COR | Cortisol

Cortisol (COR) is the main glucocorticoid produced in the adrenal cortex. Cortisol levels are most often tested in the diagnosis of diseases caused by excess cortisol production in Cushing's syndrome, lack of adrenal steroids in Addison's disease, and for monitoring treatment. Elevated serum levels are found in stress response, psychiatric illness, obesity, diabetes, alcoholism, and pregnancy, which may present diagnostic difficulties in Cushing's syndrome. Low cortisol levels are found in patients with rare adrenal enzyme deficiencies and chronic stress. Normally, the highest secretion of cortisol is found in the second half of the night, and the peak of cortisol concentration is reached in the early morning. After that, the cortisol concentration starts to fall during the day, and the lowest concentration is reached in the first half of the night. Thus, circadian variations in cortisol secretion and effects of stress must be taken into account when sampling cortisol.