The nonpathogenic role of hyponatremia in the onset of osteoporosis: A Mendelian randomization study

The relationship between hyponatremia and osteoporosis is controversial, and it remains unclear if there is a causal link between the two. This study employed a 2-sample Mendelian randomization (MR) analysis to investigate the potential causal relationship between hyponatremia and osteoporosis. The instrumental variables were derived from genome-wide association studies conducted in European populations. These included hyponatremia (n = 465,348) as the exposure factor, with genetic summary data for bone mineral density (BMD) at the forearm (n = 8134), femoral neck (n = 32,735), lumbar spine (n = 28,498), and heel (n = 265,627) as outcomes. The inverse variance weighted method did not identify any causal effect of hyponatremia on BMD. Additionally, other methods, such as MR-Egger, weighted median, simple mode, and weighted mode, also did not show evidence of a causal relationship between hyponatremia and BMD. Pleiotropy and heterogeneity analyses indicated that the MR findings were robust. There is no significant causal relationship between hyponatremia and osteoporosis. The previously observed associations may be due to confounding factors. It is unlikely that hyponatremia is a causal factor for osteoporosis.