Definition
What CO2 (Bicarbonate) measures
The CO2 test on a metabolic panel measures mostly bicarbonate, the blood's primary buffer against acid. Lungs and kidneys adjust it continuously to hold pH steady.
Illustrative sample band · Synthetic
25mmol/L
19Sample target 23–28 mmol/L31
Why it matters
How clinicians usually read it
It is the acid-base line on the panel: sustained shifts hint at kidney compensation, breathing patterns, GI losses, or medication effects worth explaining.
When it reads low
A lower value can mean
A lower CO2 suggests more acid load or bicarbonate loss — seen with kidney issues, diarrhea, some medications, or very low-carbohydrate states.
When it reads high
A higher value can mean
A higher CO2 can follow vomiting, some diuretics, or breathing patterns that retain bicarbonate. It is interpreted with electrolytes and the clinical story.
Questions for a clinician
Bring the number into a real conversation
01
Is this shift explained by a medication, diet, or GI symptoms?
02
Does the rest of my electrolyte pattern support an acid-base story?
03
Would a repeat draw or additional testing clarify it?
Educational boundary
Educational information only. Displayed ranges are illustrative sample bands, not a diagnosis, treatment plan, or substitute for the contracted laboratory report and a qualified clinician.
See it as a sample result
The sample dashboard shows an illustrative reading, target band, and trend for CO2 (Bicarbonate).