DKA

Question 1

Diagnostic criteria for DKA

Answer 1

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

Question 2

Outline the mechanism of severe dehydration in DKA

Answer 2

• 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

Question 3

Outline the mechanism of ketogenesis in DKA

Answer 3

• 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

Question 4

Explain the mechanism of Kussmaul breathing in DKA

Answer 4

Hyperventilation creates a respiratory alkalosis to compensate for the metabolic acidosis

Question 5

List other causes of raised anion gap acidosis

Answer 5

Alcohol

‘MUDPILES’: Methanol, uraemia, [DKA], paraldehyde, isoniazid, lactate, ethylene glycol, salicylates

Carbon monoxide/cyanide

Question 6

What are the three main components of DKA management?

Answer 6

1. Fluid resuscitation
2. Fixed rate insulin IV infusion
3. Potassium replacement