What are the differences between metabolic acidosis and metabolic alkalosis?
Nov 25, 2025
Source: Cainiu Health
Dr. Wang Lei
Introduction
The differences between metabolic acidosis and metabolic alkalosis mainly lie in aspects such as changes in acid-base parameters, common etiologies, typical clinical manifestations, characteristics of laboratory findings, and core treatment principles. Both conditions require comprehensive evaluation based on medical history and diagnostic tests. During treatment, arterial blood gas analysis and electrolytes should be dynamically monitored, and therapeutic strategies should be adjusted according to the patient's condition to avoid overcorrection, which may lead to new acid-base imbalances.
Metabolic acidosis and metabolic alkalosis differ mainly in terms of changes in acid-base parameters, common causes, typical clinical manifestations, laboratory findings, and core treatment principles. A detailed analysis is as follows:
1. Acid-base parameter changes: Metabolic acidosis is characterized by decreased bicarbonate ions (HCO₃⁻) in the blood, with a pH below 7.35; metabolic alkalosis involves elevated bicarbonate levels and a pH above 7.45. Both conditions trigger compensatory mechanisms in the body, but the directions of change in core acid-base parameters are completely opposite.
2. Common causes: Metabolic acidosis often results from accumulation of acidic substances or loss of alkaline substances, such as diabetic ketoacidosis, renal insufficiency, or severe diarrhea. Metabolic alkalosis is commonly caused by excessive intake of alkaline substances or loss of acidic substances, such as severe vomiting, prolonged use of diuretics, or large-volume infusion of alkaline fluids.
3. Typical clinical manifestations: Patients with metabolic acidosis typically present with deep and rapid breathing (Kussmaul respiration), fatigue, drowsiness, nausea, and vomiting, progressing to confusion in severe cases. Those with metabolic alkalosis may experience tetany, perioral numbness, restlessness, and in some cases, arrhythmias and muscle weakness.
4. Laboratory characteristics: In metabolic acidosis, in addition to reduced pH and HCO₃⁻, there is often hyperkalemia and an increased anion gap. In metabolic alkalosis, elevated pH and HCO₃⁻ are observed, frequently accompanied by hypokalemia and hypochloremia, while the anion gap is usually normal.
5. Core treatment principles: The management of metabolic acidosis focuses on correcting the underlying disease and administering alkali agents, along with correction of electrolyte imbalances. For metabolic alkalosis, treatment involves removing causative factors, restoring volume with normal saline and potassium chloride supplementation, and in severe cases, using acidifying agents for neutralization.
In both conditions, diagnosis requires comprehensive evaluation based on medical history and test results. During treatment, arterial blood gas analysis and electrolyte levels should be dynamically monitored, and therapeutic strategies adjusted accordingly to avoid overcorrection and the development of new acid-base disturbances.
