Growth Hormone in the Clinic

Question 1

What pathologies are associated with Growth Hormone?

Answer 1

Excess GH→Growth acceleration pathologies

GH Deficiency→Growth retardation pathologies

Question 2

Describe Clinical ranges for Growth Hormone

Answer 2

Normal serum levels of Growth Hormone: 0-30 ng/ml.

But…

Isolated blood test usually not very informative!

Question 3

Suspected Growth Hormone Deficiency-Growth Hormone: Describe the stimulation Test

Answer 3

• Fasting blood sample.
• Intravenous administration of insulin or arginine.
• Timed interval GH measurements.
• Typical normal result in children is ~10ng/ml and adults is 5ng/ml.

Question 4

In the case of suspected Acromegaly (excessive GH)-

Describe the growth Hormone Suppression Test

Answer 4

• Fasting blood sample.
• Standard drink containing 75g glucose.
• Timed interval GH measurements.
• Diagnostic criteria for acromegaly is usually failure to suppress GH levels below 1ng/ml.
• But false-negative rate is high ~50%.

Question 5

Effects of too much growth hormone depend on age of exposure:

Answer 5

before puberty→gigantism

after puberty→acromegaly

Question 6

Gigantism

Answer 6

Robert Pershing Wadlow

(1918 – 1940)

• Tallest person ever recorded
• Height 2.72m
• Died of an infection aged 22
• Excessive growth caused by pituitary tumour (expanded the number of somatotrops within the anterior pituitary so he released excessiv amounts of growth hormone)

Question 7

What are the clinical presentations of acromegaly

Answer 7

Clinical presentations:

• Soft tissue swelling of hands/feet (arthritis and carpel tunnel syndrome)
• Excessive bone thickening
• Changes in facial features

Question 8

What is Growth Hormone Deficiency

Answer 8

• aka hypopituitary dwarfism
• ~ 1 in 4000 births
• Common signs are poor growth/shortness
• Growth hormone levels are low
• Often no obvious cause = idiopathic

Question 9

How is growth hormone deficiency treated?

Answer 9

By Growth Hormone Replacement therapy

Question 10

Describe Laron Dwarfism

Answer 10

• Congenital disorder (present at or before birth) caused by autosomal recessive mutation of the GH receptor.
• Tissues are insensitive to GH because the receptor is non-functional.

Growth hormone replacement therapy doesn’t work in these patients.

• Symptoms include short stature, prominent forehead, underdeveloped jaw, central obesity, micropenis.
• Treated with IGF-I.

Question 11

What are the effects of Platelet derived growth factor (PDGF)?

Answer 11

Stimulates collagenase, fibronectin and hyaluronic acid synthesis

Question 12

Transforming growth factor (TGF)

Answer 12

Promotes angiogenesis and collagen production

Question 13

Describe the effects of vascular endothelial growth factor (VEGF)

Answer 13

Promotes angiogenesis during tissue hypoxia

Question 14

Describe the effects of Epidermal growth factor (EGF)

Answer 14

Stimulates proliferation of keratinocytes and fibroblasts

Question 15

Discribe the effects fibroblast growth factor (FGF)

Answer 15

Promotes angiogenesis, granulation and epithelialisation

Question 16

Describe the effects of Interleukins

Answer 16

Chemotactic for neutrophils and fibroblasts

Question 17

Describe the effects of Colony stimulating factor (CSF)

Answer 17

Stimulates granulocyte and macrophage proliferation.

Question 18

Describe the effects of Keratinocyte growth factor (KGF)

Answer 18

Stimulates keratinocyte migration, differentiation and proliferation