Vitamin B6 (Pyridoxine) Concentration in Serum or Plasma

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like fatigue, nerve pain, or unusual behavior that could be linked to vitamin B6 deficiency. They might also order it to monitor vitamin B6 levels if you’re taking certain medications that can deplete it, such as some anticonvulsants or chemotherapy drugs. Rarely, it’s checked in cases of malabsorption or chronic illness that may interfere with vitamin absorption.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a specific protocol. Wear a comfortable shirt for easy access to your arm. If you’re taking supplements, ask your provider whether to stop them temporarily.

What the Test Results Mean

Results are typically reported as a concentration in micrograms per deciliter (µg/dL). While reference ranges vary by lab, low levels may indicate deficiency, while very high levels could suggest overconsumption or certain medical conditions. Your provider will interpret results in the context of your overall health.

Common Causes of Abnormal Results

Low vitamin B6 levels can result from poor diet, certain medications, malabsorption disorders (like celiac disease), or chronic illnesses. High levels may occur from excessive supplementation or rare genetic conditions. Your provider will discuss possible causes with you.