Prevalence, clinical characteristics, and health outcomes of dysmagnesemia measured by ionized and total body concentrations among medically hospitalized patients.

Ionized Mg (iMg) may offer a more reliable indicator of Mg status during acute illness than total Mg (tMg) concentrations. This study aimed to determine the prevalence of dysmagnesemia and their relationship using iMg and tMg. The clinical and biochemical characteristics as well as health outcomes and their association with iMg and tMg were also assessed. A prospective study including all eligible adult patients (≥18 years) who were hospitalized in the General Internal Medicine unit at Sultan Qaboos University Hospital (SQUH) for 3.5 months in 2023. The iMg and tMg concentrations were collected on all at the admission. In total 500 patients were included (females 49.2%) with a median age of 64.5 years (IQR: 48-77). The prevalence of hypomagnesemia and hypermagnesemia by iMg concentrations was 3.4% and 26.6%, respectively, while by tMg concentrations 13.2% and 11.0%, respectively. The agreement between both measurements was strong (r=0.665, p<0.01). An increased tMg concentration was independently associated with high dependency units' admission (adjusted odds ratio (aOR): 4.34, 95%CI: 1.24-15.06, p=0.02) and cardiac arrest (aOR: 14.64, 95%CI: 3.04-70.57, p<0.01), and 6-month all-cause mortality (aOR: 11.44, 95%CI: 2.46-53.17, p<0.01). During follow-up hypermagnesemia using tMg had a higher mortality compared to other groups (hazard ratio (HR): 1.82, 95%CI: 1.11-3.01, p=0.02) while no significant findings were demonstrated using iMg concentrations. iMg and tMg concentrations had a strong correlation that might be supporting the potential use of point-of-care devices. Multivariant regression analysis showed that hypermagnesemia by tMg was associated with adverse outcomes. However, the generalizability of the study findings should be taken with caution and the difference in the associations with outcomes highlight the importance of further research to examine the complex associations and impacts of dysmagnesemia in various clinical settings.