Background & objective: Hyponatremia is the most common electrolyte disorder and is a predictor of osteoporosis, inflammation and cognitive dysfunction leading to falls in the elderly patients. We compared glutamate levels in normonatremic elderly patients with those with hyponatremia, admitted with osteoarthritis, to find correlation between the cognitive status with cerebrospinal fluid (CSF) glutamate as a biomarker for hyponatremia.

Methodology: In an observational prospective study; 70 patients, more than 70 y of age, admitted to trauma unit of Assiut University Hospital with fractures around the hip, were investigated for the frequency of on-admission hyponatremia. The CSF glutamate level was determined using radio-immune assay. We compared glutamate level in 18 hyponatremic patients with 10 normonatremic elderly patients admitted with osteoarthritis for elective joint replacement (control group) to find correlation between the cognitive status assessed by Modified Mini-Mental State (3MS) examination and CSF glutamate as a biomarker for hyponatremia.

Results: Hyponatremia is highly prevalent in elderly with fractures around the hip; we recorded it in 41.4% of the study sample. Most patients were females (62.86%). CSF glutamate was significantly increased in hyponatremic patients than the controls (P< 0.001).

Conclusion: Prevalence of hyponatremia is high in old aged patients probably due to due to prevalent hot weather in the south of Egypt. CSF glutamate level can be a marker for mild cognitive impairment caused by hyponatremia.

Abbreviations: 3MS: Modified Mini-Mental State examination; CSF: cerebrospinal fluid; RPM …