{"id":"vitamin-b12","name":"Vitamin B12 (Cobalamin)","shortName":"Vitamin B12","aliases":["Vitamin B12","Cobalamin","B12","Cyanocobalamin","Vitamin B12, Serum","Vitamin B-12","Vit B12 Level","Serum B12","Vitamin B12 Level","Vitamin B12 Assay","Cobalamin (Vitamin B12)","Vitamin B 12","Vit B-12","B-12","Total Vitamin B12","Cobalamin, Serum","Vitamin B12, Total","Vitamin B12 Blood Test","Cyanocobalamin (Vitamin B12)"],"abbreviations":["B12","Vit B12","Cbl","VB12"],"loinc":[{"code":"2132-9","primary":true},{"code":"14685-2","primary":false},{"code":"35201-3","primary":false}],"specimen":"serum-or-plasma","units":[{"ucum":"pg/mL","display":"pg/mL"},{"ucum":"pmol/L","display":"pmol/L"}],"referenceRanges":[{"population":"Adults","low":232,"high":1245,"unit":"pg/mL","unitDisplay":"pg/mL","note":"Labcorp's published adult interval (test 001503). Labcorp lists a single interval with no sex or age split on its test page. MedlinePlus gives 299–1054 pg/mL (219–773 pmol/L) and says ranges vary by lab and assay, so use the range printed on your own report. Different assays also put the lower limit in different places, and many clinicians treat results in the lower part of the range as needing a second test.","sources":[{"title":"Vitamin B12 (test 001503)","url":"https://www.labcorp.com/tests/001503/vitamin-b12","publisher":"Labcorp"},{"title":"Vitamin B12 level","url":"https://medlineplus.gov/ency/article/003705.htm","publisher":"MedlinePlus (National Library of Medicine)","year":2026}]}],"review":{"status":"ai-draft","label":"AI-drafted. Awaiting verification","lastReviewed":"2026-10-03"},"summary":"Measures the vitamin B12 in your blood. Your nerves and red blood cells need B12, so this is the usual first check of your B12 status.","url":"https://bloodtesttracker.com/markers/vitamin-b12","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}