Niacin (Vitamin B3) Serum Concentration

This test measures the amount of niacin, also known as vitamin B3, in your blood. Your doctor may order it if you have signs of a deficiency, such as skin rashes, digestive problems, fatigue, or confusion, or to see how well your vitamin supplements or nutrition plan are working.

Your healthcare provider may order this test if you have symptoms of niacin deficiency, such as fatigue, digestive issues, or neurological problems. It may also be checked during nutritional assessments, especially if you have conditions like malabsorption syndromes or certain dietary restrictions.

A low niacin level may point to poor nutrition, trouble absorbing vitamins from food, or heavy alcohol use, while a high level can mean you are taking more supplement than your body needs. Your doctor will interpret your results together with your symptoms, diet, and overall medical history before deciding on next steps.

Low levels might indicate a deficiency, which could affect how your body processes nutrients or energy. High levels could suggest overconsumption, particularly from supplements, or certain medical conditions that increase niacin production.

Niacin testing is often used to monitor conditions such as pellagra, malnutrition, Crohn's disease and other digestive disorders that limit vitamin absorption, Hartnup disease, and high cholesterol that is being managed with prescription niacin therapy.

This test is sometimes used alongside other vitamin checks to monitor nutritional health, especially in patients with chronic illnesses like liver disease or those on long-term medications that may alter vitamin absorption.

A blood sample is usually drawn from a vein in your arm during a quick office visit. You may be asked to fast for a few hours beforehand, so follow any instructions your doctor provides, and tell the staff about all vitamins, medicines, and supplements you currently take.

A blood sample is drawn from a vein in your arm. The blood is processed to separate serum (the liquid part after clotting), which is then analyzed in a lab using a specialized immunoassay or similar method to measure niacin concentration.