Alkalosis

At a glance

• Metabolic alkalosis is a primary rise in bicarbonate (above about 28 mmol/L). It is the commonest acid-base disorder in hospital, mostly from diuretics and vomiting.
• Two steps keep it going: something generates it (acid loss or alkali gain), and something stops the kidney excreting the excess (volume and chloride depletion, hypokalaemia or mineralocorticoid excess).
• Split it by urine chloride and blood pressure. That one step sorts nearly every cause.