Total Thyroxine (T4) Blood Test

Also Known As

Total Tetraiodothyronine, Total T4 Concentration, Thyroxine Test by Equilibrium Dialysis, Thyroxine Screening

Purpose of the Total Thyroxine Test

Doctors often request a total T4 blood test to evaluate thyroid health and detect thyroid problems or diseases, like hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid).

What Does the Total T4 Blood Test Measure?

A total thyroxine (T4) test screens from free and bound T4. Free T4 is thyroxine that travels without attaching to any substance as it enters the tissues needing it freely, while bound T4 binds with proteins in the blood.

Most T4 is bound, consisting of 99% of the combined concentration of both thyroxine forms. However, free T4 plays a crucial part in measuring the hormone in its natural state.

Who Should Take a Total Thyroxine (T4) Blood Test?

You should consider taking a T4, total blood test if you show symptoms of hypothyroidism or hyperthyroidism. Observe if you experience the following:

Hypothyroidism Symptoms

• Dry skin
• Brittle nails
• Depression
• Weight gain
• Feeling cold
• Constipation
• Low sex drive
• Body weakness
• Extreme tiredness
• Muscle pain and cramps
• Tingling sensation in extremities

Hyperthyroidism Symptoms

• Anxiety
• Itchiness
• Low libido
• Weight loss
• Chronic fatigue
• Enlarged thyroid
• Sensitivity to heat
• Muscle weakness
• Irregular heartbeat
• Sleeping problems
• Frequent urination

T4 Total Blood Test Preparation

No special preparation is necessary prior to blood sample collection.

Total Thyroxine Test Results

The normal range for total T4 is between 4.5 to 12 ug/dL.

High total T4 test values indicate hyperthyroidism, which can be due to health conditions, such as Grave’s disease, benign (non-cancerous) tumor in the pituitary gland, goiter (enlarged thyroid gland), and thyroiditis (thyroid inflammation).

Whereas total T4 lower than the normal range suggests hypothyroidism. This can be linked to thyroid problems, like Hashimoto’s disease and thyroiditis.

However, the total thyroxine test does not detect these disorders on its own. Other tests have to be taken, so your doctor to make an accurate diagnosis. These tests include the TSH (thyroid-stimulating hormone) blood test, T3, total blood test, iodine test, and other thyroid function blood tests.

You may also be required to have lifestyle adjustments to naturally improve your thyroid functions, alongside any prescribed medication.

Where Can I Get a Total T4 Blood Test Done Near Me?

You can take the thyroxine total blood test without the hassle. Simply follow these steps.

Step 1: Check out the thyroid function tests section on our website to order the total thyroxine test. Download the lab test order, which serves as your doctor’s order.

Step 2: Find a partner medical center using our lab locator.

Step 3: Visit the laboratory you chose to have your blood collected.

Step 4: Expect the lab test results within 2-10 business days in your Personalabs account.

For an exact turnaround time for results, don’t hesitate to get in touch with us at 1-888-438-5227. We will contact the lab of your choice (Quest Diagnostics or LabCorp) as turnaround times vary depending on testing location or lab testing provider.