Pituitary Flashcards
What are the 6 hormones secreted by the anterior lobe of the pituitary?
1 - ACTH (Adrenocorticotropic) 2 - TSH (Thyroid stimulating) 3 - GH (Growth) 4 - FSH 5 - LH 6 - Prolactin
What are the 2 hormones secreted by the posterior lobe of the pituitary?
1 - Vasopressin (ADH)
2 - Oxytocin
What 2 factors regulate hypothalamus function?
1 - Hormone mediated signals, e.g. negative feedback.
2 - Neural inputs.
Which 3 nuclei of the hypothalamus have the greatest influence on the regulation of endocrine functions?
1 - Paraventricular
2 - Supraoptic
3 - Ventromedial
What is the name of the bone in which the pituitary sits?
The sphenoid bone.
How does the hypothalamus convey hormones to the anterior pituitary? What about the posterior pituitary?
Anterior - Through the hypothalamic - hypophyseal portal system.
Posterior - Through neurosecretory axons extending the length of the stalk.
Which hormones stimulate and inhibit the release of growth hormone from the anterior pituitary?
Growth hormone releasing hormone (GHRH, from hypothalamus) - stimulates.
Somatostatin (from kidney delta cells) - Inhibits.
Which hormone stimulates the release of FSH and LH from the anterior pituitary?
Gonadotropin Releasing Hormone (GnRH).
Which hormone stimulates the release of adrenocorticotropic hormone from the anterior pituitary?
Corticotropin releasing hormone (CRH).
Which hormone stimulates the release of thyroid stimulating hormone from the anterior pituitary?
Thyrotropin releasing hormone (TRH).
Which hormone inhibits the release of prolactin from the anterior pituitary?
Dopamine.
What is the function of ACTH?
Regulates cortisol (glucocorticoid) release from the glomerulosa fasciculata.
What is the function of prolactin?
- Stimulates the mammary gland to produce milk.
- Suppresses the release of gonadotropin releasing hormone.
What is the function of oxytocin?
- Contraction of the womb during childbirth.
- Plays a role in lactation.
What is the function of vasopressin / ADH? How does it carry out its function?
- Increases water reabsorption at the collecting duct of the kidney.
- Acts on V2 receptors in the kidney.
- Causes aquaporins to fuse with the luminal membrane.
What term can be used to describe the nature of release of growth hormone?
Pulsatile.
What 3 factors stimulates growth hormone release? What suppresses it?
1 - Hypoglycaemia.
2 - Exercise
3 - Sleep.
-Suppressed by hyperglycaemia.
What molecule mediates the effects of growth hormone?
IGF-1
Where is IGF-1 produced?
In the liver.
What are the 5 main effects of growth hormone?
1 - Linear growth in children.
2 - Increases bone mass.
3 - Stimulates protein synthesis, lipolysis and glucose metabolism.
4 - Improved psychological well-being.
What are the effects of FSH and LH?
- FSH stimulates the ovarian follicle, causing an egg to grow.
- Also triggers the production of estrogen in the follicle.
- The rise in estrogen stimulates the pituitary gland to stop producing FSH and to start making more LH.
- The shift to LH causes the egg to be released from the ovary, a process called ovulation.
What is the function of TSH?
Stimulates the thyroid to release T3 and T4.
What is the difference between T3 and T4?
- T3 is active, T4 is inactive.
- Differ structurally by one iodine atom.
In which nuclei of the hypothalamus is vasopressin / ADH synthesised?
In the suraoptic and paraventricular nuclei.
How do secretory granules of ADH reach the posterior lobe?
Through axons of the supraoptichypophyseal tract.
What are the major stimuli for secretion of vasopressin / ADH?
- Hyperosmolarity.
- Circulating volume depletion.
How is the release of oxytocin controlled?
By positive feedback.
What is pituitary disease?
Hormone hypersecretion by an adenoma.
What is an adenoma?
A benign tumor of glandular tissue.
What are symptoms and complications of a pituitary adenoma?
- Headaches
- Hypothalamic damage
- Damage to cranial nerves 2, 3, 4, 5, 6.
List 5 causes of hypopituitarism.
1 - Pituitary tumours.
2 - Radiotherapy.
3 - Pituitary infarction.
4 - Trauma
5 - Hypothalamic releasing hormone deficiency (e.g. Kallmann syndrome).
List 6 symptoms of growth hormone deficiency in adults.
1 - Decreased abdominal fat.
2 - Impaired lipid profile.
3 - Decreased muscle strength and exercise capacity.
4 - Impaired cardiac function.
5 - Decreased bone mineral density.
6 - Impaired psychological well-being.
How is growth hormone deficiency diagnosed?
By GH stimulation tests:
- Insulin tolerance test.
- Glucagon
- GHRH + Arginine
- IGF-1
What is a treatment for growth hormone deficiency?
Hormone replacement therapy.
What are the symptoms of FSH/LH deficiency in children?
Delayed puberty.
List 7 symptoms of FSH/LH deficiency in men.
1 - Decreased libido.
2 - Impotence.
3 - Decreased secondary sexual characteristics.
4 - Decreased muscle mass and strength.
5 - Osteoporosis.
6 - Anaemia.
7 - Decreased psychological well-being.
List 6 symptoms of FSH/LH deficiency in women.
1 - Decreased libido.
2 - Menstrual disorders.
3 - Infertility.
4 - Dyspareunia (painful intercourse).
5 - Osteoporosis.
6 - Premature atherosclerosis.
How is FSH / LH deficiency diagnosed?
In women:
By monitoring FSH, LSH and oestradiol (type of oestrogen).
In men:
By monitoring FSH, LH and morning testosterone.
How is FSH / LH deficiency treated?
Hormone replacement therapy.
List 7 symptoms of ACTH deficiency.
1 - Fatigue.
2 - Weakness.
3 - Nausea.
4 - Anorexia / weight loss.
5 - Hypoglycaemia.
6 - Hypotension.
7 - Anaemia.
How is ACTH deficiency diagnosed?
By measuring 9am serum cortisol and ACTH.
Dynamic tests:
- Short Syncathen tests.
- Insulin tolerance tests.
- Glucagon tests.
How is ACTH deficiency treated?
With cortisol replacement.
List 8 symptoms of TSH deficiency.
1 - Fatigue.
2 - Weakness.
3 - Cold intolerance.
4 - Bradycardia.
5 - Weight gain.
6 - Puffiness.
7 - Pale and dry skin.
8 - Constipation.
How is TSH deficiency diagnosed?
By monitoring TSH, free T4 and free T3.
How is TSH deficiency treated?
Hormone replacement therapy using levothyroxine.
What is central diabetes insipidus?
Deficient secretion of vasopressin / ADH.
List 7 causes of central diabetes insipidus.
1 - Autoimmune destruction of supraoptic and paraventricular nuclei.
2 - Genetic.
3 - Tumours.
4 - Neurosurgery.
5 - Trauma.
6 - Infections.
7 - Hypoxic encephalopathies (severe ischaemia).
List 3 symptoms of ADH deficiency.
1 - Polyuria of dilute urine.
2 - Polydipsia (excessive thirst).
3 - Nocturia (need to wake up to urinate).
List 5 causes of polyuria.
1 - Diabetes mellitus.
2 - Diabetes insipidus.
3 - Renal failure.
4 - Primary polydipsia.
5 - ADH deficiency.
List 7 ways in which ADH deficiency can be diagnosed.
- By monitoring urine output.
- By measuring the osmolarity of the urine.
- By measuring blood electrolytes (substances that give ions when dissolved in water).
- By measuring blood glucose.
- By measuring blood urea.
- By measuring blood creatinine.
- Water deprivation test.
How is ADH deficiency treated?
Hormone replacement therapy using ADH analogues.
What is acromegaly?
A disorder caused by a pituitary adenoma that results in hypersecretion of GH.
List 8 symptoms of acromegaly.
1 - Enlargened bones of the face, feet and hands.
2 - Excessive hair growth in women.
3 - An enlargened jaw or tongue.
4 - A prominent brow.
5 - Excessive growth spurts.
6 - Weight gain.
7 - Swollen and painful joints.
8 - Left ventricular hypertrophy.
List 3 ways in which acromegaly can be diagnosed.
1 - Oral glucose tolerance test.
2 - Monitoring IGF-1.
3 - Pituitary imaging.
List 3 ways in which acromegaly can be treated.
1 - Surgically.
2 - Using drugs.
3 - Using radiotherapy.
List 3 medical treatments for acromegaly.
1 - Dopamine agonists.
2 - Somatostatin analogues.
3 - GH receptor antagonists,
List 2 symptoms of a prolactinoma.
1 - Hypogonadism.
2 - Galactorrhoea (excessive production of milk).
List 2 ways in which a prolactinoma can be diagnosed.
1 - Exclde other causes of high prolactin.
2 - Pituitary imaging.
What is a prolactinoma?
A tumour of the pituitary that results in excessive production of prolactin.
List 3 ways in which a prolactinoma can be treated.
1 - Surgically.
2 - Using drugs.
3 - Using radiotherapy.
What medical treatment is used to treat prolactinomas?
Dopamine agonists.
What is Cushing’s syndrome?
Excessive cortisol released by the adrenal gland.
Two types:
1 - ACTH - Dependent:
-Abnormal secretion of ACTH or CRH.
2 - ACTH - Independent:
- Iatrogenic (due to medical treatment) due to administration of steroids.
- Adrenal diseases (adenomasor hyperplasia).
List 8 symptoms of Cushing’s syndrome.
1 - Weight gain.
2 - Slow healing of cuts.
3 - Increased risk of infection.
4 - Fatigue.
5 - Weakness.
6 - Glucose intolerance.
7 - Decreased psychological well-being.
8 - Striae on the skin.
List 5 ways in which Cushing’s syndrome is diagnosed.
1 - Monitor 24 hour urinary free cortisol.
2 - Monitor midnight serum or salivary cortisol.
3 - Dexamethazone suppression test (measures whether ACTH can be suppressed).
-Differentiates between ACTH dependent and ACTH independent.
4 - Measure 9 am ACTH.
5 - Imaging of the pituitary and adrenals.
List 4 ways in which Cushing’s syndrome can be treated.
1 - Pituitary surgery.
2 - Radiotherapy.
3 - Drugs.
4 - Bilateral adrenalectomy (removal of both adrenal glands).
List 3 drug treatments for Cushing’s syndrome.
1 - Metyrapone.
2 - Ketokonazole.
3 - Mitotane.
Give an example of a symptom of a TSHoma.
Thyrotoxicosis (excess T3 / T4).
List 4 symptoms of an FSHoma.
1 - Menstrual irregularities.
2 - Ovarian hyperstimulation.
3 - Testicular enlargement.
4 - Infertility.
