Endocrine/Reproductive - Hypothalamic tumours

Question 1

What is growth hormone?

Answer 1

Growth hormone is produced by the anterior pituitary gland = responsible for stimulating cell reproduction and the growth of organs, muscles, bones and height.
Stimulates the release of insulin-like growth factor (IGF-1) by the liver = important for promoting growth in children and adolescents.

Question 2

Congenital growth hormone deficiency Definition

Answer 2

Congenital growth hormone deficiency results from a disruption to the growth hormone axis at the hypothalamus or pituitary gland.
Causes:
- Known genetic mutation such as:
= GH1 (growth hormone 1)
= GHRHR (growth hormone releasing hormone receptor) genes
- Another condition e.g. empty sella syndrome = where the pituitary gland is under developed or damaged

Question 3

Acquired growth hormone deficiency definition

Answer 3

Can be secondary to infection, trauma or interventions such as surgery

Question 4

How can growth hormone deficiency occur?

Answer 4

• In isolation
• In combination with other pituitary hormone deficiencies = called hypopituitarism or multiple pituitary hormone deficiency e.g.
  = hypothyroidism
  = adrenal insufficiency
  = deficiency of gonadotrophins (LH and FSH).

Question 5

Signs and symptoms

Answer 5

Neonates:
- Micro-penis (in males)
- Hypoglycemia
- Severe jaundice
Older infants and children can present with:
- Poor growth, usually stopping or severely slowing from age 2-3
- Short stature
- Slow development of movement and strength
- Delayed puberty

Question 6

Diagnosis

Answer 6

FIRST LINE: Growth hormone stimulation test:
- e.g. glucagon, insulin, arginine and clonidine
- monitored regularly for 2-4 hours after administering the medication
- positive test = poor response stimulation

Other investigations:
- test for other deficiencies e.g. thyroid and adrenal deficiency
- MRI brain for structural pituitary or hypothalamus abnormalities
- Genetic testing = for Turner syndrome and Prader-Willi syndrome
- Xray (usually of the wrist) = DEXA scan can determine bone age and help predict final height

Question 7

Treatment

Answer 7

• Daily subcutaneous injections of growth hormone (somatropin)
• Treatment of other associated hormone deficiencies
• Close monitoring of height and development