Thyroid Levels – What You Really Need To Know?

Learn about normal levels of thyroid hormones. These hormones are primarily responsible for metabolism regulation.

The thyroid is a gland shaped like a butterfly found in the neck. Its primary function is to produce hormones that control how the body uses energy. There are two most common types of thyroid problems which are hypothyroidism and hyperthyroidism.

Thyroid Levels – What You Really Need To Know?
Levels of thyroid hormones

Hypothyroidism is when the thyroid is producing low levels of hormones. On the other hand, hyperthyroidism is when the thyroid produces high levels of hormones. Both problems can be harmful and can cause a range of symptoms like unexplained weight changes, fatigue, anxiety and depression.

In this article, we will be taking a look at the normal levels of thyroid hormones to help you determine if you have hypothyroidism or hyperthyroidism.

The Meaning of Thyroid Levels

The most common question is regarding the normal thyroid level range. The thyroid produces two types of hormones which are T3 and T4. These hormones are primarily for the regulation of metabolism. The levels of these hormones are directly connected to another hormone called thyroid stimulating hormone (TSH) which is secreted by the pituitary gland.

TSH is responsible for stimulating the secretion of T3 and T4. When the TSH level increases, this may be an indication that the thyroid gland is not working normally which may indicate hypothyroidism. When it decreases, it may be an indication that the thyroid gland is producing too much T3 and T4.

Normal TSH Level

There are different scales for TSH levels. For instance, the normal level for TSH in the United Kingdom is 0.5 to 5.5 and the United States used the same scale until 2003. The normal levels in the United States were changed to 0.3 to 3.3 which is believed to be more accurate according to the Society of Endocrinologists.

Take note that TSH levels fluctuate throughout the day reaching its peak at night time. However, most doctors suggest having the blood test in the morning and the patient may be asked to fast.

Normal T3 Level

There is only a very small level of T3 in the body but it is crucial when it comes to regulating metabolism. The normal level for total T3 in is from 80 to 220. When it is below 80, this may indicate an underactive thyroid and anything above 220 may indicate an overactive thyroid. There are specific levels for particular age groups.

Normal T4 Level

T4 is transported from the thyroid through the bloodstream towards the liver where it is converted into T3. The normal level for total T4 is from 4.5 to 12.5. If the level of a patient is outside the normal range then it is likely that he/she is suffering from a form of thyroid disorder.

How Do Thyroid Levels Affect Your Health?

Abnormal thyroid levels can have many negative effects on your health. For instance, if you have an underactive thyroid (hypothyroidism) you can suffer from a range of symptoms including fatigue, constipation, unexplained weight gain, high cholesterol and depression.

When left untreated, hypothyroidism can lead to more severe conditions like myxedema which can even be fatal. The symptoms of hyperthyroidism or an overactive thyroid include fatigue, muscle weakness, rapid heartbeat, irregular heartbeat and trouble sleeping.

Thyroid Disorders and Pregnancy

Thyroid disorders are common in adult women and it can complicate pregnancy. During pregnancy, thyroid disorders can affect both the mother and baby. According to experts, there is a direct link between mothers affected with hypothyroidism during pregnancy and the delay of development in their children after they are born. Early studies also indicate that children of mothers with hypothyroidism during pregnancy had impaired psychomotor development and lower IQ.

The most common cause of hypothyroidism is iodine deficiency which is the reason it is a common problem in iodine-deficient areas of the country. However, with proper treatment which involves increasing the amount of thyroid hormone, women who have hypothyroidism can have babies that are unaffected.

The treatment is simple wherein synthetic T4 is given in order to make up for the deficiency of the hormone. Nonetheless, close monitoring of TSH by a physician or specialist is crucial throughout the pregnancy.


If you are suffering from some of the common symptoms of thyroid disorders like unexplained weight gain/loss, fatigue, anxiety, depression and low energy levels, you need to get your thyroid hormone levels checked. You may be suffering from a thyroid disorder which can affect your overall health and well-being.

The levels in this article can guide you and help determine if you have a thyroid problem. If you have low or high levels of thyroid hormones, you need to consult your healthcare provider for the appropriate treatment.

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Sam Kramer is a Registered Dietitian, Licensed Dietitian Nutritionist, Six Sigma Green Belt Certified, and Certified Sports Nutritionis

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