Pituitary disorders Flashcards
the pituitary gland is known as
the conductor of the endocrine audience
Poster pituitary is derived from
brain- neuroectoderm (nerve cells)
features of the PP
fast acting- neurological
what does the PP release
Vasopressin (ADH) and oxytocin (produced in the hypothalamus)
Anterior pituitary is an
up growth of gut- hormone producing and secreting
hormones secreted by the AP
- growth hormone (GH)
- prolactin (PRL)
- follicle-stimulating hormone (FSH)
- luteinizing hormone (LH)
- adrenocorticotropic hormone (ACTH)
- thyroid-stimulating hormone (TSH)
Disorders of the pituitary are rare, and can manifest themselves as
either an over or under secretion of pituitary hormone.
Clinical presentation of pituitary tumours
1. Mass effect of tumour on local structure- visual loss, headache
2.Abnormality in pituitary function – hypo or hyper-secretion
most common pituitary tumour
Most commonly caused by pituitary adenoma- a benign pituitary tumour.
most pituitary tumours are
non functioning (do not produce any hormone) but can cause inadequate production of one or more pituitary hormone due to the physical pressure of the growing tumour on glandular tissue
symptoms of non-functioning tumour
Headaches
Visual loss
Nausea and vomiting
Functioning tumour (hyper-secreting)
Rarer
Clinical symptoms dependent on which pituitary hormone they are over-secreting and its systemic effects
investigations required if pituitary tumour is suspected
- MRI scan
- Assessment of visual field
- Blood tests measuring hormone levels
picture of a nonrmal pituitary and its interactions with local structures
upwards (superior) growth of pituitary tumour causes
visial field loss due to compression on the optic chiasm
how would an upwards (superior) growth of pituitary tumour effect vision
bitemporal hemi-anopia
Sideways (lateral) growth of pituitary gland
would cause pain, double vission and left sided eye compressive problems
what cause a tumour to be hypo-functioning
pressure on gland by adenoma
hyper- functioning tumour
hypersecreting adenoma
When a tumour blocks the hypothalamic-pituitary access… which hormones will decrease
Hormones that decrease (due to being under positive control of hormones produced in the hypothalamus)
- GH
- LH/FSH
- TSH
- ACTH
When a tumour blocks the hypothalamic-pituitary access… which hormones will increase
Hormones that will increase (due to be under under negative control of hormones produced in the hypothalamus)
- Prolactin (positive control by dopamine)
cause of hypopituitarism
- Most commonly caused by a pituitary adenoma putting pressure on the pituitary glandular tissue.
- Tumour could be blocking hypothalamic control of the pituitary
- causes a progressive loss of anterior pitutiary function
- posterior pit usually only affected if the tumour also affects hypothalamic function (secretion of ADH and oxytocin normally unaffected)
ADH deficiency
May occur from a hypothalamic tumour or pituitary tumour that has ended up in the hypothalamus.
Symptoms of ADH deficiency
- Dilute urine
- Dehydration
- Increased thirst
- Diabetes insipidus
GH deficiency
Loss of GH
GH deficiency hard to diagnose
Can be hard to diagnose because GH is released in a pulsatile fashion
symptoms of GH deficiency in adults
Adults (adenoma)
- Decreased exercise tolerance
- Decreased muscle tone
- Increased body fat
- Reduced sense of wellbeing
symptoms of GH deficiency in children
Children (idiopathic- specific mutations and autoimmune may be linked)
Short stature in children- can be treated with GH manufactured by recombinant DNA technology
Gonadotrophin deficiency
LH and FSH deficiency
symptoms of Gonadotrophin (LH and FSH) deficiency: general
- Delayed puberty in children
- Loss of secondary sexual characteristics in adult
symptoms of Gonadotrophin (LH and FSH) deficiency: female
- Reduced libido
- Infertility
- Oligomenorrhea
- Amenorrhea
Oligomenorrhea
- infrequent menstrual periods
Amenorrhea
- absence of periods
symptoms of Gonadotrophin (LH and FSH) deficiency: male
- Reduce libido
- Impotence
Impotence
- inability to achieve erection of orgasm)
TSH and Adrenocorticotropic hormone deficiency
Late features of pituitary tumours
- TSH and ACTH deficiency
TSH deficiency
- Low thyroid hormones
- Symptoms:
- Cold
- weight gain
- tiredness
- slow pulse
- low T4 and non-elevated TSH
ACTH deficiency
- Low cortisol
- Symptoms:
- Tired
- dizzy
- low BP
- low sodium
sumamry of hypopituitarism
hyperpituitarism
Caused by a hypersecreting pituitary adenoma
three hormoens most commonly saffecte dby hyperpituitarism
Prolactin
GH
ACTH
two rarer hormones affected by hyperpituitarism
TSH
LH/FSH
prolactin excess
Most common form of pituitary disorder.
most common cause of prolactin excess
prolactinoma
what is classes as a large tumour
macro-adenoma = >1cm
other causes of prolactin excess
Pregnancy
Suckling
Stress
Exercise
symptoms of prolactin excess
Galactorrhoea (milky nipple discharge)
Gynecomastia (proliferation of male breast glandular tissue)
Hypogonadism (low testosterone symptoms)
Amenorrhea (absence of period)
Erectile dysfunction
Galactorrhoea
(milky nipple discharge)
Gynecomastia
(proliferation of male breast glandular tissue)
Hypogonadism
(low testosterone symptoms)
MOA of prolactin
- Increased conc of plasma prolactin increases negative feedback on the hypothalamus
- Increase in production of dopamine to try and bring prolactin back within normal limits
- This decreases release of GnRHà diminished sex hormone production
prolactin excess treatment
Treated with drugs not an operation- Dopamine receptor agonist (dopamine inhibits prolactin e.g. bromocriptine)
Never send patients for surgery until prolactin is known
Make sure pt isn’t pregnant
Surgery (rare)
Radiotherapy (rare)
GH excess cause
Large growth-hormone secreting pituitary adenoma
symptoms of GH excess
Headaches
Visual field defects
Cranial nerve palsies
signs of growth hormone excess
Broad nose
Coarse facial features
Thick lips
Prominent superorbital ridge
Enlarged hands and feet
Greasy skin
Excessive sweating
Deepening of voice
in children GH excess is
gigantism
in adults GH excess is
acromegaly
MOA of GH excess
- Systemic effects are through both the direct actions of GH and through the stimulation of local IGF-1 production
- Usually takes years to develop
- GH antagonises insulin –> diabetes mellites can occur. Increased IGF-1 associated with cancer
GH excess treatment
- Surgery to remove adenoma
- Radiation or drug therapy
- E.g. somatostatin analogues, GH receptor antagonists
ACTH stands for
Adrenocorticotropic hormone
ACTH excess is the cause of
cushings syndrome
symptoms of cushins syndrome
Hyperglycaemia
Hypertension
Purple striae
Abdominal obesity
Buffalo hump
Moon-shaped face
summary of hyperpituitarism
Hyperprolactinaemia caused by
Prolactinoma
prolactin > 5,000 then high prolactin
is likely to be due to active prolactin secretion (prolactinoma)
prolactin is under tonic inhibitory control by
dopamine
anything blocking the stalk will lead to prolactin disinhibition (increase in prolactin)
prolactin directly inhibits …… secretion
LH
If prolactin < 5,000
the high prolactin might be due to disinhibition (‘stalk effect’) rather than active prolactin secretion
Biochemical assessment of pituitary disease types
Basal blood tests
Dynamic blood tests
basal blood tests sufficient
-
Thyroid axis
- T4
- TSH
-
Gonadal axis
- LH, FSH
- Testosterone (men)
- Oestradiol (women)
-
Prolactin axis
- Serum prolactin
-
HPA
- 0900 cortisol
-
GH axis
- GH/IGf-1
Dynamic assessment of HPA and GH axes types of tests
stimulation and suppression test
stimulation tests used for
suspected hormone deficiency
supression test used in
suspected hormone excess
test for suspected adrenal axis deficiency
- Direct stimulation of adrenals by ACTH (synACTHen test )
- Response to hypoglycaemic stress (insulin stress test)
test for suspected adrenal axis excess
Supress ACTH axis with steroids (dexamethasone suppression test)
test for suspected GH axis deficiency
Response to hypoglycaemic stress (insulin stress test)
test for suspected GH axis excess
Supress GH axis with glucose load (glucose tolerance test)
Radiological assessment of pituitary disease
Using MRI
Specific conditions caused by Pituitary disorders
Acromegaly
Cushing’s disease
Diabetes insipidus
Pituitary apoplexy
Acromegaly
“large extremities’
- Acromegaly is a rare condition where the body produces too much growth hormone, causing body tissues and bones to grow more quickly.
- Over time, this leads to abnormally large hands and feet, and a wide range of other symptoms.
- Acromegaly is usually diagnosed in adults aged 30 to 50 but can affect people of any age. When it develops before puberty, it’s known as “gigantism”.
cause of acromegaly
GH-secreting pituitary tumour- can be visualised using a PET scan
symptoms of acromegaly
- Swollen hands and feet
- Tiredness and difficulty sleeping
- Gradual changes in facial features
- Brow
- Lower jaw
- Nose getting larger
- Teeth become more space
- Numb ness and weakness in hands caused by a compressed nerve (carpal tunnel syndrome)
long term complications of acromegaly
- Long term complications
- Premature CVS death
- Increase risk of colonic tumour
- Increase risk of thyroid cancer
- Disfiguring body changes may be irreversible
- Hypertension
- Diabetes
Biochemical tests to confirm acromegaly
- OGTT with GH response
- Failure to supress GH<1ug/:
- Elevated IGF-1
- Growth hormone day curve – elevated mean GH
acromegaly treatment
- Surgical removal of tumour (through nose)
- Medical treatment
- Reduce GH secretion:
- Dopamine agonist- bromocriptine
- Somatostatin analogues- octreotide
- Block GH receptor- pegvisomant
- Reduce GH secretion:
- Radiotherapy
- External beam- multiple short bursts over several weeks
- Gamma knife
- High conc over single time
examples of acromegaly
cushings syndrome caused by
ACTH (adrenocorticotropic hormone) pituitary tumour
classical changes in appearance of Cushings disease patients
- Round pink face with round abdomen
- Skinny and weak arms and legs
- Thin skin and easy bruising
- Red stretch marks (striae) on abdomen
- High bp and diabetes
- Osteoporosis.
cushings disease vs cushings syndrome
- CD caused by pituitary tumour
- CS may be caused by other pathologies
- Adrenal tumour
- Ectopic ACTH
- Steroid medication
Examples of cushings disease
what does insipidus mean
large quantities of pale urine
how many types of diabetes insipidus
- Cranial DI
- Nephorgenic DI
- Dispogenic DI
- Gestational DI
cranial DI
- Lack of ADH (p.pituitary)
- ADH usually decreases urine output to increase BP by increasing reabsorption of water in the kidneys
causes of cranial DI
Inflammation
Infiltration
Malignancy
Infection
nephrogenic DI
Vasopressin resistant kidney disease
symptoms of diabetes insipidus
- Large quantities of pale (insipid) urine
- Extreme thirst due to fluid loss
consequences of untreated DI
Severe dehydration
Very high sodium levels (hypernatremia)
Reduced consciousness, coma and death
treatment of DI
- Cranial DI responds well to synthetic vasopressin (ADH)
- Desmopressin nasal spray, tablets or injection
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Pituitary apoplexy
‘Apoplexy’ is the old-fashioned word for stroke
- Sudden vascular event in a pituitary tumour
- Haemorrhage
- Infarction
clinical presentation of pituitary apoplexy
Sudden onset of headache
Double vision
Visual field loss
Cranial nerve palsy
Hypopituitarism (cortisol deficiency)
