Paget's Disease of Bone

A serum alkaline phosphatase (ALP) level three times higher than normal, found on routine laboratory examination, prompted further evaluation of a 57-year-old man. At admission, his temperature was 36.8°C (98.2°F), blood pressure was 120/85 mm Hg, pulse rate was 90 beats per minute, and respiration rate was 19 breaths per minute. The physical examination was unrevealing, and the patient's personal and family medical histories were unremarkable.

Laboratory findings, including complete blood cell count and urinalysis, were normal. Serum protein electrophoresis results were also normal, as were parathyroid hormone and vitamin D levels. An ECG and chest film revealed no abnormalities, while roentgenographic evaluation of long bones and the skull was inconclusive.

A radionuclide bone scan with technetium-labeled phosphonates demonstrated increased uptake at the skull, as seen here. There was increased excretion of hydroxyproline in the urine. The diagnosis of Paget's disease of bone was established, and therapy with monthly intravenous infusions of pamidronate was initiated. The treatment resulted in a progressive decrease of serum ALP levels.

Drs Haralampos Milionis, Andreas Fotopoulos, and Moses Elisaf of Ioannina, Greece, add that isolated increased ALP levels may be an incidental finding in asymptomatic or oligosymptomatic patients with Paget's disease. A thorough diagnostic work-up includes a complete physical examination; roentgenographic studies or radionuclide bone scans; and appropriate laboratory tests, such as determination of hydroxyproline or pyridinoline excretion levels.