Hypomagnesemia and Acute Cognitive Decline in Older Adults: An Evaluation of Clinical Practice and Cognitive Outcomes at a National Health Service (NHS) Trust in England.

Introduction Magnesium is essential for regulating cardiovascular, neuromuscular, and respiratory functions. Hypomagnesemia in older adults is often overlooked and insufficiently managed. Inadequate monitoring and correction of hypomagnesemia may leave old and frail patients more vulnerable to acute cognitive decline, which in some cases can be preventable. This study assessed the current management of hypomagnesemia in older adults admitted to the geriatric wards of an NHS Trust and its association with acute cognitive decline, which is defined in this study as any sudden deterioration from baseline cognition, including delirium or new-onset confusion, identified using the 4-AT tool (score ≥4) and collateral history. The 4AT Rapid Clinical Test for Delirium Detection encompasses four components, namely Alertness, Abbreviated Mental Test-4, Attention and Acute change or fluctuating course. Methods  A retrospective review of old and frail patients admitted to geriatric wards across two hospital sites over a month was conducted. Patients aged 65 years or above and those aged between 55 to 64 with clinical frailty were included. Electronic records were used to compare acute cognitive outcomes in patients with hypomagnesemia and those with normal magnesium levels. Multivariate analysis was performed to assess the predictors of acute cognitive impairment.  Results  Of the 667 hospitalized older adult patients included, 149 (22.3%) had hypomagnesemia, while 518 (77.7%) had normal levels. Among the 149 patients, 18 (12.2%) had moderate-to-severe deficiency (≤0.5 mmol/L); of these, 27.8% received intravenous supplementation, 38.9% received oral supplementation, and 33.3% received no treatment. Among the remaining 131 patients with mild hypomagnesemia, 34.4% received some form of supplementation, while 65.5% had none. After the check-up at admission, only 40.3% of all hypomagnesemic patients had their serum magnesium levels checked at intervals recommended by the trust guideline. In the multivariable logistic regression model, after adjusting for age, sex and potential clinical confounders, i.e. infection, electrolyte disturbances including hypocalcemia, hypercalcemia, hyponatremia and hypernatremia, acute kidney injury, pain, acute stroke, and constipation, patients with hypomagnesemia had 2.35 times greater odds of developing acute cognitive deterioration (OR (Odds ratio) =2.354; 95% CI (Confidence interval): 1.543-3.604; p<0.001).  These findings suggest the independent association between hypomagnesemia and cognitive decline, underscoring the need for its improved recognition and management in clinical practice.  Conclusion Hypomagnesemia may be a significant contributor to acute cognitive impairment in old and frail patients.