Bicarbonate Measurement and Interpretation

Measurement and Calculation

• The American Thoracic Society notes that on a Basic Metabolic Panel (BMP), serum bicarbonate is typically measured directly as total CO2 content rather than being calculated, which includes bicarbonate (HCO3-), dissolved CO2, and other minor carbon dioxide components 1
• The bicarbonate value reported on a BMP is actually a measurement of total serum CO2, which is performed using chemical methods that measure all CO2 liberated from the serum, with bicarbonate representing approximately 96% of the total 1

Clinical Applications

• The American College of Chest Physicians recommends that serum bicarbonate levels are useful for screening certain conditions, such as Obesity Hypoventilation Syndrome (OHS), where a level >27 mmol/L may indicate the need for arterial blood gas measurement to confirm hypercapnia 2, 3