Pit pathology Flashcards
What are the three broad categories of pathology of the pit gland?
Too little hormone
Too much hormone
Too big
How do you test for too much/little hormone?
Blood tests
How do you test for a pit gland that is too big?
Imaging- MRI or US
In a dynamic endocrine test for too much hormone what do you do?
See if you can suppress the hormone
In a dynamic endocrine test for too little hormone what do you do?
See if you can stim hormone
Give examples of a dynamic endocrine test for too little hormone?
Insulin stress test
Water deprivation test
Synacthen test
How does the insulin stress test work?
Drop blood glucose to <2.2 using insulin to stim cortisol and GH release
What is a safer alternative to the insulin stress test?
Prolonged glucagon test
What should cortisol rise to in the insulin stress test for it to be normal?
> 500
What should GH rise to in the insulin stress test for it to be normal?
> 7 micrograms/l
How does the water deprivation test work?
Deprive of liquid for 8h and check is Ur/Serum osmol ratio is >2.
What does a Ur/Serum osmol ratio of <2 suggest?
Diabetes insipidus
When do you not need to do a water deprivation test?
If the baseline reading is >2
What is the second part of the water deprivation test?
Give desmopressin. If it improves after DDAVP then problem with pit/hypo if not problem with kidneys.
What are two causes of too little pit hormone?
Panhypopituitarism
Tumour in one cell type squeezing out others
What is the main cause of too little pit hormone?
Panhypopituitarism
What causes panhypopituitarism?
Pit tumour Pit apoplexia Lung/breast met Infection- TB/sarcoidosis Vascular disease Trauma/ iatrogenic Hypothalamus disease- TB/meningitis Autoimmune Sheehan's syndrome Congenital Drugs
What is Sheehan’s syndrome?
Necrosis of pit due to blood loss during birth
How can panhypopituitarism present?
Menstrual irregularities Infertility/impotence Gynaecomastia Abdo obesity Dry skin/ pale Hypothyroid face Growth retardation Lack of sexual charcteristics
How can you test for panhypopituitarism?
Blood tests for: TSH/fT4 LH/FSH (naturally increased post menopause) Prolactin IGF-1 Test/oestrogen Random cortisol Synacthen/ITT for cortisol Symptoms of DI
How do you treat panhypopituitarism?
Hormone replacement: Thyroxine Hydrocortisone- Give first ADH GH Testosterone- in males Oestrogen/progesterone- in females
How important is GH in adults?
Not needed but good for quality of life.
How is testosterone normally given?
IM injection or daily topical
What are some side effects of testosterone?
Enlarged prostate- Does not cause cancer
Hepatitis from tablets.
Blood count issues
Fusion of growth plates
What two sizes of pit tumours are there?
Microadenoma <1cm
Macroadenoma >1cm
What to categories of pit tumours are there?
Functioning
Non-functioning
What pathology can non-functioning pit tumours cause?
Too big
Too little hormone
What pathologies can a ‘Too big’ tumour cause?
Compression of optic chiasm
Compression of CN 3, 4, 6
Compression of carotid artery
What pathologies can a ‘Too little hormone’ cause?
Hypoadrenalism Hypothyroidism Hypogonadism GH defects DI- rare as anterior tumours rarely impact on post
What pathologies can a functioning pit tumour cause?
Too much hormone: Prolactin GH ACTH TSH
What is the most common functional pit adenoma?
Prolactinoma
Are TSH secreting tumours common or rare?
Rare
What is a craniopharyngioma?
Tumour derived from the remnants of Rathke’s pouch
How do craniopharyngiomas present?
Cystic
5-15 and 60-70
Headaches + visual disturbances
What can cause increased prolactin production?
Prolactinoma
Physio- Breastfeeding, pregnancy, sleep
Pharma- DA antagonists: antipsychotics/depressants
Patho- Hypothyroidism (TRH can stim prolactin release)
Stalk lesion (prevent DA reaching pit)
How does increased prolactin production present in females?
Early presentation
Galactorrhoea
Menstrual irregularities
Infertility
How does increased prolactin production present in males?
Late presentation Impotence Visual field abnormalities Headaches Ant pit function
How do you test for increased prolactin production?
Serum prolactin conc
MRI
Visual fields
Pit function tests
How do you treat increased prolactin production?
DA agonists- will shrink but not cure:
Cabergoline- best option
What complications can too little prolactin production cause?
None known
What can excessive GH production produce?
Acromegaly
How can acromegaly present?
Giant if occurs before epiphyseal fusion Thickened soft tissue Hypertension -> LVH -> CF Headaches- due to vascular complications DM due to increased blood glucose Colon cancer and polyps
How do you test for acromegaly?
Blood IGF-1 and GH levels- not diagnostic GTT Insulin suppression test Visual fields MRI/CT pit function test
How do you perform a GTT for acromegaly?
Give 75g oral glucose.
Check GH levels at: 0, 30, 60, 120
If <0.4 then normal
How do you treat acromegaly?
Pit surgery- transsphenoidal common
Radiotherapy
Somatostatin analogues (suppress GH)- Can cause gall stones
GH antagonists- Block GHR but can increase tumour size- last resort.
What complications can a lack of growth hormone cause?
Growth retardation in children
Increased abdo fat and decreased muscle in adults
Is GH essential in adults?
No but needed for a good quality of life
What can lack of LH and FSH cause?
Genital atrophy
What is pituitary apoplexy?
Hemorrhage into pit leading it be compressed and die
What happens after a pit apoplexy?
When it drains get an open cavern and no pit
What kind of prolactin levels can prolactinomas cause?
Big- 15000mU/l due to prolactin production
Small- ~1500mU/l due to pressing on stalk
What physiological things can cause increase prolactin levels?
Just about anything:
Exercise
Stress
What is the main chemical treatment for acromegaly?
Somatostatin analogues
In panhypopituitary which treatment should you give first and how long for?
Cortisol replacement for 72hrs
Then thyroxine
Can you give thyroxine to someone who is steroid deplete?
No!!!
Which type of pit tumour (micro or macro) tends to be the most hormonally active?
Micro
How does a macroadenoma cause issues?
Non-functioning but produces problems due to mass effect
