Resting blood pressure and bone mineral content are inversely related in overweight and obese Hispanic women

Background: Previous studies have shown that hypertension is related to abnormalities of calcium metabolism such as increased calcium losses from kidney and secondary activation of parathyroid glands. In animal studies, high blood pressure (BP) has been shown to increase the risk of bone mineral loss; however whether hypertension is associated with reduced bone mineral content (BMC) in human beings is inconclusive. The relationship between BP and BMC has not been previously studied in Hispanic individuals. Methods: Total body BMC of 33 overweight and obese (mean BMI = 31.1 kg/m(2)) premenopausal Hispanic women 22 to 51 years of age from Los Angeles, CA, was measured using dual-energy x-ray absorptiometry. Seated systolic BP (SBP) and diastolic BP (DBP) were measured using a standard mercury sphygmomanometer. Results: Partial correlations revealed an inverse relationship among BMC and SBP (r = -0.61, P <.001), DBP (r = -0.52, P <.01), and hypertension (r = -0.69, P <.0001). In multiple linear regressions, SBP was negatively related (beta = -0.31, P =.001) to BMC and explained 10% of the variance. The DBP did not make a significant contribution to the variance. When fat mass and fat-free mass were controlled for, hypertensive women (n = 9) had significantly lower BMC (2119 g v 2441 g; P <.0001) than normotensive women (n = 23). Conclusions: These results reveal that BMC is partially and inversely correlated with resting SBP and DBP in premenopausal Hispanic women; in addition hypertensive women have lower adjusted means of BMC than normotensive women. Sustained hypercalciuria and ensuing hyperparathyroidism as consequences of high BP may be the mechanisms that explain the pathophysiology of increased bone mineral loss in hypertension.