generalist – Page 26

Philosophical Repose

A recent episode of much-needed filing in my office uncovered some prior contributions I had written for the Journal of the Kentucky Medical Association as part of its editorial board. One of these, written over a decade ago, resonated with me. The editorial represented what at the time I had termed a “daily devotional.” How timely that I should discover and reread this as it came on the heels of several (and not uncommon) frustrating days in the office.

The article highlighted a beautiful mosaic in the lobby of the hospital where I had my practice for 20 years. It featured Maimonide’s Prayer. Maimonide was a 12^th century physician and philosopher. Here is a copy of the script:

Almighty Father of Mercy,
I begin once more my daily work,
Grant that I may be able to devote myself,
Body and soul, to Thy children who suffer from pain.
In all my efforts to heal the sick may I be filled with love for my fellow man.

One needn’t be particularly religious to understand and appreciate the very simple meaning of this prayer. It reminds us, that as laboratory professionals, we, as part of the healthcare team, ultimately need to remember that our personal daily devotion is to patient care. It is good from time to time to have a moment of philosophical repose.

I believe the next time daily events are extremely exasperating, when frustrations of practice threaten to overshadow my day, I shall have a copy of Maimonide’s Prayer close by to provide a bit of realignment and re-commitment to this professional purpose.

-Dr. Burns was a private practice pathologist, and Medical Director for the Jewish Hospital Healthcare System in Louisville, KY. for 20 years. She has practiced both surgical and clinical pathology and has been an Assistant Clinical Professor at the University of Louisville. She is currently available for consulting in Patient Blood Management and Transfusion Medicine. You can reach her at cburnspbm@gmail.com.

Body Fluid Testing

When I started my career in laboratory medicine, we tested any fluid that was handed to us, for any analyte requested by the doctor. We did this for a number of reasons that we thought were good ones including that the doctor is a medical professional who knows what he wants and needs, and that the test results will help diagnose and treat the patient. We were trying to be helpful. Along the way though, laboratory professionals have come to understand that testing like this may not provide accurate results and may be doing more harm than good.

Now days, CLIA has clearly mandated that if the manufacturer of an FDA-approved assay system has not validated that system for a specific fluid type, the lab must perform that validation before testing and reporting results on that fluid type.

This is sometimes a hard rule to explain to the medical staff who have been trained in medical school to order such things as amylase on peritoneal fluid to look for pancreatic injury, or glucose on nasal fluid drainage when a CSF leak is suspected. And these doctors often have literature references for what they wish to have measured, although in general the references are not recent. I have a three-pronged approach to the explanation I give doctors as to why I won’t analyze the sample they sent me.

First, and probably most importantly, I cannot guarantee the accuracy of the result. Matrix effects are real and a test designed for serum will not perform the same on urine. Similarly, a test designed for serum and urine will not perform the same on a pharmacy preparation or an ascitic fluid sample. The result I provide if I test that sample could very well be wrong.

Secondly, I have no way to interpret the results of the test on an un-validated fluid type. There are no established reference intervals that allow us to determine the meaning of the result we’re providing. For example, who knows how much glucose is normally present in nasal drainage? I would assume no one knows, because why would you measure it in normal nasal drainage, and for that matter, what constitutes normal nasal drainage? Thus if I test that unknown sample for the analyte requested, I’m providing a possibly inaccurate result that is uninterpretable. And the physician is going to treat the patient on the basis of that result. In most cases, the physician changes his or her mind at this point in the discussion.

However, if that isn’t enough, I bring out the big guns. The agencies under which the lab operates forbid me from analyzing this sample for this analyte unless I validate the sample fluid type in my lab using the stringent validation criteria described in CLIA. This validation would take a considerable amount of time and resources and enough patient samples to set a reference interval.

If a doctor would still like to be able to order that test on that sample type after the discussion, I request that the doctor be involved in the validation process. First of all, I will want to know that enough of these tests will subsequently be ordered that the time and effort spent to validate the test will be worth it. In addition, the doctor will need to collect sufficient numbers of that sample type to allow us to perform an adequate validation and reference interval study. Also, QC material with the same matrix as the fluid type will need to be used and may have to be made in-house as it’s generally not commercially available. Biannual proficiency testing for that fluid type will need to be performed also, with internal PT developed for it. All of these considerations mean that the number of body fluid types and analytes we have validated is small, but we do not analyze un-validated fluid types. We will often try to locate a reference lab who does analyze them for a doctor. When that fails we will try to help the doctor find an answer to his medical question through use of other, legitimate tests.

-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.

Sweat Testing

August in Texas is a good time to write a blog post about sweat. In this case though, I’m going to specifically talk about testing collected sweat samples for chloride concentration. Sweat chloride concentrations are measured in people who are suspected of having Cystic Fibrosis (CF). Because CF has classically been considered a disease of childhood, sweat chloride testing is performed almost exclusively in pediatric institutions.

CF is a disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This is a large gene which codes for a large, transmembrane protein that acts as a chloride channel. More than 1500 mutations have been detected in the CFTR gene, not all of which are known to cause disease. Thus, even though the full gene has been sequenced, CF remains a diagnosis which is made by a combination of the presence of characteristic clinical features, or history of CF in sibling, or a positive newborn screen, PLUS identification of a disease-causing mutation in the gene or protein or laboratory evidence of chloride channel malfunction such as an elevated sweat chloride level.

Collecting a sweat sample for testing is an interesting manual process. The first step involves stimulating the sweat glands to produce sweat. This is accomplished by a process called iontophoresis, in which a sweat-gland-stimulating compound called pilocarpine is driven into the skin using a small electrical current between a set of electrodes applied to the skin. After a 5 minute stimulation, the electrodes are removed, the skin is cleaned, and the sweat that is subsequently produced in that stimulated area is collected for the next 30 minutes. The collection is either via absorption of the sweat into a piece of gauze or filter paper, or by a collection device which funnels the sweat into a small plastic tube as it’s produced. The amount of sweat collected after 30 minutes is determined by weight if gauze or filter paper is used, and by volume if the tubing is used. There is a lower acceptable limit for both cases, below which the sweat collection is insufficient (QNS) and must be repeated. The process sounds simple, however collecting a sufficient quantity of sweat can be problematic, and collecting too little may cause falsely elevated results.

After collection, the amount of chloride present in the collected sample is measured. In a normal sample, the amount of chloride present is well below the measurement range of the usual chloride ion-selective electrodes found in chemistry or blood gas instruments. For this reason, the chloride concentration in a sweat sample is most commonly measured using a method called coulometric titration in which a silver electrode placed in the sample gives off silver ions during a current flow. The silver ions complex with the chloride and precipitate as silver-chloride. This reaction continues until all the free chloride is gone, at which point a timer stops. Quantification is accomplished essentially by comparing the time necessary to complex all the patient’s chloride versus the time necessary to complex a known concentration of chloride in a standard. Calculations are performed using the time and the weight or volume of the sweat collected, among other parameters.

The entire test is very manual. Collection of appropriate sweat samples requires training and practice. In general the QNS rate – how often an adequate collection is not achieved – is carefully monitored by the lab, the CF clinic and the CF Foundation which accredits the clinic. In addition, measuring the chloride in the sweat by chloridometer is not an automated process of placing the sample on an instrument and pushing a button to go. For these reasons, the CFF recommends not performing sweat testing unless you perform a minimum number per year in order to stay proficient. In this day and age of increasing automation, sweat chloride testing remains the anomalous, old fashioned test requiring significant technologist time and expertise.

Regulation of Laboratory Developed Tests (LDTs) – Revisited

Two years ago this coming September I posted a blog about the FDA’s intent to regulate LDTs and the need for laboratory professionals to both keep an eye on what happens and to be a part of it. I believe it’s time for an update on what has been happening and a further exhortation to stay involved.

The FDA is definitely going to regulate all LDTs. This is no longer a future possibility, but is now an approaching reality. In October of 2014, the FDA put out two new draft guidance documents for 120-day comment periods. One document, “Framework for Regulatory Oversight of Laboratory Developed Tests (LDTs)” lays out the FDA’s various risk categories and classifications for different LDTs and also lays out the FDA’s timeline for enforcing regulation of them. The second document, “FDA Notification and Medical Device Reporting for Laboratory Developed Tests (LDTs)” delineates how labs will report their LDT testing to the FDA and the protocol for adverse event reporting to the FDA, which all labs performing LDTs will be required to do.

During the 120-day comment period, many groups commented, weighing in on their perspective about the FDA regulation of LDTs. AACC and the Association for Molecular Pathology (AMP) published position statements. CAP Today did a comprehensive article. Although nearly everyone agrees that some form of LDT regulation is necessary, there is a wide range of opinions on what that regulation should entail, and even who should ultimately be responsible for it.

Despite many suggestions that perhaps the FDA should approach this regulation differently, they plan to move forward. Their “Framework . . .” document lays out about a nine-year timeline for regulating all LDTs, starting first with the highest-risk group. LDTs will broadly be classified into three groups: low-risk, which are also known as “traditional” LDTS, moderate-risk and high-risk. Traditional LDTs are those developed by a single lab for use on a single patient population. This classification will cover many hospital-based LDTs and it will have the least rigorous regulation by the proposed guidance documents. Moderate and high-risk LDTs will be tackled first by the FDA and will require pre-market review and approval as part of the regulatory requirements.

The FDA is perhaps listening to some of the comments being generated however. Most recently the FDA has announced that an interagency taskforce will be formed to deal with LDT regulation. Currently that task force includes the FDA and CMS, although many laboratory associations are hoping it will be expanded to include more groups. As laboratory professionals, it’s up to us to stay informed of this new regulation headed our way, and to do our best to be involved in the process.

CLSI Publishes New and Revised Standards on POC Testing

From the press release:

“CLSI recently released new and revised standards on point-of-care testing in relation to glucose measuring and monitoring. Effects of Different Sample Types on Glucose Measurements, 1st Edition (POCT06-Ed1), provides information to assist the clinical and point-of-care staff in result and measurement procedure comparisons of glucose tests. Glucose Monitoring in Settings Without Laboratory Support, 3rd Edition (POCT13-Ed3), focuses on performance of point-of-care glucose monitoring systems, with an emphasis on safety practices, quality control, training, and administrative responsibility.“

These documents, including their sample pages, can be found on the CLSI Shop.

What’s That Interference?

I’ve heard it said that there is no such thing as a lab test with no interferences, and I have to admit, I believe that to be true. For every method devised to measure a specific analyte, something else can interfere with that measurement. For example, photometric measurements using absorbance assume that only the analyte of interest absorbs light at the wavelength being used. Quite often, many other compounds absorb light at that wavelength as well. In chromatography methods, we assume only the compound of interest elutes from the column at a specific time point, and again, many other compounds often do. Various types of mass spectrometry are touted as specific for the compounds being measured, however, even using mass spectrometry, compounds may fragment in similar patterns when looking at mass spectra, or fragment into the same size precursor and/or product fragments using tandem MS.

Thus, we routinely report test results knowing that most often what we are reporting is accurate. However, we must always be aware that the result we’re reporting may not be accurate due to interferences.

I recently had an occurrence related to test interference. Like all such cases, the tech responding to the clinician’s call used our standard response. He located the original sample and repeated the test. The assay gave the same results on the repeat and the result was reported back to the clinician as real and accurate, even when questions were raised by the healthcare staff about the result not fitting the clinical picture. And in fact, although the result was reproducible and in the realm of possibility, in this case the result was wrong.

The analyte in this case was plasma free hemoglobin which is performed in our lab by an assay which measures absorbance at one of the wavelengths at which hemoglobin absorbs light and subtracts a background wavelength reading. The test was persistently giving very high plasma free hemoglobin results even though the patient had no other evidence of hemolysis. When the healthcare staff became adamant about the discrepancy, the sample was sent to an outside lab which performs the assay using a full spectrophotometer, and the sample was found to have no hemoglobin present. An interferent in this patient’s sample was being measured as hemoglobin by our method.

Of course, once it’s been determined that a test is experiencing interference the next question from the healthcare provider is always, what is interfering? That’s a much more difficult question to answer, although occasionally it can be answered with some investigation. Looking into the patient’s drug regimen can help, as well as checking other health parameters to see what else is occurring. In the case of the elevated plasma free hemoglobin, the patient did have an elevated myoglobin which may have interfered.

The take home message here is that no matter how reproducible the results are, interferences are possible. As laboratory professionals, we should always be ready to look for ways to prove our results other than by repeating them, especially when the result does not fit the clinical picture and is being questioned by our healthcare colleagues. Sending the test to be run by a different method is one good way of determining interference. Another way is to check the patient’s chart for drugs or other substances that are known to interfere and are listed in the package insert. Finally, understanding the realities of assay interferences, and being willing to continue looking for answers is also important in the laboratory.

MERS Outbreak in the Republic of Korea

Lablogatory spoke to Kyung Jin Cho, PhD, from the Department of Health and Environmental Science at Korea University about the current outbreak of MERS in the Republic of Korea. This is what he had to say.

Lablogatory: What can you tell us about MERS in the Republic of Korea?

Dr. Cho: MERS is a viral respiratory infection caused by Middle East Respiratory Syndrome Coronavirus (MERS-CoV). The MERS-CoV belongs to the coronavirus family (beta coronavirus). Many MERS patients developed severe acute respiratory illness with symptoms of fever, cough, expectoration, and shortness of breath. The cause of MERS is not yet fully understood. Some infected people had mild symptoms or recovered. Incubation period is known as 2-14 days. The incubation periods are still under dispute since a few cases in Korea reported incubation periods longer than 14 days. Fortunately, the MERS outbreak appears to be subsiding with one or two new cases are reported daily. Many people under the house quarantine at the peak of MERS outbreak are now released.

STATISTICS
The Korean MERS portal reported that there are 27 deaths from 175 cases as of June 23, since the first MERS patient was confirmed on May 20, 2015 (Fatality rate: 15.4%). Most of the people who died had an underlying disease such as chronic lung and kidney disease, cancer, and diabetes mellitus. Of the 27 deaths, 74.1% were male and all were over the age of 40. Of the 175 confirmed cases, male 107 (61.1%), female 68 (38.9%); the Inpatient/outpatients 80 (45.7%), family members/visitors visiting sick persons 62 (35.4%), staff and other hospital employees 33 (18.9%). Most of the MERS cases were infected within the medical facilities. The cumulative number of released individuals from quarantine is 10,718. The current number of isolated is 2,805 (home 2,091 and institution 714).

Lablogatory: How fast is it traveling within Republic of Korea?

Dr. Cho: The major second place of MERS spread was a mammoth hospital which is a top-class institution in Seoul. Within a large hospital, the Hospital S, nearly half of the cases (82 of 166 cases, As of Jun 20, 2015) were exposed to the MERS during June 5th through June 10th. The hospital S admitted the 14^th case of MERS and became the epicenter of the second generation of MERS cases. The health authority failed to carry out timely control measures against MERS. The authority and the hospital S were harshly blamed for the late response in the beginning of MERS outbreak.

During the MERS outbreak, a few doubtful MERS patients roamed about a few institutions. Some local hospitals had to refer their untreated cases to the tertiary hospitals located in big cities, like Seoul or Busan, which have excellent specialists and more resources. Unfortunately, some of the hospitals could not cope with the unexpected MERS outbreak. The triage systems in some medical institutions and the house quarantines were not operated successfully at the beginning, which contributed to the spread.

Lablogatory: Beyond the basic protocols, what other measures are being put in place, or SHOULD be put in place to stop the spread of this virus?

Dr. Cho: The Government’s rapid-response team (RST) should have activated much earlier. Government should have timely announced the list of hospitals in which MERS cases appeared and should have issued the compulsory order for the closure or partial closure of the few target hospitals much earlier. We realized that there are too few officials who are working for the government as experts in the epidemiology.

Also, the number of efficient Airborne Infection Isolation Room (AIIR) is largely insufficient. The possibility of MERS spread within the patients’ rooms and emergency room might be much higher than we would have expected.

Even though the government and some hospitals didn’t make timely responses, they disclosed the list of 84 hospitals (As of June 20th, 2015) that had MERS cases onset or MERS cases passed by. They also announced the list of 251 safe hospitals so that general citizens and respiratory patients can take the treatment under the safe conditions.

Seoul City authority asked citizens of Seoul to report MERS outbreak to Dasan Call Center (120) or official website of the Seoul metropolitan city. Citizens of other areas can report the outbreak to Korea government’s official website.

Through text messages or phone calls, the Hospital S tried to reach all the people who visited the Hospital S during the periods of high MERS exposure. Most of citizens are now well complying with the government measures.

Since some MERS patients in Korea exhibited symptoms beyond the two-week latency period, local health authorities will maintain a tent at the entrance of the town for more five days with staff to monitor if any villagers show symptoms.

The health authority is monitoring three hospitals intensively ( Hospital G in Seoul, Hospital A in Chungcheong province and Hospital G in Busan) that could possibly become new epicenters for the spread of MERS.

Lablogatory: How should institutions protect laboratory workers? What steps can clinical laboratory scientists take to protect themselves?

Dr. Cho: Information can be found here:“The Guidelines on Diagnostic Testing for MERS.” These guidelines include information about specimen collection, transport, and testing.

Continue reading “MERS Outbreak in the Republic of Korea”

Troubleshooting Complex Instrumentation

When we talk about technological advances in laboratory medicine, the discussion usually focuses on analyzers, methodology, or ancillary equipment that makes testing more accurate or efficient (hello conveyer belts and molecular testing; goodbye bleeding time). While all of those are valid conversations, one component that gets left out of the mix is troubleshooting. After all, an instrument that runs 600 tests an hour is nothing more than a place to put sticky notes if it’s not working properly.

When I first started in the laboratory, “troubleshooting” more often than not meant “put a ‘do not use’ note on the analyzer and call in the service rep.” Unless the fix was something simple (like removing a jammed cartridge), we left it to the professionals. That attitude gradually changed, however. When I left the bench, most of my coworkers thought nothing of “lifting the lid” to change tubing, observing the inner workings of an analyzer as it operated, and repairing an instrument with the assistance of a service rep over the phone. In fact, manufacturers trained us fairly extensively in troubleshooting each time we bought a new analyzer. Thanks to the ubiquity of the internet, it is commonplace for a service rep to remotely take control of an analyzer in order to diagnose and repair software (and even some hardware) issues while offsite.

So what’s next? Videoconferencing software so a service rep can see a malfunction in action, maybe, or virtual reality software that can assist a bench technologist with complex repairs. Maybe even analyzers that diagnose or repair themselves!

What do you think? What is the next innovation in clinical laboratory instrumentation in terms of troubleshooting?

–Kelly Swails, MT(ASCP), is a laboratory professional, recovering microbiologist, and web editor for Lab Medicine.

Biomarkers of Renal Disease

When most laboratory professionals think of tests for renal disease, we think of creatinine and blood urea nitrogen (BUN). These two tests have been considered renal function tests for many years (creatinine for over 100 years), and yet neither is a very good marker of early damage to the kidneys.

Creatinine is a biomarker that really needs individual rather than population-based reference intervals. Each person has a range of creatinine values that are “normal” for them, and that individual range is generally much narrower than the population reference interval. Because the reference interval for creatinine is fairly broad, a person can lose 25 – 50% of their renal function before their creatinine rises out of the reference interval for “normal.” Thus creatinine does not detect early renal damage. BUN is also not great for detecting early acute renal damage. BUN concentrations rise when the kidneys sustain damage, but a rise in BUN is not specific to kidney damage. Other causes can elevate BUN as well, such as starvation and increased protein breakdown or intake. In general, BUN and creatinine provide the most useful information in conjunction with each other, and for trending when significant damage to the kidneys has already occurred.

For these reasons, there is a continuous search for better markers of renal damage, especially markers that indicate early renal damage, when perhaps something can be done to reverse it. Cystatin C is another biomarker that is being increasingly used to assess renal damage, and originally was hoped might outperform creatinine in detecting early renal damage. Cystatin C is a small protein which is freely filtered by the glomerulus and doesn’t have many of the drawbacks of creatinine, such as creatinine’s relationship to muscle mass. Unfortunately, although many studies have been done, cystatin C has not been shown to be better than creatinine at indicating early renal damage, and is considered a renal biomarker with uses similar to creatinine and BUN.

Currently, protein or albumin in the urine, and especially very small amounts of protein/albumin in the urine, is probably the earliest indicator of renal damage that is available in the US. Very small amounts of albumin in the urine, what has been called microalbuminuria, is one of the earliest indicators of renal disease.

A new biomarker for early acute renal damage that is gaining the most widespread acceptance is NGAL. Neutrophil gelatinase-associated lipocalin (NGAL) is being extensively studied and has been shown to detect early, acute kidney injury (AKI). In addition, NGAL levels have been reported to be associated with the amount and severity of renal damage. Already in use clinically in Europe, tests for this biomarker are currently working their way through the FDA in the US.

Some other new biomarkers for AKI that are being studied, but are not progressing toward general usage as quickly as NGAL include kidney injury molecule 1 (KIM-1), β-trace protein, liver-type fatty acid-binding protein (L-FABP) and interleukin-18. These are all proteins that appear to be up-regulated in response to AKI. Studies are on-going to see which of these biomarkers may be useful for detecting early AKI and for differentiating between types and causes of AKI. In addition, for all these new kidney biomarkers, studies are needed on the biomarkers’ efficacy in helping with clinical decision-making regarding treatment options and outcomes. It will be interesting to see if any of them become clinically useful tests for the detection of early acute renal damage.

Computers and Diagnostic Algorithms

As sophisticated as computers are now, isn’t about time we began using them more to help with the diagnosis of disease? Physicians tend to be diagnosticians, and primary care physicians need to have a massive breadth of knowledge these days in order to correctly diagnose the multitude of disorders in patients that may walk through their doors. The same goes for ER physicians. Currently, new doctors are relying more and more on information at their fingertips rather than information remembered. Perhaps relying even more on computers than we already do makes sense. Currently, we routinely use simple computer algorithms in clinical laboratory testing. Things like test results above an AMR causing the computer to direct the instrument to dilute and repeat the assay on that sample before reporting a result. Or diagnostically, a negative monospot test for Epstein Barr Virus (EBV) on a child under 4 years of age can be programmed to automatically order an EBV IgM and IgG, since the utility of the monospot test is unclear in that age group. This sort of “reflex” testing is already in use, and requires no operator intervention.

Here’s an example of a diagnostic approach that could be used: A sick infant comes in to the ED and has blood work run immediately. The initial results show a low pH, low bicarbonate and high pCO2. When a software program sees that combination of results, it could reflexively order more tests based on the differential diagnoses associated with a high anion gap metabolic acidosis (for example, ordering a blood glucose to detect diabetic ketoacidosis). If that is ruled out, the software then looks at the next most common cause of metabolic acidosis, and so on. The computer would not be diagnosing the child; the software would simply be ordering the appropriate next step tests to allow a rapid diagnosis, and probably doing it faster than the average multi-tasking ED doctor.

Software-based diagnostic systems exist and are on the market. So why are we so slow to adopt these systems into everyday use? We should let technology help us as much as we can. Software-based diagnostic systems have not been shown to be better than humans for diagnosing (http://www.nejm.org/doi/full/10.1056/NEJM199406233302506), and may never be. However, I would opine that they are faster than humans at deciding what tests to order based on lab results, or on a combination of lab results and clinical signs and symptoms. Using them this way would then leave the human to human interactions and the final diagnosis to the doctor and his patient when he has all the necessary test results at hand.