Pituitary Flashcards
What is the medical term for the anterior pituitary?
adenohypophis
Where is the ant pit derived from?
rathke’s pouch
What are the trophic hormones secreted from the ant. pit?
TSH
ACTH
FSH
LH
What are the non trophic hormones secreted from the ant. pit?
GH
PRL
What are the three cell types of cells seen under the the microscope of ant. pit?
Acidophils
Basophils
Chromophobe
What hormones are secreted from Acidophils?
Somatotrophs (GH)
Mammotrophs (PRL)
What hormones are secreted from basophils?
Corticotrophs (ACTH)
Thyrotrophs (TSH)
Gonadotrophs (FSH/LH)
What is the medical term for posterior pituitary?
neurohypophis
Where is the post. pit derived from?
extension of neural tissue and modified glial cells and axonal processes
What hormones are secreted by the post. pit
ADH
Oxytocin
What is the histological appearance of the post. pit?
Non myelinated axons of neurosecretory neurons
What is the PRL axis?
Hyp: DA-
Pit: PRL
To rest of body
(NB, DA has a negative control PRL)
What are the physiological causes of a raised PRL?
Breast feeding
Pregancy
Stress
Sleep
What drugs can increase PRL?
Dompamine agonists (metaclopramide)
Antipsychotics
Antidepressants
What are the pathological causes of raised PRL?
Hypothyroidism
Stalk lesions (iatrogenic,RTA)
Prolactinoma
What are the syptoms of raised PRL in Females?
Early presentation Galactorrhoea (30-80%) Menstrual irregularity Ammenorrhoea Infertility
What are the symptoms of raised PRL in Males?
Late presentation Galactorrhoea(<30%) Visual field abnormalities Headache Impotence Ant pit malfunction
What investigations can be done to assess for Prolactinoma?
PRL concentration
MRI pituitary
Visual feilds
PFTs (other hormones)
What is being assessed in MRI pituitary for prolactinoma?
Macro/Micro (>1cm/<1cm)
Pituitary stalk involvement
optic chiasm involvement
What visual field defect presents in prolactinoma?
Bitemporal heminopia
What is the treatment for prolactinoma?
Dopamine agonist
Give an example of medication used to treat prolactinoma
Cabergoline (2x week)
Quinagolide (OD)
Bromocriptine (TD)
What dopamine agonist has least side effects?
cabergoline
What are the aims when using a dopamine agonist in prolactinoma?
normal prolactin
menstruation regained
pregnancy achievable
tumour shrinkage
What is the GH axis?
Hyp: GHRH+
Pit: GH
To rest of body
What condition is caused by GH excess?
Acromegaly
What are the symptoms and signs in acromegaly?
Thickened soft tissues (skin, large jaw, sweaty large hands) Hypertension Cardiac Failure Headaches (vascular) Snoring Sleep apnoea Diabetes mellitus Local pituitary effects (visul feilds, hypopituitism) Early CV death
How is acromegaly diagnosed?
IIGF1* GTT* (glucose tolerance test) Visual feilds CT/MRI pituitary PFTs
What happens in a GTT test?
75g oral glucose
Check GH every 30 mins for 2 hours
What should happen in a normal GTT test?
GH suppresses to<0.4ug/l after glucose
What happens in an acromegaly GTT?
GH unchanged/no suppression
Paradoxical rise
GH remains >1ug/l after glucose
How is acromegaly treated?
Pituitary surgery external radiotherappy to pit. fossa Retest GTT (GH1 needs drugs)
What drugs are used to treat acromegaly?
Dopamine agonist
Somatostatin analogue
GH antagonist (last line)
What use do somatostatin analogues have in acromegaly?
Reduces GH
Tumour shrinkage (30-50%, can reexpand)
Pre-op (relieve headache in 1 hr, improved outcome)
What are the side effects of somatostatin analogues?
Local stinging
Short term: flatulence, diarrhoea, abdo pain
Long term: Gastritis, gallstones
Give examples of somatostatin analogues and administration
Octreotide (SC TDS)* Sandostatin LAR (IM 1/28 days) Lanreotide autogel (IM 1/28 days)
What dopamine agonist is used in acromegaly and what doseage is given?
Cabergoline
>3g weekly
What is the efficacy of cabergoline in acromegaly?
GH <2ug in 15%
better if co-secreting prolactin
Give an example of a GH antagonist
Pegvisomant
What is the tumour response to pegvisomant?
Tumour does not decrease
May increase in size
What is the IGF-1 response in pegvisomant?
decreases but serum GH may increase
What is assessed in an acromegaly follow up?
Check GH and IGF-1 are clinically safe levels
Check other pit hormones esp thyroid
Cancer surveillance (colon and tubulovillous adenoma)
CVS risk
Sleep apnoea
What is the cortisol axis?
Hyp: CRH+ Pit: ACTH+ Adrenal: Coritsol To rest of body NB, negative feedback
What condition is caused by excess cortisol?
Cushing’s Syndrome
What are the symptoms of Cushing’s caused by excess cortisol?
Protein loss -myopathy -osteoporosis (fractures) -thin skin (striae, bruising) Altered CHO/Lipid metabolism -DM and obesity Altered psyche -phycosis, depression
What symptoms of cushing’s are caused by excess mineralocorticoid?
Hypertension
Oedema
What symptoms of cushing’s are caused by excess androgen?
Virilism
Hirsutism
Acne
Oligo/amenorrhoea
How is cushing’s different to obesity?
Thin skin Proximal myopathy Frontal balding in women Chemosis Osteoporosis
What are the signs of cushing’s?
Moon face red plethoric cheeks inceased abdominal fat easy bruising poor wound healing procximal myopathy thin skin buffalo hump
what condition’s are those with cushing’s more prone to?
Benign intracranial hypertension Cataracts AVN femoral head Hypertension Osteporosis Hyperglycaemia
What are the screening tests for cushing’s?
(High dose)overnight 1mg dexamethasone suppression test
Urine free cortisol
Diurinal cortisol variation
How does overnight 1mg dexamethasone work in a)normal b)cushing’s?
a)cortisol 100nmol/l next morning
What are the normal values for urine free cortisol?
24 hr urine collection
Total<25
What is the definitive test for cushing’s?
Low dose dexamethasone suppression test
How does low dose DST work?
2mg/day for 2 days dexamethasone
Cortisol s
What can cause cushing’s?
Pituitary malfunction
Adenoma of adrenal
Ectopic thymus/lung/pancreas
Pseudo (steroid medication, alcohol and depression)
What tests would show a pituitary origin for cushing’s?
Abn low dose dexa test
ACTH <300
High dose dexa test supresses by 50%
What tests would show an adrenal origin for cushing’s?
Abn low dose dexa test
ACTH<1
Nil suppression high dose dexa test
What tests would show an ectopic origin for cushing’s
Abn low dose dexa test
ACTH>300
high dose dexa Nil suppression
What is the treatment for
A)pituitary cushing’s
B)Adrenal cushing’s
C)ectopic cushing’s?
A)hypophysectomy, external radiotherapy if reoccurs
B)adrenalectomy
C)remove source or bilateral adrenalectomy
What drug treatment is used in chushing’s?
Metyrapone (waiting for radiotherapy to work, S/E common)
Ketoconazole
Pasireotide (somatostatin analogue)
What are the characteristics of pan hypopititarism and why?
Anterior: Growth failure:GH Hypothyroid: TSH Hypogonadism: LH/FSH Hypoadrenal: ACTH
Posterior:
Diabetes Insipidus
What are some causes of pan hypopituitarism?
Pituitary tumours Secondary mets (lung, breast) Granulomatous disease (TB, sarcoidosis) Vascular (polyarteritis) Trauma Autoimmune (Sheenan post pregnancy)
What are the symtoms of anterior pan hypopituitarism?
Menstrual irregularities F Infertility Impotence Gynaecomastia M Abdo obesity Loss facial hair M Loss axillary and facial hair Dry skin and hair Hypothyroid faces Growth retardation (C)
What are the baseline pituitary function tests?
fT4, TSH
Oestradial/Testosterone, LH, FSH
GH, IGF-1
PRL
What is the therapy for pan hypopituitarism?
Replacement therapy Thyroxine Hydrocortisone ADH GH (daily SC injection) Sex steroids (Oest/prog pill or Testosterone)
What effect does GH have in adults?
decreases abdo fat increase muscle mass and exercise capacity improves cardiac function decreases cholesterol and increases LDL Increases bone density
What are the risks of testosterone replacement?
Prostate enlargement (NOT CANCER)-monitor by PR and PSA
Polycythaemia-FBC
Hepatitis with oral tabs-LFTs
What disease is cause by posterior pit insufficiency?
Diabetes insipidus
ADH
What are the causes of DI?
Familial (DIDMOAD-DI, DM, optic atrophy, deaf) Acquired (idiopathic, trauma) Rare (tumour, sarcoid, meningitis) Nephrogenic renal resistance to ADH Paraneoplastic syndrome
How is DI treated?
Desospray (nasal)
Desmopressin (oral, sublingual, IM)*
*highest to lowest dose
