These are not exhaustive lists!

Causes of Metabolic Acidosis

Can be separated in those with or without anion gap.

Causes of metabolic acidosis with normal anion gap:

Renal tubular acidosis
Diarrhoea (HCO3- lost)
Some drugs (acetazolamide)
Addison’s disease

Causes of metabolic acidosis with increased anion gap:

Lactate acidosis (organ hyperperfusion/hypoxia, shock, sepsis)
Urate acidosis (renal failure)
Ketones (ketoacidosis – diabetes, starvation or alcohol)
Drugs/toxins (classically salicylate but others including ethanol and methanol)

Causes of Metabolic Alkalosis

Excess antacid intake
Some diuretics (e.g. frusemide)
Cushing's syndrome
Excess licorice intake