Tetany due to acute calcium deficiency

**Definition:** The hallmark of acute hypocalcaemia is tetany, which is characterised by neuromuscular irritability. The symptoms of tetany may be mild (peri-oral numbness, paresthesias of the hands and feet, muscle cramps) or severe (carpopedal spasm, laryngospasm, and focal or generalised seizures, which must be distinguished from the generalised tonic muscle contractions that occur in severe tetany). Other patients have less specific symptoms such as fatigue, hyperirritability, anxiety, and depression, and some patients, even with severe hypocalcaemia, have no neuromuscular symptoms. Factors that determine the variation in frequency and severity of symptoms include acid-base status (hypocalcaemia and alkalosis act synergistically to cause tetany), hypomagnesaemia, and potassium balance.