Thyroxine Supplementation in Small for Gestational Age (SGA) Infants With Birth Weight <1500g and TSH 6-20 mIU/ml

N/ANot Yet RecruitingNCT07625722

Shandong Provincial Hospital106 enrolled

Overview

The primary objective of this clinical trail is to evaluate whether early supplementation of levothyroxine (L-T4) at a dosage of 8 ug/kg/d, initiated in the second week of life, improves physical growth and neurodevelopmental outcomes at 2 years of corrected age in Small for Gestational Age (SGA) infants with birth weights \< 1500g and TSH levels between 6 and 20 mIU/ml. Preterm infants in the intervention group will receive 8 ug/kg/d of L-T4, while the control group will receive no supplementation. Physical growth will be assessed through height, weight, and head circumference, while neurodevelopmental status will be evaluated using the Bayley-IV scales and cranial MRI imaging findings.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Enrollment

106

Conditions

Thyroid Function Preterm SGA and Growth Neurodevelopment Outcome

Interventions

Levothyroxine Sodium (LT4) TabletsDRUG

The intervention group will receive oral levothyroxine (L-T4) initiated on postnatal day 14 at a starting dose of 8 ug/kg/day. Thyroid function will be monitored every 2-4 weeks until 36 weeks postmenstrual age or hospital discharge, with subsequent follow-up at corrected ages of 40 weeks, 3, 6, 12, 18, and 24 months. The L-T4 dosage will be dynamically titrated to achieve therapeutic targets of TSH \< 5 mIU/L and FT3/FT4 levels within the upper 50% of the age-specific reference range. Treatment will be discontinued if therapeutic targets are sustained at a dosage below 2 ug/kg/day or if FT3/FT4 levels exceed the upper limit of normal.

Eligibility

Sex: ALLMin age: 2 WeeksMax age: 2 Weeks

Medical Language ↔ Plain English

Inclusion Criteria: * Preterm infants born Small for Gestational Age (SGA) with a birth weight \< 1500g； * Admitted to a participating Neonatal Intensive Care Unit (NICU) within 7 days of birth； * Serum concentrations of TSH, FT4, and FT3 are measured weekly during the first and second weeks of life，any single TSH measurement during this period is between 6 and 20 mIU/mL； * Written informed consent obtained from the parents. Exclusion Criteria: * Diagnosis of Congenital Hypothyroidism (CH) with serum TSH \> 20 mIU/mL within the first 2 weeks of life and receiving L-T4 treatment; * Persistent serum TSH \< 6 mIU/mL throughout the first 2 weeks; * Elevated thyroid hormone levels(T3, T4, FT3, or FT4) above the reference range within the first 2 weeks; * Diagnosis of Grade III or IV Intraventricular Hemorrhage (IVH) within the first 2 weeks of life; * Presence of major congenital malformations of vital organs or known chromosomal/genetic disorders; * History of maternal thyroid disease or maternal use of thyroid-related medications.