Non functioning tumours and pituitary hormone testing Flashcards
Where do the anterior and posterior pituitary originate from?
Anterior originates from the roof of the mouth where Rathke’s pouch forms and this becomes the anterior pituitary
Posterior pituitary originates from the floor of the 3rd ventricle and develops from brain tissue. It forms the hypothalamus with axons coming down into the posterior pituitary.
What is a craniopharyngioma?
What are the effects & at what ages is it commonly found?
Benign tumours - Squamous epithelial remnants of Ranthke’s pouch.
They can be adamantinous where they form cysts and calcification or squamous papillary where they are well circumscribed.
Effects:
- Raised intracranial pressure
- Visual disturbances
- Growth failure
- Pituitary hormone deficiency
- Weight increase
Peak ages 5-14 and 50-74
What is Rathke’s cyst?
What symptoms?
Derived from remnants of Rathke’s pouch.
Single layer of epithelial cells with mucoid, seroud or cellular components in cyst fluid.
Mainly asymptomatic so usually patients go home but are told to look out for signs of hypopituitarism
Symptoms (if present):
- Headache
- Amenorrhea
- Hypopituitarism
- Hydrocephalus (CSF in brain)
What is a meningioma? What are the symptoms?
Second most common tumour in the region (most common in pituitary adenoma). Usually a complication of radiotherapy so seen in children who have had cancers or haematological malignancies and present later in life with headaches etc.
Symptoms
- Visual disturbance
- Endocrine dysfunction
What is lymphocytic hypophysitis?
When does it present?
Inflammation of the pituitary gland due to autoimmune reaction
RARE
Lymphocytic adenohypophysitis is more common in women and age of presentation around 35 (women) and 45 (men)
What is a non-functioning pituitary adenoma (NFPA)
When and how is it commonly diagnosed?
What symptoms might someone present with?
Benign growth in the pituitary gland that does not produce any excessive hormone into the blood and is not cancerous.
It is the most common pituitary mass and accounts for 14-28% of clinically relevant pituitary adenomas and 50% of pituitary macroadenomas.
Diagnosis between 20-60 years in 78% of cases
50% of diagnosis are incidental findings.
Symptoms:
50% present with visual disturbances (these need surgery urgently)
50% will have headaches
How do people with pituitary masses present?
What are some conditions caused by functioning pituitary adenoma?
- Visual field defects
- Headaches
- Cranial nerve palsy and temporal lobe epilepsy
- CSF rhinorrhea (runny nose) if tumour erodes down into sinuses.
Hormonal effects for a functioning pituitary
- Cushings, macroprolactinoma, acromegaly.
Pituitary can also be damaged causing deficiency in certainn pituitary hormones.
Why do we not carry out MRI on someone for pituitary tumour unless we are very certain they have a tumour?
We do not carry out pituitary MRI unless we have good indication of the person having pituitary tumour as 10-20% people will have asymptomatic pituitary masses which are not causing problem.
Testing would cause unnecessary worry and stress for patient.
What visual defect would a chiasmal compression from a pituitary tumour cause?
Bitemporal hemianopia (tunnel vision)
Why is it difficult to test pituitary function?
- There are many hormones: GH, LH, FSH, ACTH, TSH, ADH
- Some patients may be borderline deficient
- There are circadian rhythms and pulsatile secretions of hormones so we need to carry out testing at the right time of the day
General rule = if target organ is working then pituitary is working and we dont need to investigate.
What test do we carry out if someone is suspected to have GH deficiency?
Insulin stress test where we make the person hypoglycaemic by giving insulin and we expect to see GH levels rise if patient is functioning normal.
Glucagon test = glucagon stimulates GH secretion so we can measure this and see if they have GH deficiency.
If someone presents with symptoms of thyroid disorder, how do we differentiate between the cause of the thyroid problem using thyroid hormone levels? (pituitary, thyroid or hypothalamus problem)
- Primary hypothyroidism → Raised TSH low fT4
- Hypopituitary → Low fT4 and normal or low TSH
- Graves disease → Suppressed TSH high fT4
- TSHoma (rare) → High fT4 with normal or high TSH
- Hormone resistance → High Ft4 with normal or high TSH
If a man presents with gonadal problem, how do we differentiate between the cause?
Measure LH, FSH, testosterone
- Primary hypogonadism → Low Testosterone, raised FSH/LH.
- Hypopituitary → Low Testosterone and normal or low LH & FSH
- Anabolic steroid use → Low Testosterone & suppressed LH
Measure 0900h fasted T and LH & FSH in pituitary disease
Differentiating between causes of adrenal insufficiency using hormone levels
0900 cortisol and synacthen (synacthen similar to ACTH which should stimulate cortisol release)
Primary AI: low cortisol, high ACTH, poor response to synacthen
Hypopituitarism: Low cortisol, low or normal ACTH, poor response to synacthen
What is the effect of IGF-1 in the body?
- Stimulate systemic growth
- Increase in peripheral glucose uptake
- Decreased production of hepatic glucose causing better insulin sensitivity
