The response of malnourished babies to cold.

1. Twelve malnourished Jamaican children, aged 4-16 months, were studied before and after treatment, to see whether malnutrition impaired their response to cold.2. When they were studied in the post-absorptive state and in a neutral thermal environment, they had a lower rate of oxygen consumption per kg body weight, a slower pulse rate, lower body temperatures, lower R.Q., and evidence of a smaller peripheral blood flow on admission to hospital than they did after recovery.3. The malnourished children failed to increase their heat production above resting levels at 25 degrees C, and their rectal temperature fell at a rate of 1 degrees C/hr in spite of a further decrease in peripheral circulation.4. When they had recovered they maintained their body temperature within the normal range on exposure to this temperature, while increasing their heat production by 20%. The thermogenesis was apparently of the non-shivering type.5. There was evidence of increased metabolic activity in the interscapular brown fat pad at 25 degrees C both on admission and before discharge. In the malnourished children this activity was not sufficient to produce a measurable increase in total oxygen consumption.6. Interscapular brown fat was examined at autopsy in thirteen malnourished and fifteen well nourished children aged 1-24 months. Lipid depletion was found in this tissue in the former but not in the latter. This may explain the impaired response of the malnourished child to cold.