Background: Magnesium deficiency is common in serious diseases and is often associated with mechanical ventilation, mortality, and long-term intensive care. Awareness of hypomagnesaemia is essential because little data is available and may have prognostic and therapeutic implications.

Aim: This study was conducted to calculate the incidence of hypomagnesaemia at PICU admission and to relate it to length of PICU stay, duration of mechanical ventilation, and outcome of hospital stay or discharge.

Place and Duration: In the Pediatric Intensive Care Unit (PICU), Abbasi Shaheed Hospital, Karachi for one-year duration from April 2020 to April 2021.

Methods: This is a prospective observational study involving 200 children aged 1 month to 12 years admitted to the PICU. All qualified children underwent an interview and clinical examination. Blood was collected during admission to calculate serum magnesium level. The patients were grouped into three groups: normomagnesemia, hypomagnesaemia and hypermagnesemia, and the data were analyzed.

Results: 200 children were included in the inclusion study. Males constituted 57.0%and females 43.0%. The ratio of men to women was 1.2: 1. Most of the respondents were 5 years old. Most of the respondents were in the ICU with neurological symptoms (36.5%), followed by respiratory diseases (27%). Of the 200 patients, 138 (69%) had a mean magnesium level of 1.9 mg / dL. 51(25.5%) patients had hypomagnesaemia. The average magnesium level was 1.3 mg / dL. 11 (5.5%) patients had hypermagnesemia with a mean magnesium content of 2.7 mg / dl. The lowest measured magnesium level was 1 mg / dl and the highest was 4.2 mg / dl. There was no statistically significant association between hypomagnesaemia and gender, age, disease acceptance category, and sepsis. ≤ 27.4% of children under 5 years of age had severe acute malnutrition in the hypomagnesaemia group. Among those with normal magnesium levels, 24% had severe acute malnutrition and 27.3% had severe acute malnutrition among those with hypermagnesemia. In the study, overall mortality was 25% (50 out of 200). Mortality among people with hypomagnesaemia was 29.40%. Among those with normal magnesium levels, 21.2% died and 18.2% in the hypermagnesemia group.

Conclusion: Patients with hypomagnesaemia have prolonged PICU stay, other related electrolyte disturbances and increased mortality. Therefore, in severe ill patients, magnesium levels are monitored.

Keywords: Children, Hypomagnesaemia, Intensive Care Unit, Mortality, Outcome, ICU