Pituitary Flashcards
What hormones does the anterior pituitary gland produce?
Thyroid stimulating hormone (TSH) Adrenocorticotrophic hormone (ACTH) Follicular stimulating hormone (FSH) Luteinising hormone (LH) Growth hormone (GH) Prolactin
What hormones does the posterior pituitary gland produce?
Antidiuretic hormone
Oxytocin
What are trophic hormones? Name them.
Hormones which act on other endocrine organs
TSH
ACTH
FSH
LH
What are non-trophic hormones? Name them.
Hormones which act directly on tissue
GH
Prolactin
ADH
Oxytocin
What are the three ‘islands’ of cells of the anterior pituitary gland, what do they do and how do they look histologically?
Basophils
- produce trophic hormones
- dark purple
Acidophils
- produce non-trophic hormones
- pink
Chromophobes
- non secretory
- neutral colour
- Corticotrophs secrete _____
- Thyrotrophs secrete _____
- Gonadotrophs secrete _____
- Somatotrophs secrete _____
- Mammotrophs secrete _____
- ACTH
- TSH
- LH/FSH
- GH
- Prolactin
- ACTH is secreted by _____
- TSH is secreted by _____
- LH/FSH are secreted by _____
- GH is secreted by _____
- Prolactin is secreted by _____
- Corticotrophs
- Thyrotrophs
- Gonadotrophs
- Somatotrophs
- Mammotrophs
What is the pituitary gland formed from embryologically ?
Rathke’s pouch
What stimulates GH hormone release?
Hypothalamic GHRH
What does GH do?
Acts on cells to release IGF-1 within cells which causes general anabolic growth
What is acromegaly?
Disease caused by excess growth hormone release from pituitary gland, commonly due to a pituitary adenoma
What visual field defect do pituitary adenomas cause?
Bitemporal hemianopia
What does growth hormone cause in children whose growth plates haven’t fused?
Giantism
How does acromegaly present?
Large jaw
Large hands/feet
Thick skin
Vascular headaches
What 4 things does acromegaly increase your risk of developing?
Diabetes
Sleep apnoea
Cardiovascular disease
Colonic caner
How is acromegaly diagnosed?
Glucose suppression test (give 75mg glucose PO, GH should suppress to <0.4µg/l, stays above in acromegaly)
What is the first line treatment for acromegaly?
Surgical removal of pituitary adenoma
What drug options are there for acromegaly management?
Somatostatin analogue (ocreotide)
Dopamine agonist (cabergoline)
Growth hormone antagonist (pegvisomant)
What is diabetes insipidus?
Condition caused by a lack of ADH secretion (cranial) or ADH resistance (nephrogenic) resulting in excess water excretion
How does diabetes insipidus present?
Polyuria
Dehydration
Weakness, confusion, irritability (from hypernatraemia)
How is diabetes insipidus diagnosed?
Water deprivation test: stage 1
Stop all water intake and see if kidneys produce dilute urine
If urine remains dilute (<600mOsmol/kg) despite dehydration (8 hours of fluid restriction), patient has DI
What is the urine:plasma osmolality ratio like in diabetes insipidus?
Low
Urine is dilute (low osmolality)
Plasma is concentrated (high osmolality)
U/P = low/high = low
How can cranial diabetes insipidus be differentiated from nephrogenic diabetes insipidus?
Water deprivation test: stage 2
Give desmopressin and measure urine osmolality
In cranial diabetes insipidus, problem is lack of ADH so synthetic ADH (vasopressin) will concentrate urine (increase urine osmolality)
In nephrogenic diabetes insipidus, problem is ADH resistance so synthetic ADH (vasopressin) won’t make any difference and won’t concentrate urine (urine osmolality stays the same)
How is cranial diabetes insipidus treated?
Desmopressin
