- Pathophysiology
- Vomiting - loose HCl acid + dehydrations
- Metabolic alkalosis
- Loss of H⁺ ions via vomiting leads to direct alkalosis
- Hypochloraemia
- Direct result of loss of Cl⁻ in gastric secretions
- Hypokalaemia
- Some direct loss of K⁺ in vomit
- Aldosterone is activated due to hypovolaemia → increased Na⁺ reabsorption in distal nephron, with K⁺ and H⁺ excretion
- Paradoxical aciduria
- Despite systemic alkalosis, kidneys excrete acidic urine
- Mechanism:
- Hypovolaemia → RAAS activation → Na⁺ reabsorption and K+ loss
- In distal nephron, Na⁺ is exchanged for H⁺ (since Cl⁻ and K⁺ are low)
- H⁺ is excreted in urine → aciduria despite alkalotic blood