Increased bone resorption during the first year after stroke.

Abstract

Significant bone mineral density (BMD) reduction occurs in stroke patients on the hemiplegic side compared with the intact side. To elucidate the pathogenesis of hip fractures in this population, we measured serum markers of bone metabolism and BMD in the stroke patients within 1 year (early group) and between 1 and 2 years after onset of hemiplegia (long-term group). Sera were collected from 51 patients from the early group and 93 patients from the long-term group. All patients had hemiplegia. Sera were assayed for pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP; a bone resorption marker) and bone Gla protein (a bone formation marker). The z score of BMD was determined in both second metacarpals. Serum ICTP concentrations (ng/mL) were higher in the early group (15.4+/-4.1) than in the long-term group (6.7+/-4.4). Bone Gla protein was normal or low in both groups. Multiple regression analysis identified Barthel Index, degree of hemiplegia, and illness duration as independent determinants of ICTP in the early group, whereas Barthel Index, degree of hemiplegia, and serum calcium were determinants of ICTP in the long-term group. There were statistically significant correlations between the z score of the hemiplegic side and age, Barthel Index, degree of hemiplegia, illness duration, 25-hydroxyvitamin D (25-OHD), and ICTP in the early group and between the z score and degree of hemiplegia and 25-OHD level in the long-term group. The pathogenesis of reduced BMD differed between the early and long-term stroke groups. These results suggest that in the early group, increased bone resorption caused by immobilization was responsible for osteopenia on the hemiplegic side, whereas the degree of hemiplegia and 25-OHD level were the determinants of osteopenia in the long-term group.