Factors influencing metacarpal bone mineral density in adults with cerebral palsy

Several studies have examined bone mineral density (BMD) and related factors in children with cerebral palsy, but there are no such studies of adults with cerebral palsy. We evaluated BMD in 123 institutionalized adults (51 men aged 21-41 years and 72 premenopausal women aged 24-46 years) with cerebral palsy, and examined the associations of BMD with mobility level, use of anticonvulsant drugs, and abnormal calcium metabolism status. Hand radiographs were used to measure BMD of the second metacarpal bone (mBMD). Body weight (kg), height (in), and body mass index (BMI) were recorded. Serum calcium, phosphate, and alkaline phosphatase were measured.. Abnormal calcium metabolism, defined as calcium <8.5 mg/dl, phosphate <2.6 mg/dl, or alkaline phosphatase >260 U/l, was identified in 28% of the men and 31% of the women. Multiple regression analysis showed that the use of anticonvulsant drugs was significantly associated with lower mBMD in both sexes. Higher alkaline phosphatase level was significantly associated with lower mBMD in men. Mobility level (ambulation) was significantly associated with higher mBMD in women. Neither age nor BMI correlated with mBMD. Our findings indicated poor bone health status in adults with cerebral palsy and the existence of several factors that could affect bone metabolism in these patients.