Adrenal Gland Disorders I Flashcards
Regulation of adrenal corticosteroid production (2)
Cortisol and androgen production are regulated by hormones produced by hypothalamus and anterior pituitary gland
Aldosterone regulated by renin-angiotensin system and plasma potassium
Regulation of aldosterone: Renin-angiotensin system (3)
Major regulator of aldosterone production
Activated in response to decreased blood pressure
Leads to production of Ang II which causes direct (vasoconstriction) and indirect (aldosterone) methods of BP elevation
Mechanism of action of corticosteroids (2)
Bind intracellular receptors
Receptor/ligand complex binds DNA to affect transcription
6 classes of steroid receptors
-Glucocorticoid
-Mineralocorticoid
-Progestin
-Oestrogen
-Androgen
-Vitamin D
Major glucocorticoid actions= CNS (3)
Mood lability
Euphoria/psychosis
Decreased libido
Major glucocorticoid actions= Bone/ connective tissue (4)
Accelerates osteoporosis
- Decreased Serum calcium
- Decreased collagen formation
- Decreased wound healing
Major glucocorticoid actions= CIRCULATORY/RENAL (3)
-Increased Cardiac output
-Increased Blood pressure
-Increased renal blood flow and GFR
Major glucocorticoid actions=IMMUNOLOGICAL (4)
- Decreased capillary dilatate/permeability
- Decreased leucocyte migration
- Decreased macrophage activity
- Decreased inflammatory cytokine production
Major glucocorticoid actions= METABOLIC
(3)
Carbohydrate: Increased blood sugar
Lipid: Increased lipolysis, central redistribution
Protein: Increased proteolysis
Clinical applications of corticosteroids-principles of use (3)
Suppress inflammation
Suppress immune system
Replacement treatment
Clinical applications of corticosteroids- Role in treatment (3)
Allergic disease: asthma/anaphylaxis
Inflammatory disease: rheumatoid arthritis, ulcerative colitis, Crohns disease
Malignant disease
Mineralocorticoid Receptor (MR) (4)
-Kidneys
-Salivary glands
-Gut
-Sweat glands
Effects of aldosterone via Mineralocorticoid Receptor (MR) (5)
- Sodium/Potassium Balance
-K+/H+ excretion
-Na+ reabsorption - Blood pressure regulation
- Regulation of extracellular volume
Primary Adrenal insufficiency (3)
Addison’s disease
Congenital Adrenal Hyperplasia (CAH)
Adrenal TB/malignancy
Secondary (and tertiary) Adrenal insufficiency (3)
Due to lack of ACTH stimulation
Iatrogenic (excess exogenous steroid)
Pituitary/hypothalamic disorders
Primary Adrenal insufficeny- Causes (6)
Autoimmune/addisons
APS 1 + 2
Infections
Drug induced
Genetic
Bilateral adrenal=
-haemorrhage
-metastases
-infiltration
-adrenalectomy
Secondary Adrenal insufficeny- Causes
Pituitary =
-tumours
-surgery
-irradiation
-apoplexy
Trauma
Infections/infiltrations
Sheehans syndrome
Tertiary Adrenal insufficeny- Causes
Hypothalamic=
-tumours
-surgery
-irradiation
Trauma
Infections/infiltrations
Cushings disease
Drug induced
Diagnosis of adrenal insufficiency (8)
biochemistry
-decreased Na, increased K
-hypoglycaemia
SHORT SYNACTHEN TEST
-Measure plasma cortisol before and 30 minutes after iv/im ACTH injection
-Normal: baseline >250nmol/L, post ACTH >550nmol/L
ACTH levels
-Should be very high(causes skin pigmentation)
Renin/aldosterone levels
very high renin, decreased aldosterone
Adrenal autoantibodies
Other (e.g. imaging)
Management of adrenal insufficiency (11)
Do not delay treatment to confirm diagnosis
Hydrocortisone as cortisol replacement
-unwell, give intravenously first
-15-30mg daily in divided doses
-try to mimic diurnal rhythm
Fludrocortisone as aldosterone replacement
-careful monitoring of BP and K
Need education
-‘Sick day rules’
-Cannot stop suddenly
-Need to wear identification
Adrenal Crisis – A life threatening emergency (4)
0.9% NaCl (normal saline)
100mg iv hydrocortisone
Underlying cause/precipitant
If in doubt - TREAT
Addison’s Disease (8)
Commonest cause of primary adrenal insufficiency
-40-60 cases/million per year
-Autoimmune destruction of adrenal cortex
-90% destroyed before symptomatic
-Autoantibodies positive in 70%
Associated with other autoimmune diseases=
-Type 1 DM
-autoimmune thyroid disease
-pernicious anaemia
Clinical Features of Addison’s Disease (5)
Anorexia, weight loss
Fatigue/lethargy
Dizziness and low BP
Abdominal pain, vomiting, diarrhoea
Skin pigmentation
