Biochemistry

Question 1

What are the ACTH dependent causes of Cushing’s syndrome?

Answer 1

• Cushing’s disease - bilateral adrenal hyperplasia from ACTH-secreting pituitary adenoma.
• Ectopic ACTH production - SCLC and carcinoid tumours. Features: pigmentation, hypokalaemic metabolic alkalosis, weight loss, hyperglycaemia
• Rarely, ectopic CRF production - some thyroid and prostate cancers

Question 2

What are ACTH independent causes of Cushing’s syndrome?

Answer 2

• Iatrogenic: doses of steroids
• Adrenal adenoma/cancer
• Adrenal nodular hyperplasia
• Rarely: Carney complex, McCune-Albright Syndrome

Question 3

When should overweight/obese adults be referred to tier 3 care?

Answer 3

• Underlying causes need to be assessed
• They have complex disease states or needs that cannot be managed in tier 2 e.g. learning disabilities
• Conventional treatment has been unsuccessful
• Drug treatment is being considered for a person with A BMI >50
• Specialist interventions may be needed
• Surgery is being considered

Question 4

When can bariatric surgery be an option?

Answer 4

• BMI of 35-40 or >40 and other significant disease e.g. T2DM or HTN that could be improved if they lost weight
• All appropriate non-surgical measures have been tried but the person has not achieved clinically beneficial weight loss
• Person has been receiving or will receive intensive management in a tier 3 service
• Person is generally fit for GA
• Person commits to need for long-term follow-up

Question 5

Where do arteries for the adrenal glands arise from?

Answer 5

• Superior suprarenal artery from inferior phrenic artery
• Middle suprarenal artery from abdominal aorta
• Inferior suprarenal artery from renal artery

Question 6

What hormones are produced by each region of the adrenal glands?

Answer 6

• Zona glomerulosa - mineralocorticoids e.g. aldosterone
• Zona fasciculata - glucocorticoids e.g. cortisol
• Zona reticularis - androgen precursors e.g DHEA and androstenedione
• Medulla - catecholamines e.g. adrenaline

Question 7

What hormones are produced in the hypothalamus?

Answer 7

Oxytocin and ADH (released from posterior pituitary)

Question 8

What hormones are produced in the pituitary?

Answer 8

• TSH
• GH
• ACTH
• FSH/LH
• PRL
• Endorphins

Question 9

What are the causes of SIADH?

Answer 9

• Lung diseases - cancer, pneumonia
• Brain lesions - tumour, head injury and bleed/stroke
• Drugs e.g. carbamazipine, SSRIs

Question 10

What is primary adrenocorticol insufficiency?

Answer 10

Destruction of adrenal cortex leads to glucocorticoid and mineralocorticoid deficiency. Causes are autoimmunity, TB, adrenal metastases.

Question 11

What is secondary adrenocorticol insufficiency?

Answer 11

Commonest cause is iatrogenic, due to long-term steroid therapy leading to suppression of pituitary-adrenal axis. Other causes are rare and include hypothalamic-pituitary disease leading to decreased ACTH production.