Hypomagnesemia is a low level of magnesium, an electrolyte, in blood, characterized by a level of lower than 1.46 milligrams of magnesium per decilitre (1/10th of a litre) of blood. It generally manifests as tremor or nystagmus and in severe cases seizure and cardiac arrest.
It has numerous causes including alcoholism, malnutrition and starvation, diarrhea, increased urination and, more rarely, inability of the intestines to absorb magnesium in the diet. It is also rarely caused by an actual deficit of dietary magnesium because, like calcium, the body can draw it from bones.. It can also be a side effect of some medications, including antibiotics. Intensive care patients require careful monitoring as low magnesium levels could lead to the need for a ventilator.