Cortisol
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Clinic
- Cortisol = Hydrocortisone producedmainly by the zona fasciculata of the adrenal cortex in the adrenal gland
- Its release is increased in response to stress and low blood-glucose concentration.
- It functions to
- Increase blood sugar through gluconeogenesis
- Suppress the immune system
- Aid in the metabolism of fat, protein, and carbohydrates.
- Decrease bone formation.
Disorders of cortisol production
- Primary hypercortisolism (Cushing's syndrome): Excessive levels of cortisol
- Secondary hypercortisolism (Pituitary tumor resulting in Cushing's disease, pseudo-Cushing's syndrome)
- Primary hypocortisolism (Addison's disease, Nelson's syndrome): Insufficient levels of cortisol
- Secondary hypocortisolism (pituitary tumor, Sheehan's syndrome)
Factors increasing cortisol levels
- Viral infections increase cortisol levels through activation of the HPA axis by cytokines.
- Intense (high VO2 max) or prolonged aerobic exercise transiently increases cortisol levels to increase gluconeogenesis and maintain blood glucose; however, cortisol declines to normal levels after eating (i.e., restoring a neutral energy balance)
- Severe trauma or stressful events can elevate cortisol levels in the blood for prolonged periods.
- Low-carbohydrate diets cause a short-term increase in resting cortisol (~3 weeks), and increase the cortisol response to aerobic exercise in the short- and long-term.
- Increase in the concentration of ghrelin, the hunger stimulating hormone, increases levels of cortisol.