Alcalosis metabólica hipopotasémica: a propósito de un síndrome de Gitelman / Metabolic alkalosis: gitelman´s syndrome

RESUMEN

El síndrome de Gitelman es una tubulopatía de herencia autosómica recesiva, al igual que el síndrome de Bartter. Si bien en un principio se pensó que podían tratarse de una misma patología, hallazgos clínicos, biológicos y genéticos posteriores han demostrado que nos encontramos ante dos entidades patológicas diferentes. Ambos síndromes cursan con alcalosis metabólica hipopotasémica con normotensión, hiperreninismo e hiperaldosteronismo. Uno de los hallazgos más característicos en el Gitelman es la hipomagnesemia persistente, así como la hipocalciuria, que lo diferencian del síndrome de Bartter. La alteración fundamental se halla en el túbulo distal, concretamente a nivel del cotransportador Na/Cl sensible a las tiazidas, codificado en el cromosoma 16q. El defecto primario consiste en una incapacidad para la reabsorción de sodio que será la responsable de la secuencia de alteraciones electrolíticas que caracterizan al síndrome (AU)

ABSTRACT

We present a case of Gitelman’s Syndrome in a 20 year-old woman who come to our service with weakness, asthenia, leg cramps and tetany. Laboratory studies revealed metabolic alkalosis with hypokaliemia, hipomagnesemia and low calcium in 24 hours urine test. The diagnosis of this syndrome is made in some cases during adult life because this syndrome is asymptomatic over several years. Gitelman’s Syndrome is autosomal recessive as is Bartter’s Syndrome. The gene is located in chromosome 16q, which codifies the cotransporter Na/Cl sensitive to thiazide in distal convoluted tubule. The defect of cotransporter produces an alteration of sodium reabsorption that causes electrolytic disorders typical of this Syndrome and different from Bartter’s Syndrome. The typical electrolytic alterations are hypocalciuria and hypomagnesemia secondary to high urinary magnesium excretion. The prognosis of this syndrome is excellent and treatment consists in correction of serum electrolytes with oral administration of magnesium and potassium. In spite of this treatment, in some cases it is very difficult to reach normal serum levels of magnesium because of the high doses of oral magnesium, which produce common crises of diarrhea that increase magnesium gastrointestinal losses (AU)