Subclinical Hypothyroidism in Children: Natural History, Risk Factors, and Outcomes.

OBJECTIVE

Subclinical hypothyroidism (SH) is defined as elevated thyroid-stimulating hormone (TSH) with normal thyroid hormone levels and typically presents without specific symptoms in children. Although treatment criteria exist, predictors of progression and treatment need remain uncertain.

METHODS

To evaluate the natural course of mild SH, identify clinical conditions associated with elevated TSH, determine predictors of progression requiring levothyroxine, and assess growth outcomes. Records of children (3 months-18 years) with mild SH (TSH 5-10 mIU/L on ≥2 measurements) and ≥6 months of follow-up were retrospectively reviewed. Demographic, biochemical, anthropometric, etiological, and imaging data were analyzed. Children were categorized as idiopathic or as having associated clinical factors (autoimmune thyroiditis, iodine imbalance, obesity, or medication use). Outcomes were classified as euthyroid, persistent SH, or requiring treatment.

RESULTS

During follow-up, 45 of the study cohort of 111 children (40.5%) became euthyroid, 49 (44.2%) remained subclinically hypothyroid, and 17 (15.3%) required levothyroxine. Idiopathic cases showed the most favorable course, with only 8.6% requiring therapy. Hashimoto’s thyroiditis (HT) was the strongest predictor of progression (42.1% vs. 9.8% in non-HT). A baseline TSH>7.5 mIU/L increased treatment likelihood by ~3.5-fold. Growth parameters remained within normal limits, with no deterioration in untreated children.

CONCLUSION

Mild pediatric SH is generally benign and self-limiting, particularly in idiopathic cases. HT and higher baseline TSH levels are key predictors of progression, while growth remains stable. Management should be individualized based on underlying conditions, TSH severity, and autoimmune status.