Cushing's, Hypopituitarism and Diabetes Insipidus Flashcards
Cushing’s syndrome is cause by what?
Excess cortisol
Ass well as cortisol excess, what else is found in excess in Cushing’s syndrome?
- Androgens
- Mineralocorticoids
What is the result of excess androgens in Cushing’s syndrome?
- Virilism
- Hirsutism
- Acne
- Oligo/amenorrhoea
What is the result of excess mineralocorticoid in Cushing’s syndrome?
- Hypertension
- Oedema
Due to altered carbohydrate and lipid metabolism in Cushing’s syndrome, there is an associated with which two conditions?
- Diabetes
- Obesity
What are the conditions associated with protein loss experienced in Cushing’s syndrome?
- Myopathy
- Osteoporosis
- Thin skin
Why does hypertension occur in Cushing’s syndrome?
Excess mineralocorticoid causes Na+ and K+ retention
Does Cushing’s syndrome have an impact on mental health?
Yes
Altered psyche, psychosis and depression
Which type of myopathy is associated with Cushing’s syndrome?
Proximal myopathy
Why may obesity have a postitive outcome in Cushing’s syndrome?
Obesity increases bone desnity counteracting an increased osteoporosis risk
How may thin skin present in Cushing’s syndrome?
- Bruising
- Striae
By which eye sign can Cushing’s disease be characterised?
Conjunctival oedema (chemosis)
Frontal balding in women is a sign of which condition?
Cushing’s syndrome
Which complication must not be forgotten when assessing any fractures to the femoral head/hip in patients with Cushing’s syndrome?
Avascular necrosis
When Cushing’s syndrome is suspected, which test would be done first?
Steroid suppression test
e.g. Dexamethasone
(a urine free cortisol test can also be done)
What is the expected outcome in a steroid suppression test assuming the patient achieves a normal result?
Reduced cortisol levels
Which screening tests exist to test for Cushing’s disease?
- Steroid suppression with dexamethasone (1mg at night then test cortisol in the morning, <50nmol/l normal, >100nml/l abnormal)
- Urine free cortisol (total <250 normal, cortisol/creatinine ratio <25 normal)
- Diurnal cortisol variation (midnight vs 8am)
What is the definitive test for Cushing’s syndrome?
2 day 2mg/day low dose dexamethasone suppression test
Cortisol <50nmol/L 6 hours after the last dose confirms no Cushing’s
Most Cushing’s has what cause?
Pituitary tumour
(in these instances the condition is referred to as Cushing’s disease)
What are the main causes of Cushing’s syndrome?
- Pituitary tumour
- Adenoma of adrenal glands
- Ectopic cortisol release from the thymus, lung or pancreas
Pseudo-Cushing’s has what causes?
- Alcohol
- Depression
- Steroid medication
Can the cause of Cushing’s (pituitary tumour, ectopic cortisol release, adrenal adenoma) be determined from a low dose dexamethasone cortisol suppression test?
No
All of these will show an abnormal result
Can the cause of Cushing’s (pituitary tumour, ectopic cortisol release, adrenal adenoma) be determined by measuring ACTH levels?
Yes/Potentially
- Pituitary tumour - ACTH is raised (<300)
- Adrenal adenoma - ACTH is decreased (<1)
- Ectopic cortisol release - is raised (>300)
Can the cause of Cushing’s (pituitary tumour, ectopic cortisol release, adrenal adenoma) be determined from a high dose dexamethasone cortisol suppression test?
Potentially
- Pituitary - Cortisol suppressed by around 50%
- Adrenal adenoma - No change
- Ectopic cortisol release - No change
Which arteries pass by either side of the pituitary gland?
Internal carotid arteries
What are the treatment options for pituitary tumour causing Cushing’s disease?
Hypophysectomy
(external radiotherapy if recurrence)
What is the treatment for Cushing’s disease if the cause is a adrenal tumour?
Uni or bilateral adrenalectomy
Pan hypopituitarism is a condition involving what?
Inadequate or absent production of anterior pituitary hormones
What are the main causes of hypopituitarism?
- Pituitary tumours
- Secondary metastatic tumours
- Local brain tumours
- Granulomatous disease
- Vascular diseases
- Hypothalamic diseases
- Iatrogenic
- Autoimmune
- Infection
Which type of granulomatous disease may be associated with hypopituitarism?
- TB
- Histiocytosis X
- Sarcoidosis
What are the signs and symptoms of hypopituitarism?
- Menstrual irregularities
- Infertility/impotence
- Gynaecomastia
- Central obesity
- Loss of facial hair
- Loss of axillary and pubic hair
- Dry skin and hair
- Hypothyroid faces
- Growth retardation in children
What are the replacement therapy options of hypopituitarism?
Thyroxine 100-150mcg
Hydrocortisone 10-25mg
Desmospray (nasal) or tablets - ADH
GH nightly SC - GH
HRT/Oestrogen/Progesterone - Females
Testosterone - Males
Growth hormone in adults has which positive effects?
- Decreases abdominal fat
- Increases muscle mass and strength
- Improves cardiac function
- Decreases cholesterol and LDL
- Increases bone density
What are the risks of testosterone replacement?
- Prostate enlargement
- Polycythaemia
- Hepatitis (only oral tablets)
What is polycythaemia?
When the bone marrow produces exessive quantities of red cells
What are the common causes of diabetes insipidus?
- DIDMOAD
- Idiopathic
- Trauma
- Rare causes - tumour, sarcoid, external irradiation, meningitis
How can diabetes insipidus be diagnosed?
Water deprivation test
What is the treatment for diabetes insipidus?
Desmopressin (an antidiuretic)
Desmospray, desmopressin oral tablets, desmopressin IM injection
