Thyroid autoimmunity may occur in first few years of life for some children
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Key takeaways:
- A small proportion of children at high genetic risk for type 1 diabetes were positive for thyroid autoantibodies by age 6 years.
- Girls were more likely to have thyroid autoimmunity than boys.
The presence of thyroid autoantibodies may be detected as early as age 10 months for children, and those positive for both thyroid peroxidase and thyroglobulin autoantibodies have a higher risk for thyroid disease, according to study data.
“A diagnosis of clinical thyroid disease in infants and young children is rare and is likely to be missed as the diagnosis is more common in older children and adolescents,” Berglind Jonsdottir, MD, PhD, a postdoctoral fellow and specialist physician in pediatric endocrinology at Lund University in Sweden, and colleagues wrote in a study published in The Journal of Clinical Endocrinology & Metabolism. “Our finding of thyroid autoimmunity in the very young, although in a selected cohort at risk for type 1 diabetes, stresses the importance of early awareness to avoid a delay in treatment, which may result in an increased risk for neurological damage and growth deficits.”
Researchers collected data from children with a high genetic risk for type 1 diabetes enrolled in The Environmental Determinants of Diabetes in the Young (TEDDY) study. Participants attended clinic visits and had serum samples collected every 3 months from birth to age 4 years, and then every 6 months from age 4 to 15 years. Thyroid peroxidase and thyroglobulin autoantibody levels were measured through serum samples beginning at age 8 years. Children who were positive for either thyroid autoantibody had levels measured again at the next visit for confirmation. Serum samples from earlier visits were also tested in those positive for thyroid autoantibodies to determine the earliest age of positivity. Thyroid-stimulating hormone levels and clinical thyroid disease cases were collected.
Thyroid autoimmunity may occur early
Of 5,066 children screened, 7.6% were positive for thyroid autoantibodies. The median age of first appearance of autoantibodies was 6.1 years, with the earliest appearance of thyroid peroxidase autoantibodies occurring at age 10 months and the first appearance of thyroglobulin autoantibodies occurring at age 15 months. The cumulative incidence for thyroid autoantibody positivity at age 6 years was 1% for thyroid peroxidase autoantibodies and 2.2% for thyroglobulin autoantibodies.
Among children who tested positive for thyroid peroxidase autoantibodies, 53% were later positive for thyroglobulin autoantibodies. Of those who were initially positive for thyroglobulin autoantibodies, 48% were later positive for thyroid peroxidase autoantibodies.
Girls were more likely to initially test positive for thyroid peroxidase autoantibodies (HR = 2.55; 95% CI, 1.67-3.91; P < .001) and thyroglobulin autoantibodies (HR = 2.18; 95% CI, 1.68-2.84; P < .001) than boys. Children with a DR4/4 or DR3/3 homozygous genotype for type 1 diabetes were more likely to test positive for thyroid peroxidase autoantibodies and less likely to be positive for thyroglobulin autoantibodies than children with a heterozygous human leukocyte antigen (HLA) genotype. Children with a family history for autoimmune thyroid disease had a higher risk for thyroid peroxidase autoantibody positivity (HR = 1.9; 95% CI, 1.17-3.08; P = .01) and thyroglobulin autoantibody positivity (HR = 2.55; 95% CI, 1.91-3.41; P < .001) than those with no family history for autoimmune thyroid disease.
Double positivity ups clinical disease risk
Of 371 children who were positive for thyroid autoantibodies and were not diagnosed with thyroid disease before screening, 46 had thyroid dysfunction, 43 had a TSH level of more than 4 uIU/mL and three had a low TSH level of less than 0.4 uIU/mL. Children who were positive for both thyroid autoantibodies were more likely to have a high TSH level than children who were only positive for thyroid peroxidase autoantibodies (RR = 3.29; 95% CI, 1.17-9.2; P = .023).
There was no difference in risk for progression from autoimmune thyroid disease to clinical thyroid disease between children positive for only thyroid peroxidase autoantibodies and those only positive for thyroglobulin autoantibodies. Children positive for both autoantibodies at the same visit were much more likely to progress to clinical thyroid disease than those who were only positive for thyroid peroxidase autoantibodies (HR = 6.34; 95% CI, 2.72-14.76; P < .001).
“Double positivity at seroconversion showed the highest risk for progression to clinical thyroid disease, within a HLA-selected population,” the researchers wrote. “It is of interest to further explore the etiological factors that trigger thyroid autoimmunity.”
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