Bone mineral density, blood pressure, and stroke in elderly women.

Stroke in Elderly Women To the Editor: We read with great interest the recent article by Mussolino and colleagues1 dealing with the relationship between bone mineral density (BMD) and stroke in a large national study. The results of their presented study demonstrated that no significant associations of BMD and stroke incidence or mortality were found not only for white men and women but also for blacks. The finding might be inconsistent with previous reports showing that there were significant associations between low BMD and stroke death and incidence in elderly women.2,3 As Mussolino et al discussed, essential hypertension may be linked to the increased mobilization of calcium from bone. Several studies have reported changes in BMD in hypertensive subjects. It was shown that the rate of bone loss at the femoral neck was increased with blood pressure in elderly white women.4 In a previous study, we showed, using the dual-energy x-ray absorptiometric method, that BMD in lumbar spine was significantly decreased in elderly hypertensive women compared with elderly normotensive women.5 In addition, BMD was inversely correlated with systolic blood pressure, suggesting that high blood pressure might be associated with the decrease in BMD in elderly women. There has been much evidence that hypertension is related to abnormalities of the calcium metabolism such as increased calcium losses from kidney and secondary activation of parathyroid glands.6,7 We also demonstrated that 24-hour urinary calcium excretion was significantly greater in female hypertensive subjects than in female normotensive subjects. Furthermore, the greater the calcium excretion was, the lower the BMD was in women.5 The result might suggest that increased urinary calcium could lead to a decrease in BMD in female hypertensives. In this context, it can be speculated that, in women with essential hypertension and lowered BMD, the disturbances in the calcium metabolism are more pronounced. The precise mechanisms responsible for the decreased BMD in female hypertensives are still unclear. Recent developments have advanced our knowledge of the potential role of estrogen in the regulation of BMD and various cardiovascular functions in elderly women.8–10 It is possible that estrogen deficiency after menopause might accelerate abnormalities in the calcium metabolism at both the cellular and systemic levels, which would explain, in part, osteoporosis and hypertension in elderly women. Because hypertension is the major risk factor for cerebrovascular diseases, it would be important to assess more precisely whether more bone loss with higher blood pressure may be associated with increased stroke incidence or mortality in elderly women.