Thyroxine; total
CPT4 code
Name of the Procedure
Thyroxine; total
Common name(s): Total T4, Serum thyroxine test
Technical/medical terms: Total thyroxine assay
Summary
The total thyroxine (T4) test measures the level of thyroxine in your blood. Thyroxine is a hormone produced by the thyroid gland, playing a crucial role in regulating metabolism, growth, and development.
Purpose
The total thyroxine test is used to assess thyroid function. It helps diagnose conditions such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). The goal is to determine if the thyroid gland is producing normal, too little, or too much thyroxine.
Indications
- Symptoms of hyperthyroidism: weight loss, rapid heartbeat, anxiety, insomnia
- Symptoms of hypothyroidism: weight gain, fatigue, depression, dry skin
- Routine screening for thyroid function
- Monitoring thyroid hormone levels in patients with known thyroid disorders
Preparation
- No special preparation is typically required.
- Inform your healthcare provider about any medications you are taking, as certain drugs can affect thyroxine levels.
Procedure Description
- A healthcare professional will draw a blood sample from a vein, usually from your arm.
- The blood sample is sent to a laboratory for analysis.
- The lab measures the total amount of thyroxine in your blood, including that which is bound to proteins and the free (unbound) thyroxine.
Duration
The blood draw itself takes only a few minutes. Results are usually available within a few days.
Setting
The procedure is performed in a medical office, clinic, hospital, or laboratory.
Personnel
A phlebotomist or nurse typically performs the blood draw.
Risks and Complications
The risks are minimal and may include:
- Minor bruising at the site of blood draw
- Slight dizziness or fainting
- Rarely, infection at the puncture site
Benefits
- Provides valuable information about thyroid function
- Helps diagnose thyroid disorders
- Assists in monitoring the effectiveness of thyroid disorder treatments
- Generally, results can provide clarity within a few days after the test
Recovery
- No special post-procedure care is required.
- You can resume normal activities immediately after the blood draw.
Alternatives
- Free T4 test: measures only the unbound thyroxine, offering a different perspective on thyroid function.
- Thyroid-stimulating hormone (TSH) test: often used in conjunction with T4 tests to provide a more comprehensive picture of thyroid health.
- Thyroid ultrasound or imaging: used if structural abnormalities in the thyroid are suspected.
Patient Experience
- You may feel a slight pinch when the needle is inserted and possibly some minor discomfort or bruising after the blood draw.
- Generally, the experience is straightforward and quick, and significant pain is uncommon.