ATAB – Anti-Thyroid Antibodies (Includes TPO and ATA)
Sample Type: Serum / Cerebrospinal Fluid (CSF)
Also Known As: Anti-TPO, Anti-Tg, Anti-thyroid peroxidase antibodies, Anti-thyroglobulin antibodies

Overview:
Anti-thyroid antibodies (ATAB) are autoantibodies produced by the immune system that mistakenly target and attack components of the thyroid gland. The most commonly measured anti-thyroid antibodies are:

Anti-TPO (Thyroid Peroxidase Antibodies): Targets the TPO enzyme, essential for thyroid hormone production.

Anti-Tg (Thyroglobulin Antibodies): Targets thyroglobulin, a precursor to thyroid hormones.

Occasionally, other thyroid-related antibodies (e.g., TSH receptor antibodies) may also be included in extended panels.

These antibodies are important markers for diagnosing and monitoring autoimmune thyroid diseases.

Purpose of the Test:
The ATAB test is used to:

Diagnose autoimmune thyroid disorders, including:

Hashimoto’s thyroiditis

Graves’ disease

Investigate unexplained hypothyroidism or hyperthyroidism

Assess risk of thyroid dysfunction in individuals with other autoimmune conditions

Evaluate neurological symptoms suggestive of autoimmune encephalopathy (using CSF sample)

Monitor pregnancy-related thyroid risk in autoimmune-prone individuals

Sample Collection:
Serum: Collected through standard venous blood draw.

CSF (Cerebrospinal Fluid): Collected via lumbar puncture (used in special neurological cases).

Interpretation of Results:
Positive anti-TPO or anti-Tg antibodies indicate an autoimmune response against thyroid tissue.

High levels are strongly associated with:

Hashimoto’s thyroiditis (hypothyroidism)

Graves’ disease (hyperthyroidism)

Some individuals may test positive without symptoms — indicating an increased risk of future thyroid dysfunction.

Clinical Significance:
Hashimoto’s Thyroiditis: Most common cause of hypothyroidism; nearly all cases show positive anti-TPO antibodies.

Graves’ Disease: Autoimmune hyperthyroidism; anti-TPO may be elevated, but TSH receptor antibodies are more specific.

Autoimmune Encephalopathy: Rare cases where anti-thyroid antibodies are found in CSF and linked to brain inflammation.

May also be detected in:

Type 1 diabetes

Celiac disease

Rheumatoid arthritis

Systemic lupus erythematosus (SLE)

Limitations:
Presence of antibodies doesn’t always mean thyroid disease is present — clinical correlation with symptoms and other hormone tests (TSH, T3, T4) is essential.

Some people may have low titers without disease.

Not useful as a general screening test in asymptomatic individuals.

Conclusion:
The ATAB test, including anti-TPO and anti-Tg antibodies, is a key diagnostic tool in evaluating autoimmune thyroid disorders and related complications. It helps in early diagnosis, monitoring, and predicting disease risk, particularly in autoimmune-prone individuals.