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Pituitary disease
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- 1Define pituitary tumours.Almost always benign adenomas
They may be divided by size:
Micro adenoma: < 1 cm
Macroadenoma > 1 cm - 2Histological types of Pituitary tumours?Chromophobe (70%): PRL, ACTH, GH, some cause hypopituitarism. Local pressure effect in 30%
Acidophil (15%): GH or PRL, local pressure effect in 10%
Basophil (15%): ACTH, local pressure effect rare. - 3Most common type of pituitary tumour?Prolactinoma,
second most is GH - 4Describe the symptoms and signs of pituitary tumours.Headache, visual field defects ( bitemporal hemianopia, due to compression of pituitary chiasm),
Palsy of cranial nerves 3, 4, 6 --O, T, T
( pressure or invasion of cavernous sinus)
Diabetes insipidus
Disturbance of hypothalamic centres of Temp., sleep, and appetite. - 5Pathophysiology of Pituitary tumours?Non-functional pituitary adenomas are associated with hypermethylation of the p16 locus, cyclin dependent kinase inhibitor 2A (CDKN2A) gene, on chromosome 21.3. The CDKN2A gene is a tumour suppressor gene, and its product, CDKN2A protein, is important in the control of G to S phase transition in the cell cycle via inhibition of CDK4-mediated retinoblastoma protein 1 (RB1) phosphorylation. Hypermethylation of this gene inactivates the gene with no CDKN2A protein synthesis, leading to unregulated cell growth. Pituitary tumour transforming gene (PTTG) overexpression has been implicated in pituitary tumorigenesis.
- 6Investigations to confirm the presence of a pituitary tumours.MRI; accurate assessment of visual fields;
Screening tests: PRL, IGF-1, ACTH, Cortisol, TFTs, LH/FSH, testosterone (M), short synacthen test, Glucose tolerance test if Acromegaly suspected. Water deprivation test if DI is suspected. - 7What is hypopituitarism?Decrease secretion of anterior pituitary hormones. They are affected in order:
GH
Gonadotropins: LH, FSH
PRL
TSH
ACTH
Panhypopituitarism: Deficiency of all anterior pituitary hormones. - 8Describes symptoms and signs of hypopituitarism?Features are due to hormone lack:
GH lack: Central obesity, atherosclerosis, dry wrinkly skin, reduced strength, and exercise ability. Decrease CO, osteoporosis, Low glucose.
Gonadotropins (LH, FSH): Few, scant or no menses (oligomenorrhoea or amenorrhoea), reduced fertility, Decrease libido, osteoporosis, Erectile dysfunction, hypogonadism.
Thyroid lack: As for hypothyroidism
Corticotropin lack: adrenal insufficiency. - 9Investigations of hypopituitarism?Basal tests: LH, FSH ( N or decrease), testosterone or oestradiol (D), TSH ( N or D)
T4(D), Prolactin ( may be increase), IGF-1(D): measure of GH axis, Cortisol (D), U&E,
Dynamic tests: 1. Short synacthen test, 2. Insulin Tolerance test (adrenal and GH axis)
3. Arginine + GH releasing hormone test, Glucagon stimulation test alternative for ITT.
MRI scan for hypothalamic or pituitary lesion. - 10Describe symptoms and signs of Acromegaly.Acroparaesthesia (burning, tingling sensations in the extremities), amenorrhoea, reduced libido, headache, increased sweating, snoring, arthralgia, backache.
Signs: Increase growth of hands and feet, coarsening face, wide nose, macroglossia, widely spaced teeth, big supraorbital ridges, Acanthosis nigricans, obstructive sleep apnoea, carpel tunnel signs. - 11Symptoms and signs of hyperprolactinaemia in women of reproductive age.This is the commonest hormonal disturbance of the pituitary. Prolactinomas are the most common type of functional adenomas. The presentation depends on the patient's age and sex.
Commonly present with: either oligomenorrhoea ( infrequent or very light menstruation, 4-9 periods/ year)
--or galactorrhoea ( the spontaneous flow of milk from the breast unassociated with pregnancy or breast feeding.
-- These patients often have very small tumours and so present early. - 12Symptoms and signs of hyperprolactinaemia in men and post menopausal women.Usually present with mass effect such as headache or visual disturbance, however they may present with symptoms such as galactorrhoea.
The tumours are typically larger at presentation. - 13Where is pituitary gland is present?The pituitary gland sits in the sella turcica of the sphenoid bone and is attached to the hypothalamus.
Composed of 2 parts:
Anterior pituitary
Posterior pituitary - 14Hormones of anterior pituitary.FATGP
F: FSH, LH
A: ACTH
T: TSH
G: Growth Hormone
P: Prolactin - 15Hormones of posterior pituitaryOxytocin
ADH ( vasopressin) - 16Causes of raised plasma prolactin?PRL release is inhibited by the dopamine produced in the hypothalamus.
1. Excess production from the pituitary, e.g. prolactinoma.
2. Disinhibition, by compression of the pituitary stalk, reducing local dopamine levels.
3. Use of a dopamine antagonist (metoclopramide, domperidone, haloperidol, antipsychotics etc.) - 17Dopamine agonist?Bromocriptine
Cabergoline - 18What is diabetes Insipidus?passage of large volume (> 3L/day) of dilute urine due to impaired water absorption by kidneys, because of reduced ADH secretion from the posterior pituitary (cranial DI)
--or impaired response of kidneys to ADH
( nephrogenic DI) - 19Describe the symptoms and signs of DI (diabetes Insipidus)Polyuria, polydipsia, dehydration, symptoms of hypernatraemia.
- 20Investigations of DIU&E, Ca, Glucose (exclude DM), serum and urine osmolalities.
Diagnosis: water deprivation test
Significant DI is excluded if urine to plasma (U:P) osmolality ratio is more than 2:1. - 21How to calculate serum osmolality?2x (Na+K) + urea+ glucose ( all in mmol/L)
Normal plasma osmolality: 285-295 mOsmol/Kg and urine can be concentrated to more than twice this concentration. - 22What is water deprivation test?This test aim to determine whether the kidneys continue to produce dilute urine despite dehydration, and then to localise the cause.
Normal: urine osmolality > 600 mOsmol/kg
--Cranial DI: Urine osmolality increases to > 600mOsmol/kg after desmopressin.
--Nephrogenic DI: No increase in urine osmolality after desmopressin.
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- Endocrine Fichas sobre Pituitary disease, creado por Rahul sharma el 02/10/2016.
- Creado por
- Rahul sharma
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