Adrenal function after upper femoral fracture in elderly people: persistence of stimulation and the roles of adrenocorticotrophic hormone and immobility.

Previous work has shown persistent elevations in plasma cortisol concentration following upper femur fracture in elderly people. To investigate this phenomenon further, we measured plasma cortisol and adrenocorticotrophin (ACTH) and performed overnight dexamethasone suppression tests in carefully characterized patients and controls (mobile and immobile). There was no difference in cortisol or ACTH, either basally or after dexamethasone, between the mobile and immobile controls. At 2 and 8 weeks after injury, basal plasma cortisol was significantly higher than in either control group and was not related to an index of the patients' mobility potential. The ACTH concentrations also tended to be raised after injury, but the differences in concentration between injured and control subjects did not reach statistical significance. At both 2 and 8 weeks after injury, the post-dexamethasone cortisol concentration was significantly higher in the fracture patients, particularly the least mobile. Our results show that the elevation in plasma cortisol concentration in elderly femur-fracture patients, which may persist for at least 8 weeks after injury, is not explained by immobility and is probably mediated by an increased central drive to the hypothalamic-pituitary-adrenal axis.