Paget Disease18

GENERAL PRINCIPLES

Paget disease of bone is a focal skeletal disorder characterized by rapid, disorganized bone remodeling. It usually occurs after the age of 40 years and most often affects the pelvis, femur, spine, and skull.

DIAGNOSIS

Clinical Presentation

• Clinical manifestations include bone pain and deformity, degenerative arthritis, pathologic fractures, neurologic deficits because of nerve root or crani al nerve compression (including deafness), and, rarely, high-output heart failure and osteosarcoma.

• Most patients are asymptomatic, with disease discovered incidentally because of elevated serum alkaline phosphatase or a radiograph taken for other reasons.

Diagnostic Testing

• Serum alkaline phosphatase is elevated, reflecting the activity and extent of disease. Serum and urine calcium are usually normal but may increase with immobilization, as after a fracture.

• The radiographic appearance is usually diagnostic. A bone scan will reveal areas of skeletal involvement, which can be confirmed by radiography.

TREATMENT

• Indications for therapy include (1) bone pain because of Paget disease, (2) nerve compression syndromes, (3) pathologic fracture, (4) elective skeletal surgery, (5) progressive skeletal deformity, (6) immobilization hypercalcemia, and (7) asymptomatic involvement of weight-bearing bones or the skull.

• Bisphosphonates inhibit excessive bone resorption, relieve symptoms, and restore serum alkaline phosphatase to normal in most patients. Zoledronic acid, 5 mg IV by a single infusion, is the drug of choice. The effectiveness of therapy is monitored by measuring serum alkaline phosphatase annually. Therapy can be repeated if serum alkaline phosphatase rises above normal. Bisphosphonates are not recommended in patients with renal insufficiency.