[Pseudo-Bartter syndrome as manifestation of cystic fibrosis with DF508 mutation]

BACKGROUND

Pseudo Bartter syndrome (PBS) is defined as hypokalaemic hypochloraemic metabolic alkalosis in the absence of renal tubular pathology. Children with cystic fibrosis (CF) are at risk of developing electrolyte abnormalities and even PBS may occur.

CASE REPORT

5 months old female infant with a history of two events of dehydration with vomit, refusal to eat, chronic cough, polyuria, malnutrition, metabolic alkalosis, hypokalemia, hyponatremia, hypochloremia and acute renal failure. Chronic cough study was performed, discarding pulmonary tuberculosis, gastroesophageal reflux disease and impaired swallowing. PBS was diagnosed due to hypokalaemic hypochloraemic metabolic alkalosis in the absence of renal tubular pathology. CF was corroborated by electrolytes in sweat and through molecular analysis of the delta F508 mutation. This is one of the few reported cases linking PBS and this mutation.

CONCLUSIONS

In patients with hyponatremic dehydration episodes with hypokalaemic hypochloraemic metabolic alkalosis, PBS should be considered as differential diagnosis. CF could be presented as PBS, mainly in patients younger than 2 years.

Pseudo-Bartter's syndrome revealing cystic fibrosis in an infant caused by 3849 + 1G>A and 4382delA compound heterozygosity

Pseudo-Bartter's (PB) syndrome characterized by hypokalemic metabolic alkalosis and persistent failure to thrive constitutes a rare typical presentation of cystic fibrosis (CF) with prevalence of 16.8%. We present a case of CF presenting with failure to thrive, dehydration, PB syndrome associated with chest infection and primo-colonization with Pseudomonas aeruginosa. Sweat chloride test was 102 mmol/L. DNA analysis identified 2 mutations 3849 + 1G>A (intron 19) and 4382delA (exon 24) present in heterozygous status. To the best of our knowledge, our case is the first reported case in the literature of CF manifested by PB syndrome associated with chest infection and primo-colonization with Pseudomonas aeruginosa.

CONCLUSION

The genotype 3849 + 1G>A/4382delA found in our patient is described for the first time in the literature. It explains the lung involvement with the dehydration and electrolyte disturbances. The role of the mutation in exon 24 in cases of CF with PB syndrome remains to be determined.