Q21

Describe the mechanism of action of thiazides.

  • Inhibition of Na/Cl transporter in the distal convoluted tubule leading to increased NaCl excretion and diureses

Pass Criteria:

  • Bold to pass

What are the major clinical indications for thiazide diuretic use?

  • Hypertension
  • Heart failure
  • Nephrolithiasis
  • Nephrogenic Diabetes Insipidus
  • Generalised oedema
  • Nephrotic syndrome
  • Cirrhosis

Pass Criteria:

  • 2 bold to pass

What are the potential adverse effects of thiazide diuretics?

  • Hypokalaemia
  • Dehydration/post hypotension/hypovolemia
  • Hyponatraemia
  • Metabolic alkalosis
  • Hyperuricaemia
  • Hyperlipidaemia
  • Allergic reactions
    • Cross reactivity with sulphonamides
  • Impaired carbohydrate tolerance – hyperglycaemia
  • Hypercalcaemia
  • Pancreatitis

Pass Criteria:

  • 2 bold + 1 other

Q22

Why is mannitol used in the management of head injury?

  • Mannitol is used to reduce intracranial pressure after head injury

Pass Criteria:

  • Bold to pass

What is the mechanism of action of mannitol?

  • Osmotic diuretic
  • Alters Starling forces as it does not cross the intact blood-brain barrier
  • Draws water out of cells and reduces intracellular volume
  • (Hence reduces intracranial volume and intracranial pressure)

Pass Criteria:

  • Bold to pass

What are the other clinical effects?

  • Reduces intraocular pressure
  • Diuresis/dehydration/hypovolaemia
  • Hypernatraemia
  • Hyperkalaemia

Pass Criteria:

  • 2 of 4 to pass

Supplemental Question: What is an appropriate dose of mannitol for an adult patient with a head injury?

  • 1-2 g/kg as an IV bolus over 15 mins
  • 0.25-2 g/kg IV bolus