lab interference
6 interactions related to lab interference
levothyroxine + biotin
High-dose biotin (B7) does not directly interact with levothyroxine pharmacologically, but it interferes with biotin-streptavidin immunoassays used for TSH, free T4, free T3, and thyroglobulin. This can produce falsely low TSH and falsely high T4/T3, mimicking hyperthyroidism and leading to inappropriate dose reductions.
biotin + troponin test
High-dose biotin (vitamin B7) interferes with biotin-streptavidin-based immunoassays used to measure cardiac troponin, producing falsely low results that can mask an evolving heart attack. The FDA has received reports of patient harm, including one death linked to a missed myocardial infarction diagnosis caused by biotin-altered troponin readings.
vitamin c + glucose meter
Vitamin C (ascorbic acid) is a strong reducing agent that interferes with the electrochemical reactions used by many home and hospital glucose meters, producing falsely elevated blood glucose readings, especially with glucose dehydrogenase (GDH-PQQ) and some glucose oxidase strip chemistries. Cases have been reported where high-dose vitamin C therapy led to a wrong diagnosis of diabetic ketoacidosis and inappropriate insulin treatment.
vitamin c + stool occult blood test
Vitamin C (ascorbic acid) is a reducing agent that blocks the guaiac peroxidase color reaction used in traditional fecal occult blood tests (gFOBT, including Hemoccult), producing a falsely negative result even when significant gastrointestinal bleeding is present. Doses of 250 mg per day or higher have been documented to cause false negatives, leading to missed diagnoses of colorectal bleeding sources.
biotin + thyroid stimulating hormone test
High-dose biotin interferes with biotin-streptavidin-based immunoassays used to measure TSH, free T3, free T4, and thyroglobulin, producing a falsely low TSH and falsely elevated free thyroid hormones, a pattern that mimics Graves' disease. Patients have been incorrectly diagnosed with hyperthyroidism and started on antithyroid drugs because of biotin interference.
vitamin e + platelet function test
High-dose vitamin E (alpha-tocopherol above 400 IU per day) inhibits platelet aggregation through a protein kinase C-dependent mechanism, producing prolonged bleeding times and abnormal results on platelet function analyzers (such as PFA-100, VerifyNow, and light transmission aggregometry). The effect is most pronounced when vitamin E is combined with aspirin or other antiplatelet agents and can interfere with workup for bleeding disorders.