Hyponatremia and aging-related diseases: key player or innocent bystander? A systematic review.

Abstract

Purpose. Hyponatremia is frequent in older age, whether it is a key player, a surrogate marker, or an innocent bystander in age related diseases is still unclear. Method. To further understand the role of hyponatremia in falls, osteoporosis, fractures, and cognitive impairment in old patients, we conducted a systematic literature review. The protocol of this study is available on the International prospective register of systematic reviews (PROSPERO, number CRD42021218389). MEDLINE, EMBASE and PsycINFO database were searched. Three reviewers identified studies meeting inclusion criteria and check decisions. Each study was independently evaluated by two reviewers, discrepancies between the two reviewers were solved by the third. Two hundred and fifteen articles were retrieved. Thirty-two were included in the review. Results. The majority of the studies found a significant association between hyponatremia and falls even after correction for confounding factors. Some studies suggested an association between persistent hyponatremia and increased osteoporosis and fracture risk. On the contrary, the evidence of an association between hyponatremia and cognitive impairment is lacking. Conclusion. Here we suggest that hyponatremia may be regarded as a marker of unhealthy aging and a confounder rather than a causal factor or an innocent bystander for falls and fractures. As regards cognitive impairment, the evidence provided until now, are not sufficient to explain a real role of hyponatremia that may be regarded rather as an innocent bystander in neurodegeneration.