Diurnal variation in Eosinophil count is related to:
A i.e. CoisolDiurnal variation in eosinophilic count is reciprocally (invrsely) related to circadian levels of coisolQ.- Suprachiasmatic nuclei (SCN) of hypothalamus is the biological clock responsible for diurnal (circadian) rhythm of ACTH, which intum leads to diurnal rhythm of coisol (glucocoicoid) secretion. In humans, ACTH irregular bursts (episodes of high secretion) are most frequent in early morning and least frequent in the evening. Increased ACTH secretion is not d/t stress of getting up in the morning as these bursts occur before waking up. Even if the length of day is experimentally lengthened to >24 hrs ie if the person is isolated and day's activities are spread over more than 24h, the adrenal cycle also lengthens, but the ACTH burst still occurs during period of sleep. The circadian rhythm of ACTH secretion is present in patients Eosinophil with adrenal insufficiency receiving constant dose of glucocoicoids.- Coisol decrease the number of circulating eosinophils by increasing their sequestration in the spleen & lung. So the diurnal variations in blood eosinophilic counts is inversely related to the circadian coisol levelsQ. The eosinophilic concentration in blood is < 450 / mL usually. A reciprocal relationship to plasma coisol, causes the diurnal eosinophilic concentrations to vary -- 2 fold (40%) with eosinophilic count lowest in morning and peaking in evening.
Coisol
Thyroxine
Growth hormone
Testesterone