Thyroid function in fetuses with down syndrome.
OBJECTIVE
A mild increase in thyrotropin (thyroid-stimulating hormone; TSH) is common among Down syndrome patients but is rarely detected by neonatal screening at birth. We hypothesized that Down syndrome was associated with fetal hypothyroidism and tried to determine whether Down syndrome fetuses had evidence of hypothyroidism.


METHODS
We performed a prospective observational study on 13 fetuses with Down syndrome diagnosed prenatally. TSH and free thyroxine (FT4) levels were measured in fetal blood. The results were analyzed and compared with the findings from fetal sonography and histopathology.


RESULTS
Of the 13 fetuses, 6 had TSH values greater than the 95th percentile, and FT4 values were low. None of the fetuses had sonographic evidence of goiter. The thyroids were normal by gross examination but exhibited small follicles and histological features suggesting delayed maturation.


CONCLUSIONS
The absence of goiter even in fetuses with hyperthyrotropinemia suggests a mild decrease in TSH responsiveness.
Department of Obstetrics and Gynaecology at Hôpital Beaujon, Paris, France.
Dominique
D
Luton
Elie
E
Azria
Michel
M
Polak
Aurore
A
Carré
Edith
E
Vuillard
Anne Lise
AL
Delezoide
Jean
J
Guibourdenche
D000328:Adult; D004314:Down Syndrome / Q000097:blood*; D005260:Female; D005315:Fetal Diseases / Q000097:blood*; D005333:Fetus; D006801:Humans; D007037:Hypothyroidism / Q000097:blood*; D008297:Male; D011247:Pregnancy; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*
D013972:Thyrotropin; D013974:Thyroxine