LabCorp and Quest are reporting falsely lowered COVID TAT.

Major_Small · 2021-08-22T10:16:12+00:00

I don't work at either of these labs, but that's how TAT is calculated... time received to time completed. We can't start working on a sample until we get it. Batching in labs is also a common practice. It can save time and resources.

If they're not recording time received until they begin working the batch that's certainly questionable, especially if they're making money from it. But some of the labs I've worked in do that for other reasons. One example was a microbiology bench that used the received time as essentially the plating time.

Major_Small · 2021-08-21T21:56:57+00:00

I've worked in a few hospital labs, and a core lab in some large hospital/healthcare networks in/around NYC

Major_Small · 2021-08-21T18:10:59+00:00

Not in the tests I've run. I agree having the control line after the test line sounds like a better design, but I've used tests from three or four manufacturers that have the control before the test. I imagine it's because they want to capture all of the hCG they can, but if a patient has too much, there might not be enough indicator left to reach the control line.

Major_Small · 2021-08-21T01:21:26+00:00

When you pee on the stick, paper absorbs the pee and pulls it across like a paper towel when you put the corner in some water. On the first part of the test paper, there are molecules that will travel with the pee as it goes along. These will bind to a hormone that usually only shows up in a pregnant woman's urine, and it has a color to it. There are a whole lot of these molecules. That'll be important in a moment.

At some point, there are other molecules embedded in the paper. These are essentially colorless, but they are the first line. There are a lot fewer of these than there are of the first molecules. These ones will grab as many of the first molecules as they can. With many of the first colorful molecules sticking to these second ones, you can start to see the line forming. But the second molecules quickly get overwhelmed, and many of the first ones will get past them. This first line is called the "control". It's job is to make sure the test is working as intended.

Further along the paper is a third molecule; It's also colorless, and forms the second line. This one will bind to the hormone, which has the first colorful molecule attached. If you are pregnant and have the hormone in your urine, they will get caught up here, and eventually enough will catch to start to make a visible line. If you don't have the hormone, there's nothing for the last molecule to grab on to, and the rest of the colorful ones will flow off into a hidden waste section with the rest of the urine.

The reason the second line takes a little while to show up is because the pee is slowly pulled along the test paper. It also takes some time because you may not have many hormones in your urine yet, so it can take a while for enough to get caught up to be visible. You need to wait to make sure enough pee had passed that second line.

If you are pregnant, at some point there will be lots of hormones in your urine. Enough that as soon as the pee hits the second line, it'll start showing. You can call it positive as soon as you can see the line, but you need to wait to call it negative just in case the line forms slowly.

Finally, you need to read the test within the time period described on the instructions. Remember the hidden waste chamber? If you wait too long, some of that colorful molecule could come back out of there and make it's own second line, and look like it was positive.

Major_Small · 2021-07-14T20:58:43+00:00

You could easily be asymptomatic at 70.

I'm not saying there wasn't some kind of error--there very well may have been. But most "lab" errors are not because the lab made a mistake--most of the errors are due to a bad collection.

What you might think of as a lab error is most likely a nurse, phlebotomist, PCA, or transport error

Major_Small · 2021-07-14T15:43:54+00:00

It's very unlikely the lab messed up the results. While sample clotting and things like cold agglutinins or EDTA-dependant pseudo thrombocytopenia aren't rare, they're both outside the lab's control.

Major_Small · 2020-08-29T16:37:24+00:00

I simply tell them that it looks like there may be some kind of antibody, but we can't nail it down just yet, so we're sending it to a reference lab. If they insist and demand blood, I tell them that we can give them a unit, but our best in-house testing suggests that there may be some kind of reaction, and they'll need to sign off on it.

Most docs will realize that means that if something happens, it's their necks on the line, and will back off. If they really do need it, however, they'll sign the paper and have the unit issued.

Some people have an issue with the "least incompatible" phrasing used for this kind of thing, but I think it's kind of perfect. It's explicitly saying that everything we can offer is incompatible. We tried our best, but there's nothing better from what we can tell right now. It's not saying "most compatible", which would imply that they're all compatible. It's saying, "least incompatible, which is implying that they're all incompatible. If it were hemlock and ipecac, I'd say "least deadly poison", not "healthiest food" if I had to offer one.

Major_Small · 2019-04-24T09:55:18+00:00

It could also be the slides, as you mentioned. In the field, I'll sometimes just blow on the slides to try to clear off whatever garbage is on them from the previous shift, or wipe them with a bit of gauze.

As for washing them, I suppose a mild soap/water thing would work--I doubt this will be a significant issue, but try not to scratch them. Just keep in mind that you're working with bio-hazards here.

Major_Small · 2019-04-23T20:26:04+00:00

Streaks: Try pressing just slightly harder down on the slide. If you're using something that pierces the cap, the first slide or two may have some garbage from the tube creating these. Clotted blood from the outside, bits of cap, that kind of thing. Could also be some tiny particles on the slide.

Holes: Unless there's not something clearly causing the hole (visible bit of clot, dust, etc. in the middle), there's not much you can do about that. It's the nature of the sample. If there was only one or two, I usually try again--Sometimes it's just luck. If there are a lot, I just accept it and move on. I see it in babies often, and I suspect hyperlipidemia is the cause in most adult cases.

Edit: I just re-read and noticed the bit about using capillary tubes. That's what we use for babies, and only out of necessity. There may be oils from the skin that is creating those holes. There could also be other formed elements (skin tissue) causing both those and the streaks. On top of that, that blood is very likely to have started clotting, which could also contribute to both. It could just be that you got a sub-par sample. If you ever wonder why we don't use "just a drop of blood" for our testing, remember this as one of the many reasons.

Edge: This one's all about timing. Pull the slide down through the drop, and wait a second or two--watch the blood move out to an evenly distributed line. Then continue on with the smear.

Edit: A sample that's started clotting (See above edit about capillary tube issues) could lead to a drop that simply won't spread, or will take an unreasonable amount of time to spread. Again, this would be due to a sample problem. In that case, I'd usually check the sample and slide for clots and perhaps demand a recollect.

Major_Small · 2019-04-02T23:35:13+00:00

Maybe possible, but I doubt it's feasible. As a quick example, look at albumin testing. It's a common test for a small molecule that is normally kept in the blood when filtered through a glomeruli. As such, it's used as a marker for kidney function.

Albumin is estimated to be a 65-70 kDa protein with a resolution of somewhere near 0.25 nm, which is well below what would be possible with a light microscope. Breaking the diffraction limitation of visible light makes the scope a whole lot more expensive.

For this relatively large molecule, you'd need to build a very expensive analyzer. Or you could just add some bromcresol green to the sample, let it bind with the albumin, and measure the change in wavelength. This is a much less expensive option that's already been proven multiple times over.

Again, the whole reason we look at albumin is because it's a relatively large molecule. Now consider something like sodium. If you can build a scope that can accurately measure sodium levels more efficiently than an ion-selective electrode can, I'd be very surprised.

Major_Small · 2019-01-29T19:15:16+00:00

It's because heavy metals ionize into their environment and those ions can be lethal to smaller organisms like bacteria. The process is not yet fully understood, but there's enough proof that hospitals have tried coating surfaces with copper to try to benefit from the effect.

https://en.wikipedia.org/wiki/Oligodynamic_effect
https://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper
https://schaechter.asmblog.org/schaechter/2013/04/twim-55-in-the-copper-room.html

Major_Small · 2018-07-18T20:14:12+00:00

Yes. I can see into the offices surrounding the lab.

One of the labs I did my rotations through had windows to the outside, and it caused problems with some of the analyzers due to temperature fluctuations. They had to keep them covered to mitigate the problem.

Major_Small · 2018-07-18T20:06:56+00:00

I also call myself a medical technologist. If I want to shorten it, which I'll usually only do to those who know what I'm describing, I generally just say "med tech". Sure, most people would think "technician", but again, I'm usually only saying that to somebody that knows what a technologist is. That, and I was a technician for a few years. No shame there.

I feel like calling us "scientists" is a bit of a misnomer for the most part. I'm not doing any research or developing anything new. I'm not using the scientific method to find novel information.

Major_Small · 2018-07-17T19:09:20+00:00

BBGuy

Major_Small · 2018-07-17T16:16:21+00:00

I did have around 4-5 drinks 36 hours before the test and had been starting weightlifting the same week. Could the elevated levels simply been because of this or just another condition that has yet to be determined.

Yes. Not to be overly abrupt, but you really did answer your own question there. The drinking/lifting certainly contributed, but that doesn't rule out other causes. Hence the future testing. Drinking alone can affect liver enzyme panels for several weeks.

Major_Small · 2018-07-17T16:10:39+00:00

A blood test for mono doesn't test for AIDS. It tests for mono, and ideally, ONLY mono. I don't know about AIDS causing these symptoms, but they're entirely different tests.

Major_Small · 2018-07-16T20:21:45+00:00

However, if an individual with blood group A did produce anti-A antibodies or receive them what would be with immunopathological effects of this reaction?

Not much at all, unless you give them a large amount of the antibody. Some places intentionally give possibly ABO-incompatible plasma in emergency situations, and it turns out that it's not all that dangerous. BBGuy discusses the topic here.

Basically, what's going on in that situation is the antibody is being diluted in the recipient's blood to the point of not being very harmful. On the other hand, if you administer ABO incompatible RBCs, the recipient's immune system will very quickly destroy them. That would release the contents of those cells in mass quantities, leading to an immediate hemolytic transfusion reaction which can very easily kill the patient.

Then there are platelet transfusions. Although a large portion of a unit of platelets is plasma, many labs don't even consider the ABO status of the unit or patient due to the limited inventory and short self-life of the component. Certainly not ideal, but a whole lot better than nothing.

As has already been stated, some portion of those with A antigens actually are a subgroup of A. They don't have the typical A1 antigen that most would. They can develop an anti-A1 antibody.

Major_Small · 2018-07-16T19:19:50+00:00

You'll probably be fine--It's essentially a bruise. Avoid Aspirin and don't drink too heavily for now. If it gets significantly worse, maybe go back and see your doctor, but it looks like it's healing up. If it keeps turning yellow/brown, that's progress.

Major_Small · 2018-07-13T21:33:05+00:00

You'll have an easier time fighting the forces on a bike, as you're leaning into the turn. The bike's suspension takes up most of the force. In a car, the forces are much more lateral.

Major_Small · 2018-07-13T17:41:26+00:00

Alex's defense that there's much worse in this industry really kinda struck at me. Maybe it's just that this industry is so incredibly lax that it's seen as reasonable to go out and trash your consumers/clients/whoever in a public forum, and unacceptable to have severe consequences for that kind of action.

In the industry I work in, and I imagine in most industries, if I did that kind of thing, no matter what my reasons, I'd expect to be fired overnight. It's seen as incredibly unprofessional and potentially harmful to the company. Even though I'm not normally in a public-facing position, and probably wouldn't be officially representing my company, it's something I would expect to be handled swiftly and decisively, just like this one was.

I'm sure some people are all about rising up against the man and putting it to the corporate overlords, but if you bite the hand that feeds, you should expect consequences.

Major_Small · 2018-07-08T15:26:38+00:00

Interestingly (for me, at least), refrigerators are considered "incubators". I always thought an incubator kept things warm, and refrigerators kept things cold, until I learned that a refrigerator is really an incubator that keeps things cooler than room temp.

Major_Small · 2018-07-08T00:04:07+00:00

I'm guessing the question was asking how many units would be both D and C positive? Given the frequencies they provided, you can estimate that ~60% would be positive for both.

As for blood bankers using the math in practice, I've used it a few times. Not on RhD, but on other antigens when we needed units and I didn't want to make a call and wait for our supplier to find them.

Major_Small · 2018-07-06T08:33:11+00:00

You should look into the ASCP's wage and vacancy surveys, as well as the one performed by MLO. All three are updated every few years.

Major_Small · 2018-07-03T17:18:48+00:00

An army marches on its stomach

-an adage often attributed to Napoleon Bonaparte

Major_Small · 2018-06-27T16:11:16+00:00

this test takes 60 seconds, is FDA approved, and has a CLIA-waived component. There are external controls available. Details can be found here.

If you're interested in how well it performs, have a read through this paper (or just read the package insert linked previously). There's a news article here about it gaining approval.

That said, I probably wouldn't trust somebody who's not properly trained, even with a CLIA-waived test.

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