Pituitary Pathology Flashcards
Microadenoma
<1cm
Macroadenoma
> 1cm
What is a prolactinoma?
Prolactin producing tumour
What happens as a result of raised prolactin levels?
Galactorrhea (milk produced outside of pregnancy)
What can result in raised prolactin levels?
Breast feeding (nipple stimulation) Stress Dopamine antagonist Stalk Lesions (severance of connection) Hypothyroidism Prolactinoma
Why do dopamine antagonist result in raised prolactin levels?
Dopamine inhibits prolactin production, by reducing dopamine levels you increase prolactin levels.
Give an example of a dopamine antagonist?
Metaclopramide
Why does a stalk lesion result in raised prolactin?
Prevents dopamine transmission to the pituitary so prolactin levels are not inhibited
Why does hypothyroidism often result in a raised prolactin ?
As TRH stimulate prolactin
Hypothyroidism there is negative inhibition so TRH levels are raised.
How does a patient with a prolactinoma present?
Galactorrhea Menstrual irregularity Infertility Impotence Visual field disturbances Headaches
What is the first line investigation in a suspected prolactinoma?
Serum prolactin levels
If the prolactin levels are found to be high in a suspected prolactinoma what should be undertaken?
MRI to determine the cause
Tumour extent and size
Stalk lesion
Optic chiasm compression
In pituitary tumours what is a common side effect if they are large?
Bitemporal Hemianopia
Compression of the optic chiasm
What should also be undertaken alongside an MRI in any suspected pituitary tumour?
Visual field test
After an MRI has diagnosed the tumour what should also be taken?
Pituitary function tests- look for other hormones affected
What is the treatment of choice for a prolactinoma?
Dopamine agonists
Name dopamine agonists
Cabergoline 1st line less side effects
Bromocriptine
Cabergoline in prolactinomas
Causes tumour shrinkage
Very successful in fertility restoration
Taken 1 or 2 times a week
Side effects of cabergoline
Low mood
Nausea
Vomiting
What is acromegaly?
Growth Hormone excess in later life
What s gigantism ?
Growth Hormone excess since birth
What is the difference between gigantism and acromegaly?
Acromegaly occurs after the growth plates have fused
Epiphyseal fusion
What is the appearance of someone with acromegaly?
Large protruding jaw Round doughy face Large Hands Prominent nasolabial folds Thickened soft tissue Enlarged brow
What are the clinical features associated with acromegaly?
Sleep apnoea Hypertension Headaches Diabetes Mellitus Visual field defects
What are the risks associated with acromegaly?
Early Cardiovascular death
Colonic polyps
Why are patients with acromegaly more likely to die from cardiovascular disease?
Increased risk of heart failure due to Left ventricular hypertrophy
Whilst acromegaly doesn’t directly cause colonic cancer what risks are there?
By inducing colonic polyps they increase the likely one of these polyps, by pure chance, could become cancerous.
What is the screening test for acromegaly?
Measuring IGF-1 levels
Results are age and sex matched
Why is IGF-1 not GH used in acromegaly screening?
IGF-1 is present in peripheral tissues for a longer time, as it has a longer stable half life.
What is the diagnostic test of choice for acromegaly?
Glucose tolerance test
What is a glucose tolerance test?
75g of glucose is taken orally
GH checked at 0 30 60 90 120 mins
In a healthy patient what should happen to the GH levels in a glucose tolerance test?
Suppressed to 0.4 ug/L
What happens to a patient with acromegaly in a glucose tolerance test?
GH levels are unaffected or increase
Once tests are done what should happen next in a patient with acromegaly?
MRI and CT
Check other hormone level
In acromegaly when checking the other pituitary hormones what should be measured in regards to TSH?
Free T3/4 not TSH
Is surgery curative in acromegaly?
90% if micro
50% if macro
What can be used to shrink a tumour for surgery? Acromegaly
Somatostatin analogue
Dopamine agonist
Why do dopamine agonists work in acromegaly?
10/15% of patients with acromegaly also secrete prolactin
Somatostatin analogues
Sondostatin LAR
What are the effects of somatostatin analogues?
Tumour shrinkage
Reduces GH levels
Side effects of somatostatin analogues?
Flatulence
Diarrhoea
Diffuse abdo pain
Increased risk of gall stones
How are somatostatin analogues administered?
Injected once a month
What is the last line therapy for acromegaly due to a tumour?
GH antagonist
GH antagonist?
Peguisomal
Do GH antagonist affect the tumour?
There is no reduction in tumour size
Affects of GH antagonists?
IGF-1 and GH reduced
85% response rate
What surveillance is undertaken in those with acromegaly?
Colonoscopy
CV risk - BP lips and glucose levels
Sleep apnoea studies
What is cushings syndrome?
Excess cortisol production
What is cushings disease?
Pituitary adenoma - producing ACTH
Pan hypopituitarism
Posterior and anterior pituitary glands are completely non functional
List some common causes of pan hypopituitarism?
Pituitary tumour Iatrogenic TB Sarcoidosis Trauma Meningitis
What could be some local brain tumours that could cause hypopituitarism?
Meningioma
Glioma
Anterior symptoms of pan hypopituitarism
Menstrual irregularity Inferitility Impotence Abdominal obesity Loss of facial hair Dry skin Growth retardation
What hormone tests would be undertaken in a suspected pan hypopituitarism?
TSH IGF-1 LH FSH
Why is ACTH not regularly tested for in pan hypopituitarism?
As ACTH levels fluctuate throughout the day
What tolerance test would be undertaken in pan hypopituitarism?
SynACTHen
Insulin
What is the treatment for someone with pan hypopituitarism?
Thyroxine Hydrocortisone ADH GH Oestrogen and progesteron (female) Testosterone (male)
What is the dose of thyroxine in someone with pan hypopituitarism?
100-150mg
What is the dose of steroids in someone with pan hypopituitarism?
10mg morning
5 mg midday
5 mg dinner
What is the dose of ADH in someone with pan hypopituitarism?
Nasal spray
What is the does of Growth hormone in someone with pan hypopituitarism?
Injection nightly
When is oestrogen and progesterone replacement used in women?
Used only in pre menopausal women
What is the dose of testosterone in someone with pan hypopituitarism?
Intramuscularly every 3-4 weeks
What is the testosterone used in IM injections?
Sustanon
What is the topically applied form of testosterone?
Testogel
What are the benefits of using growth hormone in adults with pan hypopituitarism?
Improves quality of life Reduces abdominal fat Increases muscle mass and strength Increases cardiac function Increases bone density
What are the risks associated with testosterone replacement?
Prostate enlargement - not cancerous
Polycythaemia - increased risk of MI
Hepatitis - only in oral tablet
What is polycythaemia?
Increased number of red blood cells increases the viscosity of the blood
What is the main symptom due to posterior pan hypopituitarism?
Cranial diabetes insipidus
What is the diagnostic test for cranial diabetes insipidus?
Water deprivation test
Nil by mouth for 8hrs
Urine osmolarity should be >2 greater than normal
Diabetes insipidous if lower
Treatment for cranial diabetes insipidus?
Desmospray nasally
Desmopressin oral tablets
What tumour can spread to the pituitary and is a remnant of Rathkes pouch?
Craniopharyngioma
Symptoms of craniopharyngioma?
Headaches
Visual disturbance
Growth retardation
What ages are affected by craniopharyngioma?
5-15
6th and 7th decade
What is the prognosis for a craniopharyngioma?
excellent
Cushings Disease
Excess ACTH secretion from the pituitary results in High Cortisol levels
Physical sign of Cushings disease
Proximal Myopathy Abdominal Obesity Easy bruising Purple Striae Hirsutism/Virilisation Acne Moon face
Clinical manifestations of Cushings disease
Diabetes Mellitus Hypertension Oedema Periorbital Psychosis depresson Testicular atrophy Oligo/amenorrhea
How can you differentiate between an obese person with and without cushings?
Obesity protects against osteoporosis,
Cushings results in obesity with osteoporosis
What suppression test should be undertaken if cushings is suspected?
Exogenous high dose oral steroid
Should produce a low serum cortisol level
What oral steroid is used in a cortisol suppression test?
Dexamethasone
What are the screening tests for cushings?
1mg of dexamethasone at midnight
-cortisol checked at 8am
Urine free cortisol - 24hr collection
In the screening test involving dexamethasone what is the dosage and what is the expected level of cortisol?
1mg Dexamethasone
< 50nmol/l is normal
> 130nmol/l is abnormal
In free cortisol urine sampling what is the expected values?
Total <250 is normal
What is the definitive test for cushings?
Low dose dexamethasone test
- 0.5mg every 6 hours for 2 days
- 6 hours after last dose cortisol is measured
What cortisol level indicates cushings 6 hours post final dose of dexamethasone?
> 130nmol/l
If the low dose dexamethasone test is positive what else should be undertaken?
A ACTH test
In a +ve low dose dexamethasone with a V.High ACTH what does this indicate?
Ectopic ACTH
In a +ve low dose dexamethasone with a normal ACTH what does this indicate?
Pituitary pathology
What tumours can cause ectopic ACTH secretion?
Lung Thymus Pancreas
Carcinoid
Small Cell lung cancer
What is the most common cause of cushings?
High dosage steroid use
