Hyposecretion of anterior pituitary hormones Flashcards
What is the difference between primary, secondary and tertiary endocrine gland disease?
Primary = problem with the endocrine gland/hormone it releases Secondary = problem with the pituitary gland/hormone it releases Tertiary = problem with the hypothalamus
What is the term given to decreased production of ALL anterior pituitary hormones?
Panhypopituitarism
State the two types of panhypopituitarism
Congenital (rare) or acquired
What causes congenital panhypopituitarism and state the symptoms?
Usually due to mutations of transcription factor genes needed for normal anterior pituitary development (e.g. PROP1 mutation)
- Usually deficient in GH and at least 1 more anterior pituitary hormone
- Short stature (in children)
- Hypoplastic anterior pituitary gland on MRI
List the 8 potential causes of acquired panhypopituitarism
- Tumours: hypothalamic e.g. craniopharyngiomas; pituitary e.g. adenomas, metastases, cysts
- Radiation: hypothalamic/pituitary damage (GH most vulnerable, TSH relatively resistant)
- Infection (e.g. meningitis)
- Traumatic brain injury
- Infiltrative disease: often involves pituitary stalk (e.g. neurosarcoidosis)
- Inflammatory (hypophysitis)
- Pituitary apoplexy
- Peri-partum infarction (Sheehan’s syndrome)
Give the main symptoms of panhypopituitarism, with respect to the different deficient hormones
Secondary hypogonadism => Reduced libido, Secondary amenorrhoea, Erectile dysfunction
Secondary hypoadrenalism (cortisol deficiency) => e.g. Fatigue
Secondary hypothyroidism => e.g. Fatigue
What is Sheehan’s syndrome?
Specifically describes post-partum hypopituitarism secondary to a post partum haemorrhage
(Less common in developed countries)
WHY?
Normally, the anterior pituitary enlarges in pregnancy (lactotroph hyperplasia), therefore, a PPH => pituitary infarction
Describe the presentation of Sheehan’s syndrome
- Lethargy, anorexia, weight loss due to TSH/ACTH/(GH) deficiency
- Failure of lactation due to prolactin deficiency
- Failure to resume menses post-delivery
- Posterior pituitary usually not affected
What is pituitary apoplexy?
Intra-pituitary haemorrhage or (less commonly) infarction.
- Often dramatic presentation in patients with pre-existing pituitary adenomas
- May be first presentation of a pituitary adenoma
- Can be precipitated by anti-coagulants
Describe the presentation of pituitary apoplexy
- SEVERE sudden onset headache
- Visual field defect – compressed optic chiasm => bitemporal hemianopia
- Cavernous sinus involvement may lead to diplopia (CN 4/6), ptosis (CN 3)
Why is a single measurement of most pituitary or target endocrine gland hormones not useful?
Most hypothalamic hormones tend to be released in pulses, cortisol varies at different times of the day, and T4 has a 6 day half-life
What type of test do you do to test if someone is producing an abnormal amount of a hormone? Give examples for the different hormones.
Stimulated (‘Dynamic’) Pituitary Function Tests
- Insulin induced hypoglycaemia (<2.2mM) stimulates GH release and ACTH release (cortisol is measured)
- TRH (iv) stimulates thyrotrophin/TSH
- GnRH (iv) stimulates FSH and LH release
How might a radiological diagnosis for hypopituitarism prove useful?
Pituitary MRI may reveal a haemorrhage, adenoma, empty sella with a thin rim of pituitary tissue
Describe the treatment for hypopituitarism, in the case for each deficient hormone
HORMONE REPLACEMENT THERAPY
ACTH: Hydrocortisone tablet + check serum cortisol
TSH: Thyroxine/T4 + check serum T4
LH/FSH (women): Oestrogen, progestogen + check symptom improvement, withdrawal bleeds
LH/FSH (men): Testosterone gel/patch/injection + check symptom improvement, serum testosterone
GH: daily GH subcutaneous injection + monitor IGF 1 and adjust dose; check growth chart for children
List some other potential causes of short stature
Genetic Malnutrition Malabsorption Emotional deprivation Endocrine disorders
Skeletal dysplasias (e.g. achondroplasia caused by mutation in Fibroblast Growth Factor Receptor 3)
