[Paget's disease and hypercalcemia: coincidence or causal relationship?]

Paget's disease is a chronic disease in which osteoclast mediated bone resorption precedes imperfect osteoblast mediated bone repair. Symptoms include bone pain, pathological fractures, osteoarthritis and neurological symptoms. There is evidence that genetic and viral component are involved in the etiology. Hypercalcemia is rare and when it is diagnosed, primary hyperparathyroidism should be ruled out. The authors present a patient with Paget's disease and concomitant hypercalcemia. Evaluation for hypercalcemia revealed an adenoma of the parathyroid. However, despite the removal of the adenoma, the symptoms persisted. Previous studies showed that hyperparathyroidism causes hypercalcemia in Paget's disease patients. Removal of the adenoma led to improvement in calcium and alkaline phosphatase (ALP) levels but clinical improvement is seen only in patients with high calcium level prior to the operation. This leads to the assumption that symptoms of Paget's disease are due to osteoclast hypersensitivity to parathyroid hormone (PTH) and by removing the adenoma the osteoclast activity is also reduced. In summary, the most common cause of hypercalcemia in Paget's disease patients is hyperparathyroidism and adenectomy may improve the biochemical and sometimes also the clinical symptoms of Paget's disease.