Pituitary physiology and disease Flashcards
What hormones are made by what parts of the pituitary gland?
Anterior- FSH/LH, ACTH, TSH, Prolactin, GH Posterior- ADH, oxytocin
What are the clinical presentations of pituitary tumours?
Space occupying lesion affect- headache, vision loss. Hormone hypersecretion. Hormone deficiency states. Visual field defects- bilateral hemianopia
What is Cushing’s disease?
Excessive anterior pituitary ACTH secretion not to be confused with Cushing’s syndrome. This leads to overproduction of cortisol from the adrenal cortex.
What are the signs and symptoms of Cushing’s disease?
Excessive weight, buffalo hump, moonface, abdominal striae, centripetal obesity, glucose intolerance, impotence
What test is used to diagnose Cushing’s disease?
Overnight dexamethasone suppression test. Dexamthasone should reduce secretion of corticotrophin from the hypothalamus and ACTH from the anterior pituitary gland. Resulting in a decrease in production of cortisol. High dose dexamethasone should be enough to reduce the cortisol levels in Cushing’s disease. Will do nothing to reduce cortisol in Cushing’s syndrome.
What are the signs and symptoms of GH excess?
GH excess leads to acromegaly which presents with: change in appearance, excessive sweating, weight gain, increased hand and foot size, prominent supraorbital ridge, prognathism, interdental separation. thick greasy skin
What is the diagnostic test for GH excess?
Oral glucose tolerance test. Glucose should inhibit GH secretion.
What impacts do FSH/LH tumours of the pituitary gland have?
Simply space occupying
What is the most common pituitary adenoma?
Prolactinoma
What are the signs of a prolactinoma?
Hypogonadism, osteoporosis, infertility, oligo/amenorrhea, erectile dysfunction, galactorrhea, reduced facial hair
What is the treatment of a prolactinoma?
Dopamine inhibits prolactin and so dopamine agonists can be prescribed
What is the arginine test used for?
It is the second line test for GH deficiency. Arginine is administered and a subsequent rise in GH should be noted.
What is the clomifene test used for?
To assess gonadotrophin deficiency. Clomifene is a competitive inhibitor of oestrogen binding at the hypothalamus and pituitary, and should therefore trigger LH/FSH release
What is the difference between primary and secondary hypopituitarism?
Primary- Issue with pituitary
Secondary- Issue with hypothalamus
What is the characteristic sequence of failure in hypopituitarism?
GH-> LH-> FSH-> TSH-> ACTH. PROLACTIN IS RARELY AFFECTED.
Give 9 causes of hypopituaritism.
- Pituitary adenoma
- Parapituitary tumours
- Cranial radiotherapy
- Pituitary infarction- apoplexy, sheehan’s syndrome
- Infiltration- haemochromatosis, sarcoidosis
- Empty sella syndrome
- Infection
- Trauma
- Hypothalamic deficiency syndrome (Kallman’s syndrome)
What features will be notable in deficiency of the following hormones?
- GH
- LH/FSH
- ACTH
- TSH
- Prolactin
- ADH
- Short stature in children. In adults- decreased exercise tolerance, decreased muscle mass, depression, increased CVD risk
- Oligo/amenorrhoea, decreased libido
- As per secondary hypoaldosteronism
- Hypothyroidism
- No lactation
- Polyuria and polydipsia
What are the 3 most important investigations to undertake in hypopituartism?
- Basal hormone levels
- Assessing posterior pituitary function
- MRI + CONTRAST of the pituitary +/- biopsy
Does management of hypopituartism usually revolve around replacing the pituitary hormone or its target? What is the important exception to this?
The target hormone
GH
What is the management of hypothyroidism due to hypopituartism?
Levothyroxine
What is the management of sex hormone deficiency in hypopituartism?
Oetsrogen and testosterone can be administered. Gonadotrophin is required to induce ovulation however.
What is the most commonly used steroid in the mangement of ACTH deficiency?
Hydrocortisone TDS
What QOL survey is used as criteria in treatment of GH deficiency? What score indicates a requirement to treat?
ADULT GROWTH HORMONE DEFICIENCY ASSESSMENT
>/=11
How long does treatment for GH deficiency go on for and how is this divided?
9 months
3 months titration and 6 months therapeutic range
