HRE TBL 4 - Adrenals, Hormones and its Disorders

What are the three zones of the adrenal cortex?

Zona glomerulosa, zona fasciculata, zona reticularis

Which hormone is secreted by the zona glomerulosa?

Aldosterone

Which hormone is secreted by the zona fasciculata?

Cortisol

Which hormone is secreted by the zona reticularis?

Androgens (DHEA)

What cells are found in the adrenal medulla?

Chromaffin cells

What is the function of chromaffin cells?

Secrete catecholamines (epinephrine and norepinephrine)

What is the embryological origin of the adrenal cortex?

Mesoderm (intermediate mesoderm)

What is the embryological origin of the adrenal medulla?

Neural crest cells

Which amino acid is the precursor for catecholamines?

Tyrosine

What enzyme converts norepinephrine to epinephrine?

PNMT (Phenylethanolamine-N-methyltransferase)

Which hormone upregulates PNMT activity?

Cortisol

What is the main role of cortisol?

Regulates metabolism and stress response

What is the main role of aldosterone?

Regulates sodium and potassium balance

Which part of the nephron does aldosterone act on?

Distal tubule and collecting duct

What is the role of DHEA?

Precursor to sex steroids

What is the function of the adrenal capsule?

Provides structural support and protection

What are the main arterial supplies of the adrenal gland?

Superior, middle, and inferior suprarenal arteries

What is the venous drainage of the right adrenal gland?

Right suprarenal vein into the inferior vena cava

What is the venous drainage of the left adrenal gland?

Left suprarenal vein into the left renal vein

Which part of the adrenal gland is richly innervated?

Medulla

What type of fibers innervate the adrenal medulla?

Preganglionic sympathetic fibers

What does ACTH stimulate?

Cortisol and androgen production in adrenal cortex

Which hormone stimulates aldosterone release?

Angiotensin II

What is the hypothalamic hormone in the HPA axis?

CRH (Corticotropin-releasing hormone)

What is the anterior pituitary hormone in the HPA axis?

ACTH (Adrenocorticotropic hormone)

What is the target of ACTH in the adrenal gland?

Zona fasciculata and zona reticularis

What is the function of cortisol on glucose metabolism?

Increases gluconeogenesis and raises blood glucose

What is the cortisol feedback mechanism?

Negative feedback on CRH and ACTH

What is Cushing’s syndrome?

Excess cortisol

What is Cushing’s disease?

Excess ACTH from a pituitary adenoma

What are the clinical features of Cushing’s syndrome?

Central obesity, moon face, striae, hypertension

What is the first-line test for Cushing’s syndrome?

Low-dose dexamethasone suppression test

What is Conn’s syndrome?

Primary hyperaldosteronism

What are the features of Conn’s syndrome?

Hypertension, hypokalemia, metabolic alkalosis

What is Addison’s disease?

Primary adrenal insufficiency

What are symptoms of Addison’s disease?

Fatigue, hypotension, hyperpigmentation

What is the key electrolyte disturbance in Addison’s?

Hyponatremia and hyperkalemia

What is the synacthen test used for?

Assess adrenal cortisol production

What is the main cause of Addison’s disease?

Autoimmune destruction of adrenal cortex

What is phaeochromocytoma?

Catecholamine-secreting tumor of adrenal medulla

What are symptoms of phaeochromocytoma?

Palpitations, sweating, episodic hypertension

How is phaeochromocytoma diagnosed?

Plasma free metanephrines or 24-hour urinary catecholamines

What is the embryological origin of the adrenal vasculature?

Develops from surrounding mesenchyme

Which zone of the adrenal cortex is last to mature postnatally?

Zona reticularis

What is the function of the fetal adrenal zone?

Produces DHEA-S for placental estrogen synthesis

What happens to the fetal adrenal zone after birth?

It regresses (involutes)

Which enzyme is deficient in 90% of congenital adrenal hyperplasia cases?

21-hydroxylase

What is the role of 21-hydroxylase?

Converts progesterone to deoxycorticosterone and 17-OH-progesterone to 11-deoxycortisol

What are signs of 21-hydroxylase deficiency?

Virilization, salt wasting, low cortisol

What is the treatment for CAH?

Glucocorticoid ± mineralocorticoid replacement

What is adrenal crisis?

Acute deficiency of cortisol, often life-threatening

How is adrenal crisis treated?

IV hydrocortisone and fluid resuscitation

What is the role of the RAAS in adrenal hormone regulation?

Stimulates aldosterone release during low BP or Na+

What is the rate-limiting step in steroid hormone synthesis?

Transport of cholesterol into mitochondria (StAR protein)

What is the function of 11β-HSD2?

Converts cortisol to cortisone in aldosterone-sensitive tissues

What is the role of dexamethasone suppression testing?

Differentiates ACTH-dependent and ACTH-independent Cushing’s

What does a high ACTH with low cortisol suggest?

Primary adrenal insufficiency

What does a low ACTH with low cortisol suggest?

Secondary adrenal insufficiency

What adrenal hormone helps maintain vascular tone?

Cortisol

What are common causes of secondary adrenal insufficiency?

Pituitary tumors, steroid withdrawal

What is the treatment for Addison’s disease?

Hydrocortisone and fludrocortisone

What is the main action of catecholamines?

Fight or flight response: increased HR, BP, glucose

What enzyme catalyzes tyrosine to DOPA?

Tyrosine hydroxylase

What is the difference between adrenal androgens and gonadal androgens?

Adrenal androgens are weaker (e.g., DHEA)

Where does the zona fasciculata lie?

Between zona glomerulosa and zona reticularis

What is the function of the adrenal cortex?

Secretes steroid hormones (cortisol, aldosterone, androgens)

What is the function of the adrenal medulla?

Secretes catecholamines

What is the most common cause of Cushing’s syndrome overall?

Iatrogenic (exogenous corticosteroids)

What is the classic triad of phaeochromocytoma?

Headache, palpitations, sweating

What is the role of metyrapone?

Inhibits cortisol synthesis

What is the role of ketoconazole in adrenal disease?

Blocks steroidogenesis

Which enzyme is involved in aldosterone synthesis?

Aldosterone synthase

What structure surrounds the adrenal gland?

Fibrous capsule

What condition may result from sudden steroid withdrawal?

Adrenal crisis

What is the best initial imaging for adrenal tumors?

CT scan of the abdomen

What is adrenal incidentaloma?

Adrenal mass found incidentally on imaging

What is the functional assessment for incidentaloma?

Cortisol, aldosterone, catecholamines

What is adrenal vein sampling used for?

Localizing source in primary aldosteronism

What is the most common adrenal tumor in children?

Neuroblastoma

Which adrenal hormones are regulated by ACTH?

Cortisol and androgens

Which adrenal hormone is not regulated by ACTH?

Aldosterone

What is the significance of the adrenal medulla acting like a sympathetic ganglion?

Releases neurotransmitters into the bloodstream

What is the result of excess aldosterone on electrolytes?

Hypokalemia and hypernatremia

What is the clinical significance of cortisol’s circadian rhythm?

Highest in the morning; guides steroid dosing

What hormones are elevated in stress?

Cortisol, adrenaline, noradrenaline

What is the fetal adrenal gland important for in pregnancy?

Supports placental estrogen production

How is cortisol transported in the blood?

Bound to corticosteroid-binding globulin (CBG)

What is the effect of cortisol on protein metabolism?

Increases protein breakdown

What is the effect of cortisol on fat metabolism?

Promotes lipolysis

Which cells produce ACTH?

Corticotrophs in the anterior pituitary

Which test evaluates HPA axis suppression in steroid users?

Synacthen test

What is a major side effect of long-term glucocorticoid use?

Osteoporosis

What role do adrenal hormones play in immune function?

Cortisol suppresses immune responses

How does cortisol affect insulin?

Causes insulin resistance

Which disorder presents with hyperpigmentation and low cortisol?

Addison’s disease

How is adrenal medullary hormone secretion controlled?

Sympathetic nervous system (preganglionic input)

What is the role of DHEA in puberty?

Contributes to adrenarche (pubic hair, body odor)

What hormones are secreted from the adrenal cortex?

Aldosterone, cortisol, DHEA

What hormones are secreted from the adrenal medulla?

Epinephrine and norepinephrine

What is the adrenal response to acute stress?

Secretion of adrenaline and cortisol