Diagnosis of Hypothyroidism

Potential Dangers of Hypothyroidism

Because the body is expecting a certain amount of thyroid hormone the pituitary will make additional thyroid-stimulating-hormone (TSH) in an attempt to entice the thyroid to produce more hormone. This constant bombardment with high levels of TSH may cause the thyroid gland to become enlarged and form a goiter (termed a "compensatory goiter"). Our goiter page goes into this topic in detail, and outlines that a deficiency of thyroid hormone is a common cause of goiter formation. Left untreated, the symptoms of hypothyroidism will usually progress. Rarely, complications can result in severe life-threatening depression, heart failure or coma.

Hypothyroidism can often be diagnosed with a simple blood test. In some persons, however, its not so simple and more detailed tests are needed. Most importantly, a good relationship with a good endocrinologist will almost surely be needed.

Hypothyroidism is completely treatable in many patients simply by taking a small pill once a day! Once again, however, we have made a simplified statement and its not always so easy. There are several types of thyroid hormone preparations and one type of medicine will not be the best therapy for all patients. Many factors will go into the treatment of hypothyroidism and it is different for everybody.

Diagnosis of Hypothyroidism

Since hypothyroidism is caused by too little thyroid hormone secreted by the thyroid, the diagnosis of hypothyroidism is based almost exclusively upon measuring the amount of thyroid hormone in the blood. There are normal ranges for all thyroid hormones which have been calculated by computers which measured these hormones in tens of thousands of people. If your thyroid hormone levels fall below the normal range, that is consistent with hypothyroidism These tests are very accurate and reliable and are so routine that they are available to everybody.

REMEMBER

hypo = too little

thyroidism = disease of the thyroid

Thus, hypo-thyroidism = a disease of too little thyroid activity

The idea is to measure blood levels of T4 and TSH.

In the typical person with an under-active thyroid gland, the blood level of T4 (the main thyroid hormone) will be low, while the TSH level will be high. This means that the thyroid is not making enough hormone and the pituitary recognizes it and is responding appropriately by making more Thyroid Stimulating Hormone (TSH) in an attempt to force more hormone production out of the thyroid. In the more rare case of hypothyroidism due to pituitary failure, the thyroid hormone T4 will be low, but the TSH level will also be low. The thyroid is behaving "appropriately" under these conditions because it can only make hormone in response to TSH signals from the pituitary. Since the pituitary is not making enough TSH, then the thyroid will never make enough T4. The real question in this situation is what is wrong with the pituitary? But in the typical and most common form of hypothyroidism, the main thyroid hormone T4 is low, and the TSH level is high.
The next question is: When is low too low, and when is high too high? Blood levels have "normal" ranges, but other factors need to be taken into account as well, such as the presence or absence of symptoms. You should discuss your levels with your doctor so you can interpret how they are helping (or not?) fix your problems.

Oh, if only it were this simple all the time!

Although the majority of individuals with hypothyroidism will be easy to diagnose with these simple blood tests, many millions will have this disease in mild to moderate forms which are more difficult to diagnose. The solution for these people is more complex and this is due to several factors. First we must realize that not all patients with hypothyroidism are the same. There are many degrees of this disease from very severe to very mild. Additionally, and very importantly, we cannot always predict just how bad (or good) an individual patient will feel just by examining his/her thyroid hormone levels. In other words, some patients with very "mild" deviations in their thyroid laboratory test results will feel just fine while others will be quite symptomatic. The degree of thyroid hormone abnormalities often, but NOT ALWAYS will correlate with the degree of symptoms. It is important for both you and your physician to keep this in mind since the goal is not necessarily to make the lab tests go into the normal range, but to make you feel better as well! We must also keep in mind that even the "normal" thyroid hormone levels in the blood have a fairly large range, so even if a patient is in the "normal" range, it may not be the normal level for them.

For the majority of patients with hypothyroidism, taking some form of thyroid hormone replacement (synthetic or natural, pill or liquid, etc) will make the "thyroid function tests" return to the normal range, AND, this is accompanied by a general improvement in symptoms making the patient feel better. This does not happen to all individuals, however, and for these patients it is very important to find an endocrinologist who will listen and be sympathetic. (We aim to help you find this type of doctor.) Because most patients will be improved (or made completely better) when sufficient thyroid hormone is provided on a daily basis to make the hormone levels in the blood come into the normal range, physicians will often will rely on test results to determine when a patient is on the appropriate dose and therefore doing well. Remember, these tests have a wide normal range.

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