Thermoregulation of phenylketonuric children

Abstract

Children with untreated phenylketonuria exhibited abnormalities in their thermoregulatory defenses against heat and cold. At 37°, they sweated minimally, but displayed normal cutaneous vasodilatation. At 8°, they shivered and vasocon- stricted normally, yet failed to maintain core temperature. 3-Methoxy, 4-hydroxy-D-mandelic acid (vanmandelic acid, VMA) excretion (at 26°) was more depressed than that of 5-hydroxy-3-indolylacetic acid (5-HIAA) in these subjects. The apparent imbalance between these amines could account, according to the monoamine hypothesis of temperature regulation, for their deficient sweating in 37°, thereby implicating norepinephrine as a possible central transmitter in the sudomotor response of man to heat. On the other hand, the inadequate heat conservation observed at 8° probably was caused by unfavorable physical characteristics, e.g., higher surface area to weight ratio, or smaller subcutaneous insulation. Speculation The present findings suggest a possible involvement of norepinephrine and serotonin in the hypothalamic control of body temperature in man, in that the balance between these monoamines may regulate sudomotor, but not vasomotor responses to head. © 1974 International Pediatric Research Foundation, Inc.