Lab Value


A 42-year-old woman presents with symptoms of hypothyroidism with a painless, enlarged, firm, rubbery thyroid gland on exam. Which diagnosis is most consistent with her condition?

The patient in the question has classic findings of Hashimoto thyroiditis, also referred to as chronic lymphocytic thyroiditis or autoimmune thyroiditis. Common presenting symptoms are painless goiter and hypothyroidism with an enlarged, firm, rubbery thyroid gland on examination. This disease is the most common cause of hypothyroidism and occurs more often in areas of adequate iodine intake. It predominantly affects women (9:1), peak incidence is between the ages of 30 and 60 years, and there is some degree of genetic predisposition.
A small subset of patient may present with hyperthyroidism, referred to as Hashitoxicosis. Patients may also be euthyroid on presentation yet generally progress to be hypothyroid over time at a rate of approximately 5% per year. On laboratory evaluation, thyroperoxidase (TPO) antibodies are elevated in 70–90% of patients with Hashimoto thyroiditis, whereas thyroglobulin antibodies are elevated 40–70%. Imaging studies are not necessary in the diagnosis of Hashimoto thyroiditis, but ultrasound is used to evaluate for nodules. FNA should be performed on any nodules that meet criteria to exclude the presence of PTC or lymphoma, which has a slightly higher incidence in patients with this disease.

The histologic findings seen in Hashimoto thyroiditis are diffuse plasma cell and lymphocytic infiltration, extensive fibrosis, and gland destruction (see the image).

Management of Hashimoto thyroiditis includes thyroid hormone replacement for hypothyroidism and appropriate treatment of any nodules noted. Thyroidectomy is indicated for suspicion of malignancy, cosmetically unsightly goiters, and compressive symptoms.