Dec 28, 2016

What are the Blood Tests for Thyroid?

thyroid test

Have you ever thought to keep a check on your thyroid levels or ever wondered why it is even necessary? How about getting a blood test for thyroid? Have you observed symptoms such as anxiety, nervousness, hair loss, weight gain, sensitivity to cold, sore and gritty eyes lately? If you answer yes for any of these, then thyroid blood test should be a must in your priority list.

What is Thyroid and what are its functions?

The thyroid gland is a butterfly shaped endocrine gland located at the front of the neck below Adam’s apple. It is basically responsible for the secretion of thyroid hormones which regulates body processes such as respiration, body temperature, pulsation, digestion and almost all the metabolic processes in your body.

Thyroid Gland produces mainly two hormones T3 (triiodothyronine) and T4 (thyroxine) whereas thyroid stimulating hormone (TSH) which is produced by the pituitary gland, monitors the number of hormones secreted.

Working of Thyroid Gland?

The two hormones secreted by thyroid gland in the bloodstream are T3 and T4. T4 which is also known as thyroxine contains four atoms of iodine whereas when it is converted into three atoms of iodine i.e. tri-iodothyronine is known as T3. It is T3 that is biologically active and regulates your body’s metabolism.

The secretion of T3 and T4 is regulated by the pituitary gland present underneath your brain. Through receptors pituitary gland senses the presence of thyroid hormones in the bloodstream. If the level drops below the reference level the pituitary gland gets activated and secrets thyroid-stimulating hormone (TSH) which signals the thyroid gland to secret more T4 whereas if  the thyroid hormone levels rises then the pituitary stops secreting TSH so that the thyroid makes less T4.

Testing of  Thyroid

T4 test, TSH test were the most common blood tests for thyroid. The T4 test is known as the thyroxine test.

The imbalance of T3and T4 leads to two conditions: under production of hormones which leads to Hypothyroidism and over production of hormones which leads to Hyperthyroidism. The general symptoms of Hypothyroidism includes constipation, withered skin, abnormal menstrual cycles, harsh voice, joint and muscle pain, exponential increase in weight, low metabolic rate whereas symptoms of hyperthyroidism are tremendous loss of weight, disruptive sleeping cycles, shivering, reddening of eyes, overactive sweat glands, irregular menstrual cycle.

Blood Test for Thyroid

Available blood test for thyroid includes the T3, T4, and TSH.


The best approach to know the thyroid capacity is to check the TSH level in thyroid test. The low level of TSH in blood test for thyroid indicates that there is excessive production of thyroid hormones (hyperthyroidism) whereas higher level of TSH in thyroid test indicates that there is lower production of thyroid hormones (hypothyroidism).

TSH test is recommended to know the level of production of TSH (thyroid stimulating hormone) secreted by the pituitary gland and balances the production of thyroid hormones.


T4 (thyroxine test) is done to understand if the over production or under production of hormones is due to the imbalance of the pituitary gland or by the gland itself.

T4 is basically present in the blood either bounded to proteins which helps it in entering various tissues which require thyroid hormone or as free T4. Free T4 is most important during thyroid test to understand how the thyroid is working. Combining the results of TSH test with T4 thyroid test helps in precisely deciding how the thyroid gland is working.


T3 test is done to check the level of one more important thyroid hormone (triiodothyronine). In blood test for thyroid T3 tests are important to conclude   hyperthyroidism or to decide the seriousness of the hyperthyroidism. T3 testing is considered important in the hypothyroid tolerant, since it is the last test to wind up distinctly. In few circumstances such as amid pregnancy or while taking conception prevention pills elevated amounts of aggregate T4 and T3 can exist. This is on the grounds that the estrogens increment the level of the coupling proteins. In these circumstances, it is ideal to approach both for TSH and T4 for better thyroid assessment.

Thyroid antibodies

If the results for thyroid test indicates thyroid dysfunction or suspicion of an autoimmune thyroid disease than the probability of prescribing one or more thyroid antibody tests is increased. The primary antibodies are thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and thyroid stimulating hormone receptor antibodies. Standard reference range for thyroid antibodies is not possible as it’s depends upon the wide range of factors.

Thyroid Function Test Normal Values

Most common blood tests for thyroid are TSH, T4 and T3. Blood samples taken usually measures free or active T3 and T4. Thyroid test uses reference ranges to compare the results with the normal healthy population. Reference ranges for healthy thyroid are:

Test       From  To  Units 

TSH        0.4             4.0mU/l (milliunits per litre)

FT4         9.0             25.0pmol/l (picomoles per litre)

FT3         3.5             7.8pmol/l (picomoles per litre)

Blood Test To Manage Thyroid Disorder

The blood test for TSH is used to assure that  your thyroid hormones level is satisfactory and under control. As increased levels of thyroid can adversely affect the cardio system in the long run so it must be under check before it is too late. In case of thyroid cancer efforts are made to keep the patients TSH level below the thyroid function test normal values (usually to 0.1-0.5 mU/L).

In the initial stages of treatment, the blood tests for thyroid are referred every week as to keep a close check on the thyroid levels. In case of hypothyroidism a TSH test will be preferred whereas in hyperthyroidism  TSH test and T4 test are suggested. The frequency of test depends upon the severity aspect of the patient case history.

Measures before thyroid test?

Blood test for thyroid can be influenced either because of medications or illnesses. Thyroid function test normal values can be influenced widely due to some significant reasons:

  • Previously diagnosed with some kind of allergy, liver diseases or a heart attack.
  • Medication used to treat thyroid disorders, especially when taking too much or too little.
  • Ongoing medication such as contraceptive pill, steroid hormones, anticonvulsants, anti-inflammatory drugs etc.

When to have a thyroid test?

You must have a blood test once a year to keep the track of various health issues but in certain special medical cases one must definitely opt for a thyroid test as to keep a check on thyroid levels.

  • Visible symptoms of  thyroid
  • In case of swelling or thickening in the neck
  • In case of variable heart rate
  • In case you are analyzed with high cholesterol levels.
  • If you are already suffering with Osteoporosis.
  • In case of a medical history of fertility problems or irregular menstrual cycles.
  • Family medical history of autoimmune disorders such as type 1diabetes, thyroid.
  • In case you are planning pregnancy and if any of the parents have previously been diagnosed with genetical history of thyroid disorders.
  • If previously you have ever been diagnosed with thyroid disorder.

When A person is prone to thyroid?

  • In case a person is suffering from an autoimmune disease (such as type 1 diabetes).
  • In case a person has a genetic history of thyroid disease or autoimmune diseases.
  • In case you have undergone a thyroid surgery previously or any other thyroid problem like goiter.
  • Intake of iodine either through food or medication is below the desired level.
  • People above 50 years of age are more prone to thyroid especially women.
  • In case of hormonal changes due to pregnancy, childbirth, or menopause.
  • In case a person had used lithium as it is often prescribed in mental disorder or psychological treatments.
  • Having detected with chromosomal abnormalities like down syndrome.

How lifestyle affects thyroid  

There is no substitute than leading a healthy lifestyle if thyroid level didn’t met with the thyroid blood test normal range. By altering the lifestyle and adapting the healthier one you can keep a check on your thyroid levels.

  • Dietary Patterns: Eat small portions of nutrient rich meal throughout the day to keep your energy levels high and maintain a higher metabolic rate. Have bigger portions of fruits, vegetables as losing weight with Hypothyroidism will be a tough task.
  • Getting Physically Active: To burn calories and have a proper physique keep moving. Cardio, strength training, yoga, Zumba – whatever is possible and your body stamina allows you.
  • Relax: Stress can make hypothyroidism worse but by making small changes in your day to day life you can make a bigger impact about how you feel. Meditation, deep breathing or just chilling out to some relaxing music can all help reduce stress and anxiety.
  • Various elements of Health: The motto should be to stay healthy. Focus not only on physical health but also on emotional, mental, physical all the other parameters also.

Blood test for thyroid is the most important way to diagnose and manage thyroid disorders. For a healthy living one must keep the TSH level within the reference range and take proper medication in case of a thyroid disorder, there may be scope to fine-tune your treatment so that you feel better even with thyroid diagnosed.

What are the Blood Tests for Thyroid? was last modified: by

Article Tags:
· · · · · ·
Article Categories:

Comments to What are the Blood Tests for Thyroid?

  • Package price of test including T3 , T4 and TSH

    Priya January 14, 2018 4:23 am

Leave a Comment