Hyponatremia and osteoporosis: insights from the Danish National Patient Registry.

Abstract

The association between hyponatremia and osteoporosis was evaluated in humans. A significant association was found between low sodium levels, lower bone mineralization in the hip, and with several common conditions. Hyponatremia could be used as a marker of osteoporosis and systemic disease. The objective of this study was to evaluate the association between hyponatremia and osteoporosis in humans through a cross-sectional study. Patient information was gathered from regional and national Danish patient databases, both in- and outpatient settings, from 2004 to 2011. Patients with dual-energy x-ray absorptiometry (DXA) scans performed within this time were included if accompanied [Na+] was measured within 14 days prior or past the scan date. A total of 1575 patients were included. A total of 104 patients were hyponatremic (6.6 %). Total hip and lumbar spine bone mineral content (BMC) and densities (BMD) and T-scores were all significantly lower with hyponatremia. The odds ratio (OR) of osteoporosis significantly increased among hyponatremic patients at both total hip (unadjusted OR = 2.17, 95% CI = [1.40-3.34], p < .05) and lumbar spine (unadjusted OR = 1.83, 95% CI = [1.20-2.80], p < .05) regions. Dose-response found between increasing [Na+] and increasing total hip BMC (slope .174, adjusted p < .05), BMD (slope .004, adjusted p < .05), and T-score (slope .034, adjusted p < .05). Systemic disease was more prevalent in hyponatremia. The presence of hyponatremia increases the risk of concurrent osteoporosis at both the total hip and lumbar spine in humans. Hyponatremia could be used a screening tool and marker of secondary osteoporosis.