Acid-base abnormality Flashcards
Causes of normal anion gap metabolic acidosis
GI bicarbonate loss: diarrhoea, uterosignoidostomy, fistula
Renal tubular acidosis
Drugs e.g. acetozolamide
Ammonium chloride injection
Addison’s disease
Causes of raised anion gap metabolic acidosis
Lactate: shock, hypoxia
Ketones: DKA, alcohol
Urate: renal failure
Acid poisoning: salycylates, methanol
Causes of metabolic alkalosis
Vomiting/ aspiration
Liquorice, carbenoxolone
Hypokalaemia
Primary hyperaldosteronism
Cushing’s syndrome
Bartter’s syndrome
Congenital adrenal hyperplasia
Causes of respiratory acidosis
COPD
Decompensation in other respiratory conditions e.g. life-threatening asthma/ pulmonary oedema
Sedative drugs: benzodiazepines, opiate overdose
Causes of respiratory alkalosis
Anxiety leading to hyperventilation
Pulmonary embolism
Salicylate poisoning
CNS disorders: stroke, SAH, encephalitis
Altitude
Pregnancy
Anion gap calculation
(Na+ + K+) - (Cl- + HCO3-)
Normal range is 10-18mmol/L
Salicylate poisoning
Early stimulation of respiratory centre leads to a respiratory alkalosis
Later the direct acid effects of salicylates (combined with acute renal failure) may lead to an acidosis