Normal pituitary function and disease Flashcards
How is the anterior pituitary connected to the hypothalamus
Vasular connections
How is the posterior pituitary connected to the hypothalamus
Neural connections
What would be the consequence of damage to the pituitary stalk
Releasing factors from the hypothalamus can’t reach the pituitary to stimulate release of stuff from pituitary
What is the pituitary stalk
Connects the hypothalamus to the pituitary
What is hypo secretion of the pituitary normally due to
Trauma/surgery, genetic disease, tumour
What is hyper secretion of the pituitary most likely due to
Tumour
What is the most common cause of pituitary disease
Pituitary tumours. MOStly benign (adenoma)
How can pituitary tumours affect the pituitary gland
Over production of a pituitary hormone
Inadequate production of other remaining hormones
Local effects on anatomically related structures (visual disturbances, headaches)
What is prolactinoma
tumour of pituitary gland that makes the tumour secrete more prolactin
What is a consequence of prolactinoma
HYperprlactinaemia
What are the consequence s of GH- secreting pituitary tumours
Acromegaly (increase in bone size)
Gigantism in children
What is the consequence of an ACTH secreting pituitary tumour
Cushing’s disease
What are the consequences of non-secreting pituitary hormones
Mechanical symptoms such as headaches and hypopituitarism
When are stimulation tests done
IF you suspect hypo secretion
When are suppression tests done
If you suspect hyper secretion
What is a test done to see if there is secondary hypothyroidism
TRH stimulation test
What is the TRH stimulation test and what results would you expect in a normal response
TRH given
Increase in TSH and an increase in T3/T4
What would you expect in a TRH stimulation test with secondary hypothyroidism
Low T3/4 and TSH due to deficient TSH release from anterior pituitary
In a TRH test, what does a failure to stimulate TSH/T4 suggest
Deficiency of TSH
What suppression test is used to measure acromegaly
Oral glucose tolerance test- high plasma glucose usually suppresses GH release
failure to lower GH secretion suggests a GH tumour
What does a failure to suppress indicate
autonomous secretion (
What is a normal response in the oral glucose tolerance test when testing for acromegaly and therefore what is an abnormal response
There is an increase in plasma concentration of glucose and a decrease in growth hormone
-Autonomous secretion of GH from tumour cells which are independent of normal control process. Lack of suppression with high glucose
What is the difference between a macroadenoma and micro adenoma
Macroadenoma >10mm
microadenoma <10mm
What is a potential side effect of using surgery or radiotherapy to manage pituitary disease
Hypopituitarism and damage to optic pathways
What is the preferred method treatment for most pituitary tumours (and types)
surgery
- craniotomy (through the skull above the eye
- Trans-sphenoidal-through the nose
Causes of hyperprolactinaemia
Prolactinoma (prolactin secreting tumour)
Damage to pituitary stalk and loss of inhibitory influence of hypothalamic dopamine
Symptoms of hyperprolactinaemia
Loss of fertility/libido, galactorrhea (milky discharge from breast tissue)
gynaecomastia (proliferation of breast tissue)
What is the role of prolactin
Stimulates mammary glands to produce milk
Promotes growth and development of breasts
How does prolactin cause reduction in reproductive function
It decreases GnRH release
Which in turn decreases LH and FSH release
And in turn that decreases sex hormones
What drug is used to treat a hyperprolactinaemia and how does it work
Dopamine receptor agonists
Inhibit prolactin secretion and shrunk tumour
(surgery/radiotherapy considered with tumours resistant to drug therapy)
What is the most common cause of acromegaly
GH secreting tumour
What is acromegaly
Bone density increases. Coarsening of facial features and enlarged hands and feet
Symptoms of acromegaly
Headaches, vision disturbance,
sleep apnoea, general tiredness
Hypertension, cardiomegaly
Glucose intolerance (diabetes)
Irregular or loss of periods
Impotence in males
How can dentists detect acromegaly early
As lower jaw enlarges, gaps appear between teeth
Treatment for acromegaly
Surgical removal of tumour, radiotherapy in some
Drug therapy for acromegaly
Somatostatin (inhibit GH release)
If somatostatin is not effective, use bromocriptine (dopamine receptor agonist)
What causes Cushing’s syndrome
Excessive glucocorticoid activity
ACTH-secreting anterior pituitary tumour
Treatment of cushings syndrome
Surgical removal
What is pan-hypopituitarism
Deficiency of all pituitary hormones
What can cause damage pituitary stalk
Severe head trauma
What can GH deficiency lead to
Stunted growth in childhood
What can TSH deficiency lead to
secondary hypothyroidism
What can ACTH deficiency lead to
Secondary adrenal insufficiency
What can ADH deficiency lead to
Diabetes insipidis
What can a Ganadotropin (LH/FSH) deficiency lead to in a young and adult patient
-And treatment
Young- lack of sexual development (delayed puberty)
adult- infertility
Hormone therapy
