Cortisol

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.