Chronic prolonged hyponatremia (CPH) in older patients with chronic kidney disease (CKD) is associated with an increased risk of hip fracture, according to a new study.

In a case-control study of patients older than 60 years with stage 3 or greater CKD, the presence of CPH, compared with its absence, was associated with significant 36% increased odds of hip fracture compared with the absence of CPH after adjusting for comorbidities, medications, and laboratory parameters, Sagar U. Nigwekar, MD, of Massachusetts General Hospital in Boston, and colleagues reported in Bone. The investigators defined CPH as serum sodium values below 135 mEq/L on at least 2 occasions separated by a minimum of 90 days prior to the diagnosis of hip fracture.

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The study included 1236 patients who had a hip fracture (cases) and 4515 with no hip fracture (controls). CPH was present in 21% of cases and 10% of controls.

“The association between CPH and risk of hip fracture was consistent in patients with or without osteoporosis and falls and across the age strata,” the authors wrote.

In stratified analyses, CPH was associated with significant 4-fold and 2.2-fold increased odds of hip fracture among patients aged 70 years or younger and those older than 70 years, respectively.

Among patients with and without osteoporosis, CPH was associated with significant 2.4-fold increased odds of hip fracture.

“As elderly patients are particularly predisposed to chronic hyponatremia and complications from chronic hyponatremia, we believe that our findings have direct conceivable relevance to clinical care of these patients,” Dr Nigwekar’s team wrote.

Reference

Nigwekar SU, Negri AL, Bajpai D, et al. Chronic prolonged hyponatremia and risk of hip fracture in elderly patients with chronic kidney disease. Bone. 2019. doi: 10.1016/j.bone.2019.07.029