MORE VIDEOS
Explore more

Arterial Bicarbonate

Abbreviation: HCO3

Panel: Blood Gas Tests · All blood gas tests

Typical adult reference range

Conventional units22–28 mEq/L
SI units22–28 mmol/L

Ranges vary between laboratories and methods — compare your result with the range printed on your own report.

What a high or low result can mean

High arterial bicarbonate: high values can be seen in metabolic alkalosis and compensation for chronic respiratory acidosis.

Low arterial bicarbonate: low values may occur in metabolic acidosis and compensation for respiratory alkalosis.

These are associations, not a diagnosis: the same result can have several causes, and your clinician interprets it with the rest of your results and history.

Good to know

Usually calculated from pH and PaCO2 by the blood gas analyzer.

◆ Kidney note

This test is closely tied to kidney health, and it is one a kidney specialist (nephrologist) watches closely. On this site, kidney-related results are a special focus: see the kidney and dialysis medicines in our Drug Guide and the kidney condition hubs for the wider picture.

Related tests — Blood Gas Tests

Arterial pHBase ExcessCarboxyhemoglobinMethemoglobinOxygen Saturation, ArterialPartial Pressure of Carbon Dioxide, ArterialPartial Pressure of Oxygen, ArterialVenous Partial Pressure of Carbon Dioxide
Please note: Reference ranges vary between laboratories, and between the methods and instruments they use — the range printed on your own report is the one your result should be compared with. A result outside the range is not by itself a diagnosis, and a result inside it does not rule out illness. These pages are an educational summary, not medical advice: always discuss your results with the clinician who ordered them, who can interpret them in the context of your health and history.