Adrenal Flashcards
What are the layers that secrete the adrenal hormones?
- Zona Glomerulosa -> mineralcorticoids -> aldosterone
- Zona Fasiculata -> glucocorticoids -> Cortisol
- Zona Reticularis -> androgens -> sex hormones (dihydrotestosterone & estradiol)
- Medulla -> epinephrine & norepinephrine
Which enzyme is responsible for the formation of the sex hormones & cortisol?
17a -> for both
21 & 11B -> cortisol only
Which enzymes are responsible for the formation of aldosterone?
21 & 11B
if there is a deficiency in enzyme 17a, what will be affected?
- NO cortisol & NO sex hormones
- aldosterone will increases -> Conn’s disease
if there is a deficiency in enzyme 21, what will be affected?
- NO aldosterone & NO cortisol
- increase in sex hormones -> adrenogenital syndrome
if there is a deficiency in enzyme 11B, what will be affected?
- NO aldosterone & NO cortisol but their precursors are present
- so there is an increase in sex hormones but no syndrome
What will occur in case of any adrenal hormone deficiency?
- positive feedback to the pituitary gland to secrete more ACTH -> which will cause hyperplasia in the adrenal gland -> leading to an increase in the only normal pathway while the rest are still deficient
What is the function of aldosterone?
- Na & H20 retention
- K excretion
- increases blood volume -> increases blood pressure
- vasoconstriction
What are the factors that increase aldosterone?
- dehydration
- hypovolemia
- hyponatremia (decreased sodium)
- hypotension
- renin from the kidney -> increases angiotensinogen (liver) -> increases angiotensin I -> ACE (lungs) -> ANGIOTENSIN II -> increases aldosterone
What are the metabolic effects of cortisol?
1- on fat: mobilization
- if excess -> deposition in abnormal sites (face, neck, & abdomen)
2- on proteins -> anabolism
- if excess -> catabolism (muscle wasting & osteoporosis)
3- on carbs -> increase gluconeogenesis
- in excess -> decreased glucose uptake by muscles & hyperglycemia
4- on electrolytes -> Na & H20 retention & K excretion
5- on blood -> increases RBCs & decreases eosinophils & lymphocytes
6- androgenic
7- anti-allergic -> decreases Ag-Ab reaction
8- anti-inflammatory
- in excess -> decreases fibrous tissue formation (collagen) & destroys elastic fiber & decreases inflammatory cells
What are the functions of the Zona Reticularis hormones?
androgens & small amounts of estrogen & progesterone
- dehydro-epiandrosterone -> enhances protein anabolism & promotes development of secondary sexual characters
- end product (ketosteroids) are excreted in the urine (used for diagnosis)
What are the causes of Conn’s syndrome?
Primary hyperaldosteronism
- adenoma
- hyperplasia of Zona glomerulosa
- carcinoma
What is the clinical picture of Conn’s syndrome?
1- hypertension: due to sodium retention
2- hypokalemia
- apathy, paresthesia
- arrhythmias (extrasystoles)
- atony of the intestines (constipation & paralytic ileus)
- muscle weakness & episodic paralysis (dyspnea)
- impaired glucose tolerance test
3- alkalosis (metabolic)
- due to heavy loss of H+ with K in urine -> tetany due to decreased ionized calcium
4- NO EDEMA
- K diuresis -> polyuria
- impaired tubular reabsorption of water
What investigations are done in Conn’s disease?
1- BIOCHEMICAL
- hypokalemia (N = 3.5 - 5)
- hypernatremia (N=140)
- alkalosis (increased serum HC03) (N= 22 - 30)
2- URINARY
- polyuria -> due to K diuresis
- increased K & decreased sodium
- increased aldosterone excretion (N= 12-50 ug/24h)
3- MEASURE PLASMA LEVELS
- decreased Renin
- increased aldosterone despite high Na load
4- US & adrenal CT -> for adenoma & carcinoma
How is Conn’s syndrome treated?
- Surgical removal of adenoma
- MEDICAL in bilateral & hyperplasia -> Amiloride (K-sparing diuretics)
What are the causes of Cushing’s syndrome?
ENDOGENOUS tumors
1- pituitary adenoma -> secondary hypercortisol
2- adrenal -> primary Cushing’s syndrome
3- paramalignant -> increases ACTH -> increases cortisol
EXOGENOUS -> corticosteroids (most imp)
What are the general clinical features of Cushing’s syndrome?
1- abnormal fat deposition
- face -> moon face
- neck -> buffalo hump
- abdomen -> trunkal obesity (Samboxa shooed obesity)
2- protein catabolism
- Muscle wasting & weakness
- osteoporosis
3- hyperglycemia -> steroid diabetes (one of the most imp causes of secondary diabetes)
4- Hypertension (sodium & water retention) & hypokalemia (polyuria & alkalosis)
5- plethoric face due to polycythemia (increase RBCs)
6- in females -> amenorrhea, acne, & hirsutism
- in males -> decreased libido, impotence
7- decreases collagen & fibrous tissue formation (delayed wound closure)
- bruises & purpura
- STRIA RUBRA (rupture of weakened s.c tissue due to collagen deficiency)
8- decreases WBCs (eosinophils & lymphocytes) -> more prone to infection
8-
What are the clinical features that will help us identify the etiology?
- virilization -> adrenal carcinoma (increase cortisol & androgens)
- hypokalemic alkalosis, myopathy, & hyperpigmentation -> ectopic (paramalignant)
- in children -> adrenal carcinoma
- in males -> ectopic
- in women -> pituitary
What are the investigations that suggest Cushing syndrome?
1- hypokalemic alkalosis & hypernatremia
2- increased RBCs & decreased lymphocytes & eosinophils
3- impaired glucose tolerance or DM
4- osteoporosis or unexpected fractures (in young patients too young for osteoporosis)
Which investigations confirm the diagnosis of Cushing syndrome?
1- plasma cortisol level (N= 5 - 20) -> taken at 8am then 4pm
- should be higher in the morning & 50% less in the afternoon
- loss of diurnal variation suggests persistent elevation
2- urinary steroid excretion (24hr collection)
- measure hydroxycorticosteroids or free urinary cortisol
- if found in excess overnight
- > do LOW DOSE dexamethasone suppression test (1mg ORAL at night)
- after suppression test take a sample at 8am it SHOULD BE <7 (if not then Cushing’s)