Addison's and Cushing's Flashcards
What are the 3 layers of the adrenal gland?
What is secreted from each?
Zona glomerulosa → Mineralocorticoids → aldosterone
Zona fasciculata → Glucocorticoids → cortisol
Zona reticularis → Androgens
Medulla → epinephrine and norepinephrine
What is secreted from the Adrenal Medulla?
Catecholamines
Briefly explain the HPA axis in a healthy individual
What is Adrenal insufficiency?
Where the adrenal glands do not produce enough steroid hormones, particularly cortisol and aldosterone
What is primary adrenal insufficiency?
What is the specific name given to the disease?
Damage to the adrenal glands (most commonly autoimmune) resulting in reduced secretion of cortisol and aldosterone
Addison’s Disease
List 4 causes of primary adrenal insufficiency
- Autoimmune TB
- Haemorrhage
- Adrenoleukodystrophy
- Ketoconazole
What is secondary adrenal insufficiency?
A result of inadequate ACTH stimulating the adrenal glands, resulting in low cortisol release.
Due to loss or damage to the pituitary gland
List 4 causes of secondary adrenal insufficiency
- Surgery to remove a pituitary tumour
- Infection
- Loss of blood flow
- Radiotherapy
- Sheehan’s syndrome
What is Sheehan Syndrome?
Hypopituitarism caused by ischemic necrosis due to blood loss and hypovolemic shock during and after childbirth
Also known as postpartum pituitary gland necrosis
What is tertiary adrenal insufficiency?
Result of inadequate CRH release by the hypothalamus
What is the most common cause of tertiary adrenal insufficiency?
Explain why and state how this can be prevented
Long term oral steroids use (>3wks) causing suppression of the hypothalamus
When steroids are suddenly withdrawn the hypothalamus does not “wake up” fast enough and endogenous steroids are not adequately produced
Therefore, long term steroids should be tapered slowly to allow time for the adrenal axis to regain normal function
List 4 symptoms of hypoadrenalism
- Fatigue
- Cramps and weakness
- Abdominal pain
- Reduced libido
- Salt craving
- Anorexia, nausea, and vomiting, diarrhoea
- Weight loss
List 2 signs of hypoadrenalism
- Bronze hyperpigmentation (ACTH stimulates melanocytes to produce melanin)
- Hypotension (esp postural hypotension)
What investigations may you do if you suspect hypoadrenalism?
Highlight first line investigation
1. Early morning serum cortisol (8-9am) ☆
- Short synacthen test
- Serum ACTH
What is the test of choice to diagnose adrenal insufficiency
Explain this test
A short synacthen test (performed in the morning)
- Give synacthen (synthetic ACTH)
- Measure blood cortisol at baseline, 30 and 60mins after
- Synthetic ACTH will + healthy adrenals to produce cortisol
- Failure of cortisol to rise indicates 1o adrenal insufficiency (Addison’s)
What laboratory findings may indicate hypoadrenalism?
lowserum sodium, chloride, and bicarbonate
high serum potassium
mild-moderate hypercalcemia (10–20%)
Normocytic anemia, relative lymphocytosis, moderate eosinophilia
You are a medical student on the wards. The consultant asks you to take bloods from a patient who he suspects has adrenal insuffiency.
What colour tube(s) are you going to use and why?
Gold top tube- Cortisol (< 50 nmol/L is diagnostic)
Purple tube - ACTH
Treatment of Adrenal insufficiency?
- Fluid resuscitation
- im/iv hydrocortisone (replace cortisol)
- Fludrocortisone (replace aldosterone)
How does a patient with adrenal insufficency alert emergency services that they are dependent on steroids, if they are acutely unwell
Patients are given a steroid card and an emergency ID tag
What findings of ACTH would be indicative of a primary vs secondary cause of hypoadrenalism?
1o → high ACTH, pituitary is trying hard to stimulate adrenals without any (-) feedback in the absence of cortisol
2o → low ACTH, as the adrenals are not producing cortisol because they arn’t being stimulated by ACTH
List 2 Antibodies which are present in 80% of autoimmune adrenal insufficiency
- adrenal cortex antibodies
- 21-hydroxylase antibodies
What is the purpose of CT’s and MRIs in hypoadrenalism
CT / MRI adrenals → adrenal tumour,s haemorrhage, tructural pathology (not recommended by NICE for autoimmune adrenal insufficiency)
MRI pituitary → pituitary pathology
What is Cushings syndrome?
Excess cortisol
- Chronic state produced by chronic glucocorticoid excess signs
- Loss of normal feedback mechanisms of HPA
- loss of circadian rhythem of cortisol secretion
What is Cushings disease?
Specific condition where a pituitary adenoma secretes excessive ACTH
List 6 signs of Cushings syndrome
(MC SWAG BOBB)
- Moon face
- Central Obesity
- Striae (purple abdominal)
- Wasting (proximal limb muscles)
- Atrophy (skin and muscles)
- Glucose↑
- Buffalo hump (fat pad on upper back)
- Osteoporosis
- BP↑
- Bruises and poor healing
List 6 symptoms of Cushings syndrome
(WARM GP)
- Weight↑
- Acne
- Recurrent archilles tendon rupture
- Mood change (depression, lethargy, irritable)
- Gonadal dysfunction (irregular menses, hirsuism, erectile dysfunction)
- Proximal weakness
List 4 metabolic effects of raised cortisol on the body
- Hypertension
- Cardiac hypertrophy
- Insulin resistance
- Hyperglycaemia (Type 2 Diabetes)
- Obesity
- Elevated blood TAGs
List 4 causes of Cushing’s Syndrome
- Exogenous steroids (esp long term high dose steroids)
- Cushing’s Disease (pituitary adenoma - ↑ACTH)
- Adrenal Adenoma (hormone secreting adrenal tumour)
- Paraneoplastic Cushing’s
What is Paraneoplastic cushing’s?
What is the most common cause?
Excess ACTH released from a cancer (not of the pituitary), which stimulates excessive cortisol release. “ectopic ACTH”
Small Cell Lung Cancer is the most common cause
What is the test of choice for diagnosing Cushing’s Syndrome?
What is this?
Dexamethasone Suppression Tests (DST)
Low dose test → if normal, Cushing’s can be excluded. If abnormal → high dose test to determine cause
Patient takes dexamethasone (synthetic cortisol) at night, cortisol and ACTH is measured in the morning. Aim is to find out if dexamethasone suppresses normal morning spike of cortisol
Explain the DST and state what findings would be inidcative of the various causes
What is the second line investigation for Cushings?
List 4 other potential investigations
24-hour urinary free cortisol = alternative to the DST to diagnose, but does not indicate underlying cause
- FBC and electrolytes: ↑wcc and ↓K+ if aldosterone is also secreted by an adrenal adenoma
- MRI brain: for pituitary adenoma
- Chest CT: for small cell lung cancer
- Abdominal CT: for adrenal tumours
What is the treatment for Cushings Syndrome?
Treat the underlying cause:
- Iatrogenic: stop medications if possible
- Cushings disease: transphenoidal removal of pituitary adenoma
- Adenoma or Ectopic: surgical removal of tumour
