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Biotin Buggers Blood Tests!

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Here's a rather unexpected side-effect of megadose vitamin supplementation:

Beauty fad’s ugly downside: test interference
[Forum software won't let me link it; the URL is http://www.captodayonline.com/beauty-fads-ugly-downsidetest-interference/ ]
CAP TODAY | Pathology/Laboratory Medicine/Laboratory Management

September 2016
Anne Paxton

... taking unusually large doses of biotin can interfere with a broad range of immunoassay test results. [This does not mean tests of immune function: it refers to the method by which proteins in many blood tests are captured and measured. -MR] In an unexpected and dismaying coincidence, it turns out, the design of many immunoassays, including thyroid tests, cardiac markers, and others, relies on biotin to capture antibodies. [The second article below adds cortisol and testosterone, both important CR markers -MR].
In fact, “a significant percentage of immunoassays rely on biotin–streptavidin binding as part of the assay architecture,” says Ed Reineks, MD, PhD, staff pathologist at the Cleveland Clinic, which conducts millions of immunoassays per year on automated systems. “It’s a common mechanism used to capture antibodies. So this biotin interference could affect virtually every area with any immunoassay testing.”
Potentially hundreds of assays could be affected by high-dose biotin ...

At least two types of common assays use the biotin–streptavidin formulation: competitive assays, which are typically used for low-molecular-weight targets such as thyroid hormone T4; and sandwich assays, used for bigger molecules such as thyroid-stimulating hormone.

“For an example of a competitive assay,” Dr. Reineks says, “we put in some kind of label on a therapeutic drug that’s in the reagent. When it’s bound to the antibody, it’s not giving off a signal, but when I put in a patient sample and it has the same unlabeled drug, the patient’s drug is going to compete with the labeled drug. The drug that’s labeled can come off the antibody and the patient drug can bind to it, so the two are competing.”

Competitive assays, because of this mechanism, tend to produce elevated values just because of the way they use biotin-streptavadin in the assay, while sandwich assays can cause falsely low values. “So it depends on the assay type and the analyte,” Dr. Valcour says. “For the same analyte, one assay might produce a falsely high value while a different assay might produce a falsely low value.”

“You can’t make assumptions about the extent of the effect, though. It could be influenced by factors such as incubation period or buffers. For some assays, there will be a large effect, while for other assays there will be a small effect even for the same principle of the assay—sandwich or competitive. The bottom line is we don’t know a lot about this because the studies haven’t been done.”

Diagnostics manufacturers confirm that they are conducting studies on biotin interference now. “But those studies will be complicated, because not only do the actual blood levels of biotin make a difference, but also the rate at which the biotin is cleared,” Dr. Valcour points out. In certain patients—those with renal function issues, for example—clearance may take longer. “So there’s just an awful lot we don’t know about the specific effect on a given assay by a given manufacturer and the specific effect of a dose on a given patient.” ...

Here's a bit more on the problem (this article actually stimulated the clinical laboratory directors interviewed above):

Thyroid Month: Beware of Biotin

  • By Eric Seaborg
  • Endocrine News, Jan 2016
An Issue with Assays
The problem is that almost all immunoassays today contain biotin because they rely on the biotin–streptavidin attraction to either anchor the assay’s antibodies to a capture surface or capture them once they have reacted with a patient sample, according to Stefan K. Grebe, MD, PhD, professor of laboratory medicine & pathology and co-director of the endocrine laboratory at the Mayo Clinic in Rochester, Minn. ...
depending on the particular assay, biotin can skew the results to be either falsely high or falsely low. In the case of competitive immunoassays — usually used for low molecular weight targets (such as T4, T3, and cortisol) — biotin interference causes a falsely high result. In immunometric (sandwich) assays, it gives a falsely low result.
Other characteristics of the assay can also make a difference. For instance, a longer incubation time increases the opportunity for interference. Different assays for various analytes, even from the same manufacturer, can therefore vary in their susceptibility to biotin interference.
At the laboratory Mariash uses, the free T4 and total T3 assays use a biotin-streptavidin fluorescent detection system, so biotin can cause falsely elevated results, but the TSH and total T4 assays are not affected. In contrast, at Greenlee’s lab, biotin can lead to falsely low TSH results, but free T3 and free T4 tests are not affected. Biotin can also cause her lab’s assay for thyrotropin receptor antibodies (TRAb) to be falsely positive, which could lead to a misdiagnosis of Graves disease. ...
For the interference to occur, the patient’s biotin level needs to be high — at least three times the upper limit of the healthy adult reference range, according to Grebe. But that level is easy to achieve with the megadoses many are taking.
Grebe suggests that a clinician can ask the lab to try using another manufacturer’s test, but an easier route is to ask the patient to stop the biotin then get retested. Biotin is water soluble, so it washes out of the body quickly — even a single day can make a big difference in the test results.
And although literature reports mostly focus on problems with parathyroid and thyroid hormone tests, biotin interference could be considered as a potential contributor to almost any suspicious immunoassay result.


Returning to the first story:

Biotin, Dr. Reineks notes, has a very short half-life in most patients, according to the literature—under two hours—and it is usually 99 percent cleared from the body within four to five half-lives. “That’s one mitigating factor in this. The other is that the recommended intake for biotin is something on the scale of 30 µg per day ... Roche package inserts I reviewed warn about patients taking 5 mg [5,000 µg] a day, which is more than 150 times the recommended dose ... [and] supplements set the pills at 10,000 µg, more than 300 times the recommended dose. The pills are far in excess of what the recommended supplement level is,” Dr. Reineks says.

Obviously, we should try to remember this and skip any biotin supplementation the day before a test (and not take them the morning either — in general, one probably shouldn't be taking any supplements anyway, just to be sure. Antioxidants, for instance, can interfere with the glucose oxidase test for blood glucose, although it's my understanding that this test is not widely used any more). This will, of course, be PITA if one's multi already contains a lot, and one should set up some kind of mnemonic or one will probably forget.

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Interesting. Does anyone here take multis? Or biotin supps? Biotin is not super hard to get RDA from the diet, AFAICT. But now that supps and blood tests have been brought up, I'm starting to wonder about if my supps affect blood tests - zinc, vit. D3, iodine and a few others. And by affect I mean over and above things like supplementing with D3 affects my vit. D blood status.

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