Cortisol Disorders + Adrenal Medulla

Hypercortisolism and Cushing Syndrome

Hypercortisolism is excess cortisol production;

oversecretion from the adrenal cortex, usually from a tumor, causes Cushing’s Disease

long-term corticosteroid use can produce Iatrogenic Cushing’s Syndrome, which accounts for over 90% of cases

Fat is released from limbs, but collects around the trunk, in the face causing “moon facies,” on the back of the neck causing “buffalo hump”

Muscle wasting occurs and blood glucose levels rise, known as Hyperglycemia

Causes water retention in the kidneys by retention of sodium

Raises blood pressure

Increases risk of infections

Decreases osteoblast activity and interferes with absorption of dietary calcium

Treated by removing the ACTH- or cortisol-secreting tumor; Possibly decreasing corticosteroids

HPA Axis Suppression

When discontinuing corticosteroid therapy, the dose must be tapered off over a period of weeks or months

• HPA axis negative feedback loops essentially halt production of CRH and ACTH, known as HPA Axis Suppression, because of high doses of corticosteroids

• The patient’s body is unable to produce adequate cortisol for several weeks or months after stopping the therapy

• Cortisol is vital to survival when a patient is subjected to stress such as surgery, trauma, or illness

Adrenal Crisis

Inability to produce adequate cortisol when faced with a serious stressor;

causes low blood glucose, low blood pressure, fainting, vomiting, and possible convulsions

can be fatal if untreated

Slowly reducing the dose of corticosteroid to give a patient’s HPA axis adequate time to resume normal levels of CRH, ACTH, and cortisol production

Adrenal Insufficiency (Addison Disease)

involves hyposecretion of cortisol and aldosterone;

causes include abnormal adrenal gland development, deficiency of enzymes needed to make the hormones, or immune destruction of the gland;

disrupts fluid, electrolyte, and acid-base homeostasis and increases risk of an adrenal crisis

Androgenic Steroids

Sex hormones produced in small amounts in males and females by the adrenal cortex as byproducts of the pathway that produces cortisol

affect reproductive organs and many other tissues and can be converted in circulation to testosterone or estrogen

Adrenal Medulla and Chromaffin Cells

The adrenal medulla consists of neuroendocrine cells called Chromaffin Cells, which are derived from nervous tissue

Stimulated by acetylcholine released by preganglionic neurons of the sympathetic nervous system

Chromaffin cells are similar to postganglionic neurons, except they secrete their products into the bloodstream

Chromaffin cells secrete Catecholamines, chiefly Epinephrine and Norepinephrine

Hormonal epinephrine and norepinephrine have almost the same effects on target cells as the neurotransmitters of the sympathetic nervous system

Effects of Epinephrine and Norepinephrine

Increase rate and force of heart contraction

dilate bronchioles(airway passage in the lungs)

constrict blood vessels supplying skin, digestive organs, and urinary organs (increase blood pressure)

dilate blood vessels supplying skeletal muscles

dilate pupils

decrease digestive and urinary functions

prolong the sympathetic response and can affect cells not directly innervated by the sympathetic nervous system

Regulated by the sympathetic nervous system and by hormones of the HPA axis

ACTH can directly stimulate epinephrine synthesis by chromaffin cells and cortisol increases synthesis of enzymes needed to produce epinephrine