Metabolic Acidosis

Definition: metabolic acidosis is a clinical disturbance characterized by a low pH (increased H+ concentration) and a low plasma bicarbonate concentration

  • It can be produced by a gain of hydrogen ion or a loss of bicarbonate (Swenson, 2001)
  • It can be divided clinically into two forms according to values of serum anion gap
  • High anion gap acidosis
  • Normal anion gap acidosis
  • Anion gap = Na+ + K+ – (Cl + HCO3)
  • Anion gap = Na+ – (Cl + HCO3)
  • Potassium is often omitted from the equation because of its low level in the plasma
  • The normal value for an anion gap is 8 to 12mEq/L (8 – 12 mmol/L) without K+ in the equation
  • Normal anion gap acidosis results from the direct loss of bicarbonate as in diarrhea, lower intestinal fistulas, use of divertics
  • High anion gap acidosis results from excessive accumulation of fixed acid
  • If it increased to 30mEq/L (30mmol/L) or more than a high anion gap metabolic acidosis is present regardless of what the pH and the HCO3 are
  • High ion gap occurs in ketoacidosis, lactic acidosis

Clinical Manifestation

  • Signs and symptoms of metabolic acidosis vary with the severity of the acidosis may include Headache
  • Confusion Drowsiness
  • Increased respiratory rate and depth Nausea and vomiting
  • Peripheral vasodilatation
  • And decreased cardiac output occurs when the pH falls below 7 On Examination physical findings
  • Low BP
  • Cold and Clammy skin Shock (Swenson 2001)


  • ABG’s – expected blood gas changes, low bicarbonate level less than 22mEq/L and low pH less than 7.35
  • Serum electrolytes Hyperkalemia ECG


  • Treatment is directed at correcting the metabolic defects (Swenson 2001) Decrease source of chloride
  • Administer bi carbonate if pH level is less 7.1 Serum K+ level monitored closely Hypokalemia is corrected
  • In chronic metabolic acidosis low serum Ca+ are treated Hemodialysis or peritoneal dialysis

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