Purpose: We investigated the prevalence of subclinical hypothyroidism (SCH) and its risk factors in prepubertal children at age 6. We also evaluated the prevalence of thyroid nodule or cyst and its relationship with SCH in prepubertal children.
Methods: From the Environment and Development of Children (EDC) cohort study, 458 prepubertal children (243 boys, mean 5.8 years) who visited at age 6 were included in this study. Serum concentrations of free thyroxine (fT4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) were measured. With the use of ultrasound, thyroid volume (Tvol) and the presence of thyroid nodule or cyst were analyzed.
Results: SCH was detected in 27 children (5.9%). SCH group had lower birth weight z-scores (P=0.03) and higher proportions of family history of thyroid disease (P=0.04) and multiple birth (P=0.02) than normal group. SCH group had lower fT4 levels (1.1 ng/dl vs 1.2 ng/dl, P=0.008) and higher TSH levels (6.3 mIU/l vs 2.3 mIU/l, P< 0.001) than normal group. After adjusting for birth weight and multiple birth, family history of thyroid disease was independently associated with SCH (OR 4.8, P=0.024). When neck ultrasound was performed in 216 children, thyroid nodule and cyst were detected in 13 (6.0%) and 49 (22.7%) children, respectively. Children with thyroid nodule or cyst had significantly higher Tvol than those without (P=0.009). No significant differences in age, sex, birth history, BMI z-scores, and proportion of family history were found according to presence of nodule or cyst. Tvol was positively correlated with TSH levels (r=0.30, P=0.032), significantly higher Tvol in SCH group than normal group (mean 3.3 ml vs 2.9 ml, P=0.009). However, the relationship of SCH with presence of thyroid nodule or cyst was not significant.
Conclusion: In prepubertal children at age 6 years, SCH and thyroid nodule were detected in 5.9% and 6.0%, respectively. Family history of thyroid disease was independent predictor for SCH. Although the relationship of SCH with thyroid nodule or cyst was not significant, higher Tvol was significantly related to SCH and presence of thyroid nodule or cyst at age 6.
27 Sep 2018 - 29 Sep 2018