Recent studies suggest a possible association of hyponatremia with osteoporosis, falls and bone fractures. The objectives of this narrative review were to further explore this association and the related pathophysiological mechanisms and to suggest a practical approach to patients with osteoporosis or chronic hyponatremia in clinical practice. We conducted an extensive PubMed search until October 2022 with the combination of the following keywords: 'hyponatremia' or 'sodium' or 'SIADH' and 'fractures' or 'bone' or 'osteoporosis', as MeSH Terms. Review of numerous observational studies confirms a significant independent association of, even mild, hyponatremia with two- to three-fold increase in the occurrence of bone fractures. Hyponatremia is a risk factor for osteoporosis with a predilection to affect the hip, while the magnitude of association depends on the severity and chronicity of hyponatremia. Chronic hyponatremia also increases the risk for falls by inducing gait instability and neurocognitive deficits. Besides the detrimental impact of hyponatremia on bone mineral density and risk of falls, it also induces changes in bone quality. Emerging evidence suggests that acute hyponatremia shifts bone turnover dynamics towards less bone formation, while hyponatremia correction increases bone formation. The key unanswered question whether treatment of hyponatremia could improve osteoporosis and lower fracture risk highlights the need for prospective studies, evaluating the impact of sodium normalization on bone metabolism and occurrence of fractures. Recommendations for clinical approach should include measurement of serum sodium in all individuals with fracture or osteoporosis. Also, hyponatremia, as an independent risk factor for fracture, should be taken into consideration when estimating the likelihood for future fragility fracture and in clinical decision-making about pharmacological therapy of osteoporosis. Until it is proven that normalization of sodium can lower fracture occurrence, correcting hyponatremia cannot be universally recommended on this basis, but should be decided on a case-by-case basis.

中文翻译：

---

低钠血症与骨密度和骨折的关联：叙述性回顾。

最近的研究表明低钠血症可能与骨质疏松症、跌倒和骨折有关。本叙述性综述的目的是进一步探讨这种关联和相关的病理生理机制，并为临床实践中骨质疏松症或慢性低钠血症患者提出实用的方法。我们使用以下关键词组合进行了广泛的 PubMed 检索，直至 2022 年 10 月：“低钠血症”或“钠”或“SIADH”以及“骨折”或“骨”或“骨质疏松症”（作为 MeSH 术语）。对大量观察性研究的回顾证实，即使是轻微的低钠血症，也与骨折发生率增加两到三倍之间存在显着的独立关联。低钠血症是骨质疏松症的危险因素，容易影响髋部，而相关程度取决于低钠血症的严重程度和长期性。慢性低钠血症还会引起步态不稳定和神经认知缺陷，从而增加跌倒的风险。低钠血症除了对骨密度和跌倒风险产生不利影响外，还会引起骨质量的变化。新的证据表明，急性低钠血症会使骨转换动态转向减少骨形成，而低钠血症纠正会增加骨形成。低钠血症治疗是否可以改善骨质疏松症并降低骨折风险这一尚未解答的关键问题突出表明需要进行前瞻性研究，评估钠正常化对骨代谢和骨折发生的影响。临床方法的建议应包括测量所有骨折或骨质疏松症患者的血清钠。此外，在估计未来脆性骨折的可能性以及骨质疏松症药物治疗的临床决策时，应考虑低钠血症作为骨折的独立危险因素。在证明钠正常化可以降低骨折发生率之前，不能在此基础上普遍推荐纠正低钠血症，而应根据具体情况决定。