Pituitary Disorders Flashcards
What is the term for a tumour that is not cancer/benign tumour of glandular epithelial origin?
Adenoma
What are the 4 ways we asses patients with pituitary disorders?
-Clinical
-Biochemical
-Imaging
-Visual fields
What are clinical assessments?
History and examination
How might a pituitary tumour present clinically?
The adenoma affect local structures putting pressure on them:
This may cause vision loss (tunnel vision) or headaches
Pituitary may abnormally produce hormones:
Hypo-secretion
Hyper-secretion
How can superior growth of a pituitary tumour affect a patient?
Causes visual field loss
Optic chiasm is superior to pituitary
The pituitary tumour squashes the optic chiasm
What is the term given to describe tunnel vision/visual field loss?
Bitemporal hemi-anopia
Which direction of pituitary tumour growth can cause Bitemporal hemi-anopia?
Superior growth
How can lateral growth of a pituitary tumour affect a patient?
Causes pain (thunderclap headaches) and can cause Double vision (Diplopia)
Diplopia caused by nerves III and IV being squashed by tumour (responsible for eye movement)
Pain caused by nerves (Va,b) being squashed or blood vessels being squashed causing haemorrhaging
How can a pituitary tumour cause Hypopituitarism?
The tumour can block the tropic hormones that are produced by the hypothalamus from ever reaching the pituitary gland. This can have significant affects
What tropic hormones can a pituitary tumour block from ever reaching the pituitary?
GHRH Means less GH made
GnRH Means less LH and FSH made
TRH Means less TSH made
CRH Means less ACTH made
PIH/Dopamine Means MORE prolactin is made
How would blockage of GHRH by a Pituitary tumour affect a patient?
Deficiency of GH
Short stature in children (long bone growth not stimulated)
Reduced quality of life in adults (muscle and bone mass loss, reduced ability to exercise, increased visceral fat)
How would blockage of GnRH by a Pituitary tumour affect a patient?
Gonadotropin deficiency so deficient LH and FSH
Delayed puberty in children
Loss of secondary sexual characteristics in adults
(Loss of periods = early sign for women)
How would blockage of TRH by a Pituitary tumour affect a patient?
Deficiency in TSH
So low thyroid hormone levels
Affects metabolism
Causes weight gain, tiredness, slow pulse, coldness
How would blockage of CRH by a Pituitary tumour affect a patient?
Deficiency of ACTH
Low cortisol
Causes tiredness, dizziness, low BP, low sodium
CAN BE LIFE THREATENING
What happens with Hyperpituitarism due to a pituitary tumour?
The tumour causes the anterior pituitary to produce excess of the hormones that it produces
What are the 3 common hormones which are produced in excess when a pituitary tumour causes Hyperpituitarism?
Prolactin
GH (Growth Hormone)
ACTH (Adrenocorticotropic Hormone)
How can we biochemically assess for pituitary disease involving the Thyroid axis, Prolactin axis and Gonadal axis?
Basal blood tests (use amino assays)
For thyroid axis testing for free circulating thyroxine levels
Prolactin axis testing for serum prolactin levels
For gonadal testing for LH, FSH, Testosterone (Men) and Oestradiol (women) levels
How do we biochemically assess for pituitary disease involving the HPA (Hypothalamic-Pituitary-adrenal) axis and GH axis?
Dynamic blood test (continuous measurements)
Cortisol levels
GH/IGF-1 levels
If IGF-1 is low it shows GH is deficient
What 2 types of tests are done in the dynamic assessment of HPA and GH axes?
Stimulation tests (if hormone deficiency suspected try stimulate it)
Suppression tests (if hormone excess suspected try and decreases it)
What test is done if thought Adrenal axis is in deficiency?
SynACTHen test
Insulin stress test
What test is done if Adrenal axis is thought to be in excess?
Dexamthasone suppression test
What test is done if GH axis is thought to be in deficiency?
Insulin stress test (since insulin stimulates GH)
What test is done if GH axis is thought to be in excess?
Glucose tolerance test (glucose inhibits GH)
What is a macro-adenoma?
“Large tumour”
Larger than 1cm
What is a micro-adenoma?
“Small” tumour
Smaller than 1cm
What is a Prolactinoma?
A pituitary tumour which secretes prolactin
What affect does size of a Prolactinoma have on production of Prolactin?
Larger then tumour the more prolactin made
What is the best way to treat a Prolactinoma?
Tablets
Usually Dopamine cuz dopamine = prolactin inhibiting hormone
AVOID OPERATION
What disorder can Prolactinomas cause?
Hyperprolactinaemia (elevated levels of plasma prolactin)
What are the symptoms of Hyperprolactinaemia in women?
Menstrual disturbance (Prolactin Directly INHIBITS LH secretion)
Fertility problems (Prolactin directly INHIBITS LH secretion)
Galactorrhoea (milky nipple discharge outside of pregnancy)
What are the symptoms of Hyperprolactinaemia in men and why are men harder to diagnose?
LH in men causes testosterone production
Men don’t have periods so hard to see that high prolactin is inhibiting LH so men present later than women
Symptoms of low testosterone are non specific (loss of sex drive could be put down to depression, hair loss due to aging)
What affect would a pituitary adenoma blocking the pituitary stalk have on prolactin levels and why?
High prolactin
Dopamine not reaching anterior pituitary so prolactin is not being inhibited
This high prolactin due to lack of inhibition by dopamine is called Disinhibition
What levels of prolactin indicate a Prolactinoma?
Over 5000 miU/L
What prolactin levels indicate disinhibition / the stalk effect
Less than 5000 miU/L
Why must Non Functioning Pituitary Adenomas (NFPAs) be treated surgically?
They don’t secrete any biologically active hormones so aren’t inhibited by drugs like dopamine
What type of tumour can cause Acromegaly and what is acromegaly?
GH-excreting pituitary tumour
Large extremities = hands, feet and lower jaw
Biochemical tests done to confirm acromegaly?
Inhibit GH by giving oral glucose (Oral Glucose tolerance test
If suppression of GH doesn’t occur it may indicate a pituitary adenoma which secrets GH
How is acromegaly treated?
Surgical removal of GH secreting tumour
Can also reduce GH secretion
Block GH receptor
What tropic hormone does a pituitary tumour that causes Cushing’s disease secrete?
ACTH (Adrenocorticotropic Hormone)
Causes excess levels of Cortisol to be made
What changes of appearance usually happen in Cushing’s disease?
More fat on chest, stomach/abdomen
Red Puffy face
Red stretch marks on abdomen (STRIAE)
Hypertension
Diabetes
Osteoporosis
What is the difference between Cushing’s Disease and Cushing’s Syndrome?
Cushing’s disease caused by ACTH secreting pituitary tumour
Cushing’s syndrome can be caused by other pathologies (High cortisol can be caused by:
ADRENAL TUMOUR
ECTOPIC ACTH (ECTOPIC = abnormal) so ACTH also being produced in other places
STEROID MEDICATION
What does Insipid mean?
Weak/tasteless
What is Diabetes Insipidus?
Body can’t re absorb water due to lack of ADH
Lots of pale urine made (Polyuria)
Very thirsty (Polydipsia)
What is the role of Anti-diuretic Hormone (ADH)?
Affects Kidney (nephron)
Stimulates aquaporins to fuse with the membrane of the Collecting Duct and the Distal Convoluted Tubule (DCT)
Increases its permeability to water allowing water to be re absorbed back into the blood
What are the 2 types of Diabetes Insipidus?
Cranial Diabetes Insipidus (Cranial DI)
Nephrogenic Diabetes Insipidus (Nephrogenic DI)
What is Cranial Diabetes Insipidus?
ADH DEFICIENCY pituitary disease
What is Nephrogenic Diabetes Insipidus?
Kidney disease where the kidney (nephrons) are RESISTANT to ADH
Often seen in hypercalcaemia
What is the difference between Cranial DI and Nephrogenic DI?
Cranial Di caused by deficiency of ADH due to pituitary disease
Nephrogenic DI caused by ADH resistance of kidney due to Kidney disease
What are the types pathology/illness that cause Cranial Diabetes Insipidus?
-Inflammation = Hypophysitis
-Infiltration
-Malignancy
-Infection
What happens if Diabetes Insipidus is left untreated?
Severe dehydration which leads to
Hypernatraemia = High Na levels
Leads to reduced consciousness, coma and death
How to treat Cranial DI?
Synthetic ADH:
E.g. Desmopression nasal spray, tablets or injection
What does Apoplexy mean?
Stroke
What is Pituitary apoplexy?
A sudden vascular event in the Pituitary due to a tumour
What 2 things can cause a Pituitary apoplexy?
Bleeding inside pituitary tumour (haemorrhage)
Pituitary tumour cuts of blood supply to pituitary causing INFARCTION
How can Pituitary apoplexy present?
-Sudden onset headache (Thunderclap headache)
-Diplopia (Double vision)
-Bitemporal hemi-anopia (Visual field loss/tunnel vision)
-Cranial nerve palsy
-Hypopituitarism (cortisol deficiency very dangerous)
