Hypercalcemia of immobilization in neurologically injured children: a prospective study

Seven of 20 consecutive admissions to the Children's Head Injury and Spinal Injury Services of the Rancho Los Amigos Hospital demonstrated hypercalcemia ranging from 10.7 mg % to 13.2 mg %, with an average of 11.4 mg % (normal range 8.5 mg-10.5 mg %). Return to normocalcemia coincided with mobilization in five of the seven patients. Four patients in the series developed heterotopic ossification; two of these demonstrated concurrent hypercalcemia. This association has not been previously reported. This study has helped to clarify the clinical suspicion that hypercalcemia of immobilization occurs more frequently than is suggested in the literature. Elevated alkaline phosphatase levels are associated with heterotopic ossification. The role of hypercalcemia in the development of heterotopic ossification remains speculative.