High Blood Pressure and Bone-Mineral Loss in Elderly White Women: A Prospective Study

Abstract

There is evidence from animal, clinical, and epidemiological studies that high blood pressure is associated with abnormal calcium metabolism. Calcium loss apparently is followed by activation of parathyroid function and loss of calcium from bones. A defect in renal calcium handling may be responsible. If sustained for many years, ongoing mineral loss may increase the risk of osteoporosis. This prospective study examined the relationship between blood pressure and bone mineral loss in 3676 white women older than 65 years (average age, 73 years) who were followed up for an average of 3.5 years. Bone densitometry was repeated 3 to 5 years after initial assessment. The participants were generally in good health. More than 15 percent were receiving hormone replacement therapy (HRT). Approximately 17 percent of women were receiving regular antihypertensive therapy at the time of follow-up. Loss of bone mineral at the femoral neck averaged 0.5 percent per year. Both absolute and relative bone loss at this site were significantly related to age and baseline systolic blood pressure. Smokers had relatively high bone loss, whereas women receiving HRT had less than expected. Ongoing change in bone mineral density increased significantly with increasing systolic blood pressure, even after excluding women taking antihypertensive drugs. This association was not influenced by age. Diastolic blood pressure correlated with bone loss only in women younger than 75 years. Elderly white women with high blood pressure are at increased risk of losing bone mineral at the femoral neck. Because a high salt intake promotes urinary calcium excretion, less dietary salt should not only lower the blood pressure but also encourage positive calcium balance and, it is hoped, lessen the risk of hip fracture. Lancet 1999;354:971–975