According to the National Institutes of Health, "more than half of adults (53%) reported use of a dietary supplement". A separate NIH analysis of n = 11,956 confirmed that "dietary supplements are used by more than half of adults." If you are one of them, it is important to understand how those supplements could affect the accuracy of your blood work. 

HealthieOne Complete measures 250+ biomarkers, including vitamins, hormones, amino acids, metabolites, and standard blood chemistry. Understanding how supplements interact with lab testing is especially important for getting an accurate picture of your health. Learn more about How Long Should I Stop Vitamins, Supplements, and Certain Foods Before a Blood Test?

Biotin (Vitamin B7): The Most Dangerous Offender

Harvard Medical School describes a "frightening scenario" in which a patient arrives at the emergency room with symptoms of a heart attack, but the troponin blood test, which detects heart muscle damage, returns a false negative "all because of a supplement called biotin." Harvard experts warn that biotin "is typically sold in doses far higher than our bodies need, which can alter the results from an array of vital lab tests," and that this can lead to "life-threatening misdiagnoses or unnecessary additional testing." Dr. JoAnn Manson, chief of the Division of Preventive Medicine at Harvard-affiliated Brigham and Women's Hospital, states: "The worry is that an important diagnosis will be missed, such as a heart attack, or that you'll be falsely diagnosed with a serious problem because the blood testing is faulty."

The U.S. Food and Drug Administration (FDA) has issued multiple safety communications warning that "biotin can significantly interfere with certain lab tests and cause incorrect test results which may go undetected." Abbott Diagnostics reports that "many biotin dietary supplements—as well as when doctors prescribe it for health conditions—contain biotin levels up to 650 times the recommended daily intake." 

The AACC (Association for Diagnostics & Laboratory Medicine) published a formal guidance document recommending that "patients who have consumed 5 -10 mg biotin wait a minimum of 8 hours before having blood collected for laboratory tests" and that "Unless medically contraindicated, patients being prescribed a high-dose biotin therapy (≥100 mg/day) should abstain from biotin for a minimum of 72 hours before blood collection."

An MDLinx review notes that biotin can cause "falsely high results in testosterone, estradiol, cortisol, free triiodothyronine (T3), and free thyroxine (T4) levels, and falsely low results in thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone, parathyroid hormone, and human chorionic gonadotropin levels."

A case report published in Cureus documented clinically significant lab errors in a 67-year-old patient taking just 5 mg of daily biotin, including falsely low TSH and PTH and mildly elevated calcium, which "raised the concern for malignancy." All values normalized after biotin was discontinued.

Why does biotin cause this problem?

Many diagnostic tests use a technology called streptavidin-biotin immunoassay. Biotin in the test reagent binds to specific proteins being measured. When excess biotin from supplements is present in your blood sample, it competes with the biotin in the test kit, causing inaccurate readings. This is purely a laboratory interference issue: biotin supplements at typical doses do not actually change your hormone levels. They simply make the test report incorrect numbers. HealthieOne Complete uses proprietary LC-MS/MS (liquid chromatography-tandem mass spectrometry) technology, trusted by Johns Hopkins, Stanford, and NIH. This is significant because LC-MS/MS does not use the biotin-streptavidin immunoassay technology that is vulnerable to biotin interference. For markers measured by LC-MS/MS, such as vitamins, hormones, amino acids, and metabolites, biotin supplementation does not cause the same false results seen with immunoassay-based tests at other labs.

Vitamin C (Ascorbic Acid): Glucose and Cancer Screening Interference

The U.S. Food and Drug Administration (FDA) warns that "Vitamin C, acetaminophen, acetaminophen containing drugs like Tylenol, and Xylose absorption therapies may interfere with the test and may affect your glucose result" on blood glucose monitoring devices. Harvard Medical School notes that "Vitamin C can make blood sugar levels seem higher than they are when measured by glucose meters" and that "consuming more than 250 milligrams per day of vitamin C through foods or supplements can also skew stool tests that hunt for signs of colorectal cancer and gastrointestinal bleeding."

A case report published in the AACE Clinical Case Reports documented a patient death linked to pseudohyperglycemia caused by high-dose intravenous vitamin C interference with a point-of-care glucose meter. The patient "was found to have significant hyperglycemia, blood glucose >600 mg/dL on POC testing," was incorrectly diagnosed with diabetic ketoacidosis (DKA) and treated with insulin, leading to fatal hypoglycemia. A study published in the Journal of Diabetes Science and Technology confirmed that "for two of the three devices tested, increasing concentrations of ascorbic acid caused false elevations in the glucose measurements".

Iron Supplements: Masking or Inflating Your True Iron Status

Iron supplements directly elevate serum iron, ferritin, and iron saturation (TIBC) levels. If you take iron supplements and then have your blood drawn, the results will reflect your supplementation rather than your body's baseline iron stores. This can mask a developing deficiency or make your iron status appear adequate when it is not. MedlinePlus (National Library of Medicine) advises patients to tell their provider "about any medicines, vitamins, or supplements that you are taking" before lab testing, as these can affect results. Stop iron supplements at least 24 to 48 hours before testing to ensure your results reflect your true iron status.

Creatine: Mimicking Kidney Disease

Harvard Medical School warns that creatine, "a popular protein supplement marketed to increase muscle mass, may throw off lab tests that measure creatinine, a marker for kidney disease. Falsely high results could suggest your kidneys are struggling when they're not." Dr. JoAnn Manson notes: "Some other types of kidney tests wouldn't be affected, but the creatinine test itself could be."

Calcium: Falsely Reassuring Bone Density

Harvard Medical School notes that calcium supplements "can make your bones appear denser than they are if you take it in the 24 hours before a bone density scan to diagnose or monitor osteoporosis." 

While HealthieOne measures serum calcium rather than bone density, supplementing calcium shortly before a blood draw can also elevate your serum calcium reading, which may mask a developing deficiency or falsely suggest hypercalcemia.

Fish Oil and Omega-3 Fatty Acids: Shifting Your Lipid Panel

Mayo Clinic confirms that "there's strong evidence that omega-3 fatty acids can significantly reduce blood triglyceride levels" and that "there also appears to be a slight improvement in high-density lipoprotein (HDL, or 'good') cholesterol." Cleveland Clinic similarly notes that "Omega-3 fatty acids are “healthy fats” that may support your heart health. One key benefit is helping to lower your triglycerides." 

Niacin (Vitamin B3): Altering Cholesterol Values

Cleveland Clinic “Niacin is no longer recommended as a treatment for lowering cholesterol,” “It’s just not as effective at lowering cholesterol as other medications are, and it can lead to adverse effects.”  "an increase in cardiovascular events like heart attack and stroke. It also directly promotes vascular inflammation, or inflammation in the blood vessels."

HealthieOne measures nicotinamide and nicotinic acid (the two forms of niacin) directly, so supplementation will also elevate these measured vitamin levels.

Herbal Supplements and Liver Enzymes

Certain herbal supplements can elevate liver enzymes (ALT, AST, GGT), which HealthieOne measures as part of the Liver and Pancreas Health panel. Cleveland Clinic lists "herbs and supplements" among the causes of elevated liver enzymes and advises patients to "tell your provider about any medications, herbs and supplements you take." Common offenders include green tea extract, kava, echinacea, and high-dose turmeric/curcumin. List all herbs and supplements in your HealthieOne portal so we can properly interpret your results.