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Biotin supplements can cause false medical test results

Mon, 16 Feb 2026 12:16:05 GMT

Biotin (AKA vitamin B7 and Vitamin H) is often included in supplements marketed for thinning hair and brittle nails. But it can interfere with various medical tests, causing inaccurate low, normal, or high results. It is recommended to stop taking the supplements 3 to 7 days before any such test.

Biotin (Wikipedia)

Biotin and the risk of false lab test results

Biotin: Interference with Laboratory Assays

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COVID-19 test kit expiration dates

Thu, 19 May 2022 17:48:29 GMT

If your COVID-19 test kit has passed the expiration date listed on the box, it may still be good.

Do Home Covid Tests Expire?

A quirk in the regulatory process for home tests can mean the real expiration date doesn’t always match what’s on the box.
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As a result of this requirement, a home test might have a six-month expiration when it’s first authorized, but as more time passes the test maker collects more data and seeks an extension to the original shelf-life date. That means you might have a test at home that’s passed its expiration date, but if you call the company or dig through the F.D.A. authorization letters, you’ll find it has changed.
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Tests should be marked with a manufacturing date and an expiration date. An F.D.A. spokesman said that anyone with a question about an expiration date could go online to view the various regulatory documents that extend a test’s shelf life. There is a section for antigen tests here and molecular tests here. Then, you can do the math based on your test’s manufacturing date. For instance, in January, the F.D.A. extended the shelf life of the BinaxNOW test to 15 months, from 12 months, so many people can just add another three months to the expiration listed on their box.
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whether you’re using a new test or one that is a little past its expiration date, follow the instructions carefully — and make sure the control line shows up quickly, which is an indicator that the test is still working.

“The reality is that these tests are very, very stable,” Dr. Mina said. “My expectation is that most of them, if not all of them, eventually will have a two-year expiration date at least. If the control line is showing up and it’s within 18 to 24 months of the manufacture date, you should assume the test is working.”

The kits I have don't list the manufacture date, only the expiration date.
The Siemens Clinitest kit's expiration date is listed as 2022/11, so it still has time.

For the iHealth kits, I found this:

iHealth COVID-19 Antigen Rapid Test / Expiration Date Extension

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health screenings & cholesterol numbers

Sun, 19 May 2013 08:16:05 GMT

The company I work for offers free health screenings to employees every year or so. In the past, nurses from a local medical center would come onsite to do the screenings, which included blood draws for the lipid, iron, and glucose level tests.

This year, I missed out on the onsite screenings. But I got a voucher for a free screening at Walgreens (a pharmacy chain). So I did that today. Unlike the prior screenings, these tests were done via finger-pricks rather than blood draws, and the results were available right away, rather than a few weeks later.

During the years 2005 thru 2012, my numbers were in the following ranges (mg/dL):
Total Cholesterol: 121 - 133
Triglyceride: 29 - 64
HDL Cholesterol: 47 - 59
LDL: 62 - 72
VLDL: 6 - 13

The HDL + LDL + VLDL numbers equal the Total Cholesterol numbers.

I was first screened in 2002, and I skipped the next 2 years. For whatever reason, my LDL was quite a bit higher in 2002:
Total Cholesterol: 151
Triglyceride: 60
HDL: 49
LDL: 90
VLDL: 12

Today's results showed an even higher LDL value, 96. That caught my attention, as it is near the high range of optimal (<100). Then I noticed that today's results don't include VLDL. Then I noticed that today's numbers don't even add up (how could HDL + LDL > TC ??)... The sheet says:
Total Cholesterol: 121
HDL: 52
TRG: 45
LDL: 96

Hmmm.. 121 - 52 = 69. The nurse must have transposed 69 to 96 when she wrote the LDL number down. In fact, I remember looking at the machine that had analyzed my finger-prick blood sample, and seeing it display "N/A" under LDL. The nurse must have been doing arithmetic in her head.

Anyway, so this year's real LDL + VLDL number is likely 69, so rather than it being much worse than the other years, it is slightly better.

Then again, this page says:

There may be several reasons for an LDL cholesterol result of N/A. The LDL cholesterol is calculated as follows: LDL=(TC-HDL-TRG/5). If the triglyceride result is >400 mg/dL (>4.51 mmol/L), the calculated LDL cholesterol will not be accurate and the LDL result will be reported as N/A. If the TC, HDL or TRG results are outside the measuring range of the instrument, the LDL will also not be calculated and will be reported as N/A.

So maybe today's LDL number isn't reliable at all.

Hmmm... for all the prior years, VLDL = Triglyceride/5.
It appears that the VLDL and LDL numbers are always calculated, rather than measured. Only the Total Cholesterol, HDL, and Triglyceride levels are actually measured.

Today's test didn't measure my iron level. In the previous years, it ranged from 89 to 138, all within normal limits.

My blood pressure tends to be on the low side. Today it was 90/65. The highest one from prior years was 107/73.

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bits and pieces

Sat, 27 Apr 2013 06:22:21 GMT

After bad results with both a cake and a batch of brownies, I've discovered that I don't like the smell and taste of unrefined soybean oil. It tastes sickly sweet to me.

All I found on the subject is this statement on a few webpages: "Unrefined soy oil has a strong, distinctive flavor and aroma - some like it, some don't."

Next time, I should taste an oil before using it.

I do like the taste of extra virgin olive oil, but it doesn't seem like that flavor would go well in cakes and cookies. Have any of you tried baking with olive oil? Anyway, I now have some "naturally refined" safflower oil, which should be mild flavored. I used to buy Canola oil, but I began to notice it having an unpleasant stale smell and flavor, even when it wasn't particularly old.

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After months of testing different deodorants, I finally found a suitable replacement for the one I used to use. (More details on that possibly forthcoming.) But last weekend, I found out that the store I bought it from no longer is selling it. I may have to buy it online (luckily it doesn't seem to be discontinued).

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I ended up doing 2 saliva hormone tests (as referenced here and here). I took the saliva samples for both tests on the same day at the same times. Each test was processed by a different lab. I figured that using 2 different labs would give me an indication of how reliable the results were - if the results agreed with each other, that would give them more credibility than otherwise.

But the results did not at all agree with each other. So much for that. I suppose I'd need to get a blood test done somewhere for (possibly) more trustworthy results.

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I had headaches every day for 2 weeks, and then they stopped, even without me taking any meds. They must have been after-effects of the stomach bug virus. Now I'm occasionally getting headaches again, but these are more like my usual ones, and not every day.

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Qiao is now walking with only the aid of a cane. In fact, he is beginning to walk short distances even without a cane!

He recently bought himself a Sony Tap 20 portable PC. It's a giant tablet. It has a very nice screen.

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You know what would be useful? A website along the lines of "These are various sounds your car may make, along with an explanation of what part of the car may be making the noise and why". Well, actually, sort of like this, this, and this, but with actual car sound samples rather than human reproductions of them.

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more info on hormones, labs & testing

Mon, 28 Jan 2013 00:38:44 GMT

[Silly me. I thought I'd just go ahead and order those 2 tests I had decided on, and get it over with, with little ado. But no no no, my mental "am-i-really-sure-this-is-how-i-want-to-proceed" circuit hadn't yet been satisfied enough.]

"Estrogen" is actually an umbrella term for at least 3 hormones: estradiol (E2), estrone (E1), and estriol (E3).

Current Status of Salivary Hormone Analysis - a paper from 2008.
Summary: Although saliva has not yet become a mainstream sample source for hormone analysis, it has proven to be reliable and, in some cases, even superior to other body fluids. Nevertheless much effort will be required for this approach to receive acceptance over the long term, especially by clinicians. Such effort includes the development of specific and standardized analytical tools, the establishment of defined reference intervals, and implementation of round-robin trials. ...

Aetna's Clinical Policy Bulletin: Salivary Hormone Tests - has a lot of good info. Currently Aetna only covers these tests for diagnosing Cushing's syndrome. The bulletin explains why the tests are not covered for conditions such as menopause, osteoporosis, or depression.

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Monoamine transmitters include catecholamines and tryptamines (serotonin and melatonin).
Catecholamines include epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine.

"Neurotransmitter tests" are available, which are done via urine samples. There is debate whether these tests are at all useful or not. Some arguments mention that the chemicals being tested are actually produced throughout the body, not only in the brain. For example:

Approximately 90% of the human body's total serotonin is located in the enterochromaffin cells in the alimentary canal (gut), where it is used to regulate intestinal movements

Therefore, the urine levels may not correlate with the levels in a specific part of the body such as the brain.

Neurotransmitters excreted in the urine as biomarkers of nervous system activity: validity and clinical applicability. - a paper from 2010. The conclusion indicates that urine testing has promise, but that more research will be required for its use in relation to CNS (Central Nervous System) issues.

Validity of urinary monoamine assay sales under the "spot baseline urinary neurotransmitter testing marketing model" - paper from 2011. The conclusion states that as of yet, no "original research scientific peer-reviewed paper" has even been published regarding spot baseline urine sample use for neurotransmitter testing, and encourages the companies which are marketing the tests, to publish their research.

Yet the 2009 paper Urinary Neurotransmitter Analysis as a Biomarker for Psychiatric Disorders states "Urinary neurotransmitter analysis has a breadth of data to support its usefulness in clinical practice." and mentions studies going back to the 1950s. A 1986 study that found that depressed subjects with melancholia had high urinary levels of normetanephrine, whereas depressed subjects without melancholia and subjects with dysthymic disorder had levels comparable with controls.

It appears that the *type* of urine test done is significant - using a single small sample versus a sample of all urine produced during the day, or perhaps over multiple days.

Urinary neurotransmitter testing: considerations of spot baseline norepinephrine and epinephrine" - this paper from 2011 states:
"The reported laboratory test results for urinary serotonin, dopamine, norepinephrine, and epinephrine, obtained on different days from the same subjects, differed significantly and were not reproducible.
Spot baseline monoamine assays ... are of no value in decision-making due to this day-to-day variability and lack of reproducibility."

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Many of the laboratories that provide testing kits indicate that they are "CLIA-certified".

CLIA - "a program which sets standards and issues certificates for clinical laboratory testing".

CLIA website - has more info. This page has links to PDF files which list laboratories that have been convicted of fraud and abuse (etc), and ones which have had their certifications suspended, limited, or revoked, along with the reasons. There's a separate file for each year.

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blood/urine/saliva testing

Wed, 23 Jan 2013 22:53:22 GMT

For a while, I've been wanting to get some tests done to check my vitamin/mineral/amino acid levels, my hormone levels, and maybe even food sensitivities*.

I browsed various test kits that can be ordered online. Some only require saliva, urine, or blood-prick samples that you can collect yourself and mail in to a lab. Others require blood to be drawn. Some (for testing toxic metal and mineral levels) even use hair samples.

At first I wondered if the saliva tests would be as accurate as blood tests, in those cases where levels may be checked by either method (such as for hormones). It seems that they may be; but I'm a bit unclear as to the significance of levels of bound versus free hormones. Apparently, saliva tests only measure free hormones.

A person's hormone levels may fluctuate a lot. From what I read about testosterone in females, there are no agreed upon "low" or "normal" ranges. So even assuming I get back accurate measurements, I'm not sure what it can tell me. But I am curious whether my levels are on the low side or not.

Then I wondered how I could know whether the various labs were trustworthy. Maybe *none* of the ones offering do-it-yourself kits were really reliable... But then again, when you get tests done at a doctor's office, those samples get sent to labs too. Surely some of the labs must be trustworthy?

I did some web searching to find out whether various labs/tests were reliable, with mixed results. I decided not to use one particular lab, due to it having filed a defamation lawsuit against a website (QuackWatch.org) which had publicized potentially unscrupulous activity by the lab. (After reading the article in question, I would have given the lab the benefit of doubt, as it sounded to me that the medical practitioners involved were more to blame than the lab. But having the lab try to take down the article via a defamation lawsuit seems detestable to me.) Then I read something else which made me question how trustworthy the QuackWatch website was...

Sigh. Who to trust? What to trust?

Anyway, for the moment, I've decided to get a saliva hormone test done, and this nutritional test.

* - My mouth was sore for the last 3 days (a rather unusual occurrence), leading me to suspect I had eaten something that I was sensitive to. But after reading about the unreliability of some IgG tests, it's probably not worthwhile for me. I don't have any significant digestive issues anyway.

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How high can you hear?

Sun, 04 Mar 2012 07:39:48 GMT

I can hear a 12 kHz sound well. I can hear a 13 kHz sound, but it is very faint unless I turn the volume up. I can hear a 14 kHz sound faintly too, but have to turn the volume even higher. I can't hear 15 kHz, even at high volume.
I'm 40 years old.

In March 2008 (when I was 36 years old), I took the 2nd hearing test below and (by increasing the volume on my computer speakers) was able to hear all the frequencies except the last one. That means that in the last 4 years, I've lost a significant amount of high frequency hearing.

What is the highest frequency you can hear (and do you have to turn the volume up high?), and how old are you?

hearing test 1 (includes 13 and 14 kHz samples)

hearing test 2

hearing test 3

hearing test 4

I was hoping to find some graphs that show for given age groups, what the average highest audible frequencies are. But I didn't find any such graphs. If you know of any, please point them out for me.

I very rarely listen to music with headphones, and when I do, I don't play it very loud. I'm not regularly around loud industrial noise. So I wasn't expecting to have much high frequency hearing loss. But apparently I do.

According to this page, 64 kbps MP3 files cut off at about 11 kHz, and 96 kbps MP3 files cut off at about 15 kHz. Given that I can only hear well up to about 12 kHz, it makes sense that I can't tell the difference between MP3 files encoded at higher than 64 kbps.

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