TSH, T3, T4: What Your Thyroid Test Results Really Mean (A Simple Guide)

Have you ever looked at your thyroid test and thought? What does this even mean?

Let’s be honest. Most of us have been there, staring at thyroid test results full of numbers and medical words that make zero sense.

Your thyroid lab tests are actually the key to understanding why you occasionally feel tired, why your weight is all over the place, or why your mood swings seem to come out of nowhere.

Here is a simple explanation of thyroid lab test results in everyday language.

What Is a Thyroid Blood Test?

Thyroid is a small butterfly-shaped gland located in the front of your neck. A thyroid blood test is a common test that helps check how well your thyroid is working. It looks at three main things:

●      TSH (Thyroid-Stimulating Hormone)

●      T3 (Triiodothyronine)

●      T4 (Thyroxine)

What is TSH?

TSH stands for Thyroid Stimulating Hormone. TSH is made by the brain, and as the name suggests, it stimulates the thyroid gland to produce T3 and T4.

It is controlled by a negative feedback mechanism in our endocrine system, which means:

●      When T3 and T4 levels are too low, more TSH is released by the brain to stimulate thyroid and increase thyroid hormones (T3 and T4) levels.

●      Similarly, high T3 and T4 reduce TSH levels to stop more production of thyroid hormones.

Normal TSH Levels

Every lab has slightly different ranges, but most normal TSH levels fall between 0.4 and 4.0 mIU/L.

What Are T3 and T4?

The T3 and T4 are the main hormones produced by the thyroid gland. T4 is produced in large amounts but stored in the body, while T3 is the active thyroid hormone used by the body for its metabolic activities.

Low T3 and T4

●      Low T3 and T4 usually mean your thyroid is not making enough hormones.

●      You may feel slow, tired, gain weight, and feel cold.

●      This is called hypothyroidism.

High T3 and T4

●      When T3 and T4 levels are high, your thyroid is working too fast.

●      You may feel shaky, lose weight, feel hot all the time, and have trouble sleeping.

●      This is called hyperthyroidism.

Why All Three Tests Matter

If you have symptoms of thyroid dysfunction, your doctor will order a TFT (Thyroid Function Test). It contains levels of all 3 hormones (TSH, T3 and T4) in your body.

Sometimes people only get a TSH test, but it’s better to check all three: TSH, T3, and T4.

Why?

Because thyroid blood tests can sometimes show a normal TSH even when T3 or T4 levels are not right. A full thyroid function test helps doctors have a complete view of the scenario.

When Should You Get a Thyroid Blood Test?

If you:

●      Feel constantly tired

●      Gain or lose weight without clear reason

●      Constant constipation or frequent loose motions

●      Have mood swings or feel anxious

●      Notice changes in your heart rate

●      Have trouble sleeping

●      Feel unusually cold or hot

●      Have menstrual changes or fertility issues

●      Dry, rough, or itchy skin

Don’t Let the Numbers Confuse You

Thyroid function test is not something very complicated. It is a simple test to understand what is going inside your body.

●      TSH value tells you if your brain is making enough TSH to speed up or slow down the thyroid.

●      T3 and T4 tests show how much thyroid hormone is in your blood.

●      A full thyroid lab test helps your doctor figure out the best next step.

Want to start feeling your best? Book a consultation today!