Effect of Low‐Dose Thiazide Diuretics on Plasma Lipids: Results from a Double‐Blind, Randomized Clinical Trial in Older Men and Women

OBJECTIVES: To determine the effects of low doses of hydrochlorothiazide (HCTZ) on plasma lipids in healthy older men and women. DESIGN: Randomized, double-blind, placebo-controlled clinical trial for 3 years followed by a 1 year extension without medication. SETTING: Research clinic of a nonprofit health maintenance organization. PARTICIPANTS: Two hundred five women and 115 men aged 60 to 79 with normal blood pressure, bone density within two standard deviations of mean for age, and low-density lipoprotein cholesterol (LDL-C) levels less than 190 mg/dL. INTERVENTION: Placebo or HCTZ 12.5 or 25 mg/d. MEASUREMENTS: Plasma cholesterol, LDL-C, high-density lipoprotein cholesterol, triglycerides. RESULTS: There were no significant differences in the change in the plasma lipids between placebo and either group. The mean changes +/- standard deviation in LDL-C after 3 years in men were -5.2 +/- 3.9 mg/dL (placebo), -4.6 +/- 3.7 (12.5 mg), and 1.1 +/- 3.8 (25 mg) and in women were 1.3 +/- 2.8 (placebo), -1.1 +/- 2.8 (12.5 mg), and -6.8 +/- 2.8 (25 mg). No significant differences were seen when analysis was done only for subjects who adhered to study medication. CONCLUSION: This study provides evidence that low doses of thiazide diuretics have minimal effects on cholesterol metabolism in healthy older adults. Therefore, effects on lipid levels need not limit use of thiazides for prevention of osteoporotic fractures.