Adrenal Insufficiency Flashcards
Define
Deficiency of adrenal cortical hormones
→ Mineralocorticoids, glucocorticoids and androgens
Anyone on exogenous steroids for long enough to suppress the pituitary–adrenal axis, or who has overwhelming sepsis, or has metastatic cancer may suddenly develop adrenal insufficiency with deadly hypovolemic shock
Causes
Most common cause is iatrogenic
Primary causes are RARE
(Addison’s annual incidence is 8/1 000 000)
- Primary (Addison’s) – autoimmune (>70%)
- Infections – TB (commonest cause worldwide), also
- meningococcal septicaemia, CMV (in HIV pts)
- Infiltration – metastasis, lymphomas, amyloidosis
- Infarction – 2ndary to thrombophilia
- Inherited – Adrenoleukodystrophy, ACRH-R mutation
- Surgical – after bilateral adrenalectomy
- Secondary due to pituitary/hypothalamic disease
Addison’s
Destruction of adrenal cortex leads to glucocorticoid (cortisol) and mineralocorticoid (aldosterone) deficiency
- AI destruction
- TB of adrenal glands
(e.g. sudden cessation of long term steroid therapy)
Symptoms
Lean, tanned, tired, tearful ± weakness, anorexia, faints, myalgia/arthralgia
CHRONIC
Non-specific, vague symptoms: dizziness, anorexia, ↓weight, lethargy, weakness
GI: D&V, abdominal pain
Psych: Depression, psychosis, low self esteem
ACUTE (Addisonian crisis) → acute adrenal insufficient with major haemodynamic collapse often precipitated by stress (e.g. infection or surgery)
Signs
Postural hypotension
↘ Increased pigmentation – buccal mucosa, scares, skin
creases nails, pressure points
Melanocytes stimulated by ↑ACTH levels, cross-reacts ↘ Loss of body hair in women (androgen def)
↘ Associated AI conditions (e.g. vitiligo)
Addisonian crisis → hypotensive shock, tachycardia, pale, cold, clammy, oliguric
↑Pigmentation as ↑POMC leads to ↑ACTH and MSH. Increase in MSH leads to darkened skin
Investigations
To confirm the diagnosis
9 am Serum Cortisol (< 100 nmol/L is diagnostic of adrenal insufficiency)
- > 550 nmol/L makes adrenal insufficiency unlikely
Short Synacthen Test
- IM 250 mg tetrocosactrin (synthetic ACTH)
- Serum cortisol < 550 nmol/L at 30 mins indicates adrenal failure
Identify the level of the defect in the hypothalamo-pituitary-adrenal axis
- HIGH in primary disease
- LOW in secondary
- Long Synacthen Test
- 1 mg synthetic ACTH administered
- Measure serum cortisol at 0, 30, 60, 90 and 120 minutes
- Then measure again at 4, 6, 8, 12 and 24 hours
- Patients with primary adrenal insufficiency show no increase after 6 hours
Identify the cause
- Autoantibodies (against 21-hydroxylase)
- Abdominal CT or MRI
- Other tests (adrenal biopsy, culture, PCR)
Check TFTs
Investigations in Addisonian crisis
- FBC (neutrophilia –> infection)
- U&Es
- High urea
- Low sodium
- High potassium
- CRP/ESR
- Calcium (may be raised)
- Glucose - low
- Blood cultures
- Urinalysis
- Culture and sensitivity
Management
Addisonian Crisis
- Rapid IV fluid rehydration
- 50 mL of 50% dextrose to correct hypoglycaemia
- IV 200 mg hydrocortisone bolus
- Followed by 100 mg 6 hourly hydrocortisone until BP is stable
- Treat precipitating cause (e.g. antibiotics for infection)
Monitor
Chronic Adrenal Insufficiency
Replacement of:
- Glucocorticoids with hydrocortisone (3/day)
- Mineralocorticoids with fludrocortisone
Hydrocortisone dosage needs to be increased during times of acute illness or stress
NOTE: if the patient also has hypothyroidism, give hydrocortisone BEFORE thyroxine (to prevent precipitating an Addisonian crisis)
Advice
- Have a steroid warning card
- Wear a medic-alert bracelet
- Emergency hydrocortisone on hand
Complications
HYPERKALAEMIA
Death during Addisonian crisis
Prognosis
Adrenal function rarely recovers
Normal life expectancy if treated
Autoimmune Polyendocrine Syndrome
Type 1 - autosomal recessive disorder caused by mutations in the AIRE gene. Consists of the following diseases:
- Addison’s disease
- Chronic mucocutaneous candidiasis
- Hypoparathyroidism
Type 2 - also known as Schmidt’s Syndrome
- Addison’s disease
- Type 1 Diabetes
- Hypothyroidism
- Hypogonadism
