Nitric Oxide (NO) in Plasma or Serum

Nitric oxide is a gas your body produces naturally, and this test measures how much of it is present in your exhaled breath or blood sample. Because nitric oxide helps relax and widen blood vessels and plays an important role in airway function, measuring its levels can reveal inflammation or other conditions your doctor wants to evaluate.

Nitric oxide (NO) is produced by cells in response to various stimuli, including inflammation and vascular health. It helps relax blood vessels, improving circulation and lowering blood pressure. Elevated or altered levels may signal conditions affecting your cardiovascular or immune systems.

Your doctor may order a nitric oxide test to help diagnose or monitor conditions such as asthma, where elevated levels often point to airway inflammation, or to evaluate concerns like pulmonary hypertension and reduced blood vessel function. The results can guide treatment decisions and show how well your current therapy is working over time.

Your healthcare provider may recommend this test if you have symptoms like high blood pressure, poor circulation, or signs of inflammation. It could also be part of a broader evaluation for conditions such as vascular disease, autoimmune disorders, or chronic inflammation.

Depending on the type of test ordered, the sample is usually collected by having you breathe steadily into a mouthpiece connected to an analyzer, or through a simple blood draw from a vein in your arm. Before collection, you may be asked to avoid certain foods, drinks, and supplements that contain nitrates, since these can temporarily change your nitric oxide levels.

A blood sample is drawn from a vein, typically in the arm. The blood is then processed to separate plasma or serum, which is sent to the lab for analysis. This test requires fresh or refrigerated samples to maintain accuracy.

Before the test, plan to avoid smoking, vigorous exercise, and nitrate-rich foods such as leafy green vegetables and processed meats for the timeframe your care team gives you. Tell your doctor about all medications and supplements you take, because some can affect the results. Wear comfortable clothing and arrive a few minutes early so you can relax and ask questions.

No special preparation is usually needed, but you may be asked to avoid certain medications or supplements that could interfere with results. For example, some supplements or blood pressure medications might affect nitric oxide levels.