Pituitary Flashcards
Hormones secreted by anterior pituitary
GH
FSH and LH
PRL
TSH
ACTH
Hormones released by posterior pituitary
ADH
Oxytocin
Hormones synthesised in the hypothalamus
Oxytocin
ADH
CRH
GnRH
TRH
GHRH
Order in which anterior pituitary hormone secretion decreases in hypopituitarism
GH
FSH and LH
PRL
TSH
ACTH
Causes of hypopituitarism
Hypothalamus
Pituitary stalk
Pituitary
Hypothalamus causes of hypopituitarism
Kallman’s syndrome
Tumour
Infection (TB, meningitis)
Ischaemia
Pituitary stalk causes of hypopituitarism
Trauma
Surgery
Mass lesion (craniopharyngioma)
Carotid artery aneurysm
Pituitary causes of hypopituitarism
Tumour
Irradiation
Autoimmune
Ischaemia (eg. Sheehan’s)
Features of GH hypopituitarism
Central obesity
Atherosclerosis
Weakness
Osteoporosis
Hypoglycaemia
Features of gonadotropin hypopituitarism in females
Oligomenorrhoea
Infertility
Reduced libido
Osteoporosis
Dyspareunia
Features of gonadotrpin hypopituitarism in males
Erectile dysfunction
Reduced libido
Reduced muscle bulk
Hypogonadism
Features of thyroid hypopituitarism
Hypothyroidism
Features of ACTH hypopituitarism
Adrenal insufficiency
Microadenoma definition
Tumour < 1 cm across
Macroadenoma definition
Tumour > 1 cm across
Histological types of pituitary tumour
Chromophobe
Acidophil
Basophil
Features of chromophobe pituitary tumours
Many non secretory
Half produce prolactin
Some cause hypopituitarism
Features of acidophil
15% Secrete GH or PRL
10% Local pressure effects
Features of basophil pituitary tumour
15% secrete ACTH
Negative effects exerted by pituitary tumours
Hypopituitarism
Sx caused by pressure
Hormones secreted
Sx of local pressure from pituitary tumours
Headache
Visual field
CN palsy
Disturbance to hypothalamus
Mx of pituitary tumours
Hormone replacement
Surgery (usually trans-sphenoidal)
Radiotherapy
Pituitary apoplexy definition
Rapid pituitary enlargement from bleed into tumour
Pituitary apoplexy sx
Acute onset:
Headache
Meningism
Low GCS
Visual field defects
Consequences of pituitary apoplexy
Mass effects
CVS collapse
Death
Mx of pituitary apoplexy
Hydrocortisone 100mg
Fluid
Surgery
Craniopharyngioma definition
Originates from Rathke’s pouch
(between pituitary and 3rd ventricle floor)
Sx of craniopharyngioma
Amenorrhoea
Reduced libido
Mass effect
Sleep disturbance
Diabetes insipidus
Mx of craniopharyngioma
Surgery
+/- radiotherapy post op
Relationship between PRL and dopamine
Dopamine from hypothalamus inhibits PRL release
Causes of hyperprolactinaemia
Prolactinoma
Pituitary stalk compression - reduced DA inhibition
DA antagonist
Mx of hyperprolactinaemia
Dopamine agonist
Eg, Bromocriptine or Cabergoline
Cause of Acromegaly
Increased GH
Sx of acromegaly
Amenorrhoea
Headache
Reduced libido
Sweating
Snoring
Rings / Shoes no longer fitting
Signs of acromegaly
Growth of (spade) hands, feet and jaw
Macroglossia
Widely spaced teeth
Acanthosis nigricans
Wide nose
Acromegaly vs Gigantism
Acromegaly - after bone epiphyses fuse
Gigantism - before bone epiphyses fuse
Complications of acromegaly
Impaired glucose tolerance
HTN
LVH
Increased risk of colorectal cancer
Ix for acromegaly
Hyperglycaemia
High Ca and PO4
OGTT
Diagnosis of acromegaly
OGTT
Collect GH at 0, 30, 60, 90, 120 and 150 mins
If lowest GH > 1 microg/L then diagnose acromegaly
Mx of acromegaly
Tumour excision
Somatostatin analogues
Radiotherapy
GH antagonist
Somatostatin analogue examples
Octreotide
Lanreotide
GH antagonist example
Pegvisomant
Diabetes insipidus definition
Impaired water reabsorption in the kidney
Passing large volumes of dilute urine
Sx of diabetes insipidus
Polyuria
Polydipsia
Dehydration
Hypernatraemia
Types of diabetes insipidus
Cranial DI
Nephrogenic DI
Cranial DI definition
Reduced ADH secretion from posterior pituitary
Nephrogenic DI definition
Impaired response of kidney to ADH
Causes of cranial DI
Idiopathic
Congenital
Tumour
Trauma
Haemorrhage
Infection
Tumour causes of cranial DI
Pituitary
Craniopharyngioma
Mets
Causes of nephrogenic DI
Inherited
Low K
High Ca
Lithium
CKD
Diagnosis of diabetes insipidus
8 hr water deprivation test
Desmopressin
Water deprivation test for DI
Tests ability to concentrate urine or not
If urine osmolality low, diabetes insipidus likely
Desmopressin test for diabetes insipidus
Determines whether cranial or nephrogenic DI
Urine output decreases after desmopressin = Cranial
Urine output still high after desmopressin = Nephrogenic
Mx of cranial DI
MRI - find cause
Desmopressin
Desmopressin
Synthetic ADH
Mx of nephrogenic DI
Treat cause
Bendroflumathiazide
NSAIDs
Use of NSAIDs for nephrogenic DI
NSAIDs inhibit prostaglandin synthase
Prostaglandins locally inhibit action of ADH
NSAIDs lower urine volume and plasma Na
Definition of hypogonadism
Failure of testes to produce testosterone, sperm or both
Features of hypogonadism
Small testes
Reduced libido
Erectile dysfunction
Reduced muscle bulk
Gynaecomastia
Osteoporosis
Primary hypogonadism definition
Testicular failure
Causes of primary hypogonadism
Trauma
Torsion
Post-orchitis
Renal / liver failure failure
EtOH excess
Chromosomal abnormalities
Mechanism by which renal failure, liver failure or alcohol excess cause primary hypogonadism
Toxic to Leydig cells
Chromosomal abnormalities causing primary hypogonadism
Klinefelter’s syndrome
(47 XXY)
Features of Klinefelter’s syndrome
Delayed sexual development
Small testes
Gynaecomastia
Secondary hypogonadism definition
Low gonadotropins
(FSH and LH)
Causes of secondary hypogonadism
Hypopituitarism
Prolactinoma
Kallman’s syndrome
Systemic illness
Prader-Willi syndrome
Age
Kallman’s syndrome definition
Isolated GnRH deficiency
Feautures of Kallman’s syndrome
Secondary hypogonadism
Anosmia
Colour blindness
Prader-Willi syndrome definition
Congenital disorder
Chromosome 15
Sx of Prader-Willi syndrome
Excessive appetite - obesity
Learning difficulties
Hypotonia
Lack of sexual development
Short stature
