l 2 For references

We agree with Lapatsanis et al. that cystic fibrosis should be included in the differential diagnosis of unexplained hypochloraemia. On the other hand, we do not think that one should exclude cystic fibrosis in cases of water intoxication, as was our case. In the case reported by Lapatsanis et al., and in the case reported by Barbero and Sibinga,l the patients suffering from cystic fibrosis who showed hyponatraemia and hypochloraemia also had severe dehydration. The reason for the hyponatraemia was excessive loss of fluids containing large amounts ofsalt. In water intoxication the situation is the opposite. These children are overhydrated and not dehydrated. While correcting abnormal electrolytes in our patient, she also lost 5 % of her body weight. She had dilutional hypo-natraemia. Thus, when dealing with hyponatraemia and hypo-chloraemia in patients suffering from water intoxication, one does not have to rule out cystic fibrosis if the patient is overhydrated and not dehydrated