WELLNESS EDIT | No. 36 |

Biotin

Biotin (B7) is one of the most widely used supplements for hair, skin and nails, but it has an important effect that many people aren’t aware of: it can interfere with blood tests, causing results to appear falsely high or low, potentially leading to a missed diagnosis or inappropriate treatment.

Biotin, also known as vitamin B7, is a water-soluble B vitamin that helps the body metabolize carbohydrates, fats and proteins. It occurs naturally in a range of foods, and most people get enough through their diet.

Adults need around 30 micrograms (mcg) of biotin a day, yet some supplements contain 5,000 or 10,000 mcg. That means a single supplement can provide more than 100 times the daily adequate intake.

Despite its popularity for hair growth, there is limited evidence that taking additional biotin improves hair in people who are not deficient.

Which Blood Tests Can Biotin Impact?

You may be surprised by how many commonly ordered blood tests can be thrown off by a simple supplement like biotin. Certain results can appear higher or lower than they really are, changing the clinical picture your healthcare provider is seeing and, in some cases, potentially delaying an accurate diagnosis.

Below are seven very common blood tests that can be impacted by biotin supplementation.

1. Thyroid tests – This commonly includes TSH (thyroid-stimulating hormone) and T3 and T4, thyroid hormones that help regulate metabolism and energy. Biotin can make TSH appear lower and T3 and T4 higher than they really are. (PubMed)

2. Troponin — Troponin is a protein released into the blood when heart muscle is damaged. Doctors measure it when a heart attack is suspected. Biotin can interfere with some troponin tests and produce a falsely low result, potentially making the test appear less concerning than it should be and complicating or delaying a diagnosis. (PubMed)

3. Vitamin D — Vitamin D supports bone health, calcium regulation and immune function. Biotin can cause some vitamin D results to appear higher than they really are masking a true vitamin D deficiency. (PubMed)

4. Hormone tests — Biotin can interfere with hormone tests, making results appear higher or lower than they really are. This can make a normal hormone level look abnormal creating the appearance of a deficiency or excess where there isn’t one. Below are seven hormone tests worth knowing about if you supplement with biotin:

1. Estradiol — a form of estrogen commonly measured when evaluating menstrual changes, fertility or menopause.
2. Testosterone — often checked in men with symptoms of low testosterone and in women when excess androgen levels are suspected.
3. Progesterone — may be measured to assess ovulation, fertility or certain menstrual concerns.
4. LH (luteinizing hormone) — helps regulate ovulation in women and testosterone production in men and is often included in fertility or hormone testing.
5. FSH (follicle-stimulating hormone) — involved in egg development in women and sperm production in men and commonly measured when evaluating fertility or menopause.
6. PTH (parathyroid hormone) — helps regulate calcium levels and may be tested when calcium is unusually high or low.
7. DHEA-S — a hormone made mainly by the adrenal glands that may be measured when investigating excess androgens, irregular periods or increased facial or body hair.

5. Ferritin —Ferritin is a protein that stores iron and is commonly measured to help assess the body’s iron stores. Biotin can interfere with ferritin tests and produce an inaccurate result making it difficult to identify or correctly assess an iron deficiency.

6. Vitamin B12 — Vitamin B12 plays an important role in red blood cell formation and normal nervous system function. Biotin can produce a falsely high B12 result, masking a low level or deficiency.

7. PSA (prostate-specific antigen) — PSA is a protein produced by the prostate. Doctors measure PSA levels in the blood as part of prostate cancer screening and to monitor the disease following diagnosis or treatment. Biotin can cause some PSA results to appear falsely low, making an elevated level less apparent and influencing how the result is interpreted and managed. (Pubmed)

If You Supplement with Biotin, Tell Your Healthcare Provider Before Blood Work

If you take biotin, let your healthcare provider know before you have blood work done. For 5–10 mg of biotin, guidance recommends stopping it for at least 8 hours before testing, although some tests may require a longer break of up to 72 hours, and higher doses may need even more time. Because this can vary depending on how much you take and which test is being ordered, it is always worth checking with your healthcare provider or the laboratory first so you know exactly what to do.

The Bottom Line

As always, know what you are taking and why you are taking it. Supplements are not automatically harmless just because you can buy them over the counter, and biotin is a good example of why the small details matter.

If you take biotin and have had unusual or unexpected blood test results, mention it to your healthcare provider. When you fill out forms at the doctor’s office, include the supplements you take, even the ones that may not seem important. The same goes for vitamins, powders and combination products marketed for hair, skin and nails. Sometimes one small detail is all it takes to help your healthcare provider make better sense of the bigger picture.