Platform
Company
Immunology & Autoimmune
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Currently under review
Pending specialist review and validation.
Arterial oxyhemoglobin (O2Hb) measures the proportion of hemoglobin in your arterial blood that is carrying oxygen. It is performed on an arterial blood sample using co-oximetry, a laboratory method that directly analyzes hemoglobin species.
This test is often ordered with an arterial blood gas to give a fuller picture of oxygenation. Unlike a fingertip pulse oximeter, co-oximetry can differentiate oxyhemoglobin from other forms of hemoglobin that do not carry oxygen, such as carboxyhemoglobin and methemoglobin.
Your care team uses O2Hb Art to assess how effectively your lungs are transferring oxygen into your blood and whether oxygen therapy or ventilator settings are appropriate. It is commonly ordered in emergency, operating room, and intensive care settings, and in evaluations of shortness of breath or low oxygen levels.
This test is also important when exposure to carbon monoxide or drugs that alter hemoglobin is suspected, because it reveals how much of your hemoglobin is truly available to carry oxygen. Results help guide treatment decisions, monitor response to therapy, and inform whether further tests are needed.
Your result is interpreted alongside your symptoms, physical exam, and related tests like arterial blood gases and hemoglobin level. A lower than expected fraction can reflect issues such as lung disease, heart or circulation problems, low inspired oxygen, or the presence of abnormal hemoglobins that do not bind oxygen. A higher fraction generally indicates adequate oxygenation at the moment the sample was taken.
Because this is a fraction, it does not show how much hemoglobin you have overall. It is possible to have a seemingly adequate fraction yet still have limited oxygen delivery if your hemoglobin level is low. If a result seems out of step with how you feel or with other measurements, your clinician may repeat the test, check for sampling issues like air bubbles or delays to the lab, and order related tests such as carboxyhemoglobin, methemoglobin, or imaging.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Air bubbles, inadequate mixing, or delays in getting the arterial sample to the lab can change oxygen content and shift the measured oxyhemoglobin fraction.
Your current oxygen therapy and ventilator settings strongly influence the result, and changes can alter the fraction within minutes of adjustment.
Carbon monoxide from smoke or fumes increases carboxyhemoglobin, and certain drugs or chemicals can raise methemoglobin, both of which reduce functional oxyhemoglobin.
Anemia and some hemoglobin variants affect total oxygen-carrying capacity and may complicate interpretation even when the oxyhemoglobin fraction appears adequate.
Lower ambient oxygen at high altitude or during air travel can reduce arterial oxygenation, while high inspired oxygen levels can increase the measured fraction.
Fever, sepsis, shock, or sudden changes in breathing can rapidly alter oxygenation, so the result reflects your condition at the time the sample was obtained.
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