BPT Endocrine

Question 1

Causes of raised and suppressed growth hormone

Answer 1

Suppressed by: hyperglycaemia, somatostatin, chronic corticosteroid use. Stimulated by hypoglycaemia, oestrogen, ghrelin

Question 2

Diagnosis of acromegaly

Answer 2

• Raised IGF-1
• 75g OGTT fails to suppress GH
• MRI pituitary to localise
• Check prolactin (co-secreted in 25%), TFTs, FSH/LH

Question 3

Most common cause of congenital adrenal hyperplasia

Answer 3

• 21-hydroxylase deficiency (CYP21A2) - impaired c onversion of 17-OH-progesterone to 11-deoxycortisol
• increased DHEA and testosterone, low cortisol -> h igh ACTH causes adrenal hyperplasia
• Female virilisation / ambiguous genitalia if prenatal, male precocious puberty
• Raised 17-OH progesterone baseline + post-synacthen

Question 4

Biochemical profile of primary, secondary adrenal insufficiency

Answer 4

Early morning cortisol low if not on steroids; SST fails to stimulate cort (unless recent pit damage - haemorrhage, surgery); insulin tolerance test - normally cort > 550, GH >20
ACTH high (primary) or low
Renin high, aldo low (primary)
DHEAS low

Question 5

What does gastrin do and where is it secreted from

Answer 5

Secreted from stomach Antrum G cells

Gastrin is the dominant mediator of poatprandial gastric acid production 
Increases 
- HCl, Intrinsic factor, pepsinogen
- gastric mucosal growth & motility
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Question 6

What decreases the production of gastrin?

Answer 6

Somatostatin (Dcells) stomach
Secretin (S cells) Small intestine

They are both stimulated by low pH. They provide negative feedback

Secretin also stimulates HCO3- release from pancreas

Question 7

What causes hypergastinemia?

Answer 7

• prolonged Acid inhibition (PPI, H2 antagonist)
• Atrophic gastritis (pernicious anemia, H.pylori)
• Gastrinoma
  (Think MEN1)
• Vagotomy, small bowel resection

Question 8

Issues treating concurrent hypothyroidism with adrenal insufficiency (e.g. Autoimmune polyglandular syndrome)

Answer 8

Adrenal crisis can be precipitated by starting thyroxine due to accelerated metabolic clearance of cortisol

Question 9

Treatment of adrenal insufficiency

Answer 9

Cortisone 37.5mg/d (25/12.5)
Or hydrocortisone 20mg/d (10/5/5)
Fludrocortisone 100-200mcg/d in primary only