The electrolyte disorders are commonly considered as symptoms of the endocrine diseases concerning the secretion of aldosterone or antidiuretic hormone (ADH). This study is the case report of the 6-month-old girl admitted to the hospital because of the exacerbation of the chronic cough. Failure to thrive and malnutrition was also significant despite the patients good appetite reported by parents. She was referred to the department of the paediatric endocrinology due to metabolic alkalosis with hypokalemia, hypochloremia and low concentration of plasma sodium with extremely high level of plasma aldosterone. The initial intravenous fluid therapy was ineffective and only the oral intake of potassium chloride within 7 days compensated the electrolyte abnormalities. These findings suggested the Bartter Syndrome (BS) a rare disease caused by the renal salt wasting due to a mutation of the ion channel in the loop of Henle. Nevertheless the associated clinical features presented by the patient (chronic cough and malnutrition) indicated Pseudo Bartter Syndrome (PBS). PBS develops due to salt wasting in varied mechanisms. The dysfunctional cystic fibrosis transmembrane regulator (CFTR) in the sweat ducts of Cystic Fibrosis (CF) patients are responsible for excessive chloride and sodium loses, especially in infants exclusively breast-fed (human milk with a low-salt level) during the warm seasons, as it was in the case of our patient. The high secretion of aldosterone in the response to excessive skin salt loss caused increased renal loss of kalium and alkalosis. Our patient had negative neonatal screening test for CF based on blood concentration of immunoreactive trypsinogen. It has 99,5% sensitivity. However in the patient twice-repeated sweat tests revealed elevated sweat chloride concentration. CF diagnosis was confirmed by the genotyping. It has exposed two rare CTFR mutations on different alleles of chromosome 7 (3849+10kbC->T; p.His199Arg). These mutations are usually connected with residual activity of the CFTR, later onset and longer life expectancy. Finally the diagnosis of Pseudo Bartter Syndrome in the course of CF was made. The proper CF therapy was started and for now the girl is developing properly without electrolyte disorders and normal level of aldosterone. Secondary hyperaldosteronism as PBS is very rare in the course of CF but it should be always considered in CF patients with electrolyte imbalance during the warm seasons.
27 - 29 Sep 2018
European Society for Paediatric Endocrinology