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Question 1. Diagnosis of DKA

What are the three diagnostic criteria for DKA?

  • Hyperglycaemia >11 mM or known diabetes
  • Ketonaemia >3 mM or ketonuria >2+
  • Acidosis pH <7.3 and/or bicarbonate <15 mM

Question 2. Pathophysiology of DKA

Outline the mechanism of profound dehydration in DKA

  • Insulin deficiency renders cells unable to take up and metabolise glucose
  • Glucose remains trapped in the blood from where it is filtered by the kidneys in concentrations that exceed renal reabsorption capacity
  • Glycosuria causes a profound osmotic diuresis leading to severe dehydration

Outline the mechanism of ketogenesis in DKA

  • Unable to rely on carbohydrate metabolism, cells switch to fat metabolism and oxidise fatty acids to release acetyl coenzyme A (CoA) in concentrations that saturate the Kreb’s cycle
  • Excess acetyl CoA is converted to the ketone bodies acetone, acetoacetate and beta-hydroxybutyrate, which are released into the blood causing a raised anion gap metabolic acidosis

Explain the mechanism of Kussmaul’s breathing in DKA

  • Hyperventilation creates a respiratory alkalosis to compensate for the metabolic acidosis

Question 3. Differential diagnosis of DKA

List other causes of a raised anion gap metabolic aciodsis

  • Alcohol
  • ‘MUDPILES’: Methanol, uraemia, [DKA], paraldehyde, isoniazid, lactate, ethylene glycol, salicylates
  • Carbon monoxide/cyanide

Question 4. Management of DKA

What are the three main components in the management of DKA?

  • Fluid resuscitation
  • Fixed rate insulin IV infusion
  • Potassium replacement

What is the fluid resuscitation regime in DKA?

  • 0.9% saline 1 L IV over 1 hour
  • 0.9% saline 1 L IV over 2 hours
  • 0.9% saline 1 L IV over 2 hours
  • 0.9% saline 1 L IV over 4 hours
  • 0.9% saline 1 L IV over 4 hours
  • 0.9% saline 1 L IV over 6 hours

At what rate would you commence the fixed rate insulin IV infusion?

  • 0.1 unit/kg/hour

What action would you take once blood glucose became <14 mM?

  • Commence glucose 10% IV at 125 ml/hour

At what level would you add potassium supplementation to fluid resuscitation?

  • Potassium <5.5 mM