Total magnesium

Most of the magnesium in the body is present in bone tissue and influences the function of many organs, including neuromuscular tissue.
Low magnesium levels in cardiac patients can aggravate cardiac arrhythmias, while hypermagnesaemia retards neuromuscular and cardiac conduction.
Magnesium deficiency is present in cases of malnutrition, malabsorption, hypoparathyroidism, hyperaldosteronism, use of diuretics, alcoholism and hyperemesis gravidarum. Symptoms of magnesium deficiency include weakness, irritability, electrocardiographic changes, convulsions, etc.
Increased magnesium levels are commonly associated with chronic renal failure, hypothyroidism, and Addison’s disease. Symptoms of hypermagnesaemia include lethargy, nausea and vomiting.