16 Pituitary Disorders Flashcards
What is the most common cause of pituitary malfunction?
Adenoma (benign tumour)
Why would a ‘non-functioning adenoma’ result in inadequate production of pituitary hormones?
Physical pressure- growing tumour on glandular tissues.
What symptoms may an adenoma cause, other than inadequate production of pituitary hormones?
Headaches (pressure on surrounding structures in vicinity of tumour), visual problems (compression of optic nerve), vomiting+nausea
How would a clinician investigate a suspected pituitary tumour?
- MRI scan: delineate anatomy, size, location of mass
- Hormone levels in blood/ Staining sections from tumour biopsy w/. antibodies of relevant hormone: to assess endocrine function
What is hypopituitarism?
Insufficient hormone production
Apart from pituitary adenoma, what else may cause hypopituitarism?
Radiation therapy, Inflammatory disease, head injury.
How does hypopituitarism due to adenoma usually progress?
Progressive loss of anterior pituitary function- first GH and LH/FSH
What is panhypopituitarism?
Deficiency of all anterior pituitary hormones
Under which circumstances would ADH and oxytocin secretion be affected?
1- Tumour affects hypothalamic function
2- Inflammatory process involved
What are some of the symptoms of Growth Hormone Deficiency?
1- Decreased exercise tolerance
2- Decreased muscle strength
3- Increased body fat
4- Reduced sense of ‘well being’
Why is a combination of direct and indirect measurements required to to diagnose a GH deficiency?
Difficult to diagnose as GH secretion= PULSATILE
What are 2 possible reasons for GH deficiency in children?
1- Gene mutation
2-Autoimmune inflammation
How prevalent are GH deficiencies at birth?
1 in 3800 live births
How might a severe GH deficiency affect a baby prenatally?
(little effect on fatal growth)
Hypoglycaemia
Jaundice
How would a GH deficiency present in a patient from the age of 1 year-teens?
Poor Growth
Short Stature
How might a Gonadotropin Deficiency present?
Women:Lack of libido, infertility, oligomenorrhoea/amenorrhoea
Men: Lack of libido, impotence
What may cause ADH deficiency?
Hypothalamic/pituitary tumour, cranial radiopathy, pituitary surgery, autoimmune infiltration, infection (e.g. meningitis)
How does an ADH deficiency present?
- Excess excretion- dilute urine
- Increased thirst sensation (polydipsia)
What is Diabetes Insipidus?
Cranial form of ADH deficiency.
What is the normal physiological function of Prolactin?
Initiate and maintain lactation.
How is Prolactin secretion regulated?
Secreted by lacrotropes in anterior pituitary, regulated by:
Stimulator=Prolactin Releasing Hormone
Inhibitor= Dopamine (dominates)
How does hyperprolactinaemia present?
1, Galactorrhoea (unexplained milk production) 2, Gynecomastia (hard breast tissue) 3, Hypogonadism 4, Amenorrhea 5, Erectile dysfunction
Why does hyperprolactinaemia cause hypogonadism?
Higher dopamine levels- Inhibit GnRH secretion and therefore FSH and LH secretion from anterior posterior.
What’s the most common cause of prolactinoma?
Pituitary adenoma- secretes prolactin
Apart from a pituitary adenoma what other causes are there for hyperprolactinaemia?
Pregnancy, suckling, stress, exercise, drugs (e.g. antipsychotics, antidepressants)
How is hyperprolactinaemia treated?
- Dopamine receptor agonist (e.g. cabergoline)
2. (rare cases) Trans-sphenoidal surgery/ radiotherapy used
What else may increase in production and release if GH production increases?
IGF-1 production
How long might GH and IGF-1 overproduction take to present symptoms in a patient?
6+ years
How might a patient with GH excess present?
Broad nose, coarse facial features, which lips, prominent supraorbital ridge, enlargement of hand and feet, greasy skin (excessive sweating), deepening of voice
Why would the voice deepen in a patient with GH excess?
Hypertrophy of soft tissues in upper airways
What does excess GH in children result in?
Excess GH before fusion of epiphyseal plates in long bones : GIGANTISM
What is acromegaly?
Excess GH in adults
What complications might a patient have if they have an excess of Growth Hormone?
(GH antagonises actions of insulin)
Diabetes mellitus
+other metabolic complications
What are the treatment options for patients with acromegaly?
1- Surgery to remove adenoma
2- Radiation therapy
3- Drug therapy
( e.g. dopamine receptor agonists -some efficacy)
(Somatostatin analogs- suppress GH secretion)
(GH receptor antagonists)
Why does somatostatin have limited use even though it limits GH secretion?
Very short half-life
What is Cushing’s syndrome?
Excess endogenous secretion of ACTH (adrenocorticotropic hormone- regulates levels of cortisol) from anterior pituitary gland
