By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.
There is a lot of evidence from both human and animal studies to show that high blood pressure leads to loss of calcium from the body, mainly as a result of increased amounts of calcium in the urine. Most of our calcium stores are in our bones, which leads to the question whether high blood pressure might contribute to the development of osteoporosis, a common cause of weak bones and fractures in older people, particularly women.
A survey of 3,676 elderly white women living in four parts of the USA, whose average age was 73, had their blood pressures measured and also a bone density test, which was measured a second time after another three and a half years. Comparison of the bone densities over this period enabled the estimation of the rate of bone loss. The results showed that women with the highest blood pressures had nearly double the rate of bone loss in comparison with women with low blood pressure.
Osteoporosis is a major health problem for older people and accounts for more than a million bone fractures a year in the US. It affects women more than men, and whites more than blacks (which is why this study did not include black women). The reason for the link with high blood pressure which this study shows is presumed to be the increased loss of calcium in the urine, which is a direct consequence of high blood pressure. A high salt diet also leads to more calcium loss. For people who have high blood pressure the good news is that thiazide diuretics (the sort normally used to treat high blood pressure in older people) actually reduce the calcium loss, and there is some evidence that they may help to prevent osteoporosis.
Where it was published
FP Cappuccio and colleagues. High blood pressure and bone-mineral loss in elderly white women: a prospective study. Lancet 1999;354:971.