Metabolic Alkalosis DDx

• Metabolic changes that result in the accumulation of base
• Accumulation of base occurs as a result of
  • Increased acid loss
  • Excess alkali intake

Causes

• GIT excess acid loss
  • Vomit (and pyloric stenosis)
  • NGT drainage
  • Diarrhoea
  • Ileostomy
  • Dehydration
• Renal excess acid loss
  • Bartter syndrome
  • Gitelman syndrome
  • Diuretics (Loss of H+, K+, Cl-)
• Overdose of base
  • Antacid OD, Laxative, Milk-alkali syndrome
  • Massive Hartmann’s transfusion
  • Iatrogenic use of HCO3
• Endocrine
  • Cushing syndrome
  • Steroid excess
  • Hyperaldosteronism

Clinical

• Shift O2 dissociation curve to left (increased affinity for Hb-O2)
  • Right shift with increase TEMP, 2-3 DPG, H+
• Hypokalaemia, hypocalcaemia, hypochloraemia
• Symptoms related to HYPOcalcaemia and HYPOkalaemia
  • Dizzy, light-headed
  • Chest tightness
  • Anxiety, dysphasia…..laryngospasm

Correction

• Correct underlying problem
• Improve renal bicarbonate excretion (Cl, K and volume)
• Correct electrolyte imbalance
• Oxygen
• Avoid hyperventilation
• Rarely, acetazolamide or HCl infusion

References and Links

• Acid-Base: ABG analysis – Anion Gap – SID – NAGMA
• Metabolic acidosis: Overview – evaluation – DDx
• Metabolic alkalosis: Overview – evaluation – DDx
• Respiratory acidosis: Overview – DDx
• Respiratory alkalosis: Overview – DDx