Metabolic acidosis - causes, symptoms, diagnosis, treatment, pathology

Summary

Metabolic acidosis occurs when blood pH drops below 7.35 due to a decrease in bicarbonate concentration. It can be caused by increased acid production, decreased excretion, or bicarbonate loss. Classified into high anion gap (due to organic acids like in lactic acidosis or diabetic ketoacidosis) and normal anion gap (like in diarrhea or type 2 renal tubular acidosis). The body compensates by moving hydrogen ions into cells, increasing respiratory rate, and eventually, the kidneys adjust to restore pH balance.

Takeaways

• 🔍 Metabolic acidosis is a condition where blood pH falls below 7.35 due to a decrease in bicarbonate concentration.
• 🌡 Blood pH is maintained between 7.35 and 7.45, relying on the balance of bases (like bicarbonate) and acids.
• 🏥 The anion gap, which is the difference between the measured cations and anions (typically sodium, chloride, and bicarbonate), normally ranges from 3 to 11 mEq/L.
• 📉 High anion gap metabolic acidosis occurs when there's an accumulation of acids, such as from lactic acidosis or diabetic ketoacidosis.
• 🚰 Normal anion gap metabolic acidosis happens when there's a loss of bicarbonate, like in severe diarrhea or type 2 renal tubular acidosis.
• 💧 The kidneys play a crucial role in managing acid-base balance, either by excreting excess acids or reabsorbing bicarbonate.
• 🌀 Metabolic acidosis can also result from the ingestion of toxic substances like ethylene glycol or methanol, which produce organic acids.
• 🏃‍♂️ The body compensates for acidosis by moving hydrogen ions into cells, often in exchange for potassium ions, which can lead to hyperkalemia.
• 👃 The respiratory system responds to metabolic acidosis by increasing the rate and depth of breathing to expel more carbon dioxide and raise pH.
• ⏱ Over time, if not caused by a renal issue, the kidneys can correct metabolic acidosis by excreting more hydrogen ions and reabsorbing bicarbonate.

Q & A

What is metabolic acidosis?

Metabolic acidosis is a condition where blood pH is lowered below 7.35 due to a decrease in bicarbonate concentration in the blood.

What is the normal blood pH range?

The normal blood pH range is between 7.35 and 7.45.

What is the role of bicarbonate in maintaining blood pH?

Bicarbonate (HCO3-) is a base that increases blood pH. It is part of the balance between bases and acids that keep blood pH stable.

What is the significance of the anion gap?

The anion gap represents unmeasured anions like organic acids and negatively charged plasma proteins. It is the difference between the measured cations (sodium) and the sum of measured anions (chloride and bicarbonate), normally ranging between 3 and 11 mEq/L.

How does high anion gap metabolic acidosis occur?

High anion gap metabolic acidosis occurs when there is a buildup of acid in the blood due to increased production, decreased excretion, or accidental ingestion of organic acids.

What are some examples of conditions that cause high anion gap metabolic acidosis?

Lactic acidosis, diabetic ketoacidosis, and ingestion of toxic substances like ethylene glycol or methanol are examples of conditions that cause high anion gap metabolic acidosis.

What is normal anion gap metabolic acidosis?

Normal anion gap metabolic acidosis occurs when there is a loss of bicarbonate ions, such as in severe diarrhea or type 2 renal tubular acidosis.

Why does the anion gap remain normal in normal anion gap metabolic acidosis?

In normal anion gap metabolic acidosis, the decrease in bicarbonate ions is offset by the buildup of chloride ions, which are part of the anion gap equation.

How does the body compensate for metabolic acidosis?

The body compensates for metabolic acidosis by moving hydrogen ions into cells, increasing respiratory rate to expel more carbon dioxide, and, if not caused by renal issues, the kidneys will eventually correct the imbalance by excreting more hydrogen ions and reabsorbing bicarbonate.

What is hyperchloremic metabolic acidosis?

Hyperchloremic metabolic acidosis is a term used for normal anion gap metabolic acidosis, where the loss of bicarbonate ions leads to an increase in chloride ions to maintain electrical neutrality.

What are the potential consequences of the body's compensation mechanisms for metabolic acidosis?

Compensation mechanisms can lead to hyperkalemia (high potassium levels in the blood) due to the exchange of hydrogen ions for potassium ions, and respiratory alkalosis if the respiratory compensation is excessive.