Could Your Vitamin Impact Blood Test Results? | MedStar Health

Could Your Vitamin Impact Blood Test Results?

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A nurse draws blood from a patient in a hospital.

Many doctor’s appointments begin with the same question: what medications are you taking? Though going through the list might feel tedious, it’s important to share an up-to-date rundown every time to determine how these drugs may interact with each other — and even how they could impact important blood tests.

Last fall, the Food & Drug Administration (FDA) issued a safety alert regarding the water-soluble vitamin B7, or biotin, frequently found in multivitamins and supplements. Daily biotin recommendations range from 5 to 35 micrograms, depending on one’s age, gender, and other factors including pregnancy. Biotin can also be ingested naturally through common foods such as sweet potatoes, mushrooms, eggs, and spinach.

“Many dietary supplements promoted for hair, skin, and nail benefits contain biotin levels up to 650 times the recommended daily intake of biotin,” states the FDA. “Biotin in blood or other samples taken from patients who are ingesting high levels of biotin in dietary supplements can cause clinically significant incorrect lab test results.”

The FDA has seen an increase in the number of reported adverse events — including one death — related to biotin interference with lab tests. Biotin in patient samples can cause falsely high or falsely low results, depending on the test, and the influence of biotin may not always be apparent to healthcare providers or laboratories.

“Incorrect test results may lead to inappropriate patient management or misdiagnosis,” the FDA cautions. “For example, a falsely low result for troponin, a clinically important biomarker to aid in the diagnosis of heart attacks, may lead to a missed diagnosis and potentially serious clinical implications.”

High levels of biotin can skew common tests used to diagnose conditions including pregnancy, cancer, thyroid disease, heart disease, anemia, and other hormonal-related conditions. Fortunately, often only a day without taking the supplement is required for accurate test results.

Keep an up-to-date list of your current medications on file with your physician to have them available for other medical providers. Be sure to note if you are currently taking biotin, and consider bringing your labeled multivitamin to appointments to be sure its contents are recorded.

Visit to learn more about laboratory services offered through MedStar St. Mary’s and prepare for your next blood test.

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