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Test Results 101: Understanding Normal

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Everybody gets their blood test results back in a haze of unreadable numbers and words. For all the cost, you'd think that the labs would invest in some decent printers, a legible font and maybe even a decently designed graphic (or two) -- [more on this to follow]. There is no reason that any person who can successfully navigate a newspaper or website should have trouble reading the results of a blood test panel.

To begin: what the hell is 'normal'??

as a good friend always reminds me:

there is no such thing as normal

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I'd be interested in hearing more. :)

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There is a ton of QC done in the lab, and there is not as much variability as one might think. Proficiency tests are frequently done in which samples of unknown concentrations are sent to the lab and the results the lab gets must be within a certain range of the absolute value of the samples. QC is done with each new reagent lot and also with each instrument run. Certain reagents like UA test strips, antibodies, and enzymes have QC performed at the beginning of each shift. Labs are very careful to complete these practices, as they will have many problems with the joint commission, CAP, etc if they fail to comply and they would be at risk of losing their certification/accreditation. There are also defined criteria for tests (like what constitutes a 4+ white blood cell count on a specimen site slide), so they leave very little up for interpretation. Labs work very hard to ensure that their results are accurate and precise.

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17 years old

I went on a gluten free diet before my blood test ( I was so far about 2 weeks gluten free). I got a phone call from the doctor ( after my mom question the hospital if results have came back since I've been concern about it) stating that the results were normal. My next appointment, my doctor was absent due to her plane arrival late in New York, the nurse remention the test results after overlooking my profile... when I ask could I review the results, she refused and the nurse and my mom explain that it was normal. I don't understand why I can't see the results, as I've told my mom that your usually allowed to see test results done on your blood. Reasons?

Well I'm about 90% sure I'm gluten intolerance, and I also think there is something wrong with my thyroid. I have all plus more symptoms of thyroid problems, along with coarse hair, skin condition around neck, dehydration, throat clicking (sometimes, but can easily make this clicking noise with my throat), neck pain/ stiffness and more....

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This week I learned that it also pays to know which tests can be a little abnormal and still "no big deal" and which ones are a big deal when they go out of range. For example... if your liver enzymes are elevated a few points, no big deal. Once creatinine and BUN go out of range it means your kidneys are functioning at less than 40% capacity... stage 3 kidney disease (stage 5 means you need dialysis or a transplant). The reason the ranges are so wide is because mild kidney disease is pretty common in this country, thanks to the the high rates of diabetes, high blood pressure, and autoimmune disorders. Just being one or two standard deviations away from the norm doesn't always mean you're safe! Not everything fits into a neat little statistical bell curve where 90% of people are "normal" and the other 10% are not.

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There is a ton of QC done in the lab, and there is not as much variability as one might think. Proficiency tests are frequently done in which samples of unknown concentrations are sent to the lab and the results the lab gets must be within a certain range of the absolute value of the samples. QC is done with each new reagent lot and also with each instrument run. Certain reagents like UA test strips, antibodies, and enzymes have QC performed at the beginning of each shift. Labs are very careful to complete these practices, as they will have many problems with the joint commission, CAP, etc if they fail to comply and they would be at risk of losing their certification/accreditation. There are also defined criteria for tests (like what constitutes a 4+ white blood cell count on a specimen site slide), so they leave very little up for interpretation. Labs work very hard to ensure that their results are accurate and precise.

absolutely.

way back; when i was helping to develop an analytical/clinical lab for hoffman-laroche (to assay dinosaur blood samples.... ) the linear portion of the standard curve had to have an R^2 value of 0.9999 (as in 99.99%). techniques have gotten better since the abacus, and using modern QC, the PRECISION of the assays might be 10-100 times better than that. the big 'BUT' in the room (ok, another bad joke i'll leave for another time) is that while the chemistry works, it is the biology that provides the variation.

there is no getting around statistical distributions.

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This week I learned that it also pays to know which tests can be a little abnormal and still "no big deal" and which ones are a big deal when they go out of range. For example... if your liver enzymes are elevated a few points, no big deal. Once creatinine and BUN go out of range it means your kidneys are functioning at less than 40% capacity... stage 3 kidney disease (stage 5 means you need dialysis or a transplant). The reason the ranges are so wide is because mild kidney disease is pretty common in this country, thanks to the the high rates of diabetes, high blood pressure, and autoimmune disorders. Just being one or two standard deviations away from the norm doesn't always mean you're safe! Not everything fits into a neat little statistical bell curve where 90% of people are "normal" and the other 10% are not.

yes indeed. the biology is certainly the fun part!

based on my (very loose) plan for these little posts, i hope to discuss your last 2 statements in post #3. clinical labs and diagnosis have a very cozy, yet (imho) uncomfortable relationship. on the one hand, doctors make diagnoses based on the normal curve. yet for the individual being tested they are either sick or not. and, as we've all learned on the 'celiac bus', being sick and misdiagnosed stinks.

i certainly hope your 'learning' experience was not too painful and that you are well.

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i certainly hope your 'learning' experience was not too painful and that you are well.

Yes. Thankfully I learned this lesson while my labs were still "normal." In a couple of weeks I'm having some more tests to figure out if the persistent protein and leukocytes in my urine are truly "no big deal" or something to watch carefully. Meanwhile... I'm feeling pretty good :) Doing my best not to end up on the "sick and misdiagnosed" wagon again.

I look forward to your upcoming posts!

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