Elsevier

The Lancet

Volume 354, Issue 9183, 18 September 1999, Pages 971-975
The Lancet

Articles
High blood pressure and bone-mineral loss in elderly white women: a prospective study

https://doi.org/10.1016/S0140-6736(99)01437-3Get rights and content

Summary

Background

High blood pressure is associated with abnormalities in calcium metabolism. Sustained calcium loss may lead to increased bone-mineral loss in people with high blood pressure. We investigated the prospective association between blood pressure and bone-mineral loss over time in elderly white women.

Methods

We studied 3676 women who were initially assessed in 1988–90 (mean age 73 years [SD 4, range 66–91 years]; mean bodyweight 65·3 kg [11·5]; blood pressure 137/75 mm Hg [17/9]) who were not on thiazide diuretics. Mean follow-up was 3·5 years. Anthropometry, blood pressure, and bone-mineral density at the femoral neck were measured at baseline and bone densitometry was repeated after 3·5 years by dual-energy X-ray absorptiometry.

Findings

After adjustment for age, initial bone-mineral density, weight and weight change, smoking, and regular use of hormone-replacement therapy, the rate of bone loss at the femoral neck increased with blood pressure at baseline. In the quartiles of systolic blood pressure, year bone losses increased from 2·26 mg/cm2 (95% CI 1·48–3·04) in the first quartile to 3·79 mg/cm2 in the fourth quartile (3·13–4·45; test for heterogeneity, p=0·03; test for linear trend, p=0·01), equivalent to yearly changes of 0·34%(0·20–0·46) and 0·59% (0·49–0·69; test for heterogeneity, p=0·02; test for linear trend, p=0·005). There was no significant interaction with age. The exclusion of women on antihypertensive drugs did not alter the results. For diastolic blood pressure, there was an association with bone loss in women younger than 75 years.

Interpretation

Higher blood pressure in elderly white women is associated with increased bone loss at the femoral neck.This association may reflect greater calcium losses associated with high blood pressure, which may contribute to the risk of hip fractures.

Introduction

Animal, clinical, and some epidemiological evidence suggests that high blood pressure is associated with abnormalities of calcium metabolism, leading to increased calcium losses, secondary activation of the paarathyroid gland, and increased movement of calcium from bone.1, 2, 3, 4, 5, 6, 7 Some of these abnormalities are seen in children and young people5, 8 and are detected throughout adult life.1, 2, 3, 4, 6, 7 If substantial calcium loss related to high blood pressure, which may be due to defect in the kidney's ability to handle calcium,9, 10 is sustained over many decades, increased movement of calcium from bone may result in higher rates of mineral loss, thereby increasing the risk of osteoporosis. Metabolic studies in hypertensive rats show that hypercalciuria and ensuing hyperparathyroidism lead to reduced growth and detectable decrease in total bone-mineral content later in life.11, 12 However, no direct evidence is available in human beings.

We investigated prospectively the relation between blood pressure and bone-mineral loss in elderly white women.

Section snippets

Study population

Full details of the prospective Study of Osteoporotic Fractures have been published elsewhere.13, 14, 15, 16, 17, 18, 19 From September, 1986, to October, 1988 (visit 1), 9704 white women aged at least 65 years were recruited for baseline assessment from population-based listings (such as voter's registration lists) in four areas of the USA: Baltimore Country, MD; Minneapolis, MN; Portland; OR; and Monongahela Valley (near Pittsburgh), PA. African-American women, women who were unable to walk

Results

Participants were generally healthy women (table 1). Few women were smokers and more than 15% were on hormone-replacement therapy. After 3–5 years of follow-up, 16–9% of women were on regular antihypertensive therapy and had a small decline in bodyweight. Mean yearly loss of femoral-neck bone mineral was just over 3 mg/cm2, equivalent to a yearly loss of 0·5%.

Absolute and relative femoral-neck bone losses were significantly associated with age (r=−0·05, p<0·01; r=−0·07, p<0·001) and baseline

Discussion

Systolic blood pressure was a significant predictor of bone-mineral loss at the femoral neck. This increased rate of bone loss is not because of differences in age, bodyweight, or weight changes with time, initial bone-mineral density, smoking, or use of hormone-replacement therapy. Furthermore, the effect was not confounded by long-term thiazide diuretic use and persisted after the exclusion of women on other antihypertensive medications at follow-up. However, the size of the effect was

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