Hyponatremia Increases Risk of Fractures and Osteoporosis

Austin, Texas—Hyponatremia decreases bone density, possibly through osteoclast-mediated bone resorption, and is a risk factor for fragility fractures. Kalyani Murthy, MD, and colleagues recently conducted a systematic review and meta-analysis designed to examine the effects of hyponatremia on fractures and osteoporosis. They reported results of the analysis during a poster session at the NKF 2018 Spring Clinical Meetings in a poster titled Effects of Hyponatremia on Bone Density and Fractures: A Systematic Review and Meta-Analysis.

The literature review included MEDLINE and Cochrane Central databases, Embase from 1960 to 2017, and conference abstracts from 2007 to 2017. Inclusion criteria were studies in the English language in adults with serum sodium, bone-density measurements available, diagnosis of osteoporosis, and fractures. Case reports, reviews, and studies missing data on primary variables were excluded. Eligible studies were reviewed by two reviewers. When at least three studies reported the same outcome measures, random effect models meta-analysis was used.

The primary outcome of interest was fracture. The secondary outcome was osteoporosis.

Following application of inclusion and exclusion criteria, the literature search revealed 836 abstracts and 23 eligible studies. Fifteen studies reported on fractures and eight reported on bone-density and hyponatremia. Four studies focused on hip fractures and the remainder on a composite of various fractures.

Regardless of hyponatremia duration and serum sodium, hyponatremia increased the odds of fracture in both prospective and retrospective studies: summary odds ratio [OR], 2.7; 95% confidence interval [CI], 1.91-3.82 and summary OR, 2.46; 95% CI, 1.82-3.34, respectively). The odds of osteoporosis were also increased with hyponatremia: summary OR, 2.67; 95% CI, 2.07-3.43).

Data on mortality risk in studies evaluating fractures are limited; the analysis revealed a trend toward higher mortality.

“Our meta-analysis confirmed a statistically significant and strong association of hyponatremia with fractures and osteoporosis. Based on these results, we conclude it is imperative to evaluate and monitor patients with hyponatremia for fracture risk, including bone-density measurement and gait stability. Future long-term prospective studies evaluating the effect of correcting hyponatremia on bone health, falls, fractures, and mortality are required,” the researchers said.