Short Reports 469

milk preparations are inadequately diluted, will tend to produce hypernatraemia and uraemia. The child may be able to compensate for a time but the extra fluid losses that will ensue if vomiting and an osmotic diuresis occur, or if fluid losses exceed intake as in increased sweating during a fever or bout of hot weather, will rapidly lead to hypernatraemic dehydration. The importance in recognizing this condition in distinction to the commoner isonatraemic dehydra-tion is the greater mortality and morbidity that accompanies it. Of children so affected, 8 % die and 8 % have residual brain damage (Macaulay and Watson, 1967). Morris-Jones, Houston, and Evans (1967) have shown that 71 % of cases with plasma Na+ greater than 158 mEq/l. have convulsions often during the period of recovery. 87 % have convul-sions if, in addition, blood urea level exceeds 90 mg/100 ml. These may contribute to permanent brain damage and are less likely to occur if plasma osmolality is reduced slowly and rehydration is gradual. The mother of our patient found that she could only satisfy the child's 'hunger ' by greatly increasing the amount of milk powder per feed. The milk that she made up contained 86 mEq/l. sodium, osmolality 1103 mOsm/kg, the normal values being respectively 26 mEq/l. and 315 mOsm/kg. Such a high solute load will stimulate thirst but if the demands of the child are met with further highly concentrated feeds, more solute than fluid is received and a vicious cycle is set up. Hot weather may have been an important contributory factor in our patient. It would perhaps be wise for the manufacturers' instructions on tins of powdered milk to contain a warning about the dangers of exceeding the recom-mended concentration. Summary A 9-month-old infant, admitted to hospital in coma due to hyperosmolar dehydration, was slowly rehydrated over a period of 10 days. Neurological recovery, though slow and interrupted in the second week by the transient appearance of choreo-athetoid movements, was complete after 5 weeks. A regimen of gradual rehydration and slow reduc-tion in plasma osmolality may minimize the con-siderable risk of fits and permanent brain damage attendant upon this condition. This child's condition apparently resulted from the injudicious use of highly concentrated milk feeds during a bout of hot weather when increased insensible fluid losses were not replaced