A TWENTY-four-hour rhythm in circulating eosinophiles has been established for certain mammals.1 A decrease in numbers of eosinophiles from 6:30 to 9:30 of the same morning is usually characteristic of this rhythm in mature, healthy humans habitually arising about 7 a. m. This decrease (in the absence of artificial stimulation other than the subject's daily routine) is designated as endogenous eosinopenia.
The presence of a functioning adrenal cortex seems to be necessary for the manifestation of endogenous eosinopenia. It has been reported that patients with panhypopituitarism and Addison's disease fail to exhibit endogenous eosinopenia,2 and it is therefore reasonable to infer that an endogenous-eosinopenia test may serve for clinical evaluation of adrenocortical function. If a decrease in numbers of eosinophiles during the morning hours, subsequent to the initiation of activities after awakening, is accepted as reliable evidence of output of eosinopenic corticoids, it would constitute evidence against the
HALBERG F, ENGEL R, TRELOAR AE, GULLY RJ. ENDOGENOUS EOSINOPENIA IN INSTITUTIONALIZED PATIENTS WITH MENTAL DEFICIENCY. AMA Arch NeurPsych. 1953;69(4):462-469. doi:10.1001/archneurpsyc.1953.02320280050005