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 one in 3 or 4.
You are more tired than you should be, depressed, feel cold, can't concentrate; are putting on weight, losing hair, constipated, experiencing menstrual problems or infertility, stiff and aching joints.
The thyroid produces several different hormones, which control the pace of our metabolism. Every part of our body needs thyroid hormone to work properly, and our energy output depends on it, that is why we can get so many symptoms when it doesn't 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, whilst not only worsens the effect of low thyroid, but presents 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 under-active thyroid doesn't show up, and you are left tired, ill, and depressed. You need to find out what is wrong with you, so you ask your doctor and he will give you a give you a thyroid function blood test.
You wait in anticipation for 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 are 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" for the rate 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.