**5. Laboratory investigation**

American Thyroid Association (ATA) recommends serum TSH as the initial laboratory test in evaluation of MNG. If serum TSH is abnormal, then serum FT4 and serum FT3 are recommended to know the thyroid's functioning status. Antithyroid peroxidase (anti TPO) antibody and thyroglobulin (Tg) are other laboratory tests to know about thyroid autoimmunity and Tg gene mutation in patients with MNG. If TSH is high, the risk of malignancy is increased, so it warrants further evaluation with imaging and FNAC [29–30].
