Role of the parathyroid gland on bone mass and metabolism in immobilized stroke patients.

The significant bone-mass reduction that occurs on the hemiplegic side of stroke patients due to disuse and vitamin D deficiency may explain the increased post-stroke incidence of hip fractures. To further evaluate this osteopenia, the Z-score of bone mineral density (BMD) in both second metacarpals was assessed in 54 stroke patients and 27 control subjects. Serum concentrations of intact parathyroid hormone (PTH), osteocalcin (OC), tartrate-resistant acid phosphatase (TRAP) and 25-hydroxyvitamin D (25-OHD) were also determined. The patients' Z-scores were lower on the hemiplegic side than on the nonhemiplegic side. Serum concentrations of PTH, OC and TRAP exceeded those in control subjects. Serum 25-OHD was reduced in patients and correlated negatively with the Z-score on the hemiplegic side. Serum PTH was elevated markedly in 17% of the patients and correlated positively with the levels of OC, but not with TRAP, 25-OHD or the Z-scores on both sides. The results indicate that skeletal remodeling is accelerated in patients with hemiplegia and suggest that vitamin D deficiency and insufficient compensatory hyperparathyroidism stimulating skeletal turnover is an important cause of osteopenia in immobilized stroke patients.