[Magnesium homeostasis. Etiopathogeny, clinical diagnosis and treatment of hypomagnesaemia. A case study].

Magnesium is the fourth-most abundant cation in the human body and the second-most abundant intracellular cation after potassium. Magnesium is pivotal in the transfer, storage, and utilization of energy as it regulates and catalyzes more than 300 enzyme systems. Hypomagnesemia may thus result in a variety of metabolic abnormalities and clinical consequences. It results from an imbalance between gastrointestinal absorption and renal excretion of magnesium. The main consequence related directly to hypomagnesemia is cardiovascular arrhythmias secondary to hipokaliemia and if this is not recognized and treated it may be fatal. In this article we review the hypomagnesemic disorders in children with emphasis on the molecular mechanisms responsible for abnormalities in magnesium homeostasis, differential diagnosis and appropriate therapy, and we describe the clinical and biochemical manifestations as well as the genetic defect in a family with Gitelman syndrome.