Metabolic Acidosis

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Metabolic Acidosis:

• Low PH and Low HCO3
• Occurs when PH is lower than 7.35.
• Vasodilation occurs (to remove protons) (Resistance ionotropic drugs) (due increased H+)

Causes of metabolic acidosis:

High anion gap metabolic acidosis: (anion-/cation+) >12 high gap

1. Keto acidosis (DKA): prolonged period of starvation lead to lipolysis lead to beta oxidation of fat the end result will be ketone bodies.

   • Mitochondrial disorders (can’t metabolize glucose so can’t get ATP)
   • Keto diet.
   • DM (lots of glucose but can’t use it).

2. Lactic acidosis:

   • In malaria due anaerobic respiration --- glucose---- pyruvate--- lactate
   • Vigorous exercise (Glucose depletion)
   • MI (blood not reaching, cant metabolize)
   • Sepsis
   • Reduced tissue perfusion (tumor/closure vessel/ischemia/acidosis)
   • Metformin (because it inhibits gluconeogenesis; insulin sensitizer)
   • Liver cirrhosis (lactate accumulate can’t make glucose)

3. Aspirin, methanol, ethylgycol، (INHCC)

Normal anion gap

1. Proximal renal tubular acidosis (PRTA) (can’t absorb bicarbonate)

   • Eg; 1- Wilson. 2- cystinosis. 3- Multiple myeloma.

2. Distal renal tubular acidosis (DRTA)

   • Eg, 1- SLE. 2- sjogren. 3- Amphotericin B (antifungal).

3. Carbonic anhydrase inhibitors (Acetazolamide).

4. GI loss (diarrhea, pancreatic fistula).

5. Addison (renal tubular acidosis type 4)

6. Spironolactone (causes hyperkalemia--- H follows k and sodium excretion).

Clinical features:

1. Acetone breath if Diabetic patient.
2. Hyperkalemia.
3. Hyperventilation (kussmal’s breathing) deep breathing to wash out co2.

Lab investigation:

↓PH | ↓HCO3(24-28)/↓PCO2 (35-45) + measure anion gap

Treatment:

treat the cause and avoid HCO3 (will lead to Respiratory Alk and Met Alk and acid)

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N. m water phrendixin syndromes ++ acidosis - adrenal dyCC

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Pedia

Metabolic Acidosis

Metabolic acidosis may be with increased anion gap or with normal anion gap.

• Anion Gap:
  ([Na^+ + K^+] - [Cl^- + HCO_3^-]), normal value = 10–16 mmol/L.

Generally speaking, an increase in anion gap with metabolic acidosis is due to overproduction or decrease in excretion of acids.

A normal anion gap in the presence of metabolic acidosis signifies HCO3- loss rather than excess of acids.

Common Disorders of Metabolic Acidosis

• With Elevated Anion Gap (MUDPILES):

  • Methanol ingestion
  • Uremia
  • Diabetic, alcoholic, or starvation ketoacidosis
  • Paraldehyde ingestion
  • Isoniazid, salicylate, or iron poisoning
  • Lactic acidosis
  • Ethylene glycol ingestion

• With Normal Anion Gap (HARD-UP):

  • Hyperalimentation
  • Acetazolamide (medications that inhibit carbonic anhydrase)
  • Renal tubular acidosis, renal insufficiency
  • Diarrhea and diuretics
  • Uteroenterostomy
  • Pancreatic fistula