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July 10, 1995

Outcome of Hypothyroidism Caused by Hashimoto's Thyroiditis

Author Affiliations

From the Department of Medicine, Notre-Dame Hospital, University of Montreal (Quebec).

Arch Intern Med. 1995;155(13):1404-1408. doi:10.1001/archinte.1995.00430130086009

Background:  Hypothyroidism is a common condition that is frequently irreversible and requires lifelong thyroid replacement therapy.

Objective:  To assess the incidence and factors that can predict reversibility of hypothyroidism caused by Hashimoto's thyroiditis.

Methods:  We studied 79 patients in whom Hashimoto's thyroiditis was diagnosed according to suggestive cytologic features and/or the presence of thyroid antibodies (antimicrosomal antibody titer, ≥1:1600; antiglobulin antibody titer, ≥ 1:400). All patients were initially hypothyroid (serum total thyroxine level, 83.5±28.6 nmol/L [6±2 μg/dL]; thyrotropin level, 24.7±28.3 mU/L). Levothyroxine sodium was then administered for 1 year to normalize results of thyroid blood tests. Thereafter, the treatment was stopped for 3 weeks and serum thyrotropin and total thyroxine concentrations were determined.

Results:  After withdrawal of levothyroxine treatment, thyroid blood tests showed that the degree of hypothyroidism worsened in 20 patients, remained unchanged in 40, and improved in 19. Nine patients (11.4%) did show normalization of the thyroid blood tests. Before treatment, the presence of the following in a patient—of a goiter that is 35 g or larger, thyrotropin levels greater than 10 mU/L, and an anamnestic familial incidence of thyroid disease— was clearly associated with an increased incidence of recovery of normal thyroid function (relative risk, 5.4; 95% confidence interval, 2.8 to 10.7; P<.0002).

Conclusions:  Our results confirm that hypothyroidism caused by Hashimoto's thyroiditis is not always permanent. The presence of a larger goiter and high thyrotropin levels at the time of diagnosis, associated with a familial incidence of thyroid disease, may be related to an increased incidence of hypothyroidism remission.(Arch Intern Med. 1995;155:1404-1408)