A patient with Paget's disease of bone treated with etidronate disodium

A 69-year-old Japanese woman was referred to our hospital because of abnormal skull X-ray findings. Serum total alkaline phosphatase, bone-specific alkaline phosphatase 3, osteocalcin and propeptide carboxyterminal of type I procollagen (PICP) levels were markedly elevated. Urinary excretion of hydroxyproline was also increased, suggesting that both bone formation and resorption were accelerated. Radiography of the skull showed "cotton wool" appearance. T1-enhanced MRI revealed that the skull-cap and diploe were swelled up. In 99mTc-MDP bone scintigraphy, all areas of the skull and a part of the right hemipelvis showed high uptake of the radioisotope. Based on the findings we made diagnosis of Paget's disease of bone which is a rare bone disorder in Japanese. Three-month oral administration of etidronate disodium resulted in normalization of serum PICP levels and urinary hydroxyproline excretion, whereas alkaline phosphatase levels were only partially lowered. Levels of the markers of bone turnover remained normal during a follow-up period of 3 months after the discontinuation of the treatment.