Adrenals Flashcards
What is adrenal insufficiency?
Destruction of adrenal cortex = ↓adrenal hormone output:
- ↓Mineralocorticoids (Aldosterone) → Acidosis
- ↓Glucocorticoids (Cortisol) → ↓blood glucose
- ↓Androgens (Testosterone)
What is Addison’s disease?
Primary autoimmune destruction of adrenal cortex
Deficiency of glucocorticoid + mineralocorticoids
Who typically gets Addison’s?
30-50yo
Female
Metastatic Ca
Infection: TB - most common cause worldwide
What is Secondary Addison’s?
Inadequate pituitary/hypothalamic stimulation of adrenal glands
What causes secondary Addison’s?
STEROIDS Sepsis Metastatic Ca, Lymphoma SLE Antiphospholipid syndrome
How does Addison’s present?
Often diagnosed late Lean: Anorexia, ↓weight Tired Postural hypoT → syncope Tanned: Bronze skin, pigmented palmar creases + buccal mucosa Tearful + weak: Depression GI: N&V, abdo pain, D/C
What are the Sx of hypoaldosteronism?
Hyperk HypoNa Hypovolaemia Metabolic Acidosis (↓HCO3-) Muscle weakness Palpitations & Arrhythmia Cravings for salty food N&V Fatigue,Dizziness
What are the Sx of low cortisol levels?
Fatigue
Dizzy
Confused
Hyper-pigmented elbows, knees
What are the Sx of low androgen levels?
Low sex drive
Little pubic hair (women)
How is Addison’s investigated?
SYNACTHEN TEST- DIAGNOSTIC Bloods: U&E (↓Na + ↑K), ↓Glucose, FBC (↓Hb, ↓Eosin) 9am ↓Cortisol + ACTH levels ABG: Met acidosis Adrenal AutoAbx
What does a 9am cortisol level tell you?
<100 = Addison's likely 100-500 = Synacthen test >500 = Addison's unlikely
What does a 9am ACTH level tell you?
↑= primary cause ↓/n = Secondary cause
How does a Synacthen test work?
Measure plasma cortisol
Give 250ug synacthen IM
Wait 30mins
Measure plasma cortisol
<500 = Addison's >550 = NOT Addison's
How is Addison’s managed?
Hydrocortisone 15-30mg OD
DO NOT stop steroids abruptly + sick day rules apply (double dose)
Fludrocortisone 50-300ug
+/- Androgen replacement
What is an Addison’s crisis? What are the Sx?
Zona glomerulosa & fasiculata destroyed usually triggered by illness demand outweighs production)
- Unresponsive hypotension
- HyperK
- Pain in back/abdo/legs
- D&V = DEHYDRATION
- HypoV = SHOCK
How is an Addison’s crisis managed?
Emergency admission
Tx underlying cause
IM/IV 100mg Hydrocortisone
IV 0.9% NaCl to correct ↓Na+
What is Conn’s Syndrome?
Primary hyper-aldosteronism
80% adrenal adenoma or bilateral adrenal hyperplasia
How does hyper-aldosteronism present?
Asymptomatic HypoK: Weakness, cramps, paraesthesia HyperNa: Lethargy, irritable Met alkalosis HTN Headache
How is hyper-aldosteronism investigated?
Bloods: U&E (↓K+ ↑Na+ )
ABG: Met Alkalosis
Hormones: ↑Aldosterone ↓Renin - if ↑renin then NOT primary cause
HR-CT Abdo: Adenoma
How is Conn’ syndrome managed?
Laparoscopic adrenalectomy
Spironolactone 4weeks post-op
What are secondary causes of hyper-aldosteronism?
Pathology outside of adrenals ↑renin from ↓renal perfusion RAS Accelerated HTN Diuretics Hepatic failure SIGNS: ↓K+ ↑Na+, ↑Aldosterone ↑Renin
What is hyper-aldosteronism?
Excess levels of aldosterone
Produced in zone glomerulosa
Acts on DCT of nephron to stimulate ↑K+ excretion, ↑Na+ and ↑HCO3- retention
What is Cushing’s syndrome?
Chronic excessive cortisol secretion
Decreased feedback to hypothalami-pituitary-axis
Loss of normal circadian rhythm of cortisol secretion
What are the 2 types of Cushing’s?
-ACTH independent: Exogenous steroids!!, adrenal adenoma, adrenal nodular hyperplasia, albright syndrome
ACTH dependent: Cushing’s disease (B/L adrenal hyperplasia), ectopic ACTH producing tumours (SCLC), ectopic CRH production (thyroid & prostate Ca)
What is Cushing’s disease?
Benign pituitary adenoma causes ↑ACTH
What is the feedback loop of ACTH?
1) Hypothalamus secretes CRH
2) Stimulates ant pituitary to produce ACTH
3) Stimulates zona fasciculata in cortex to secrete cortisol
4) High cortisol negative feedback to pituitary to stop producing ACTH
When is cortisol normally high?
Peak 8am
Trough 12am-midnight
What are the Sx of Cushing’s?
↑Weight → Central Obesity/ moon face HyperG HTN Bruises + purple striae Gonadal dysfunction: Erectile dysfunction + irregular periods Muscle weakness + wasting= PROXIMAL MYOPATHY Depression/lethargy/psychosis Acne Infection prone/poor healing
How is Cushing’s syndrome investigated?
OVERNIGHT DEXAMETHASONE SUPPRESSION TEST 24hr Urinary free Cortisol Bloods: FBC, U&E, plasma ACTH + Cortisol ABG: Met Alkalosis ECG: U waves (hypoK)
How is an overnight Dexamethasone suppression test done?
1) 1mg Dex at midnight
2) Measure Cortisol at 8am
Cushing's= ↑Cortisol (No suppression) Normal = Cortisol <50
If positive → High dose Dex test:
- If Cushing’s disease then some sort of suppression
- No suppression in ACTH dependent causes
How is a 24hr Urinary free Cortisol carried out?
1) 3 separate urine collections
2) Measure creatinine excretion at same time
>280/24hours = Cushing’s
How is Cushing’s syndrome managed?
Metyrapone
How is Cushing’s disease managed?
Removal of pituitary adenoma
What do the plasma ACTH + cortisol levels tell you?
- Non-detectable ACTH, ↑Cortisol = INDEPENDENT- ACTH → CT Abdo to find cause
- ↑ACTH ↑Cortisol = DEPENDENT ACTH → Dex suppression test/ CRH test to decide if pituitary or ectopic cause
What is a Phaeochromocytoma?
RARE
Catecholamine producing tumour
Arising from chromatin cells of adrenal medulla
↑Adrenaline + ↑Dopamine
How does a Phaeochromocytoma present?
Episodic headache
Sweating
Tachycardia & HTN
Often precipitated by stress/straining/exercise/beta-blockers/surgery
How is Phaeochromocytoma investigated?
Bloods:
↑Glucose, ↑Ca2+, ↑Hb
24hr urinary collection of met-adrenaline= DIAGNOSTIC
How is a Phaeochromocytoma managed?
1) A-blocker
2) Surgery- Definitive
How can hypoaldosteronism be categorised?
1) Hyporeninemic: ↓ renin
2) Hyperreninemic: ↑ renin
How is hypoaldosteronism investigated?
Plasma renin activity
Serum aldosterone
Serum cortisol
How is hypoaldosteronism treated?
Low K+ diet
Fludrocortisone
AVOID: ACEi & K+ sparing diuretics
Hyporeninemic = Furosemide to correct K+
What are the Sx of HPA suppression?
Adrenal insufficiency Flu-like Sx Fever/chills Headache D&V Weakness Fatigue Vertigo HypoT Depression Salt craving Vitiligo (depigmentation)
When is an Addison’s crisis most likely to occur?
Infection Surgery Burns Pregnancy MI