generalist – Page 29

Dilutions: How Are You Doing Yours?

If you ask someone to dilute a sample in half, pretty much everyone will do it the same way – add an equal volume of sample to an equal volume of diluent, whether that’s 1 mL to 1 mL or 100 µL to 100 µL. But if you ask people to do a 1 to 2 dilution, you may be surprised to get different results. That’s because I’ve found that the convention for writing dilutions is taught differently at different Medical Laboratory Science (MLS) schools.

A 1 to 2 dilution should be written as ½. It means to dilute something in half. But many times it will be written as 1:2. These two forms are actually not equal, despite the fact that they are used interchangeably in the laboratory. One is a dilution and the other is a ratio. In the scientific literature, if you see “1:2”, it means to add 1part to 2 parts. That will be 1 mL added to 2 mL, for a total of 3 mL, or a 1/3 dilution.

Unfortunately, this problem is prevalent in the laboratory. I’ve seen 1 to 10 dilutions written both as 1/10 and 1:10. It’s very important to know how the technologists in the lab are performing that 1 to 10 dilution. Are they doing a true 1/10 (1 mL sample plus 9 mL diluent) or are they actually doing a 1 to 11 dilution (1 mL sample plus 10 mL diluent)? Your patient results may be different depending on who does the dilution!

Coming into this field from a scientific background rather than an MLS background, I prefer the convention of writing a dilution as 1 over something, ½, 1/10, rather than as a ratio, 1:2, 1:10. However, perhaps the majority of medical laboratory scientists are taught the ratio. Either convention works fine as long as it is clear to everyone in the lab what dilution they are actually performing and being asked to perform. You might want to just check your own MLS and see how they do their dilutions.

-Patti Jones PhD, DABCC, FACB, is the Clinical Director of the Chemistry and Metabolic Disease Laboratories at Children’s Medical Center in Dallas, TX and a Professor of Pathology at University of Texas Southwestern Medical Center in Dallas.

Management and Administration Housekeeping Items

A few items relevant to your interests have crossed the editor’s desk over the past few days.

1. As we mentioned several months ago, laboratories need to provide lab results to patients (or their representative) when requested to do so. The Privacy Rule amendments went into effect on October 6, 2014. Is your lab compliant? Read the regulations to be sure.

2. The Draft Guidance for the FDA regulation of LDTs has been published. You can read them here and here. The FDA will accept comments about the draft for the next 110 days.

Making Solutions

It often seems to me that the art (or science) of making solutions is becoming a lost one. In this current day and age when most of our solutions come in a pre-made form and only require mixing, or at most, thawing and mixing, I believe we’re losing the ability to make solutions ourselves.

This thought came to me when I overheard a comment in a hallway about a shortage of physiological saline. It was back-ordered and we’d be in dire straits soon if we didn’t get any in. And I wondered: if we have solid sodium chloride in the laboratory and we have water, how can we have a shortage of physiological saline? And physiological saline is incredibly easy because you don’t even need to know the molecular weight of sodium chloride. If you want 0.9% physiological saline, that 0.9 grams of NaCl in 100 ml of water.

The same is true for any other easily made-up solution. We’re so used to having them pre-made for us, that we’re forgetting everything we learned in school about how to make solutions. Of course, being able to make solutions from scratch does presuppose that the lab still has chemicals, a balance and a pure water source. My lab does, but that’s because we run a lot of laboratory developed tests (LDT). Most laboratories may no longer keep chemicals, and even if they do, using a home-made reagent turns your assay into a LDT. Plus so many pre-made reagents have proprietary formulas that making them up from scratch is not possible. But for simple reagents like physiological saline, that perhaps is being used to perform dilutions or wash cells, I find it kind of sad that we rely on “store bought” reagents so much that we never consider making them ourselves. In that respect, I guess I’m something of a lab dinosaur.

Don’t get me wrong. I’m totally in favor of making our lab lives as easy as possible and pre-made solutions are one of the wonderful things that do that for us. In addition, if you buy pre-made reagents, you remove one variable that can affect results – was the reagent made up correctly, using the correct chemicals. On the other hand, I believe it’s also a good idea to know how to make up a solution if you should need to do so.

It’s a little comforting to know that this loss of ability may not be confined to the lab. I heard a pharmacist talk about a shortage of total parenteral nutrition (TPN) solution, which I suspect at one time every pharmacist knew how to make up from scratch.

Pandora’s Box

Archived in the ever-rich and exotic mythologies of the Greeks is the story of Pandora’s Box. It was actually a “jar”—which is strangely close to a “test tube” in my opinion. Pandora was given a wedding gift, a beautiful jar, with instructions not to open it under any circumstances. Curiosity killed the cat, so to speak, and she finally couldn’t resist. When she opened it, all the evil contained in the jar escaped and spread over the earth. She tried to close it but too late—the contents had already escaped. Only one thing remained in the jar at the very bottom—the Spirit of Hope.

I’m not sure the World Health Organization would agree with me, but “Pandemic” is very close to “Pandora.” In a world where international travel is commonplace the spread of contagious disease is a major concern. Rats on ships carrying plague may be a thing of the past, but viral-loaded passengers on an international flight happen every hour of every day. Think of all the headlines in the past decade that have highlighted international health risk issues. It seems that Pandora has unleashed a few additional mutated “evils,” and I doubt we’re through with all her mischief.

As laboratory professionals, we are essential to solving the public health issues confronting our world today. Rapid diagnosis, evidence-based research, viral load monitoring, susceptibility and pharmacological validation, managing toxicity—familiar territory for us, and just think of how much relies on our expertise? We are called on daily to be the platform and framework for “pandemic control” measures. Sitting in our clean, efficient, well-lit, safe and busy laboratories throughout our country it’s easy to forget there are bacterial and viral war zones not far from our shores…all it takes is a small rat on a creaky ship (or a young child on a red-eye international flight) to initiate a modern day plague world-wide.

Next time you hear “pandemic”, remember Pandora. Wash your hands, put on a mask, and peer inside that jar of hers and shake out some Spirit of Hope. Sprinkle it liberally around our laboratories and colleagues, and let’s roll up our lab coat sleeves—we have a lot of work to do!

–Beverly Sumwalt, MA, DLM, CLS, MT(ASCP) is an ASCP Global Outreach Volunteer Consultant.

Perfection

When I was in school I learned a lot about science and the laboratory science body of knowledge. The one thing that was emphasized over and over was accuracy and precision. It wasn’t until I secured my first position and started training did I realize just how important those two words were. Not only are we counted on for our accuracy, we are counted on for the repeated accuracy of everything we report to physicians. I have heard some statistics reported that up to 80% of physician decisions on courses of treatment are based on lab results. I really do not get caught up in that number because if you think about it every single value we report is going into a patient’s clinical picture and can affect a decision on a treatment one way or another. So the question always comes up, how do we deal with errors? This question is multifaceted and as a supervisor/administrator we are responsible for much more than just the correction of the error.

I wrote this in my 5 year progress report article but I think it deserves repeating. Everyone makes mistakes, but, it is how you recover and learn from your mistake that is most important. Everyone has had that sinking feeling in their stomach when they learned they have either reported out an incorrect result or have mislabeled a specimen. As a laboratory professional it is our biggest fear and each and every day we sit down at the bench and are expected to be absolutely perfect. Zero errors are a standard that not even the most efficient manufacturers know is possible yet we are expected to perform on this level each and every day. Errors happen to everyone, and when they do it is what happens afterwards that is key to inhibiting that error to occur again. Especially with newer technologists it is important to teach them so that they are able to recover and not make the mistakes again.

The first thing I do when an error is discovered is address it with the technologist. Ask them, “do you remember this sample or this patient? Do you remember what you were doing at the time this error happened?” One thing to watch is how much the technologist can remember. If they cannot remember too many details, were they trying to do too much at once? If they mislabeled did they have a pile of tube and labels while also trying to result specimens? With mislabels I found it helpful for myself to read the name in my head as I was labeling the tube. That way if what I was reading in my head did not match the label underneath I would stop to look. If it is a procedural error why did the technologist deviate from the actual process? Did they learn a shortcut but that shortcut actually increases the chances of error? Going over this with the technologist also will help them with their problem solving skills. Especially with new technologists building problem solving skills is vital to the success or failure of a young technologist. We know humans are not perfect, but when you work in an industry that accepts nothing less, each error made is amplified but also that much more important.

–Matthew Herasuta, MBA, MLS(ASCP)CM is a medical laboratory scientist who works as a generalist and serves as the Blood Bank and General Supervisor for the regional Euclid Hospital in Cleveland, OH.

Enterovirus D68

Over the past few weeks, hospitals around the country have seen a sharp uptick in cases of respiratory distress in children. The majority of patients test positive for Enterovirus D68, and most seem to have a history of asthma.

Only select laboratories test for this strain of enterovirus. If a suspected case comes to your facility, contact the CDC or your local health department for information about specimen collection and shipping.

Laboratory Testing in A High-Containment Facility

The team at Emory that cared for the patients infected with the Ebola Virus have published a paper on Lab Medicine about laboratory testing within a high-containment facility. You can read the entire paper on the Lab Medicine website.

Biobanking and Sample Stability

A common question often asked of laboratory professionals is the length of time an analyte is stable in a sample. This question may arise simply because a sample has been delayed reaching the lab, but can also be asked in the case of adding on a test to an existing sample a day later, or a week later. Most laboratory professionals can tell you the stability of an analyte in a patient sample, at both ambient temperature and refrigerated, because assay manufacturers perform those short term stability studies when they create their tests. And many of them also include the stability of the analyte in a frozen sample. Beyond this information, it’s harder to find stability information for analytes.

Some stability information can be found at large reference labs, as they have often done their own stability studies and may know how stable an analyte is when frozen for a month, or for 6 months. The really difficult information to come by is how stable an analyte is for really long term storage. This is a question that needs to be answered as biobanking becomes increasingly popular.

Biobanking is the use of repositories to store biological samples, usually for use in later research. Biological material can be stored frozen in many forms, including tissue, cell culture, serum and plasma and dried blood spots. Determining how stable an analyte is under long term storage conditions is important in order to be able to use those samples for research in the future. And yet sometimes determining the long term stability is itself difficult. For example, if a person wished to see if albumin was stable frozen at -80 degrees for 25 years, the difficulty would be in having the same assay available 25 years apart to perform both sets of measurements. (Not to mention the personnel). Measurement technologies change over time, some very rapidly, making longitudinal studies difficult.

The design of studies utilizing biobanked samples will be important. Even when not performing longitudinal studies, if a sample has been stored for 10 years frozen in a biorepository and I remove it and measure the calcium, how do I know the calcium present is the amount of calcium that was present when the sample was stored? If I have knowledge of the patient the sample came from, I could use this data to say that in stored samples, patients with X disease have higher calcium than patients without disease, but I could not necessarily make the jump to what is true in vivo, without knowing how stable calcium is upon long term storage.

Often stored samples are used for measuring analytes that weren’t able to be measured when the samples were originally stored. In those cases, you may be able to infer stability if the amount of analyte measured in the stored samples is comparable to the amount measured in fresh samples.

Biobanking is a growing enterprise, and stability studies will need to grow along with it.

Ebola Information for Laboratory Professionals

While it’s unlikely you will ever encounter a case of Ebola, it’s best to be prepared. The CDC has a health advisory page full of information, including specimen requirements for Ebola testing. The laboratory’s first step is to contact their state health department.

CDC Interview About Ebola

Medscape interviewed the CDC about the current Ebola outbreak. In it, the CDC reiterates that healthcare workers are at particular risk for infection. While the interview doesn’t specifically mention laboratory professionals, of course they are included in that risk group. Protect yourself using standard precautions (sometimes called contact or droplet precautions). This includes gloves, gowns, face mask, and eye protection when handling specimens from a potential victim.

You can read the entire interview here.