Clinical chemistry/data interpretation

Question 1

Metabolic acidosis

Answer 1

Normal anion gap:

• GI bicarb losses (diarrhoea, fistulae)
• Renal tubular acidosis
• drugs (acetazolamide)
• Ammonium chloride injection
• addinsons

Increased Anion gap:

• lactate - shock/hypoxia
• ketones - DKA, alcohol
• Urate (renal failure)
• acid poisoning - salicylates, methanol

Question 2

Metabolic alkalosis

Answer 2

• vomiting
• diurectics
• liquorice/carbenoxolone
• hypokalaemia
• primary hyperaldosteronism (Conns)
• Cushing syndrome
• Bartters syndrome
• Congenital adrenal hyperplasia

Question 3

Respiratory acidosis

Answer 3

• COPD
• Decompensation in other resp conditions - life threatening asthma, pulmonary oedema
• sedative drugs (benzos, opiates)

Question 4

Respiratory alkalosis

Answer 4

• anxiety + hyperventilation
• PE
• salicylate poisoning
• CNS disorders (stroke,SAH, encephalitis)
• altitude
• pregnancy