Hypernatraemia in early infancy.

Hypernatraemia, defined as serum sodium > 150 mmol/l, is still seen frequently in tropical environments. We describe two infants, one with poor fluid intake and excessive wrapping and the other with a high solute intake, both of whom presented in a state of severe hypernatraemia. The pathophysiology of this condition is outlined, as are the major causes, such as sodium overload, inadequate water intake, increased water loss of non-renal origin, increased water loss of renal origin and essential hypernatraemia. The literature is reviewed and the current basis for management is appraised and discussed.