growth hormone

Question 1

What is the pattern of release of GH?

Answer 1

Pulsatile release, increased release at night.

Question 2

In which stage of life are GH levels the greatest?

Answer 2

puberty

Question 3

What are the functions of GH?

Answer 3

Promotes growth of bone and muscle, and increases blood glucose levels

Question 4

How does GH stimulate bone and muscle growth?

Answer 4

GH stimulates the release of IGF-1 (insulin-like growth factor), which stimulates mitosis in bone and muscle

Question 5

What are the metabolic effects of GH?

Answer 5

Restricts cellular uptake of glucose to raise blood glucose. Stimulates lipolysis in adipose tissue to supply fatty acids for energy. Increases gluconeogenesis in the liver. Stimulates protein synthesis in muscle

Question 6

What are the negative feedback loops for GH?

Answer 6

GH and IGF-1 provide negative feedback to the hypothalamus

Question 7

What hormone inhibits release of GH?

Answer 7

Growth Hormone Inhibiting Hormone (GHIH), AKA somatostatin

Question 8

What condition is caused by excess secretion of GH in childhood?

Answer 8

Gigantism

Question 9

What are the causes of gigantism?

Answer 9

pituitary adenoma, genetic mutations

Question 10

What are the symptoms of gigantism?

Answer 10

Abnormally rapid childhood growth of height/size. Enlarged hands, feet, facial features. Joint pain

Question 11

What investigations may diagnose gigantism?

Answer 11

Bloods may show elevated GH or IGF-1,
Oral glucose tolerance test may fail to supress GH levels indicating adenoma.
MRI/CT may show adenoma

Question 12

What are the non-pharmalogical treatments for gigantism?

Answer 12

surgical/radiation tumor removal

Question 13

What are the pharmalogical treatments for gigantism?

Answer 13

Somatostatin analogue (potent inhibitor of growth hormone release)

Question 14

What condition is caused by excess GH in adults?

Answer 14

Acromegaly

Question 15

What are the causes of acromegaly?

Answer 15

Pituitary adenoma, ectopic GH or GHRH producing tumor

Question 16

What are the symptoms of acromegaly?

Answer 16

enlarged hands, feet, jaw, nose, brow. Thickened skin, deepened voice, increased tooth spacing, glucose intolerance

Question 17

What investigations are used to diagnose acromegaly?

Answer 17

Bloods may show elevated GH/IGF-1, oral glucose tolerance test not supressed suggests adenoma, MRI/CT may show adenoma

Question 18

What are the non-pharmalogical treatments for acromegaly?

Answer 18

Surgery/radiation removal of adenoma

Question 19

What are the pharmacological treatments for acromegaly?

Answer 19

somatostatin analogues

Question 20

What condition is caused by a lack of growth hormone?

Answer 20

Pituitary dwarfism/growth hormone deficiency

Question 21

What are the causes of GH deficiency?

Answer 21

Congenital pituitary abnormalities, pituitary damage from trauma/tumours/radiation/infection

Question 22

What are the symptoms of GH deficiency?

Answer 22

slow growth rate, short stature, reduced muscle mass, delayed puberty, high lipids

Question 23

What are the investigations used to diagnose GH deficiency?

Answer 23

GH stimulation test will show no response to insulin, Bloods will show low GH/IGF-1, xrays will show delayed bone age

Question 24

What is the pharmacological intervention for GH deficiency?

Answer 24

Somatotrophin (growth hormone analogue) injections

Question 25

What is a glucose supression test?

Answer 25

Glucose is given to a patient and GH levels are tested to see if they are inhibited normally. If suppression does not occur then there is likely a GH secreting tumor