To investigate the clinical significance of the prevalence of thyroid-related antibodies in childhood systemic lupus erythematosus (cSLE) patients for the detection of thyroid injury and autoimmune thyroiditis (AITD).

Fifty children with first-onset cSLE who were hospitalized at the Department of Rheumatology and Immunology, Children′s Hospital Affiliated to Capital Institute of Pediatrics from January 2017 to August 2021 were selected into this study and included in cSLE group. Another fifty healthy children who underwent physical examination at same hospital were also selected and included in control group. The general clinical data and positive rate of thyroid-related antibodies of 2 groups were retrospectively analyzed. Moreover, the clinical characteristics, positive rate of thyroid-related antibodies, thyroid injury, treatment and follow-up of patients in cSLE group were retrospectively analyzed. Thyrotropin receptor antibody (TRAb), thyroglobulin antibody (TgAb), and thyroid peroxidase antibody (TPOAb) were detected by electrochemiluminescence method. The procedure followed in this study was in line with the requirements of the Helsinki Declaration of the World Medical Association revised in 2013. Informed consent for clinical research was obtatin from each patient′s guardians.

① There were no significant differences in general clinical data such as gender ratio and age between two groups (P>0.05). ② Among 50 children in cSLE group, the age ranged from 4 to 15 years old [(11.0±2.5) years old], and all the 50 children had negatime family history of thyroid diseases. At the first visit, Systemic Lupus Erythematosus Disease Activing Index (SLEDAI-2k) of all children were higher than 5, and only one patient presented with thyroid injury. TRAb, TgAb and TPOAb were positive in 6 cases (12.0%), 18 cases (36.0%) and 20 cases (40.0%) of 50 children with cSLE, respectively. There were no significant differences in the positive rates of thyroid-related antibodies among cSLE children with different disease activities (P>0.05). ③ The positive rates of three thyroid-related antibodies in cSLE group were higher than those in control group, and the differences between two groups were statistically significant (P<0.05). ④ Among 50 children in cSLE group, 13 case (26.0%, 13/50) were diagnosed as AITD, including 12 cases (24.0%, 12/50) were Hashimoto′s thyroiditis (HT) and 1 case (1/50, 2.0%) was Graves disease (GD); 2 cases (2/50, 4.0%) were diagnosed as hypothyroidism (subclinical type); 9 cases (9/50, 18.0%) had no symptoms of thyroid diseases, and their thyroid function and ultrasonic examination results were normal, although thyroid-related antibodies were positive. The remaining 26 cases had no thyroid injury. ⑤After treatment with glucocorticoids and immunosuppressants, cSLE in 50 children was relieved from 6 months to 18 months after treatment (SLEDAI-2k score <5). Among them, 13 cases with cSLE complicated with AITD were given levothyroxine or methimazole orally. After 6 to 48 months of follow-up, the symptoms disappeared, the thyroid function returned to normal, and the thyroid-related antibodies turned negative or even medication discontinuation. Two cases with cSLE complicated with hypothyroidism and negative thyroid-related antibodies were given oral levothyroxine. With the remission of the primary disease, thyroxine tablets could be reduced, and the thyroid-related antibodies did not turn positive.

Thyroid injury is more common in children with cSLE, most of whom have AITD, with HT predominating, but most thyroid injuries are insidious. Therefore, for children with newly diagnosed cSLE, especially those with active SLE, thyroid autoantibodies should be routinely detected in addition to thyroid function, regardless of whether SLE is severely active or not. Once thyroid injury is found, cSLE should be actively controlled, and thyroxine or methimazole should be taken as symptomatic treatment. With the remission of cSLE, thyroid-related antibodies can turn negative and thyroid function can be restored.