TSH or thyroid stimulating hormone is a hormone produced in the anterior pituitary gland. This is used to help stimulate the thyroid to produce triiodothyronine (T3) or thyroxine (T4), hormones that help stimulate the metabolism. If your pituitary gland is producing TSH trying to stimulate the thyroid but the thyroid does not respond, it can result in high TSH level in the bloodstream. This can be caused by stress, illness, an obstruction or surgery causing the thyroid to malfunction or be sluggish.

What Is a TSH Test?

A TSH test is a lab test that analyzes your blood to determine the body's overall TSH levels. If you begin to show signs of a malfunctioning thyroid, your doctor my order a test to check for the TSH levels in your system. If the resutls show a high level of TSH, you may have a sluggish thyroid, but low levels of TSH signal that your thyroid may be overactive.

During a TSH test, your doctor will take a blood sample to check the hormone levels. A needle will be placed in a sterilized are of your arm, then attached to a tube to collect the blood. After this is finished, the needle is removed and you will be asked to put pressure and a bandage on the site to stop the bleeding. In some cases, an elastic band may be placed around the arm to make it easier to collect the blood. You should not feel a great deal of pain from the elastic band or the needle, though you may develop a bruise at the injection site.

Your doctor will be focusing on the two hormones that control the metabolism, triiodothyronine (T3) and thyroxine (T4). Results of the TSH test are typically available 2-3 days after the test is given. If you have high TSH or low TSH, your doctor will explain what may be going wrong and what you can do treat this condition.

What is the Normal Range of TSH?

There are a range of levels that your TSH levels can be. Learning what these levels mean will help you work with your doctor to address your condition adequately.

• Normal TSH - Adults should have TSH hormone levels that range from 0.4-4.2 mU/L. This indicates that the signals from your pituitary gland match the activity of your thyroid gland. Your doctor will use this hormone level alongside the other signals and side affects you may be showing to determine if there is an underlying health issue at hand.
• Low TSH - Low TSH levels can be a sign that you are dealing with an overactive thyroid gland from conditions such as goiter, noncancerous tumors or Graves's disease. The thyroid may also become overactive during the first trimester of pregnancy. If you are already being treated for thyroid issues, you may develop low TSH levels if you are taking too much thyroid medication. If you are not showing signs of overactive thyroid, you may have damaged the pituitary gland, causing it to produce less TSH.
• High TSH - High levels of TSH are typically caused by an underactive thyroid or hypothyroidism. This is typically caused by Hashimoto's thyroiditis. If you are already being treated for a thyroid disorder this can be a sign that you need to increase your medication. In rare cases, you may be showing high than normal TSH levels because you have developed a tumor that is causing the pituitary gland to over-produce TSH.

Conditions That Cause TSH Level High 

Once it is determined that you have excessive levels of TSH in your system, your doctor will start narrowing down what is causing the trouble.

• Hypothyroidism - Hypothyroidism is a condition that is defined by your body failing to produce enough hormones to adequately manage your metabolism. Patients suffering from this condition will typically experience dry skin, increased sensitivity to cold, thinning hear, impaired memory, muscle aches, puffy face, unexplained weight gain, constipation, fatigue, hoarseness, elevated cholesterol, irregular menstrual periods or depression. A number of circumstances such as surgery, taking psychiatric medications, radiation therapy or an autoimmune disease can lead to this condition. Hypothyroidism is typically managed with medication that will artificially replace these hormones.
• Pituitary Tumors - In rare cases, excessive high TSH levels are a sign that your pituitary gland is not functioning properly. In some cases this is because a group of cells has begun to grow on top of the gland. In most cases these tumors are not cancerous, but they can cause interference in your bodily functions that can lead to other negative side effects which could be dangerous to the body. The overproduction of TSH can lead to an overactive thyroid.
• Thyroid Disorder - Thyroid disorders such as enlarged thyroid gland, cancer or abnormal hormone production can cause the thyroid to function poorly. Some of these conditions are harmless, but many will require medical intervention to avoid unpleasant side effects such as a sluggish metabolism that will lead to damage throughout the body.