Prevalence and functional significance of thyrotropin receptor blocking antibodies in children and adolescents with chronic lymphocytic thyroiditis.
BACKGROUND
TSH receptor (TSHR) blocking antibodies (Abs) inhibit TSH-induced thyroid growth and function in some adults with chronic lymphocytic thyroiditis (CLT), but their role in the pediatric age range is unknown.


OBJECTIVE
Our objectives were: 1) to determine the prevalence of TSHR blocking Abs in children and adolescents with CLT and 2) assess their functional significance both in vivo and in vitro.


METHODS
This was a retrospective study in a referral outpatient setting.


METHODS
Sera from a total of 87 CLT patients and 33 controls were studied.


METHODS
TSHR Abs were measured by both ELISA and bioassay.


RESULTS
Eight of 87 children and adolescents with CLT (9.2%), including one as young as 4 yr of age, had TSHR Abs in serum as measured by ELISA. The prevalence was significantly higher in individuals whose serum TSH concentration was 20 mU/liter or greater within 3 months of study than in less hypothyroid patients (eight of 45 vs. none of 42, P < 0.005). Conversely, TSHR Ab-positive patients were significantly more hypothyroid at diagnosis but only when the analysis was restricted to those with severe hypothyroidism was a decreased prevalence of goiter observed. IgG purified from TSHR Ab sera retained the TSH binding-inhibitory activity and TSHR Ab-positive sera inhibited TSH-induced stimulation of cAMP significantly more than normal.


CONCLUSIONS
TSHR-blocking Abs contribute significantly to the severity of the hypothyroidism in some children with CLT, but as compared with adults, they appear to play less of a role in determining the presence or absence of a goiter.
Division of Endocrinology, Children's Hospital Boston, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.
Shiri B
SB
Feingold
Jessica
J
Smith
Jeff
J
Houtz
Erica
E
Popovsky
Rosalind S
RS
Brown
D000293:Adolescent; D000328:Adult; D019138:Antibodies, Blocking / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis / Q000096:biosynthesis; D008137:Longitudinal Studies; D008297:Male; D011989:Receptors, Thyrotropin / Q000037:antagonists & inhibitors* / Q000276:immunology*; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000097:blood; D013967:Thyroiditis, Autoimmune / Q000276:immunology*; D013972:Thyrotropin / Q000037:antagonists & inhibitors
D019138:Antibodies, Blocking; D007074:Immunoglobulin G; D011989:Receptors, Thyrotropin; D013963:Thyroid Hormones; D013972:Thyrotropin