GH & ADH

Question 1

What is Kallmann Syndrome?

Answer 1

Congenital hypogonadotropic hypogonadism

Question 2

What is the definition of short stature?

Answer 2

Individuals below the 3rd percentile for their particular age and gender

Question 3

Name 6 examples of hypothalamic control of anterior pituitary endocrine hormone release (both release and inhibiting).

Answer 3

Hypothalamic → Anterior pituitary
1) CRH → ↑ACTH
2) TRH → ↑TSH (& PRL)
3) GHRH → ↑GH
4) GnRH → ↑FSH & LH
5) Somatostatin → ↓GH (& TSH)
6) Dopamine → ↓PRL

Question 4

What are 2 major actions of GH?

Answer 4

1) Linear growth of skeleton (childhood)
2) Intermediary metabolism

Question 5

The effects of GH are mediated by ______.

Answer 5

IGF-1 (Insulin Growth Factor-1)

Question 6

Describe the control of GH release by the anterior pituitary.

Answer 6

Normal:
GH → ↑IGF-1 → -ve feedback to hypothalamus
→ ↑GHIH/Somatostatin → ↓GH by AP

Low:
Secretion of GHRH by hypothalamus → ↑GH by AP

Independent:
Thyroid hormones → ↑GH by AP

Question 7

What are 5 non-endocrine factors that affect GH secretion?

Answer 7

1) Diurnal rhythm/sleep
2) Age
3) Body weight/Obesity
4) Stress
5) Exercise
6) Blood Glucose
7) Amino Acids

Question 8

What are 2 tests to assess for growth hormone deficiency?

Answer 8

1) Exercise growth hormone stimulation test
2) Glucagon growth hormone stimulation test

Question 9

How is gonadotropin deficiency tested?

Answer 9

Measure serum LH and FSH

Question 10

How is ADH secreted?

Answer 10

1) ▲ECF osmolality → Osmoreceptors / ▲ ECF volume → Baroreceptors

2) SON & PVN of Hypothalamus → axons project into PP gland → secrete ADH

Question 11

What are 3 physiologic defenses against hyponatremia?

Answer 11

1) Adequate fluid delivery to diluting segment
2) Normal functioning diluting segment
3) Suppression of ADH

Question 12

What is the hallmark of SIADH?

Answer 12

Hyponatremia

Question 13

What are 5 possible causes of dysfunction in the body’s physiological defence against hyponatremia?

Answer 13

1) Excessive fluid intake
2) Low volume states (adrenal deficiency, hypothyroidism)
3) Diuretics
4) very low GFR
5) Low solute intake

Question 14

What are 4 causes of SIADH?

Answer 14

1) CNS disorders (central)
2) Drug-induced
3) Lung diseases (eg. lung cancer → paraneoplastic syndrome)
4) Neoplasia
5) Others

Question 15

How is GH excess diagnosed?

Answer 15

1) IGF-1 measurement
2) GH (glucose challenge)
3) Anatomical (acromegaly)

Question 16

How is aldosterone production limited to the zona glomerulosa?

Answer 16

Aldosterone synthase is only located in the zona glomerulosa and not the reticularis or fasciculata