Hyponatremic dehydration and metabolic alkalosis as dominant manifestation in cystic fibrosis infants with mild phenotype - a case series

Abstract

Introduction. Due to increased losses of chloride and sodium in the sweat, children with cystic fibrosis (CF) are predisposed to develop episodes of hyponatremic/hypochloremic dehydration with hypokalemia and metabolic alkalosis when they sweat excessively. Even the patients with mild phenotype may have such episodes of dehydration and salt depletion. Outline of cases. Six cases of pancreatic sufficient (PS) CF patients complicated with episodes of severe hyponatremic dehydration with metabolic alkalosis in infancy are presented. The mean age was 6.3 ± 2.16 months at admission. All the cases had no symptoms suggestive of CF before admission. The most common clinical symptoms at the time of hospitalization were vomiting, anorexia, weight loss, dehydration, irritation, or lethargy. Mean values of blood pH, serum bicarbonate, sodium, chloride, and potassium (mmol/l) were as follows: 7.59 ± 0.06, 41.73 ± 5.78, 117.52 ± 2.88, 66.0 ± 11.58 and 2.62 ± 0.37, respectively. Sweat chloride test was pathological and ranged 69–120 mmol/L. The determination of fecal elastase-1 proved that they were PS (values > 200 μg/g stool). CF transmembrane conductance regulator gene analyses in six cases confirmed the diagnosis of CF; namely, patients were compound heterozygotes for F508del and other rare mutation or compound heterozygotes for two rare mutations. Conclusion. Distinctive about these cases is that they were PS and had very mild presentation of CF. Without these episodes of dehydration, these patients would have remained undiagnosed until later age. CF should be considered in infants and children presenting with hypoelectrolytemia and metabolic alkalosis even in the absence of respiratory or gastrointestinal symptoms.

Keywords

• cystic fibrosis
• CFTR genotype
• hyponatremic dehydration
• metabolic alkalosis