The following is a guest post by Jason MacDonald.
Is all laboratory testing the same?
The simple answer is no, the testing can be vastly different.
Many people believe that just because one lab offers a Total T4 test, they can go to any lab that offers the same Total T4 test and get a similar result. They are wrong. There are a number of methods that can be used to run the test and many different pieces of equipment, all of which are factors in the final result. Chemiluminescence and Radio Immuno Assay (RIA), are the more common methods used to test Total T4.
The age of the chemicals used and how frequently calibrations are performed are additional factors. If you a use a reagent that is older, the sensitivity and accuracy of the reagent will be diminished. If the machine has not been calibrated to the reagent in a while, again you will not get accurate results.
Some laboratories will offer a modified version of a test and label it incorrectly as if it is the same thing.
University of Tennessee offers a profile that has some similarities, but they do not offer a Total Estrogen. They offer many components of Estrogen, but when compared to a Total Estrogen, these can fall short as they may not be identifying the portion of Estrogen that is abnormal. We have seen several cases where a sample has been submitted to both and the results that they get back from University of Tennessee are normal for their ranges even though there are significant clinical symptoms, while the results that we get, often identify the underlying abnormality. I am not saying that they are doing poor work...quite the contrary, from my observations, their work appears quite accurate. But in identifying the endocrine & immune issues that we look for, I feel that their testing is incomplete.
The Total Estrogen test that we perform is custom produced for us, as is the Immunoglobulins. We are the only ones who perform these tests using the reagents and methods that we do. There is no manufactured kit available to the public for the Total Estrogen. There is another company that does manufacture some Immunoglobulin kits, but I believe they are for use within their own laboratory and not available for sale. Since these kits are custom made for us exclusively, the reference ranges we use for them are not comparable with any other laboratory out there.
The Total T3, Total T4 & Cortisol tests are commercially available. The reference ranges we use for these test are based on more than 25,000 tests performed over 30+ years, comparing clinically normal patients and clinically abnormal ones.
When we perform our testing, we calibrate every test at the beginning of our run. We also run controls before the first sample and after the last sample, as well as after every 10 patients. When we evaluate the controls, we do not want them to be barely within the range, we want them as close to the middle as possible. If I am not happy with them, I will evaluate the reason the results were not in the middle, re-calibrate and run the controls again until I am happy.
We have also found that some of the tests are sensitive to temperature. The Total Estrogen is very susceptible to fluctuations in temperatures. When we receive a sample, we pre-process it and place it in a -80 degree C freezer until we are ready to perform the actual testing. When we are ready to start the testing, the samples are gently thawed and brought to 60 degrees F. Once set up, they unused portion goes back into the deep freeze.
Keep in mind that the quality of the results that we get are only as good as the quality of the sample that is provided. We provide a guide on our website that will assist the practitioner in getting a good quality sample.
Jason MacDonald, MLT
National Veterinary Diagnostic Services, LLC
26856 Clark Road
Waller, TX 77484