Hashimoto’s disease is an autoimmune condition and the most common cause of hypothyroidism in industrialized countries with about 2% of women affected. The progression from the normal thyroid function to the hypothyroid state in Hashimoto’s is a matter of time. About a quarter of Hashimoto’s patients who have a normal thyroid function develop hypothyroidism within the next 10 years.
It is not yet clearly understood whether the high thyroid antibodies present in Hashimoto’s disease patients play a direct role in the disease development or appear as a response to the ongoing inflammatory reaction. However, high levels of thyroid autoantibodies is currently considered to be the main criteria in the diagnosis of Hashimoto’s thyroiditis.
Structural changes within the thyroid gland, destruction of the thyroid cells and goiter are also very common. At the advanced stage of Hashimoto’s disease, most patients develop hypothyroidism with an abnormally elevated TSH and low thyroid hormone levels.
According to the Thyroid Multidisciplinary Clinic at the University of Wisconsin, Hashimoto’s disease has been more frequently diagnosed as expected among the patients who were referred to the clinic for an evaluation of their thyroid health issues. Based on the biopsies performed at this medical facility for cancer screening on 761 patients with thyroid nodules, 13.4% of them were diagnosed with Hashimoto’s.
Cytological studies using fine needle aspiration (FNA) biopsy pointed to Hashimoto’s in 6.2% of patients who had TSH in the normal range. Interestingly, thyroid antibodies were found in only 50% of biopsy diagnosed Hashimoto’s patients. Despite being clinically disease free and asymptomatic, the autoimmune process in these individuals was already initiated. Based on this finding, cytological diagnosis of Hashimoto’s using FNA may precede clinical diagnosis.
Most participants of this study were pre-menopausal females and women in child bearing age. High prevalence of cytology-proven Hashimoto thyroiditis and especially high prevalence of disease in patients with TSH in the normal range puts the women at the following health risks:
- Diagnosis of early autoimmune process could be missed due to the wide range of normal values for TSH and absence of thyroid autoantibodies in many euthyroid Hashimoto’s patients.
- Risk of miscarriage, fetal and neonatal death increases with higher TSH levels. Moreover, the risk of fetal loss occurs even when the pregnant woman had free T4 levels in the normal range.
- Risk of development of full-blown Hashimoto’s disease and hypothyroidism increases during and after pregnancy. Thyroid function in women with cytologically-proven Hashimoto’s should be monitored by a qualified physician in pre-conception and through delivery stages.
- If the cytology of Hashimoto thyroiditis indicates a chronic active inflammation of the thyroid gland, high normal TSH may represent a manifestation of a common underlying autoimmune process.
There are numerous studies reporting that using L-thyroxine in euthyroid Hashimoto’s patients who do not have abnormal test results has a positive outcome. Prophylactic thyroid hormone therapy with L-thyroxine treatment appears to be effective in:
- decreasing the levels of antibodies
- shrinking the goiter
- reducing the thyroid inflammation
- slowing down the ongoing autoimmune attack on the thyroid gland and disease progress
- alleviating depression in women
Early cytological diagnosis using FNA and treatment of euthyroid Hashimoto’s patients with L-thyroxine may not only slow down the disease but also affect the course and severity of the autoimmune condition and prevent pregnancy complications.
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Hashimoto thyroiditis is more frequent than expected when diagnosed by cytology which uncovers a pre-clinical state. Thyroid Res. 2010 Dec 20;3(1):11.
Effects of prophylactic thyroid hormone replacement in euthyroid Hashimoto’s thyroiditis. Endocr J. 2005 Jun;52(3):337-43.
Down-regulation of the auto-aggressive processes in patients with hypothyroid Hashimoto’s thyroiditis following substitutive treatment with L-thyroxine. Eur Cytokine Netw. 2009 Mar;20(1):27-32.