The Pituitary Gland- hypersecretion, hyposecretion and pituitary tumours Flashcards
List the hormones produced by the anterior pituitary.
TSH (thyroid stimulating hormone)
ACTH (adrenocorticotropic hormone)
LH (luteinizing hormone)
FSH (follicle stimulating hormone)
GH (growth hormone)
Prolactin
What does ACTH control?
Steroid production from the adrenal gland
List the hormones produced by the posterior pituitary.
Antidiuretic hormone
Oxytocin
RECAP- what is the role of antidiuretic hormone?
Urine production and rate.
RECAP- what does oxytocin do?
Assists in uterine contraction during delivery
What do LH and FSH do?
Stimulate the ovary for oestrogen and progestin production.
Stimulates testes for production of testosterone.
What role does prolactin have?
Milk secretion
Hypersecretion of GH can lead to what?
Acromegaly
Gigantism
->some say Goliath had gigantism because he was so tall. Also, he did not see the stone coming towards him shot by David suggesting there was compression of his optic chiasm from a pituitary tumour leading to bitemporal hemianopia.
Hypersecretion of ACTH can lead to what?
Cushing’s disease
Hypersecretion of prolactin can lead to what?
Hyperprolactinemia
If there is a tumour of the pituitary gland, what structure may it compress?
Optic chiasm
->this can cause bitemporal hemianopia
What is the main cause of hyper and hyposecretion?
Tumours
Tumours can also cause hyposecretion of hormones. List some of the hormones that are hyposerceted from tumours in the anterior pituitary.
FSH/LH
GH
ACTH
TSH
Tumours can also cause hyposecretion of hormones. List a hormone which is hyposerceted from tumours in the posterior pituitary.
Vasopressin
What can the posterior hyposecretion of vasopressin lead to?
Diabetes insipidus a.k.a Arginine Vasopressin Deficiency (AVD)
-> rare condition in which people produce a large amount of water and often feel thirsty
RECAP- what is acromegaly?
Overproduction of GH which causes widening of bones (not lengthening, that’s gigantism and that occurs before bones fuse in childhood).
What re some of the clinical features of acromegaly?
Spade like hands- rings often don’t fit anymore
Wide feet- complaints in shoes not fitting
Thick lips and tongue
Carpal tunnel syndrome
Sweating
Jaw more widely spaced- may be picked up by dentist
What are some of the complications of acromegaly?
Headaches- tumour size or excess GH
Optic chiasm compression
Diabetes mellitus
Hypertension
Cardiomyopathy
Sleep apnoea- due to large tongue
Colonic polyps
Accelerated osteoarthritis
What is the definitive test to diagnose acromegaly?
Glucose tolerance test
What should the glucose load do to GH in normal individuals having a glucose tolerance test?
Should supress GH
Sometime a screening test can be used before the diagnostic glucose tolerance test.
Raised levels of what suggest that the patient should go onto have a glucose tolerance test?
Elevated IGF-1 (insulin-like growth factor 1)
If the glucose tolerance test is positive, which further investigation is done and why?
MRI to see if the rets of the pituitary function is normal or if there is a mass
When would a pituitary tumour need to be removed more quickly?
If the vision of the patient is affected
Excess corticosteroids causes what?
Cushing’s syndrome
Is cortisol an anabolic or catabolic hormone?
Catabolic- causes tissue breakdown
Why can Cushing’s syndrome cause hypertension and even heart failure?
Cortisol increases sodium retention
How can Cushing’s syndrome cause diabetes mellitus?
Cortisol antagonises insulin
List some of the signs and symptoms of Cushing’s syndrome.
Skin atrophy
Osteoporosis
Growth arrest in children
Easy bruising
Proximal myopathy
Facial mooning
Central obesity
Cushing’s syndromes may be caused by iatrogenic cause as patients can be given cortisol to help with conditions such as…
Asthma, bowel disease, neurological conditions
-> iatrogenic cause is the most common cause of Cushing’s
Therefore, causes of Cushing’s may be ACTH dependant or independent.
What are some ACTH-dependant causes of Cushing’s syndrome?
Pituitary tumour
Ectopic ACTH secretion e.g. lung carcinoid
Therefore, causes of Cushing’s may be ACTH dependant or independent.
What are some ACTH-independent causes of Cushing’s syndrome?
Adrenal tumour
Corticosteroid therapy e.g. asthma, IBD
When the cause of Cushing’s syndrome in a pituitary tumour, what is this more specifically known as?
Cushing’s disease
What are some physiological causes of hyperprolactinaemia?
Pregnancy
Lactation
Stress
What are some pharmacological causes of hyperprolactinaemia?
Dopamine depleting and antagonist drugs
What are some pathological causes of hyperprolactinaemia?
Primary hypothyroidism
Pituitary lesions
What are some of the clinical features of hypopituitarism in adults?
Tiredness
Weight gain
Depression
Menstrual problems
Skin pallor
Reduced body hair
What are some of the clinical features of hypopituitarism in children?
Reduced linear growth
Delayed puberty
RECAP- Lack of vasopressin can cause what?
Diabetes insipidus ( Arginine Vasopressin Deficiency or AVD)
What test can be done to confirm diabetes insipidus?
Water deprivation test
-> deprive patient of water overnight and then supervised over next eight hours. If urine, remains clear, injection of DDAVP and see if the urine concentrates.
Clear urine suggests diabetes insipidus
List some of the differential diagnosis for diabetes insipidus.
Post-trauma, e.g. pituitary surgery
Metastatic carcinoma
Other brain tumours
RECAP-if the pituitary gland increases in size upwards, what can it compress?
Optic chiasm
RECAP-compression of the optic chiasm can cause what?
Bitemporal hemianopia
If pituitary tumours spread towards the side, particularly in the cases of a pituitary bleed, what can this cause to happen?
Third of fourth nerve palsy
What is the management option for hypersecreting pituitary tumours causing prolactinoma?
Dopamine agonists
What are the management options for hypersecreting pituitary tumours causing acromegaly?
Somatostatin analogues
GH receptor antagonist
What is used in the management of hyposecretion in a normal pituitary gland?
Replacement of hormones e.g. cortisol, sex steroids, GH, T4, desmopressin.
What is used in the treatment of a pituitary tumour?
Surgery- usually transsphendoidal
Radiotherapy
What are some of the benefits of somatostatin analogues in acromegaly?
Improve soft tissue overgrowth, headaches, sweating, sleep apnoea
Induce tumour shrinking
Reduce morbidity and mortality
What are the side effects of somatostatin analogues
Nausea, cramps, diarrhoea, flatulence
Cholesterol gallstones
What are some of the negatives of somatostatin analogues?
Expensive
Side effects
What is a side effect of radiotherapy of the pituitary gland?
Hypopituitarism- doesn’t make enough hormones
Prolactinomas are the most common type of pituitary adenoma. They can be classified as microprolactinoma or macroprolactinoma.
What size is a microprolactinoma?
<10mm
What is the treatment for microprolactinoma macroprolactinoma?
Dopamine agonists
What size is a macroprolactinoma?
> 10mm
What are some of the adverse effects of dopamine agonists?
Nausea and dizziness
Addictive behaviours
Fibrotic disorders of lungs and cardiac valves
If a patient is on dopamine agonists for a long period, which investigation should be done at 3-5yr intervals?
Echocardiogram
Just checking- what is the difference between an ECG and an ECHO?
ECG- records hearts electrical activity
ECHO- uses ultrasound to check for anomalies in heart structure
What is the clinical symptoms of hyperprolactinaemia in women?
Galactorrhoea- 80% of women have this symptom
Menstrual irregularity
Infertility
Galactorrhoea?
Production of milk from the breast not relating to lactation
What are the symptoms of hyperprolactinaemia in men?
Galactorrhoea- only in 5%
Impotence- unable to get an erection
Visual field abnormalities
Headache
Extraocular muscle weakness
Anterior pituitary malfunction
Who tends to presents later in the stages of hyperprolactinaemia and why?
Men- women notice Galactorrhoea, the most common symptom fairly quickly. In men, it make take visual field problems for them to realise something is wrong
