Diuretic use and bone mineral density in older USA men: the osteoporotic fractures in men (MrOS) study

Abstract

SIR—It is estimated that 25–40% of adults aged 65 years and over use diuretics [1]. The three major classes of diuretics have different effects on renal calcium balance. Loop diuretics increase renal calcium excretion [2], while thiazide and potassium-sparing diuretics exert a hypocalciuric effect. Thiazides facilitate the reabsorption of calcium in the early segment of the convoluted distal tubule, and potassium-sparing diuretics promote reabsorption of calcium in the late segment of the distal tubule [3–5]. Epidemiological data [6–14] and results from randomised controlled trials [15–17] suggest that thiazide diuretic use is associated with a small increase in bone mineral density (BMD) or a decreased rate of bone loss. However, these associations were observed primarily among women. There are few data regarding the effects of loop diuretics on BMD and findings are not consistent across studies [18, 19]. Although some studies have shown that loop diuretic use may be associated with an increased risk of hip and osteoporotic fractures [20–22], it is uncertain whether this possibly elevated fracture risk was mediated by the effect of loop diuretics on bone or rather on fall-related mechanisms, such as dizziness and orthostasis. To our knowledge, no studies have specifically examined whether potassium-sparing diuretics have an independent effect on BMD. Therefore, we conducted a cross-sectional study among participants in the Osteoporotic Fractures in Men (MrOS) study, an ongoing prospective study of community-dwelling men, to investigate the association between current diuretic use and BMD at multiple skeletal sites. We hypothesised that compared with diuretic non-users, loop diuretic users would have a lower mean BMD, while thiazide and potassium-sparing diuretic users would have a higher mean BMD.