Long Term Follow-up and Outcomes of Autoimmune Thyroiditis in Childhood
2Pediatric Endocrine Institute, Ha'emek Medical Center
3Clalit Health Services, Northern Region
4The Rappaport Faculty of Medicine, Technion, Institute of Technology
Background:
Autoimmune thyroiditis (AIT) is the most common cause of acquired hypothyroidism in children. The natural outcome of AIT in childhood has been reported previously, however follow-up duration is generally short and results variable.
Objectives:
To characterize clinical and biochemical findings at presentation of AIT, evaluate long-term outcomes and assess which factors at presentation predict evolution over time.
Study Cohort:
201 children under 18 years of age at presentation (82% female) were enrolled. Subjects were divided into five subgroups according to thyroid stimulating hormone (TSH) level at referral.
Results:
Mean follow-up was 8.1 years (range 0–29 years). At presentation, 34% of patients had overt hypothyroidism, 32% subclinical hypothyroidism (SCH), 16% compensated hypothyroidism, 14% were euthyroid, and 3.7% had Hashitoxicosis. Children with overt hypothyroidism were younger (10.6 vs. 13.2 years) and had higher thyroid peroxidase antibody titers. Fifty patients (25%) had an additional autoimmune disease diagnosed either before or after AIT diagnosis and in 40%, a family history of thyroid disease was present. At the time of the study, levothyroxine (LT4) therapy was required in 26% of children who were euthyroid at presentation, 56% of SCH patients, 83–84% of those with TSH above 10 mIU/L, and 57% of those with Hashitoxicosis. Over the years, 16% of children presenting with overt hypothyroidism stopped therapy. Free T4 at presentation was the only predictor of outcome over time.
Conclusions:
Our findings suggest that only 26% children who were euthyroid at presentation developed hypothyroidism, whereas over 50% of those with SCH went on to require treatment. Of those presenting with overt hypothyroidism, 16% recovered with time. The only predictive parameter for LT4 therapy at the end of the study was free T4 levels at presentation. Long-term follow-up is required to determine ongoing therapy needs and screen for additional autoimmune diseases.
