A 40 year old female came to your OPD with complaints of excessive fatigue, constipation, alopecia & gives history of weight gain of around 5 kg in last 3 months despite regular diet & physical activity. Her thyroid profile show TSH- 20 mU/L & free T4 is low. Your next step in diagnosis of etiology would be?

The most common cause of hypothyroidism in India is Hashimoto thyroiditis Since TSH levels are elevated in this patient, we will suspect primary cause of hypothyroidism. Therefore, Anti peroxidase antibody test is useful If TSH level is low then we suspect secondary cause (pituitary) and go for MRI head Antithyroglobulin antibodies- found in Hashimoto's disease Thyroid ultrasound- useful for presumed multinodular goiter Radioiodine uptake scan- will not be useful