What is the Range of Normal Thyroid Stimulating Hormone (TSH) Levels According to Age?

What does Thyroid Stimulating Hormones (TSH) mean?

As the name suggests, Thyroid Stimulating Hormone (TSH) Is the one which produces vital hormones in the body by arousing the thyroid gland. These hormones produced by the thyroid gland are required for the metabolism of the body, like thyroxine. The pituitary gland that is present in the human brain produces it. Further, the TSH also supports other important functions like nerve functions and the maintenance of general energy levels, among others.

Moreover, if the thyroid levels in the body become low, it means that the pituitary gland generates higher TSH levels. Likewise, when the body’s range of thyroid is high, the TSH generated by the pituitary gland is low. So, the problems related to the functioning of the thyroid gland can be identified by the TSH.

What are the Normal TSH Levels in terms of Age?

Your body’s TSH level is monitored in range. So, the normal range of TSH level comes within 0.45 – 4.5 mU/L. However, the normal thyroid levels or TSH in the body also varies depending on the person’s age.

The following table shows the age-wise normal thyroid or normal body TSH levels:

Age Group	TSH Normal range (mU/L)
0 – 4 days	1.6 – 24.3
2 – 20 weeks	0.58 – 5.57
20 weeks – 18 years	0.55 – 5.31
18 – 30 years	0.5 – 4.1
31 – 50 years	0.5 – 4.1
51 – 70 years	0.5 – 4.5
71 – 90 years	0.4 – 5.2

In the case of male, if there is an abnormality in the TSH level such as a low or high TSH, it affects the fertility factor of the person as it produces less sperm formation.

What does it mean if my thyroid levels are abnormal?

The below table will guide you about the various thyroid levels and the conditions they might cause:

Lab Results	Condition
High TSH (low thyroid hormone)	Primary hypothyroidism
High TSH (normal thyroid hormone)	Subclinical hypothyroidism
Low TSH (high thyroid hormone)	Primary hyperthyroidism
Low TSH (normal thyroid hormone)	Early or mild hyperthyroidism
Low TSH followed by High TSH (high thyroid followed by low thyroid)	Thyroiditis (Thyroid Inflammation)
Low TSH (low thyroid hormone)	Pituitary disease

The Level of Normal TSH During Pregnancy

Among women, the level of TSH varies during pregnancy. Here is a table showing the thyroid normal range in female who are pregnant:

Pregnancy stages	Normal range of TSH level (mU/L)
First 3 months (1st trimester)	0.6 – 3.4
Middle 3 months (2nd trimester)	0.37 – 3.6
Last 3 months (3rd trimester)	0.38 – 4.0

A high TSH level during pregnancy might pose a risk of miscarriage among females and hence, it is important to keep a check on the thyroid normal value of women during pregnancy.

What Does a High TSH Level Mean?

When the thyroid normal range chart among women goes beyond 4.5 mU/L, it is regarded as the thyroid gland is underactive and the condition is called hypothyroidism. Generally, women are inclined to have high TSH levels during the time of mensuration, pregnancy and menopause.

Some common symptoms of high TSH level called hypothyroidism are constipation, dry skin, gain in weight, weakness, heavy flow or irregular menstrual cycles, cramps in the muscle, joint pain, thinning of hair, slow rate of heart, brittle nails, Trouble focusing and so on.

What Does a Low TSH Level Mean?

When your body shows low TSH level, it means a hyperactive thyroid gland, which is termed as hyperthyroidism.

Some common symptoms of low TSH level or hyperthyroidism include, increase in appetite, weight loss, palpitations, modifications in menstrual cycle, weakness in muscle, sleep issues, loss of hair or change in the texture of hair, problem with vision, feeling nervous etc.

Patterns of thyroid tests associated with thyroid disease

• Thyroiditis – Thyroiditis is the Thyroid inflammation that causes damage to the thyroid gland. People suffering from thyroiditis may have hyperthyroidism for a short duration followed by getting hypothyroidism.Transient, a form of thyroiditis, is caused due to an infection and may be cured on its own. Thyroiditis caused due to cancer immunotherapy or tyrosine kinase inhibitors may have permanent hypothyroidism. This requires long-term treatment.
• Central Hypothyroidism – A condition of low TSH and a low FT4 results in pituitary disease. This might also cause problems in other pituitary hormones, which require imaging tests to check the pituitary gland. It can be treated by the process of thyroid hormone replacement.Central hypothyroidism may be caused due to pituitary gland disease, pituitary surgery, pituitary inflammation due to autoimmune disease, and cancer immunotherapy.
• Primary Hypothyroidism – It is a condition of high TSH and low thyroid hormone. It occurs when the thyroid gland secretes a very scanty level of thyroid hormone. Some symptoms can be constipation, weight gain, decreased energy, and feeling cold. It may be caused due to:
  • Autoimmune disease like Hashimoto’s thyroiditis
  • Due to some medications like amiodarone, tyrosine kinase inhibitors, etc.
  • for the removal of thyroid gland
  • Any radiation therapy damaging the thyroid
  • Excess use of anti-thyroid medicines

• Primary Hyperthyroidism – A condition characterized by low TSH and high thyroid hormones indicates primary hyperthyroidism. It occurs if the thyroid gland releases excess thyroid hormone. Symptoms that can be seen are palpitations, restlessness, tremors, frequent bowel movements, disturbed sleep, and weight loss due to unknown reasons. Some causes include:
  • Graves’ disease
  • Multinodular goiter
  • Thyroiditis
  • Due to some medicines
  • Excess thyroid hormone therapy

• Other occasional grounds of abnormal thyroid pattern

• • Iodine-induced hyperthyroidism
  • TSH-secreting tumor
  • Germ cell tumors, etc.

Causes of High TSH

If the TSH level is high in a person (above 4.5 mU/L) it means an underactive thyroid, which is commonly known as hypothyroidism. This condition arises when the thyroid gland in your body doesn’t create sufficient thyroid hormones as per the requirement of the body. The connotation of high TSH will vary depending on whether a person is already suffering from thyroid disease or not.

Here are some of the causes:

1. Autoimmune disease – Hashimoto’s disease is an autoimmune condition and the main cause of hypothyroidism. Under this autoimmune condition, the immune system makes antibodies that attack the healthy tissues of your body. This process, at times, involves the thyroid gland and restricts its capacity to produce thyroid hormones.
2. Thyroid surgery – If a person undergoes surgery to remove the thyroid gland or a part of it, it might affect the capacity of the gland to produce thyroid hormones
3. Radiation therapy – If someone undergoes radiation therapy as part of cancer treatment of the head and neck, it may also cause hypothyroidism.
4. Some medicines –Intake of some medicines may also be a cause of Hypothyroidism. Lithium is one such medicine mainly prescribed to cure psychiatric disorders. So, people using the medicine should consult their medical care provider.
5. Birth issues – Sometimes, hypothyroidism is a condition that a baby is born with, while in some cases, some babies are born without a thyroid gland.
6. Pituitary disorder – Failure of the pituitary gland to make enough thyroid hormone is another rare cause of hypothyroidism.
7. Pregnancy – Some females develop hypothyroidism during and after pregnancy. Such conditions may have an adverse effect on the baby and require treatment.
8. Not enough iodine – The thyroid gland makes the thyroid hormones by using iodine. If you have too little iodine or excessive iodine, it may cause issues of hypothyroidism. Excess iodine can even make hypothyroidism worse in people suffering from thyroid.

Causes of Low TSH

When you say a low TSH level, it means a raised level of thyroid hormones in an individual. If the TSH is below 0.4 mU/L, it means a low TSH level. This indicates an overactive thyroid, which is commonly known as hyperthyroidism. Under this condition, your body is creating an excess amount of thyroid hormone than required.

Here are some of the causes:

1. Graves’ disease – An autoimmune condition called Graves’ disease is a primary cause of hyperthyroidism. Under this condition, the immune system attacks the thyroid gland and prompts it to produce excess thyroid hormone.
2. Overactive thyroid nodules. Also called toxic multinodular goiter, Plummer disease, or toxic adenoma, this condition occurs when a thyroid adenoma generates enough of thyroid hormone. An adenoma forms noncancerous lumps, which makes the thyroid increase in size than usual.
3. Thyroiditis – If the thyroid gland inflames, this condition takes place. For some people, it may be due to an autoimmune disorder. For others, the reason may not be clear. Due to inflammation, extra thyroid hormone leaks into the bloodstream causing hyperthyroidism.