Endocrinology Flashcards
What hormones are produced by the adenohypophysis?
FSH/LH Prolactin Growth hormone Thyroid stimulating hormone ACTH (Cortisol)
What is a primary endocrine gland disease?
Where the gland itself does not work correctly
e.g. the thyroid of the adrenal gland
What is a secondary endocrine gland disease?
Where the signal from the pituitary gland doesn’t work so the signal is not sent to the gland
What is a tertiary endocrine gland disease?
Where the hypothalamic releasing hormones don’t work: this is not measured clinically
What is panhypopituitarism?
A decreased production of all anterior pituitary hormones or of specific hormones
Can be congenital or acquired
What is congenital panhypopituitarism? How common is it? What causes it? What are the symptoms?
A deficiency in growth hormones and at least 1 more pituitary hormone. It is rare
Usually due to mutations of transcription factor genes needed for normal pituitary development- e.g. PROP1 mutation
Short stature- plus other features
Hypoplastic anterior pituitry gland on MRI
What are the possible causes of acquired panhypopituitarism?
1) Tumours hypothalamic, pituitary 2) Radiation hypothalamic/pituitary damage 3) Infection e.g. meningitis 4) Traumatic brain injury 5) Infiltrative disease often involves pituitary stalk e.g. neurosarcoidosis 6) Inflammatory (hypophysitis) 7) Pituitary apoplexy haemorrhage (or less commonly infarction) 8) Peri-partum infarction (Sheehan's syndrome)
What hormone is deficient in secondary hypogonadism? What are the symptoms?
FSH/LH
Reduced libido
Secondary amenorrhoea
Erectile dysfunction
What hormone is deficient in secondary hypoadrenalism? What are the symptoms?
ACTH (cortisol deficiency)
Fatigue
What hormone is deficient in secondary hypothyroidism? What are the symptoms?
TSH
Fatigue
Weight gain
What is Sheehan’s syndrome? When and why does this occur?
Post-partum hypopituitarism secondary to hypotension (post-partum haemorrhage)- happens around delivery of baby
Less common in developed countries
Adenohypophysis enlarges in pregnancy (lactotroph hyperplasia)
Post-partum haemorrhage leads to pituitary infarction
What is the presentation of Sheehan’s syndrome?
Lethargy, anorexia, weight loss - TSH/ACTH/(GH) deficiency
Failure of lactation - PRL deficiency
Failure to resume menses post-delivery
Posterior pituitary usually not affected
What is pituitary apoplexy? How does it present?
Intra-pituitary haemorrhage or (less commonly) infarction. It is a medical emergency
SEVERE sudden onset headache, visual field defect- compressed optic chiasm (bitemporal hemianopia)
Cavernous sinus involved; may lead to diplopia or ptosis
What properties of the different pituitary hormones makes them difficult to measure?
Cortisol varies depending on the time of day
T4 circulating half-life of 6 days
FSH/LH are cyclical
GH/ACTH are pulsatile
What biochemical tests can you perform for hypopituitarism?
- Basal plasma concentrations of pituitary or target endocrine gland hormones
- Insulin-induced hypoglycaemia stimulates GH and ACTH release
If you are deficient in ACTH what is used as a replacement and what should you check?
Replace: Hydrocortisone
Check: Serum cortisol
If you are deficient in TSH what is used as a replacement and what should you check?
Replace: Thyroxine
Check: Serum free T4
If a woman is deficient in LH/FSH what is used as a replacement and what should you check?
Replace: HRT (E2 plus progestagen)
Check: Symptom improvement, withdrawal bleeds
If a man is deficient in LH/FSH what is used as a replacement and what should you check?
Replace: Testosterone
Check: Symptom improvement, serum testosterone
If you are deficient in GH what is used as a replacement and what should you check?
Replace: Growth hormone
Check: IGF-1, growth chart (children)
What is the result of growth hormone deficiency in children?
Results in short stature
2SD < mean height for children that age and sex
What are the causes of short stature? (7)
1) Genetic Down's syndrome, Turner's syndrome, Prader-Willi syndrome 2) Emotional deprivation 3) Systemic disease Cystic fibrosis, Rheumatoid arthritis 4) Malnutrition 5) Malabsorption Coeliac disease 6) Endocrine disorders Cushing's syndrome, hypothyroidism, GH deficiency, poorly controlled T1DM 7) Skeletal dysplasias Achondroplasia, osteogenesis imperfecta
What hormone inhibits the release of growth hormone?
Somatostatin
What mutation causes achondroplasia?
Mutation in fibroblast growth factor receptor 3 (FGF3)