Growth Hormone Disorders Flashcards
What cells produce growth hormone and where is it stored
Stored in granules
Produced in …
Anatomy of pituitary gland
Weighs 0.5g and is composed of 3 parts:
• Anterior pituitary (75%): adenohypophysis
• Posterior pituitary (25%): neurohypophysis
• Pituitary stalk: connects pituitary gland to hypothalamus
Synthesis of growth hormone
pre-pro growth hormone
pro-growth hormone
growth hormone
Action of the growth hormone
-It’s action is mediated by insulin-like growth factors (IGF-I and IGF-II)
- These promote cellular proliferation and cellular differentiation
Function of growth hormone
• increases cellular uptake of amino acids • increases synthesis of proteins
• increases blood [glucose]
• increases fat metabolism
• promotes epiphyseal bone growth
How is growth hormone regulated
-shows diurnal variation
-release affected by growth hormone releasing hormone and somatostatin
What is somatostatin
Growth hormone-inhibiting hormone
Normal growth
• rapid growth during first 2 years of life
• steady growth for about 9 years
controlled by growth hormone
• rapid growth during puberty controlled by growth and sex hormones
Other Hormones involved in Growth
• thyroxine
• cortisol
• insulin
What can deficiency in growth hormone cause
Dwarfism/some not affected in both adults and children
What can happen when there is an excess of growth hormone
Gigantism and acromegaly in both children and adults
Acromegaly
Disorder with excess growth In certain parts of the human body eg hand feets
Short Stature in Children
• parents who are both short
• inherited diseases eg achondroplasia • poor nutrition
• chronic illness
• psychological factors
• hormonal disorders
• growth hormone deficiency
Causes of Growth Hormone Deficiency
• non-endocrine tumours of pituitary and or hypothalamic origin
• generalised pituitary disease of any cause
• congenital deficiency of GHRH
Clinical Features of Growth Hormone Deficiency
• short height
• immature face
• skeletal immaturity
• other anterior pituitary hormone deficiencies
Biochemical Diagnosis of Growth Hormone Deficiency
• random serum [GH] of limited value
• serum [GH] rises after exercise test
• serum [GH] rises during sleep
• failure of clonidine to increase serum [GH] • urinary GH secretion is low
Management of Growth Hormone Deficiency
• administration of GH until complete growth
• administration of GHRH analogues • use of somatomedin therapy
Growth Hormone Deficiency in Adults
• impaired hair growth
• proneness to hypoglycaemia • poor muscular tone
• osteoporosis
Causes of Growth Hormone Excess
• pituitary adenoma
• ectopic GH production
adenoma
Bening tumor
Clinical Features of Growth Hormone Excess in Children (Gigantism)
• abnormal height • myopathy
Myopathy
Disease of the muscle in which the muscle fibres do not function properly
Clinical Features of Growth Hormone Excess in Adults (Acromegaly)
• enlargement of bones
• thickening of soft tissues
• prognathism
• increased sweating
• enlargement of internal organs
• headaches / visual disturbances
• paraesthesiae
• impaired glucose tolerance / diabetes • increased incidence of CHD / CVD
Biochemical Diagnosis of Growth Hormone Excess
• basal serum [GH] is raised in GH excess
• serum [IGF-I] is raised in GH excess
• OGTT to confirm diagnosis of GH excess
Management of Growth Hormone Excess
• surgical removal of tumour • radiotherapy
• drugs: bromocriptine
octeotride
What controls the release of hormones from the pituitary gland
-controlled by peptides released from the hypothalamus eg hypothalamus releases trh that acts on anterior pituitary gland to release tsh whcih acts on the thyroid
What controls the release of hormones from the pituitary gland
-controlled by peptides released from the hypothalamus eg hypothalamus releases trh that acts on anterior pituitary gland to release tsh whcih acts on the thyroid
