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TSH Range

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Confused about your recent thyroid test? Here is some information on TSH range.

The Thyroid Stimulating Hormone (TSH) plays a very vital role in our bodies – and is just as important as the thyroid hormones in the body. The TSH or thyrotropin does not come from the thyroid itself but is instead secreted by the pituitary gland. Once it is secreted, the thyrotropin makes its way to the thyroid gland, where its receptors are located. Once the hormones attach to its receptors, it stimulates the thyroid gland to synthesize and release thyroid hormones.

There are plenty of preconceived notions about the Thyroid Stimulating Hormone, especially when it comes to TSH levels.

TSH and The Thyroid

To understand how thyrotropin affects the thyroid and the whole body, it’s important to take a look at the thyroid first. First off, what’s the thyroid, and what stimulates it?

The thyroid gland is a butterfly-shaped gland that is located on the front lower part of the neck, just underneath a person's Adam’s apple. The thyroid gland has a bridge in the middle part that unites two side lobes.

The function of the thyroid gland is that it produces thyroid hormones that regulate the growth of the body and the body’s metabolism. Its function is also like a thermostat which controls the consumption of energy in the body as well as its temperature.

However, the thyroid gland does not work alone. Its function is regulated by another type of hormone – the thyroid-stimulating hormone or TSH, which is secreted by the pituitary gland.

Because the TSH regulates thyroid function, the TSH levels in the body may cause the thyroid to act normally or become overactive or underactive.

With that, the TSH level is very important, since it regulates the function of the thyroid gland, which in turn affects numerous functions of the body.

Problems Caused By Low or High TSH Levels

There can be complications in the body if the person has imbalanced TSH levels. This may lead to hypothyroidism or hyperthyroidism.

Hypothyroidism occurs when the thyroid does not produce enough T3 and T4 hormones. This means that the thyroid is underactive, which may lead to energy loss and lethargy. The body may also experience changes, such as dry skin and brittle, dull hair.

The person who is experiencing hypothyroidism may also have difficulty in losing weight. It may also affect the body’s reproductive system. Men run the risk of infertility and high cholesterol. On the other hand, women may have chances of birth defects or miscarriage.  

Hyperthyroidism is the state in which the thyroid gland is overactive and produces too much T3 and T4 hormones. Having too much thyroid hormones in the body is just as bad as having too little thyroid hormones – as it may cause a barrage of ill effects as well. An individual suffering from hyperthyroidism may experience restlessness, hyperactivity, anxiety, irritability, and palpitations and may have a high risk of developing a goiter.

Diagnosis of TSH Levels

If a person shows symptoms of a thyroid disorder, his or her doctor will most likely require a TSH test. The TSH test determines the level of TSH in the body, as well as T3 and T4 hormone levels too. It is the best way to know if one has a thyroid problem.

The TSH Levels Test is used to:

  • Identify if the person has a thyroid disorder, such as hypothyroidism or hyperthyroidism, especially if the person has shown symptoms of either beforehand
  • Monitor children with possible thyroid disorders
  • Keep track of the effects of thyroid replacement therapy in people who have hypothyroidism

Normal and Abnormal Test Results

Although various professional health bodies have specified the normal range for TSH to be 0.4 - 4.5 mIU/L in the past, new regulations recognize that this range is too wide.

Currently, the standard reference range for TSH is 0.4 - 3.0 mIU/L. However, clinical data show that 95% of euthyroid patients fall in the range of 0.4 - 2.5 mIU/L. Also, adults with TSH levels over 2.0 mIU/L are likely to develop hypothyroidism later in life.

Therefore, the ideal range of TSH is 0.4 - 2.0 mIU/L.

Children, generally, have higher TSH levels than adults. The National Academy of Clinical Biochemistry recommends 1.3 - 19 mUI/L for newborns. These values drop with age and by the first year, the TSH level for an infant should be between 0.4 mIU/L and 7 mIU/L. 

Once TSH levels are measured, the results are then interpreted as the following:

Interpretation of Test Results
TSH (high), T4 (normal), T3 (normal) = Mild Hypothyroidism
TSH (high), T4 (low), T3 (low/normal) = Hypothyroidism

TSH (low), T4 (normal), T3 (Normal) = Mild Hyperthyroidism

TSH (low), T4 (High/Normal), T3 (High/Normal) = Hyperthyroidism
TSH (low), T4 (low/normal), T3 (low/normal) = Non-thyroidal illness or rare pituitary hypothyroidism

Treatment of High and Low TSH Levels

The results of the TSH test will be interpreted by the doctor, and this will be the basis for choosing the right treatment. If a person is found to suffer from hypothyroidism, he may be prescribed with hormonal replacement. For cases of hyperthyroidism, the doctor may recommend thyroid hormone-blocking drugs or radioactive iodine treatment.

The doctor will choose the right medication and dose to make sure that the condition is fully managed.

Next Article: Thyroid Health | How to Boost T3 and T4 Levels