What are T4 & T3 Tests, and How Can They Benefit You?

What are T4 and T3 tests?

A test to measure T3 and T4 levels helps your doctor understand how well your thyroid functions. For example, if you have higher than normal levels of these hormones, then your thyroid is overactive, or you have hyperthyroidism. You have an underactive thyroid or hypothyroidism if these levels are abnormally low.

According to UCLA Health , normal total T4 levels in adults should range from 5.0 to 12.0 μg/dL. Normal total T3 levels for adults should range from 80 to 220 ng/dL.

How to know when to get T4 and T3 levels tested

If you are experiencing signs of thyroid issues, then it is probably a good idea to test your thyroid hormone levels. Because thyroid hormones affect your metabolism, abnormalities in these hormones usually manifest as issues with weight, energy levels, and sleep.

Here are some more common signs of thyroid issues:

Signs of hyperthyroidism

• Unexplained weight loss
• Fast heart rate
• Heart palpitations
• High blood pressure
• Nervousness
• Frequent bowel movements
• Muscle weakness
• Hand tremors
• Goiter or enlargement in the neck
• Lighter or shortened menstrual periods

Signs of hypothyroidism

• Fatigue
• Slow mental processing
• Depression
• Sensitivity to cold
• Numbness in the hands
• Constipation
• Heavier than usually menstrual periods
• Dry skin and hair

How can you get tested?

You can get your thyroid hormones tested in three main ways: in-home DIY kit, in-home with a professional nurse, or in-person at a clinic. 

In-home with a DIY kit

You can test your thyroid hormones at home using a DIY test kit. Simply order a test online, collect your samples by following the included instructions, package and ship them, then wait for your results to come back. This is a convenient option but not always the most reliable one.

Pros

• Convenient
• You don’t have to go anywhere to get tested
• Test results are usually back quickly

Cons

• It can be less reliable when testing yourself rather than having a healthcare professional do it.

In-home with a professional nurse

If you don’t want to go anywhere to get your thyroid hormones tested but want to ensure your results are reliable, then you should use an at-home health service. This means a trained professional can come to your home to collect your blood sample.

Pros

• You don’t have to collect your sample yourself
• Get tested in the comfort of your home
• Reliable results

Cons

• You’ll have to schedule your visit and be home for it
• It may take longer to get results back

In person at a clinic

You can also have your thyroid hormones tested in person at a clinic. This will likely yield reliable results, and you don’t have to worry about collecting your blood. However, it does require you to make an appointment, commute to a clinic, and potentially wait to be seen.

Pros

• Reliable results
• You don’t have to collect your blood
• Have your results interpreted by a professional

Cons

• It may take longer to get results back
• You have to take time out of your schedule and drive to a clinic

How much do tests cost?

The cost of thyroid hormone tests varies depending on the method you choose. At-home tests usually cost around $100. If your thyroid hormone test is medically necessary, then it may be covered by your insurance.

How can you treat low T4 and T3 levels (hypothyroidism)?

If your test results come back and you have low levels of T4 and T3, then this means you have hypothyroidism. Hypothyroidism is usually treated with medication, diet, and exercise.

Medication

Hypothyroidism is commonly treated with synthetic thyroid hormones. This medication offers a replacement for the hormones that you are lacking. Figuring out the proper dosage may take some time, and your doctor will want to recheck your thyroid levels a few weeks after you’ve started treatment to determine if you’re taking the right amount.

Diet

There is no set diet for individuals with hypothyroidism, but you’ll generally want to eat a diet high in iodine and limit goitrogenic foods. Goitrogenic foods or goitrogens are foods that inhibit thyroid function and include cruciferous vegetables such as broccoli, cabbage, kale, and cauliflower.

Exercise

Exercise can also help if you have hypothyroidism. Try to incorporate a weekly exercise plan into your routine. If you’ve never worked out, you’ll want to start with slower workouts, such as daily walking.

Treatment options for high T4 and T3 levels (hyperthyroidism)

If you have an overactive thyroid or hyperthyroidism, your T3 and T4 levels are abnormally high. Hyperthyroidism is commonly treated with antithyroid medication, radioactive iodine, and surgery.

Antithyroid medication

The antithyroid medication works to stop the thyroid from functioning. For some people, antithyroid medication is all they need to treat hyperthyroidism.

Radioactive iodine

Radioactive iodine is taken by mouth, and it absorbs into your thyroid. The radioactive substances cause the thyroid gland to shrink, stopping it from being overactive.

Surgery

If you cannot tolerate the other types of treatments or if they do not work, you may need to have all or part of your thyroid surgically removed. Thyroidectomy is a routine surgery many people undergo yearly and is a permanent solution to hyperthyroidism.

Testing T3 and T4 levels can help give you and your doctor a clear idea of what’s going on in your body. Symptoms of a thyroid disorder are uncomfortable, so you’ll want to get them figured out as quickly as possible. Having your thyroid hormones professionally tested can help ensure that your results are accurate and interpreted by a professional.