Vitamin B3 Niacin Testing
Below is a plain-language overview of the vitamin b3 niacin testing. Vitamin B3 (niacin) testing measures the amount of niacin in your blood. It is ordered when a doctor suspects a deficiency or, less commonly, too much niacin from supplements.
- Sample type
- blood
- Category
- Vitamin & Mineral
- Turnaround
- 1-3 business days
- Price
- $49
- Referral
- Not required
Vitamin B3 (niacin) testing measures the amount of niacin in your blood. It is ordered when a doctor suspects a deficiency or, less commonly, too much niacin from supplements.
What it measures
- Niacin (Vitamin B3) — The main form of vitamin B3 measured in blood.
- Nicotinamide — Another active form of vitamin B3.
- NAD (Nicotinamide Adenine Dinucleotide) — A key coenzyme that reflects niacin status.
- NADP (Nicotinamide Adenine Dinucleotide Phosphate) — A related coenzyme also used to assess niacin levels.
Who it is for
A doctor may order this test if you have symptoms of deficiency such as skin rash, digestive problems, or confusion, or if you take high-dose niacin supplements.
Preparation
No special preparation is usually needed. You may be asked to avoid niacin supplements for a short time before the test.
Results and what they mean
Results are reported as a number or range for each marker. Your doctor interprets them along with your symptoms and diet. This is general information, not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the vitamin b3 niacin testing is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Do I need to fast for this test?
Fasting is not typically required, but follow any instructions from your doctor.
What symptoms might prompt this test?
Symptoms like a sun-sensitive rash, diarrhea, or mental confusion may lead a doctor to check niacin levels.
Can I take my niacin supplement before the test?
Ask your doctor. They may ask you to skip it for a day to avoid affecting the results.
How long until I get results?
Results are usually available in 1 to 3 business days.