Endo 1 - Hyposecretion of APG Hormones

Question 1

Achondroplasia is not an endocrine cause of short stature. But what is it?

Answer 1

Dwarfism caused by mutation in the Fibroblast Growth Factor receptor 4 (FGF3).
Abnormal growth plate chondrocytes which impairs linear growth
Short limbs but average size trunk

Question 2

What is a chondrocyte?

Answer 2

Cells which secrete cartilage matrix

Question 3

How can Laron dwarfism be treated?

Answer 3

IGF-1 can be given

Question 4

Name 3 causes of acquired GH deficiency in adults

Answer 4

Trauma
Pituitary tumour
Cranial radiotherapy

Question 5

Why is measuring GH randomly not a good idea?

Answer 5

GH release is pulsatile

Question 6

GH is measured under stress. What are the GH provocation tests?

Answer 6

1. Insulin - GH release via hypoglycaemia
2. Glucagon (i.m)
3. GHRH and Arginine (combined)
4. Exercise (children better)

Plasma GH measured at time points before and after

Question 7

How is Growth hormone administered?

Answer 7

Daily subcutaneous injection given. Clinical response monitored and dose adjusted to IGF-1

Question 8

What are the signs and symptoms of GH deficiency

Answer 8

1. Impaired psychological wellbeing
2. Decreased HDLs, more LDLs
3. Reduced muscle strength and bulk
4. Reduced lean mass, increased waist:hip ratio
5. increased adiposity

Question 9

What are the benefits of taking GH?

Answer 9

Improved body composition, better lipid profile, increased muscle strength and exercise capacity, increased bone mineral density, improved psychological well being

Question 10

What are the potential risks of GH therapy in adults?

Answer 10

1. (Increased susceptibility to cancer but not evidence supported)
2. V expensive (42k for lifelong GH treatment)

Question 11

What are the 5 APG hormones?

Answer 11

1. GH
2. Prolactin
3. TSH
4. LH/FSH
5. ACTH (used to make cortisol)

Question 12

Differentiate between 1 and 2 endocrine gland disease?

Answer 12

1 = when the gland at the end of the chain isn't working
2 = problem with secretion of hormone

Question 13

What are some features of primary hypothyroidism?

Answer 13

High TSH, Low T4

Question 14

What is panhypopituitarism?

Answer 14

Decreased production of all APG hormones

Question 15

Hypopituitarism can be a decrease in production of specific hormones also.

Answer 15

t

Question 16

Describe congenital causes of hypopituitarism?

Answer 16

TF genes are mutated (e.g. PROP1). GH deficient and at least one other APG hormone.
Short stature, hypoplastic APG on MRI

Question 17

Name the causes of panhypopituitarism

Answer 17

1. Tumour (hypothalamic/pituitary)
2. Radiation
3. Infection
4. Traumatic brain injury
5. Infiltrative disease
6. Inflammatory
7. Pituitary apoplexy
8. Peri-partum infarction

Question 18

What are hypothalamic tumours called?

Answer 18

Craniopharyngiomas

Question 19

What are pituitary tumours called

Answer 19

Adenoma (pituitary)

Question 20

Which hormone is most resistant to radiation damage?

Answer 20

TSH

Question 21

Which hormone is most susceptible to radiation damage?

Answer 21

GH

Question 22

Give an example of an infiltrative disease that can cause panhypopituitarism

Answer 22

Neurosarcoidosis - diseases typically involve pituitary stalk

Question 23

How can panhypopituitarism present?

Answer 23

1. Low FSH/LH = secondary hypogonadism, secondary amenorrhoea, reduced libido, erectile dysfunction
2. Low ACTH = secondary hypoadrenalism - fatigue
3. Low TSH = secondary hypothyroidism - fatigue

Question 24

How does Sheehans syndrome arise?

aka peri-partum infarction

Answer 24

1. Pregnancy - prolactin produced so lactotrophs grow - APG grows.
2. APG has very little blood supply and may cause potential impingement
3. Higher risk of haemorrhaging (higher risk in poorer countries).
4. Haemorrhaging means APG doesn’t get enough blood so infarcts

Question 25

How does Sheehans syndrome present?

Answer 25

Lethargy, anorexia, weight loss due to TSH/ACTH/GH deficiency.

MAJORLY, failure to lactate due to prolactin deficiency. Failure to resume menstruation

PPG usually unaffected

Question 26

What is pituitary apoplexy?

Answer 26

Haemorrhaging of the pituitary gland. May present if patient has pre-existing pituitary tumour

Question 27

What is often the first presentation of pituitary adenoma?

Answer 27

Pituitary apoplexy which causes severe sudden headache with visual field defect (due to compressed optic chiasm - bitemporal hemianopia). May also cause diplopia (IV, V) or Ptosis (III)

Question 28

Pituitary apoplexy may be precipitated by what?

Answer 28

Anticoagulants

Question 29

Why shouldn’t basal concentrations of APG hormones really be measured?

Answer 29

ACTH/GH = pulsatile

FSH/LH = cyclical

Cortisol = time dependent

T4 = long half life (6 days)

Question 30

How is hypopituitarism biochemically diagnosed?

Answer 30

Insulin injection - BG < 2.2mM -> stimulates GH release and ACTH release (cortisol measured)

TRH given - stimulates TSH

GnRH - FSH and LH release

Question 31

ACTH deficiency. Treat

Answer 31

Hydrocortisone - check serum cortisol

Question 32

TSH deficiency. Treat

Answer 32

Give thyroxine - check serum free t4

Question 33

FSH/LH deficiency in woman. Treat

Answer 33

HRT (E2 and progestogen) - check symptom improvement and withdrawal bleeds

Question 34

FSH/LH deficiency in man. Treat

Answer 34

Testosterone - check symptom improvement and serum testosterone

Question 35

GH deficiency. Treat

Answer 35

GH - check IGF-1 and growth chart (if child)