Serum negative autoimmune thyroiditis displays a milder clinical picture compared with classic Hashimoto's thyroiditis.
Level 4 - case-series / case-control
Retrospective case-control study
PubMed 24743395 · doi:10.1530/EJE-14-0147
What was done
A retrospective case-control study compared 55 patients with seronegative chronic autoimmune thyroiditis (SN-CAT; elevated TSH with negative anti-thyroid antibodies) against 110 patients with classic chronic autoimmune thyroiditis (CAT; elevated TSH with positive anti-thyroid antibodies). Serum free triiodothyronine (FT3), free thyroxine (FT4), TSH, thyroglobulin antibodies (Tg Abs), and thyroperoxidase antibodies (TPO Abs) were measured in all patients alongside thyroid volume, thyroid nodule prevalence, and overt hypothyroidism rates.
What was found
Compared with classic CAT patients, SN-CAT patients had significantly lower mean TSH (6.6 ± 3.4 vs 10.2 ± 9.8 µU/ml, P = 0.009), higher mean FT4 (1.1 ± 0.2 vs 0.9 ± 0.2 ng/dl, P = 0.0002), and smaller mean thyroid volume (8.1 ± 3.7 vs 11.2 ± 6.5 ml, P = 0.001), while FT3 levels were similar. Overt hypothyroidism was less prevalent in SN-CAT (5.4% vs 20.9%, P = 0.012). Female sex and thyroid nodule prevalence were similar between groups. On logistic regression, FT4 (OR 0.123, 95% CI 0.019-0.775, P = 0.026) and thyroid volume (OR 1.243, 95% CI 1.108-1.394, P = 0.0002) were independently associated with diagnosis.
Why it matters
This study provides evidence that seronegative thyroiditis presents with less severe thyroid dysfunction, smaller goiter size, and lower rates of overt hypothyroidism compared to classic antibody-positive Hashimoto's disease.
Limits
The study is limited by its retrospective case-control design, modest sample size (55 seronegative cases), lack of histological confirmation, and absence of longitudinal follow-up to evaluate progression over time.
Cited by
- supports Patients can have autoimmune Hashimoto's thyroiditis with seronegative antibody test results.