{"id":"vitamin-b6","name":"Vitamin B6 (Pyridoxal 5-Phosphate)","shortName":"Vitamin B6","aliases":["Pyridoxal 5-Phosphate","Pyridoxal 5'-Phosphate","Vitamin B6","PLP","P5P","Vitamin B6, Plasma","Vitamin B6 (P5P)","Vitamin B6 (PLP)","Vitamin B6 (Pyridoxal 5-Phosphate)","Pyridoxal Phosphate","Pyridoxal 5-Phosphate (PLP), P","Vitamin B6 Profile (PLP and PA), P","Vitamin B6 Pyridoxal 5 Phosphate"],"abbreviations":["PLP","P5P","B6"],"loinc":[{"code":"30552-4","primary":true},{"code":"62236-5","primary":false}],"specimen":"plasma","units":[{"ucum":"ng/mL","display":"ng/mL"},{"ucum":"nmol/L","display":"nmol/L"}],"referenceRanges":[{"population":"Adults","low":5,"high":50,"unit":"ng/mL","unitDisplay":"ng/mL","note":"Mayo Clinic Laboratories (LC-MS/MS, heparin plasma, fasting), printed as 5-50 mcg/L, which equals ng/mL. Quest prints 5.1-54.8 ng/mL for adults. ARUP prints a much narrower 20-125 nmol/L (about 4.9-30.9 ng/mL) for a fasting sample, and a healthy Chinese adult cohort had a 2.5th-97.5th percentile spread of about 9-173 nmol/L (Front Nutr 2026), so intervals differ between labs and populations. Use the interval printed on your own report. PLP also shifts with inflammation, kidney function, albumin and alkaline phosphatase activity (Front Nutr 2026), and long-term high-dose B6 supplements have been linked to sensory neuropathy (Sun 2025).","sources":[{"title":"Vitamin B6 Profile (Pyridoxal 5-Phosphate and Pyridoxic Acid), Plasma - Test ID B6PRO (Mayo Clinic Laboratories Extended Catalog)","url":"https://www.testcatalog.org/show/B6PRO","publisher":"Mayo Clinic Laboratories"},{"title":"Vitamin B6 (Pyridoxal 5-Phosphate) (test 0080111)","url":"https://ltd.aruplab.com/Tests/Pub/0080111","publisher":"ARUP Laboratories"},{"title":"Vitamin B6, Plasma (Quest Diagnostics test, adult interval as listed by Fullscript)","url":"https://us.fullscript.com/labs/quest/vitamin-b6-plasma","publisher":"Fullscript (listing Quest Diagnostics test data)"},{"title":"Age- and sex-specific reference intervals and determinants of plasma vitamin B6 metabolites in healthy Chinese adults","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12954621/","publisher":"Frontiers in Nutrition","year":2026},{"title":"Toxic Effects of Excess Vitamins A, B6, and Folic Acid on the Nervous System","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12350011/","publisher":"Behavioural Neurology","year":2025}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"Measures pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, to see how much B6 your body has available.","url":"https://bloodtesttracker.com/markers/vitamin-b6","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}