Endocrinology (Adrenal) Flashcards
cushings disease vs cushings syndrome
Cushings syndrome is a set of sign and symptoms due to prolonged exposure to glucocorticoids which may be endogenous or exogenous
Cushings disease is where a pituitary tumour secretes excess adrenocorticotropic hormone (ACTH) leading to the increased release of cortisol - leads to cushings syndrome
most common causes of exogenous cushings
most common causes of exogenous glucocorticoids
e.g. taking corticosteroids for too long
most common causes of endogenous cushings
ACTH-secreting pituitary adenomas are the most common endogenous cause of Cushing’s syndrome
ACTH-dependent cushings
These are endogenous causes that lead to inappropriately raised ACTH levels resulting in excess glucocorticoid production. They may be:
- Cushing’s disease – ACTH-secreting pituitary adenoma
- Ectopic ACTH-secreting tumours (e.g. small cell lung cancer)
ACTH-independent
These are endogenous causes that lead to excess glucocorticoid production despite having low or normal ACTH levels. They may be:
- Exogenous glucocorticoids
- A unilateral adrenal adenoma
- An adrenal carcinoma
presentation of cushings syndrome
- Moon face
- Truncal obesity
- Red face
- Buffalo hump
- Purple striae
- High glucose
- Acne
- Ostoeporosis
- Depression
- Easy burising
- Muscle weakness (proximal)
- irregular periods or amenorrhoea
- Hirsutism
Pituitary tumour: bitemporal hemianopia
Pseudo-Cushing’s syndrome
- Often due to alcohol excess, severe depression/anxiety, obesity, or poorly-controlled diabetes mellitus
- Avoidance of alcohol results in normal cortisol levels after a few days
investigations for cushings
Specific
- Overnight dexamethasone supression test
- 24-hour urinary free cortisol
Others
- FBC
- UEs - hypokalaemic metabolic alkalosis
- Blood glucose -raised
Imaging
- pituitary MRI
Dexamethasone suppression tests
Administering dexamethasone should lead to decreased cortisol secretion due to negative feedback on the hypothalamus and pituitary gland. This negative feedback should lead to reduced cortisol-releasing hormone (CRH) from the hypothalamus and ACTH from the pituitary, leading to low cortisol levels.
The dexamethasone suppression tests are based on this principle and help to localise where the problem is.
how many types of Dexamethasone suppression tests
2
- Low dose dexamethasone suppression test
- High dise dexamethasone suppression test
Low-dose dexamethasone suppression test
- Cortisol suppressed (low) – normal
- Cortisol not suppressed (high/normal) – Cushing’s syndrome
High-dose dexamethasone suppression test:
- This is done if the low-dose test shows Cushing’s syndrome may be present
- Cortisol suppressed and ACTH suppressed – Cushing’s disease
- Cortisol not suppressed but ACTH suppressed – adrenal adenoma
- Cortisol not suppressed and ACTH not suppressed – ectopic ACTH
Cortisol suppressed and ACTH suppressed
Cushings disease - pit adenoma
Cortisol not suppressed but ACTH suppressed
adrenal adenoma
Cortisol not suppressed and ACTH not suppressed
ectopic ACTH
management of cushings
1st-line: manage underlying cause, examples are:
- Cushing’s disease: transsphenoidal pituitary adenomectomy
- Ectopic ACTH: manage cause (e.g. chemotherapy/radiotherapy/surgery for cancer)
complications of cushings
- Diabetes mellitus
- Metabolic syndrome
- Hypertension
- Obesity
- Hyperlipidaemia
- Thrombophilia
Adrenal insufficiency
is characterised by insufficient steroid hormone production from the adrenal glands. There are usually reduced amounts of glucocorticoids (cortisol) and/or mineralocorticoids (aldosterone), which are both types of steroid hormones.
types of adrenal insufficiency
Primary
Secondary
Tertiary
Primary adrenal insufficiency (Addison’s disease):
- The problem is within the adrenal cortex itself leading to impaired steroid hormone synthesis and secretion
Secondary adrenal insufficiency:
The problem is with the pituitary gland and there is inadequate adrenocorticotropic hormone (ACTH) release, leading to impaired steroid hormone synthesis and secretion
Tertiary adrenal insufficiency:
The problem is with the hypothalamus and there is inadequate corticotropin-releasing hormone (CRH) release, leading to impaired steroid hormone synthesis and secretion
causes pf primary adrenal insufficiency
- Addison’s disease – around 80% of cases
- Trauma
- Tuberculosis
- HIV
- Congenital adrenal hyperplasia
pathophysiology of addisons
This describes the autoimmune destruction of the adrenal glands
Causes of secondary adrenal insufficiency
- Pituitary tumours – some can lead to hypopituitarism
- Trauma
- Radiotherapy
- Neoplasia
presentation of adrenal insufficiency
- Fatigue
- Weight loss
- Loss of appetite
- Hyperpigmentation:
- Craving salt
- Vague abdominal pain:
- Nausea and vomiting
- Loss of pubic hair:
- Orthostatic hypotension:
- Presenting in an Adrenal crisis