Revision - Endocrinology

Question 1

What is congenital adrenal hyperplasia (CAH)?

Answer 1

Deficiency of 21-hydroxylase enzyme

This results in OVERproduction of androgens and UNDERproduction of cortisol & aldosterone.

Question 2

How is CAH inherited?

Answer 2

Autosomal recessive

Question 3

What is 21-hydroxylase enzyme responsible for?

Answer 3

Normally converts progesterone into cortisol & aldosterone.

Note - Progesterone is also used to create testosterone, but this conversion does not rely on the 21-hydroxylase enzyme.

Question 4

Pathophysiology in congenital adrenal hyperplasia?

Answer 4

1) Defect in the 21-hydroxylase enzyme (this normally converts progesterone into aldosterone and cortisol).

2) There is extra progesterone floating about that cannot be converted to aldosterone or cortisol, so it gets converted into testosterone instead.

3) Result is low aldosterone, low cortisol and abnormally high testosterone.

4) Lots of ACTH secreted in response to low cortisol levels.

5) ACTH further stimulates the production of adrenal androgens

Question 5

What is progesterone converted to in congenital adrenal hyperplasia?

Answer 5

Testosterone

Question 6

Presentation of severe cases of congenital adrenal hyperplasia?

Answer 6

1) females can present at birth with virilised (‘ambiguous’) genitalia w/ enlarged clitoris - due to high levels of testosterone

2) hypoglycaemia, hyponatraemia, hyperkalaemia

This leads to:
- poor feeding
- vomiting
- dehydration
- arrhythmias

Question 7

Define virilised

Answer 7

To assume masculine characteristics, as through a hormonal imbalance or hormone therapy.

Question 8

When do mild cases of CAH typically present?

Answer 8

Patients who are less severely affected present during childhood or after puberty.

Their symptoms tend to be related to high androgen levels.

Question 9

Presentation of mild CAH in females?

Answer 9

1) tall for age

2) deep voice

3) absent periods

4) acne

5) facial hair

6) early puberty

Question 10

Presentation of mild CAH in males?

Answer 10

1) tall for age

2) deep voice

3) large penis

4) small testicles

5) early puberty

Question 11

What is a key dermatological sign of CAH?

Answer 11

Skin hyperpigmentation (due to raised ACTH)

Question 12

What investigation is used to confirm the diagnosis of CAH?

Answer 12

ACTH stimulation test

Question 13

How can GH deficiency present in in neonates?

Answer 13

1) micropenis (males

2) severe jaundice

3) hypoglycaemia

Question 14

What does a GH stimulation test involve?

Answer 14

Measuring the response to medications that normally stimulate the release of GH.

In GH deficiency, there will be a poor response to stimulation.

Question 15

What medications are used in GH stimulation test?

I.e. which medications normally stimulate the release of GH?

Answer 15

1) glucagon

2) clonidine

3) arginine

Question 16

Impact of glucagon on GH?

Answer 16

increases GH

Question 17

Management of congenital GH deficiency?

Answer 17

1) daily SC injections of GH (somatropin)

2) treatment of other associated hormone deficiencies

3) close monitoring of height and development

Question 18

What medication is used for GH replacement?

Answer 18

Somatropin

Question 19

Features of adrenal insufficiency in neonates?

Answer 19

• lethargy
• vomiting
• poor feeding
• hypoglycaemia
• jaundice
• failure to thrive

Question 20

Cortisol, ACTH, aldosterone & renin levels in Addisons vs 2ary adrenal failure?

Answer 20

Addison’s:
- low cortisol
- raised ACTH
- low aldosterone
- high renin

2ary adrenal failure:
- low cortisol
- low ACTH
- normal aldosterone
- normal renin

Question 21

What test can be used to confirm adrenal insufficiency?

Answer 21

Short Synacthen Test (ACTH Stimulation Test)

Question 22

What short synacthen test result indicates 1ary adrenal failure?

Answer 22

Failure of cortisol to rise more than double the baseline

Question 23

How is congenital hypothyroidism often diagnosed?

Answer 23

Newborn blood spot screening test

Question 24

What are some signs that may be picked up on examination in congenital hypothyroidism?

Answer 24

Poor growth
Macroglossia
Myxedema
Large fontanelles
Hypotonia
Bradycardia
Distended abdomen with umbilical hernia
Goitre

Question 25

If there is a suspicion of cerebral oedema following DKA treatment, what is the investigation?

Answer 25

CT head

Question 26

Management options for cerebral oedema 2ary to DKA treatment?

Answer 26

1) slow fluids

2) iv mannitol

3) iv hypertonic saline

Question 27

What type of fluid therapy is given in cerebral oedema?

Answer 27

HYPERtonic –> reduces ICP

Question 28

How much 0.9% saline should be given to children with DKA as an initial bolus:

a) for children in shock

b) for children not in shock

Answer 28

a) 20ml/kg of 0.9% sodium chloride over 15 minutes

b) 10mL/kg 0.9% sodium chloride over 1 hour