Understanding the body's acid-base balance
The human body maintains a delicate acid-base balance, or homeostasis, to ensure all its systems function correctly. This balance is primarily regulated by the lungs, which control carbon dioxide (a respiratory acid), and the kidneys, which manage bicarbonate (a metabolic base). When this equilibrium is disturbed, a primary acid-base disorder occurs. The four main types are metabolic acidosis, metabolic alkalosis, respiratory acidosis, and respiratory alkalosis. Each is associated with a different set of underlying diseases and physiological malfunctions.
Diseases linked to metabolic acidosis
Metabolic acidosis is characterized by a buildup of acid in the blood due to either an increase in acid production, a loss of bicarbonate, or the kidneys' inability to excrete acid. High anion gap acidosis can be caused by conditions such as Diabetic Ketoacidosis (DKA) in type 1 diabetes, Lactic Acidosis from conditions like severe infections, Kidney Failure, and poisoning. Normal anion gap acidosis can result from severe diarrhea, Renal Tubular Acidosis, and Addison's Disease.
Respiratory acidosis: A lung-related issue
Respiratory acidosis occurs when the lungs don't remove enough carbon dioxide (CO2) through breathing. Causes include Chronic Obstructive Pulmonary Disease (COPD), severe asthma attacks, neuromuscular disorders, obesity hypoventilation syndrome, and over-sedation.
Diseases associated with metabolic alkalosis
Metabolic alkalosis results from losing too much acid or gaining too much bicarbonate. This can be caused by severe vomiting, diuretic use, hyperaldosteronism, cystic fibrosis, and inherited conditions.
Respiratory alkalosis: Too much ventilation
Respiratory alkalosis is caused by hyperventilation. Causes include panic attacks, pulmonary embolism, liver failure, high altitude, sepsis, and salicylate toxicity. For a detailed list of conditions associated with respiratory alkalosis, refer to {Link: DynaMed dynamed.com}.
Comparison of major acid-base disorders
| Feature | Metabolic Acidosis | Respiratory Acidosis | Metabolic Alkalosis | Respiratory Alkalosis |
|---|---|---|---|---|
| Primary Disturbance | Low serum bicarbonate (HCO3-) | High partial pressure of CO2 (PCO2) | High serum bicarbonate (HCO3-) | Low partial pressure of CO2 (PCO2) |
| pH change | Decreased (acidemia) | Decreased (acidemia) | Increased (alkalemia) | Increased (alkalemia) |
| Associated Diseases | Diabetes, kidney failure, sepsis | COPD, neuromuscular disease, over-sedation | Severe vomiting, diuretic use, Conn syndrome | Anxiety, high altitude, pulmonary embolism |
| Compensatory Response | Increased respiration (Kussmaul breathing) | Increased renal excretion of acid | Decreased respiration (hypoventilation) | Increased renal excretion of bicarbonate |
Conclusion
Acid-base disorders are often indicators of underlying health problems rather than standalone diseases. They are linked to conditions ranging from chronic issues like diabetes and kidney disease to acute events. Proper management requires treating the root cause. For comprehensive information, consult the {Link: Merck Manual merckmanuals.com}.
