Chronic metabolic alkalosis in a newborn infant caused by congenital chloride diarrhea

The case of a female preterm infant (gestational age 36 weeks) is described, who presented with abdominal distension, diarrhoea, dehydration and metabolic alkalosis at the fifth day of life. After different diagnostic tests had been performed, congenital chloride diarrhoea was suspected and chloride supplementation was started. However, this diagnosis could not be confirmed, until the measurement of electrolytes in faeces had been improved. Then, we found the typically elevated fecal chloride concentration (130-153 mmol/l) which exceeded the sum of the fecal concentration of sodium (64-90 mmol/l) and potassium (28-35 mmol/l). The chloride supplementation was increased to 6 mmol/kg/d NaCl and 2 mmol/kg/d KCl. The most recent examination at the age of 1 year revealed the girl to be in good clinical condition, with normal growth and psychomotor-development and with no evidence of renal impairment.