as a screening test for Paget's disease or for monitoring treatment of the disorder.