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EXPLANATION ABOUT NORMAL REFERENCE RANGES

AN EXPLANATION ABOUT THE NORMAL REFERENCE RANGES OF THYROID FUNCTION BLOOD TESTS AND WHAT THEY MEAN

You can be born with a weak thyroid; it can attack you as a young adult, in the prime of your life or in your mature years. The risk is about 1 in 3 or 4.

You are more tired than you should be, depressed, feel cold, and cant control the pace of your metabolism. Every part of our body needs thyroid hormone to work properly and our energy output depends on it, which is why we can get so many symptoms when it doesnt work properly. (It can, much less commonly, overact; then we get thin and shaky and hot). Having a low metabolism from a thyroid winding down has other effects. One is that the urinary system runs down too, so that you are more likely to get infections, and less able to fight cancer; your adrenals which fight stress, also weaken, which not only worsens the effect of low thyroid, but prevents the treatment working properly.

Most doctors can quite easily diagnose it from your story and a simple examination; but it can be terribly wrong when only blood tests are done more than half the time, an underactive thyroid doesnt show up, and you are left tired, ill and depressed. You need to find out what is wrong with you, so ask your doctor and s/he will give you a thyroid function blood test.

You wait in anticipation of the results and then your doctor will probably tell you your test was out of the normal range handing you a sheet of paper showing a set of test results and numbers. Your heart races in fear that you are really sick.

What does this statement mean? Should you be concerned? The simple answer is that any blood test results out of the normal reference range are a signal that further investigation should be taken.

Test results all medical data can only be understood once all the pieces can be put together. One of the simplest medical indicators of all is your heart rate. You can take your resting heart rate right now, by placing your fingers lightly on your pulse and counting the beats for one minute. Most of us know that the average heart rate is about 70 beats per minute. How do you know what a normal heart rate is? We know this on the basis of taking the pulse rate of millions of people over time.

You probably also know that if you do regular exercise or are otherwise in good physical shape, your pulse rate could be considerably lower so a pulse rate of 55 could also be normal. Say you walk up a hill your heart rate is now 120 beats a minute. That would be high for a resting heart rate but normal during this kind of activity.

Your heart rate, like any medical observation, must be considered in context. Without the proper context, any observation or test result is absolutely meaningless. To understand what is normal for you, your doctor must know what is the normal heart rate of most other people of your age, and what activity you are doing at the time or just before your heart rate is measured.

The interpretation of any clinical laboratory test involves an important concept in comparing the patients results to the tests reference range. It is also commonly called the normal range but today, reference range is considered a more descriptive term.

Some tests provide a simple yes or no answer. Was the culture positive for strep. throat? Did the test find antibodies to a virus that indicates an infection?

But for many more tests, the meaning of the results depends on their context. A typical lab report will have your results, followed by normal or reference range. For example, your results for your thyroid stimulating hormone (TSH) test might look something like: 2.0 m-IU/L, ref. range 0.5 5.0m-IU/L. Such a test result indicates that it falls within the normal range.

How was the reference range established? The short answer is, by testing a large number of apparently healthy people and observing what appears to be normal for them.

The first step in determining a given reference range is to define the population to which the reference range will apply, for example, healthy females between 20 and 30 years old. A large number of individuals from this category would be tested for a specific laboratory test. The results would be averaged and a range (plus or minus two standard deviations of the average) of normal values would be established.

The term reference range is preferred over normal range because the reference population can be clearly defined. Rather than implying that the test results are being compared with some ill defined concept of normal, the reference range means the results are being considered in the most relevant context. When you examine test results from different populations, you quickly discover that what is normal for one group is not necessarily normal for another group. For example, pregnancy changes many aspects of the bodys chemistry, so pregnant women have their own set of reference ranges.

This is the problem we Thyroidians and CFS ME FM folk, along with others with chronic illnesses, are being tested against a reference range that was established for a group of normal people. People who were healthy at that time didnt have any health issues. A new reference range must be established especially for sufferers showing the unexplained symptoms which most of us are presenting with.

To stop all the confusion and misdiagnosis (OR NO DIAGNOSIS IN TENS OF THOUSANDS OF CASES) that come from lack of correct interpretation, everybody should have their thyroid levels checked automatically to see what their normal reference range is when they are, say, a healthy 18 year old. Then when they present with unexplained symptoms, blood tests would then be a fairer comparison.

By not being correctly diagnosed and treated, if we have a low metabolism from our thyroid winding down we suffer other effects. One is that our urinary system runs down, so that we are more likely to get infections and less able to fight cancer; our adrenals which fight stress also weaken, which not only worsens the effect of low thyroid, but prevents any treatment from working properly.

NEVER accept that if your test results fall within the so called normal reference ranges that your health is normal and that you dont have a thyroid problem, whatever your doctor might tell you. Your doctor should give you a thorough clinical examination and address all of the symptoms and signs you are presenting with. If any of your tests show your levels are at the bottom or near the top of the range ask for a referral for a second opinion, preferably to an endocrinologist who has a specialty in thyroid disease, rather than diabetes.

Always ask your doctor for a copy of all your blood test results together with the reference range for each test done. If you are a member of the TPA Internet Thyroid Support Forum post these results on the Message Board so others can help with their interpretation.

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