Detailed medical history: This includes the description of symptoms by the patient. The doctor also checks for characteristic signs of hypothyroidism in skin, hair, heart, and abdomen.

Physical examination: It is done with particular attention to the thyroid gland which is sometimes (not always) enlarged.

Laboratory investigations:

  1. Thyroid Function test
  2. Antibodies against thyroperoxidase and thyroglobulin: The antibody level is high in patients with Hashimoto’s thyroiditis.
  3. Other blood tests: Serum cholesterol, liver enzymes, and creatinine kinase are increased in hypothyroidism.
  4. Electrocardiogram (ECG or EKG) and Echocardiography (ECHO) may be required to see involvement of heart.
  • Serum TSH level: TSH levels are increased in hypothyroidism but it may be normal or low in some cases (secondary hypothyroidism)
  • Serum T4 level: Serum T4 is decreased.
  • Serum T3 level: Serum T3 is decreased.
  • Resin T3 uptake test: Resin T3 uptake is decreased.
  • Free Thyroxine index: It is decreased in cases of hypothyroidism.
  • Radioactive iodine uptake test: Radioactive iodine uptake is also decreased.

V.  X-ray chest may be needed to detect lung involvement.