Thyroid hormone levels in children with Prader-Willi syndrome: a randomized controlled growth hormone trial and 10-year growth hormone study.
Level 2 - randomized trial
Individual randomized controlled trial combined with a longitudinal cohort study
PubMed 39049789 · doi:10.1093/ejendo/lvae088
What was done
Serum free T4 (FT4), T3, and TSH were evaluated in children with Prader-Willi syndrome (PWS) receiving growth hormone (GH, 1.0 mg/m²/day [~0.035 mg/kg/day]). The study comprised a 2-year randomized controlled trial (RCT) of 49 children (GH group median age 7.44 years vs control group 6.04 years) and a 10-year longitudinal GH cohort study of 240 children (median age 1.27 years).
What was found
During the first 6 months of the RCT, median FT4 SDS in the GH group fell from -0.84 (-1.07 to -0.62) to -1.32 (-1.57 to -1.08; P < .001) while T3 SDS increased from 0.31 (-0.01 to 0.63) to 0.56 (0.32 to 0.79; P = .08); control group FT4 and T3 SDS showed no change. In the 10-year cohort, median FT4 SDS remained stable between 2 and 10 years (-0.87 at 2 years vs -0.88 at 10 years, P = .13), while TSH SDS decreased from -0.35 (-0.50 to -0.21) to -0.68 (-0.84 to -0.53; P < .001).
Why it matters
These results clarify that the early reduction in FT4 after starting GH in children with PWS reflects increased peripheral conversion to T3 rather than developing central hypothyroidism, and demonstrates that thyroid hormone levels remain stable during long-term therapy.
Limits
The RCT portion had a small sample size (n=49) with baseline age imbalances between groups. The 10-year longitudinal component lacked an untreated control group, and the abstract does not report the incidence of clinical hypothyroidism requiring levothyroxine supplementation.
Cited by
- supports Growth hormone promotes the conversion of T4 to T3.