DISTURBANCES IN THE FUNCTIONS OF THE SUPRARENAL GLANDS
- Adrenal glands are bilateral structures located at the apex of each kidney
- They are composed of two parts:
- Medulla
- Inner portion → secretes epinephrine and norepinephrine
- Part of the sympathetic nervous system
- Cortex
- Outer part
- Composed of three layers that produce hormones:
- Zona glomerulosa (outer) → produces mineralocorticoids
- Zona fasciculata → produces glucocorticoids
- Zona reticularis → produces androgens
Hormone action
- Mineralocorticoids
- Main hormone is aldosterone
- Regulates potassium and sodium levels and water balance
- Aldosterone promotes sodium retention in the kidneys with potassium loss
- Glucocorticoids
- Main hormone is cortisol
- Respond to stress and are essential for survival
- Involved in carbohydrate, protein and fat metabolism
- Androgens
- Most important is DHEA
- Contributes to development of sex characteristics
Pheochromocytoma
- Benign tumor of chromaffin cells in the adrenal medulla and sympathetic ganglia
- Results in hyperproduction of catecholamines (epinephrine and norepinephrine)
- Symptoms = tachycardia, headache, diaphoresis (profuse sweating), hypertension, pallor, weight loss, hyperglycemia
Primary adrenal insufficiency (Addison’s disease)
Primary disorder so you have high ACTH so ↑POMC so ↑MSH so you experience hyperpigmentation
- Deficiency of adrenal cortical hormones (mainly mineralocorticoids and glucocorticoids) with elevated ACTH levels due to lack of feedback inhibition
- Caused by destruction of the adrenal gland due to:
- Autoimmune adrenalitis
- Hemorrhagic infarction
- Carcinoma
- Infection (TBC, meningococci, cytomegalovirus)
- Tuberculosis
- Symptoms:
- Low cortisol
- Fatigue, nausea, vomiting, muscle weakness, weight loss
- Low aldosterone
- Hyponatremia → due to increased loss of sodium in urine
- Hyperkalemia → due to reduced excretion of potassium
- Dehydration (iso/hypotonic) → due to increased water loss in urine
- Orthostatic hypotension → shock
- Syncope
- Increased ACTH levels
- Hyperpigmentation → bronzed skin
- Occurs only in primary adrenal insufficiency
- Melanocyte-stimulating hormone (MSH) and ACTH share the same precursor (pro-opiomelanocortin)
- Higher levels of ACTH mean higher levels of POMC which can lead to more MSH → stimulates melanocytes