Objective:

To generate hypotheses on the effectiveness and safety of pre-treatment thyroid volume as an adjunctive parameter for guiding initial levothyroxine (L-T4) dosing in children with congenital hypothyroidism (CH).

Approach:

• Study Design: Retrospective cohort study of children diagnosed with CH at Huizhou First Maternal and Child Health Hospital from 2021 to 2023.
• Patient Groups: Patients were divided into three groups based on thyroid volume: reduced (A), normal (B), and enlarged (C).
• Data Collection: Outcomes measured included time to thyroid function normalization, L-T4 dose requirements, physical growth, and Gesell Developmental Quotient (DQ) up to 24 months.

Key Findings:

• Group A and Group C had significantly higher TSH levels (P < 0.001) and lower FT4 levels (P < 0.001) than Group B.
• In Group C, thyroid volume positively correlated with pre-treatment TSH (r = 0.705, P < 0.001).
• The median time to TSH normalization was longer in Group A (28 days) compared to Groups B and C (14 days each).
• Significant differences in L-T4 dose requirements were observed among groups, with Group A requiring more than Group C, which required more than Group B.
• No significant differences in body weight, length/height, or DQ were observed between any CH group and the healthy control group.

Interpretation:

Children with CH and abnormal thyroid volume may require higher initial L-T4 doses and a longer time to TSH normalization.

Limitations:

• The retrospective design limits causal inference.
• The small sample size may affect generalizability.
• There is a lack of long-term follow-up data on neurodevelopmental outcomes.

Conclusion:

Thyroid volume may serve as a valuable adjunct in guiding initial L-T4 dosing in children with CH.