Vitamin B6: Testing, Levels, and What They Mean

What Is Vitamin B6?

Vitamin B6 is a water-soluble vitamin. This means your body doesn’t store it, and you need to get it regularly through food.

It helps turn the food you eat into energy. It also supports your brain, nerves, and immune system (your body’s defense against illness). Vitamin B6 helps make chemicals in the brain called neurotransmitters that affect your mood and sleep.

Doctors use vitamin B6 tests to check for deficiency (too little) or excess (too much). Abnormal levels can point to health problems, poor nutrition, or issues with how your body absorbs vitamins.

When Is Vitamin B6 Testing Recommended?

Vitamin B6 testing helps check if your levels are normal. It is often ordered when symptoms of a deficiency or excess appear.

You might need this test if you have:

• Ongoing tiredness
• Muscle weakness or cramps
• Tingling or numbness in hands or feet
• Mood changes, depression, or confusion
• Trouble focusing or remembering
• Skin problems or sores
• Weak immune system
• Digestive diseases (like Crohn’s or celiac)
• Long-term alcohol use
• Poor diet for a long time

How Is Vitamin B6 Testing Conducted?

The most common way to check vitamin B6 levels is through a blood test. A healthcare provider takes a small sample from a vein in your arm. The lab measures pyridoxal 5’-phosphate (PLP), the active form of vitamin B6 in your blood. 

This method gives the most accurate and reliable results.

Other Possible Testing Methods

In some cases, urine tests may also be used to check how your body is processing vitamin B6. However, urine tests are less common and not as precise as blood tests.

Vitamin B6 may also be included in micronutrient panels or nutritional tests that check multiple vitamins and minerals at once.

How to Prepare for the Test

• No fasting is usually needed
• Avoid vitamin supplements for at least 48 hours before the test
• Let your doctor know about any medications or health conditions

What Are the Normal Vitamin B6 Levels?

For healthy adults, vitamin B6 levels in blood usually range between 5-50 µg/L.

Note: Normal ranges can vary depending on the lab and testing method.

What Do Abnormal Levels Mean?

Vitamin B6 High Levels

Too much vitamin B6 is rare, but it can happen, especially if you take large amounts of supplements for a long time.

Causes include:

• Supplement overuse - Taking high doses of B6 without medical advice
• Liver or kidney issues - These organs help process and remove vitamins
• Rare genetic disorders - Such as hypophosphatasia, which affects bone and vitamin balance

• Stop or lower vitamin supplements (only with your doctor’s advice)
• Check your liver and kidney health
• Avoid self-treating with high-dose vitamins
• Retest levels if symptoms continue

Vitamin B6 Low Levels

Low vitamin B6 is more common. It can cause tiredness, nerve problems, and weak immunity.

Causes include:

• Poor diet - Not eating enough foods with vitamin B6
• Digestive disorders - Like Crohn’s disease or celiac disease, which affect nutrient absorption
• Alcohol abuse - Alcohol blocks vitamin absorption
• Chronic illness - Some diseases increase your body’s need for B6
• Parasitic infections - Can interfere with nutrient use

• Eat more B6-rich foods like: chicken, turkey, or fish, potatoes and bananas, whole grains, and cereals
• Reduce or stop alcohol use
• Avoid exposure to cigarette smoke
• Treat any underlying health problems
• Ask your doctor about supplements if needed

Which Specialist Should You Consult?

If your B6 levels are off, the right specialist can help:

• General doctor - First step for testing and guidance
• Gastroenterologist - For digestion-related issues
• Nutritionist or dietitian - For help with diet and supplements
• Pediatrician - For children with symptoms
• Neurologist - If you have nerve-related symptoms like tingling or numbness