How can I measure bicarbonate levels in my body?

How to Measure Bicarbonate Levels in Your Body

You can measure bicarbonate levels through a simple blood test called a Basic Metabolic Panel (BMP), which your doctor can order as part of routine bloodwork drawn from a vein in your arm. 1

Primary Measurement Method: Serum Bicarbonate

The standard and most practical way to measure bicarbonate is through venous blood sampling as part of a Basic Metabolic Panel. 2, 1 This test:

• Measures "total CO2 content" which includes bicarbonate (representing approximately 96% of the total), dissolved CO2, and other minor carbon dioxide components 2, 1
• Requires only a routine venous blood draw from your arm—no arterial puncture needed 3
• Is widely available, affordable, and frequently ordered as part of standard laboratory panels 3

When Arterial Blood Gas (ABG) Testing May Be Needed

While venous blood testing is sufficient for most purposes, arterial blood gas analysis may be necessary in specific clinical situations:

• If your serum bicarbonate is >27 mmol/L and you have obesity with sleep-disordered breathing, your doctor may order an ABG to confirm hypercapnia (elevated CO2) 3
• ABG involves drawing blood from an artery (usually in the wrist), which is more uncomfortable than venous sampling but provides additional information about oxygen and carbon dioxide levels 3

Important Note on Venous vs. Arterial Sampling

For most clinical purposes, venous bicarbonate from a BMP is more reliable for screening than ABG bicarbonate. 2 Research shows:

• In diabetic ketoacidosis, venous and arterial pH differ by only 0.02 pH units on average, making them clinically interchangeable in stable patients 4
• Venous serum bicarbonate can reliably predict arterial pH in metabolic acidosis 5

Normal Range and Clinical Significance

• Normal serum bicarbonate levels are typically 22-26 mmol/L 2
• Levels <22 mmol/L suggest metabolic acidosis 6
• Levels >27 mmol/L may indicate metabolic alkalosis or chronic respiratory acidosis with compensation 3, 2

Common Pitfalls to Avoid

• Sequential rather than simultaneous sampling can lead to differences between serum and ABG bicarbonate values, especially if your condition is changing rapidly 2, 6
• The term "serum bicarbonate" is not strictly accurate since the test measures total CO2, but bicarbonate comprises 96% of this value 2, 1
• Normal oxygen saturation does not rule out acid-base disturbances, so bicarbonate assessment remains important even when oxygenation appears adequate 6

Practical Steps

To get your bicarbonate measured:

1. Ask your doctor to order a Basic Metabolic Panel (BMP) or Comprehensive Metabolic Panel (CMP) 1
2. Go to a laboratory or hospital for a routine venous blood draw 2, 1
3. Results are typically available within hours to a day 1
4. Your doctor will interpret the results in the context of your symptoms and other laboratory values 6