Endocrinology Flashcards
Basics of endocrine testing
If you suspect a hormone excess
SUPPRESSION test
If you suspect a hormone deficiency
STIMULATORY test
Except thyroid function
Symptoms of hypothyroidism
dry coarse hair loss of eyebrow hair puffy face goitre bradycardia weight gain constipation frequent/heavy periods or infertility dry skin brittle nails cold intolerance fatigue forgetfulness muscle aches
symptoms of hypothyroidism
hair loss bulging eyes sweating goitre tachycardia weight loss loose or frequent stools oligo-amenorrhoea soft nails warm moist palms tremor of fingertips heat intolerance irritability sleep disturbance muscle weakness
common causes of hypoadrenalism
LOSS OF MINERALOCORTICOID AND GLUCOCORTICOID:
- withdrawal of exogenous -steroid treatment
- 1y AI destruction
- TB
LOSS OF GLUCOCORTICOID ONLY; low ACTH
- 2y pan-hypopituitarism
- HIV/AIDS
causes of hypoadrenalism (less common)
CAH- defect in the enzymes involved in adrenal steroid biosynthesis Adrenoleucodystrophy adrenalectomy metastatic deposits amyloidosis sarcoidosis haemochromatosis adrenal haemorrhage/infarction
clinical features of adrenal insufficiency
LOSS OF GLUCOCORTICOID ACTIVITY: Tiredness, weakness Anorexia, nausea/vomiting Weight loss Hypoglycaemia
LOSS OF ADRENAL ANDROGEN PRODUCTION:
Loss of body hair (female)
LOSS OF MINERALOCORTICOID:
Dizziness
Postural hypotension
EXCESS ACTH
Pigmentation
Describe the provocation test for adrenal insufficiency
Can you normalise the cortisol with a stimulation test?
SynACTHen test
Stress test eg Insulin induced hypoglycaemia
Random cortisol may not be helpful
Pathophysiology of addison’s disease
Destruction of the entire adrenal cortex
No glucocorticoids – cortisol/stress hormone
No mineralocorticoids – aldosterone/maintains blood pressure
No adrenal androgens – loss of body hair in women
Often AI
Difference between cushing’s syndrome and cushings disease
Cushing’s syndrome - glucocorticoid/cortisol excess
Cushing’s disease - glucocorticoid/cortisol excess due to elevated ACTH production from anterior pituitary gland
what 2 things do you need to exclude when diagnosing Cushing’s disease
Exogenous corticosteroid treatment
Pseudo Cushing’s syndrome - depression, alcohol excess, obesity - < 2%
Causes of cushing’s syndrome
Exogenous*
ACTH dependent
Cushing’s disease 68% (pituitary)
Female preponderance (3-8:1), peak age 30-50yrs
Ectopic ACTH production 12%
Classically small cell bronchial carcinoma
ACTH independent
Adrenal gland
Adenoma 10%, carcinoma 8%, hyperplasia 1%
clinical features of cortisol excess
GLUCOCORTICOID EFFECT
-diabetes/glucose intolerance
INHIBITION OF FIBROBLAST FUNCTION
-Truncal obesity – moon face, buffalo hump
Thin skin, bruising, striae
MYOPATHY
-Muscle weakness & wasting –proximal
MINERALOCORTICOID EFFECT
-HT
INHIBITS BONE FORMATION AND INCREASED RESORPTION
-Back pain (osteoporosis & vertebral collapse
DIRECT CNS EFFECT
-Psychiatric disturbances – euphoria, mania, depression
IMMUNOLOGICAL AFFECTS
-Susceptibility to infection
ANDROGENIC ACTIVITY
-Menstrual irregularity; hirsutism; acne
Describe the provocation test for cushing’s
Can you suppress excess cortisol production?
Dexamethasone suppression test
2 stages of Cushing’s syndrome Ix
Confirm glucocortoid excess
Screening
Confirmatory
Differentiate cause
describe the test to screen for glucocorticoid excess
Outpatient screening:
1mg overnight dexamethasone suppression test (2% false negatives, up to 20% false positives in inpatients)
24 hour urinary free cortisol excretion (5-10% false negative rate)
Suppressed cortisol reflects normal biofeedback axis
False positives/pseudo-Cushing’s - depression, obesity, alcoholism, OCP (high CBG), drugs ( dexamethasone metabolism)
