Investigations For Common Endocrine Conditions

Question 1

Diagnostic Criteria for Diabetes if patient is SYMPTOMATIC

Answer 1

• fasting blood glucose > or equal to 7.0 mol/l
• random blood glucose > or equal to 11.1 mol/l (or after 75g oral glucose tolerance test)
• HbA1c > or equal to 48 mmol/mol

Question 2

Diagnostic Criteria for Diabetes if patient is ASYMPTOMATIC

Answer 2

Symptomatic criteria apply but must be demonstrated on TWO separate occasions

Question 3

When should HbA1c use be avoided?

Answer 3

• pregnancy → hba1c typically lower
• children
• conditions with decreased red cell survival (haemolytic anaemia, haemoglobinopathy, severe blood loss, antiretroviral drugs)
• increased red cell survival (splenectomy)
• iron and B12 deficiency
• renal dialysis reduces HBA1c

Question 4

First-line investigation for PRIMARY HYPERALDOSTERONISM

Answer 4

Plasma aldosterone/renin ratio

• should show elevated aldosterone and reduced renin due to the negative feedback due to sodium retention from aldosterone

Question 5

2nd and 3rd line investigations for PRIMARY HYPERALDOSTERONISM

Answer 5

2. High resolution CT abdomen and adrenal vein sampling used to differentiate between unilateral and bilateral sources of aldosterone excess
3. Adrenal venous sampling can be used to identify the gland secreting excess hormone in primary aldosteronism