Endocrine Abstracts

Background: Magnesium, the second most abundant intracellular cation, plays a key role in cellular and metabolic reactions including protein synthesis, neurotransmission and electrolyte balance. There are no specific signs or symptoms of hypomagnesaemia and it can coexist with other electrolyte abnormalities. According to various surveys the prevalence of low Magnesium varies between 2–10% in hospitalized patients. However, there are no clear guidelines about when to screen for hypomagnesaemia.

Aims & objectives: To assess the prevalence of calcium and other electrolyte abnormalities in hospitalised patients with hypomagnesaemia.

Material & methods: All patients with Mg levels below the reference value of 0.7 mmol/l over a 2-year period (July, 2006–June, 2008) were included in this review. Each patient was evaluated for sodium, potassium, calcium and PTH levels (if measured) at the time of hypomagnesaemia.

Results: A total of 227 patients were detected to have hypomagnesaemia (mean: 0.55 mmol/l, range:0.09–0.69, median 0.59) over the period studied. Most of the requests were made by anaesthetists (Intensive care unit), gastroenterologist and endocrinologists. Serum Potassium and Sodium levels were low (K⁺<3.6 mmol/l; Na⁺<135 mmol/l) in 88 (38.8%) and 80 (35%) patients respectively. Hypocalcaemia (< 2.1 mmol/l, average 1.89 mmol/l, range 1.37–2.09, median 1.93), was detected in 71 patients (31.3%). There was no correlation between level of hypomagnesaemia and calcium levels. PTH levels were measured in 15 out of 71 patients with hypocalcaemia. 2 of these patients had low PTH levels, whilst 6 had elevated levels.

Summary: Hypomagnesaemia is an under-recognised electrolyte abnormality, seen commonly in patients admitted to intensive care and in alcoholics/malnourished patients.

In view of the high prevalence of hypomagnesaemia and its association with other electrolyte abnormalities, the routine measurement of Mg is warranted in all hospitalised patients with persistent hypokalaemia and hypocalcaemia.We discuss the investigation and management of hypomagnesaemia.