Comparative physiological observations on prickly heat, mammillaria and anhidrotic heat exhaustion

Abstract

A raised sweat chloride and a decreased conductivity of heat through the skin were present in cases of mammillaria whether the anhidrotic syndrome was also present or not. The sweat chloride began to rise while prickly heat was present and before the mammillaria had become visible. A raised sweat chloride might thus be associated with severe prickly heat since it was often after severe prickly heat that mammillaria developed. In some cases of severe prickly heat the sweat chloride was high even though mammillaria failed to develop later, and it is possible that this occurs more often in a dry climate than a humid one. A high sweat pH approaching neutrality, and a high skin temperature, were found only in anhidrotic heat exhaustion. The reduction in sweating in areas of active prickly heat was confirmed. After exposure for 2 months to a hot and humid environment the cutaneous insensible perspiration in normal subjects was unaltered or decreased. It was increased in every case of acquired anhidrosis, and in two out of four cases of prickly heat. In cases of anhidrotic heat exhaustion there was a delay in diuresis after the ingestion of water and a prolongation of the antidiuretic action of pitressin. There was some evidence that the delay in diuresis may persist for many months even after return to a temperate climate.