Bicarbonate Sample Type: Serum

Summary of Bicarbonate (HCO₃⁻) – Serum Test The serum bicarbonate test measures the level of bicarbonate in the blood, which plays a key role in maintaining the body's acid-base balance. It helps evaluate metabolic and respiratory function, especially in conditions like metabolic acidosis, alkalosis, kidney disease, and lung disorders. Normal range is typically 22–29 mmol/L. Low levels may indicate acidosis, while high levels may suggest alkalosis. No special preparation is usually required for the test.

By Allschoolabs · August 5, 2025 · 38 views

Bicarbonate (HCO₃⁻) – Serum Test
Overview
Bicarbonate (HCO₃⁻) is a vital component of the body’s pH buffering system. It helps maintain the acid-base balance in the blood and other bodily fluids. Measuring serum bicarbonate provides valuable insight into a person’s metabolic and respiratory status.

Purpose of the Test
The serum bicarbonate test is used to:

Evaluate acid-base balance in the body

Monitor patients with kidney disease, lung disorders, or metabolic conditions

Help diagnose conditions such as:

Metabolic acidosis (low bicarbonate levels)

Metabolic alkalosis (high bicarbonate levels)

Respiratory acidosis/alkalosis

Monitor the effectiveness of treatments for acid-base imbalances

Sample Type
Serum: Blood is drawn from a vein and allowed to clot, then the serum is separated for analysis.

Normal Reference Range
Typically: 22 to 29 mmol/L
(Ranges may vary slightly depending on the laboratory)

Causes of Abnormal Levels
Low Bicarbonate (Metabolic Acidosis)
Kidney disease (renal failure)

Diabetic ketoacidosis

Lactic acidosis

Severe diarrhea

Addison's disease

High Bicarbonate (Metabolic Alkalosis)
Prolonged vomiting or gastric suction

Excessive antacid use

Cushing's syndrome

Chronic respiratory diseases (compensation for respiratory acidosis)

Clinical Significance
Abnormal serum bicarbonate levels may indicate underlying metabolic or respiratory disorders and are often interpreted along with other electrolyte and blood gas results (e.g., pH, PCO₂, and anion gap).

Test Preparation
No special preparation is usually needed.

Inform your healthcare provider about medications, as diuretics and antacids can affect bicarbonate levels.

Conclusion
The serum bicarbonate test is an essential diagnostic tool for assessing the body's acid-base homeostasis. Regular monitoring may be needed for patients with chronic kidney or lung conditions, and those receiving treatments that can alter electrolyte balance.