Studies have consistently found that the use of thiazide diuretics is associated with a 30% to 50% reduced risk for hip fracture. Now a team of researchers in Seattle has discovered why: older patients taking thiazides demonstrate preservation of bone mineral density (BMD) at both the hip and spine.

More than 300 healthy male and female patients 60 to 79 years old and without hypertension were randomly assigned to receive 12.5 mg hydrochlorothiazide, 25 mg hydrochlorothiazide, or placebo daily. BMD was assessed every six months for three years.

Patients taking hydrochlorothiazide demonstrated dose-related reductions in BMD loss in comparison to their baseline BMD measurements; and some patients gained BMD in the hip and spine by the end of the study, compared to those receiving placebo. Although the benefits of hydrochlorothiazide were modest, administration of this medication for 10 to 20 years might contribute to the reduced fracture rates observed in epidemiologic studies of women taking thiazide drugs. Thiazide effects on BMD were stronger in women than in men.

LaCroix AZ, et al. Ann Intern Med 2000;133(7):516-26.