Thyroid hormone levels in children with Prader-Willi syndrome before and during growth hormone treatment.
BACKGROUND
Prader-Willi syndrome (PWS) is a neurogenetic disorder characterized by muscular hypotonia, psychomotor delay, obesity and short stature. Several endocrine abnormalities have been described, including GH deficiency and hypogonadotrophic hypogonadism. Published data on thyroid hormone levels in PWS children are very limited.


OBJECTIVE
To evaluate thyroid function in children with PWS, before and during GH treatment.


METHODS
At baseline, serum levels of T4, free T4 (fT4), T3, reverse T3 (rT3) and TSH were assessed in 75 PWS children. After 1 year, assessments were repeated in 57 of the them. These children participated in a randomized study with two groups: group A (n = 34) treated with 1 mg GH/m(2)/day and group B (n = 23) as controls.


RESULTS
Median age (interquartile range, IQR) of the total group at baseline was 4.7 (2.7-7.6) years. Median (IQR) TSH level was -0.1 SDS (-0.5 to 0.5), T4 level -0.6 SDS (-1.7 to 0.0) and fT4 level -0.8 SDS (-1.3 to -0.3), the latter two being significantly lower than 0 SDS. T3 level, at 0.3 SDS (-0.3 to 0.9), was significantly higher than 0 SDS. After 1 year of GH treatment, fT4 decreased significantly from -0.8 SDS (-1.5 to -0.2) to -1.4 SDS (-1.6 to -0.7), compared to no change in untreated PWS children. However, T3 did not change, at 0.3 SDS (-0.1 to 0.8).


CONCLUSIONS
We found normal fT4 levels in most PWS children. During GH treatment, fT4 decreased significantly to low-normal levels. TSH levels remained normal. T3 levels were relatively high or normal, both before and during GH treatment, indicating that PWS children have increased T4 to T3 conversion.
Festen
D A M
DA
Dutch Growth Foundation, Rotterdam, The Netherlands. d.festen@erasmusmc.nl
Visser
T J
TJ
Otten
B J
BJ
Wit
J M
JM
Duivenvoorden
H J
HJ
Hokken-Koelega
A C S
AC
D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D019382:Human Growth Hormone / Q000008:administration & dosage* / Q000172:deficiency*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D011218:Prader-Willi Syndrome / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology*; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood
C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D014284:Triiodothyronine; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013972:Thyrotropin; D013974:Thyroxine