Background and aims Metabolic alkalosis in association with low serum electrolyte concentration (hyponatremia, hypochloremia, and hypokalemia) is known complication of cystic fibrosis (CF) in infancy. The condition is a metabolic mimickery of Bartter’s syndrome, therefore is sometimes referred to as pseudo-Bartter’s syndrome in CF. The aims of study were to estimate the prevalence of this metabolic disorder as a first manifestation of CF and the influence of some clinical and genetic factors on its developing.
Methods The records of all 85 newly diagnosed infants with CF in the period from 1998 to 2013 were reviewed. In addition to data of acid-base and electrolyte status at first admission, clinical and CFTR genotype data of patients with pseudo-Bartter’s syndrome were analysed.
Results 16 infants had manifestations of hyponatremic/hypochloremic dehydration with metabolic alkalosis, therefore the prevalence of pseudo-Bartter’s syndrome among newly diagnosed infants with CF in our region was 18.8%. Mean age of patients was 3.5 (range 1–8) months. Most of them were breastfed. Mean values of blood pH, serum bicarbonate, sodium, chloride and potassium (mmol/L) were: 7.57 ± 0.06, 44.89 ± 7.23, 117.87 ± 5.38, 67.06 ± 8.48, 2.69 ± 0.47, respectively. Concerning CFTR genotypes of these patients, a great variability was found: F508del/ F508del (7), F508del/G542X (3), F508del/621+G >T (1), F508del/457TAT >G (1), F508del/711+3A >G (1), G126D/V456F(1) and F508del/Unknown (2). Three of them were pancreatic sufficient.
Conclusions The possibility of CF should be seriously considered in any infant with metabolic alkalosis and hypoelectrolytemia, whether or not there are associated pulmonary and/or gastrointestinal symptoms. The initial diagnosis of Bartter’s syndrome can be excluded by hypochloruria.