Content :
◉ What is TPO test?
The thyroperoxidase antibody TPO test is a diagnostic blood test that measures the level of antibodies directed against thyroid peroxidase (TPO) enzyme.
The TPO is an enzyme that is involved in the production of thyroid hormones.
The anti TPO test can help diagnose autoimmune thyroid diseases, such as Hashimoto's thyroiditis or Graves' disease, which are conditions where the immune system mistakenly attacks the thyroid gland and causes inflammation, swelling, and reduced function.
◉ Why the test is Performed
The main purposes of the TPO test are as follows:
- Diagnosis: The TPO test helps healthcare providers confirm the presence of autoimmune thyroid disorders, particularly Hashimoto's thyroiditis and Graves' disease.
- Differential Diagnosis: The TPO test can assist in differentiating between various thyroid conditions. While TPO antibodies are strongly associated with Hashimoto's thyroiditis, they are not as strongly associated with Graves' disease, another autoimmune disorder that causes excessive production of thyroid hormones.
- Monitoring and Management: The TPO test is useful for monitoring the progression of autoimmune thyroid disorders and their response to treatment.
◉ How can I prepare for the test?
To prepare for the TPO test, you should follow these steps:
- Ask your doctor if you need to stop taking any medications that could affect your thyroid levels, such as thyroid hormone replacement, biotin, or iodine supplements.
- Fast for 8 to 12 hours before the test, unless your doctor tells you otherwise. You can drink water, but avoid coffee, tea, or other beverages that contain caffeine or sugar.
- Go for the test at the same time and in the same manner, that is, fasting or non-fasting, as you did for previous thyroid tests, if any. This will help ensure consistency and comparability of the results.
◉ Normal range
The normal range for the anti-thyroid peroxidase (anti-TPO) test can vary depending on the laboratory conducting the test and the specific assay used.
In general, a normal range for anti-TPO antibodies is typically considered to be below a certain threshold, which is often reported in international units per milliliter (IU/mL) or as a negative result. It is commonly set at around 0-34 IU/ml or as negative.
◉ A positive result on an TPO test
High values of the anti-thyroid peroxidase test results indicate that the body is producing antibodies against the enzyme thyroid peroxidase (TPO). This can cause inflammation and damage to the thyroid gland, leading to autoimmune thyroid disorders, such as Hashimoto's disease or Graves' disease.
2. Causes
Causes of positive results of ANA may be various, encompassing both autoimmune and non-autoimmune diseases. Here are some examples:
- • Genetic factors: Some people may inherit a tendency to develop autoimmune thyroid disorders from their parents or relatives.
- • Environmental factors: Exposure to certain chemicals, infections, stress, or radiation may trigger or worsen the immune system's attack on the thyroid gland.
- • Other autoimmune diseases: Having another autoimmune disease, such as rheumatoid arthritis, or lupus, may increase the risk of developing autoimmune thyroid disorders.
- • Pregnancy: Some women may develop postpartum thyroiditis, a temporary condition that causes inflammation and dysfunction of the thyroid gland after giving birth. This may be due to changes in the immune system during pregnancy and after delivery.
2. Symptoms of Positive TPO test
Some of the symptoms of high anti thyroid peroxidase test results depend on the type and severity of the thyroid disorder. They may include:
Hypothyroidism
- Low levels of thyroid hormones due to reduced function of the thyroid gland.
- Symptoms may include fatigue, weight gain, cold intolerance, dry skin, hair loss, constipation, depression, and menstrual irregularities.
Hyperthyroidism
- High levels of thyroid hormones due to increased function of the thyroid gland.
- Symptoms may include nervousness, weight loss, heat intolerance, sweating, tremors, palpitations, insomnia, and eye problems.
Goiter
- Enlargement of the thyroid gland due to inflammation or overstimulation.
- Symptoms may include difficulty swallowing, breathing, or speaking, and a visible lump in the neck.
◉ Low values of the anti TPO test
2. Causes
- Low values of the anti-thyroid peroxidase test results indicate that there are no or very low levels of antibodies against the enzyme thyroid peroxidase (TPO) in the blood.
- This means that the immune system is not attacking the thyroid gland, which is involved in the production of thyroid hormones.
2. Symptoms
Low values of the TPO test are usually considered normal and do not cause any symptoms or health problems.
Note
- Low values of the anti TPO test do not necessarily rule out the possibility of having a thyroid disorder.
- Some people may have other types of thyroid antibodies, such as thyroglobulin antibodies or thyroid-stimulating immunoglobulin that can also affect the thyroid function and cause inflammation or damage to the gland.
- Therefore, it is important to have a comprehensive evaluation of the thyroid function and structure, which may include other tests.
◉ Additional tests
Some of the related analytical tests to the anti-thyroid peroxidase test are:
- Thyroid-stimulating hormone (TSH) test: This test measures the level of TSH in the blood, which is a hormone that stimulates the thyroid gland to produce thyroid hormones.
- Free thyroxine (FT4) test: This test measures the level of FT4 in the blood, which is the active form of the thyroid hormone T4.
- Free triiodothyronine (FT3) test: This test measures the level of FT3 in the blood, which is the active form of the thyroid hormone T3.
- Thyroid Antibodies Panel: In addition to the anti-TPO test, a thyroid antibodies panel may include other tests such as anti-thyroglobulin antibodies (anti-Tg) and thyroid stimulating immunoglobulin (TSI). These tests help in the diagnosis and differentiation of autoimmune thyroid diseases, such as Hashimoto's thyroiditis and Graves' disease.
- Thyroid ultrasound: This is an imaging test that uses sound waves to create a picture of the thyroid gland and its surrounding tissues. The thyroid ultrasound can help detect the size, shape, and structure of the thyroid gland and identify any abnormalities.
◉ Conclusion
In summary, the anti-thyroid peroxidase test is a valuable tool in the diagnosis and management of autoimmune thyroid disorders. Its ability to detect anti-TPO antibodies aids in confirming the presence of autoimmune thyroid disease, guiding appropriate treatment decisions, and monitoring disease progression.
When used in conjunction with other clinical evaluations and laboratory tests, the anti-TPO test provides valuable information for healthcare professionals in managing patients with thyroid disorders effectively.