If you’re taking a supplement containing biotin (also called vitamin B7 or B8, vitamin H or coenzyme R), commonly found in products promoting nail, skin and hair health, it is recommended that you wait at least 72 hours from your last dose before sample collection.
Get tested to help diagnose one cause of anemia or neuropathy; to evaluate nutritional status in some people; to monitor the effectiveness of treatment for vitamin B12 or folate deficiency.