Hashimoto's thyroiditis (HT), an inflammatory disorder of the thyroid, is the most common cause of hypothyroidism, but a study has suggested that even when thyroid function is normal, HT may increase symptoms and decrease quality of life, as described in an article in Thyroid, a peer-reviewed journal published by Mary Ann Liebert, Inc.

Hashimoto's thyroiditis most commonly affects middle-aged women and is associated with an array of symptoms that include chronic fatigue, dry hair, chronic irritability, difficulty concentrating, constipation, and chronic nervousness. Affected patients tend to report decreased quality of life. HT is an autoimmune disorder in which the body produces an antibody that attacks the thyroid gland resulting in inflammation, and often decreased thyroid function (hypothyroidism).

Johannes Ott and colleagues from Kaiserin Elisabeth Spital and Medical University of Vienna, Austria, report that women with higher levels of anti-thyroid antibody had a significantly higher number of symptoms, even though their levels of thyroid-stimulating hormone (TSH) -- a measure of thyroid function -- did not differ from TSH levels measured in women with lower antibody levels. In the article, "Hashimoto's Thyroiditis Affects Symptom Load and Quality of Life Unrelated to Hypothyroidism: A Prospective Case-Control Study in Women Undergoing Thyroidectomy for Benign Goiter " the authors conclude that hypothyroidism is only one factor contributing to HT symptoms.

"This study raises important clinical issues. Although the authors did not study thyroid hormone treatment for Hashimoto's thyroiditis, it raises the possibility that optimal doses of thyroid hormone will not completely ameliorate all symptoms. Further studies are required to confirm the findings of Ott et al. and to determine if patients with hypothyroidism due to Hashimoto's thyroiditis still have residual symptoms despite achieving an ideal biochemical response to thyroid hormone replacement therapy," says Charles H. Emerson, MD, Editor-in-Chief of Thyroid and Professor Emeritus of Medicine at the University of Massachusetts School of Medicine, in Worcester.