Supplementary water for breast-fed babies in a hot and dry climate--not really a necessity.

even in healthy infants,5 unmasks the true nature of the underlying disorder in many such infants who, already profoundly salt-depleted and unable to tolerate further fluid loss, sink rapidly into severe dehydration and shock. The aldosterone content of breast milk is unknown, but it may, as in the case of progesterone, reflect blood concentration.6 The possibility that this or other breast milk steroids might exert a therapeutic effect on breast-fed infants with SL-CAH cannot be excluded, but given the profound salt wasting present in these infants, the plasma concentration of such hormones after absorption from the gastrointestinal tract would seem to be insufficient to influence renal sodium conservation. SL-CAH should be included in the differential diagnosis of failure to thrive at the breast, and plasma electrolytes determined before the introduction of formula which may precipitate vomiting. For this reason, although breast feeding should always be encouraged, it is particularly desirable in babies with suspected SL-CAH while the results of confirmatory diagnostic tests are awaited and treatment is begun.