Reference intervals for free thyroxine, total triiodothyronine, thyrotropin and thyroglobulin for Quebec newborns, children and teenagers.
OBJECTIVE
Paediatric reference values, although essential for interpreting patients' results, are scarce. Moreover, they are often population- and instrument-dependent. We have measured free thyroxine (Free T(4)), total triiodothyronine (Total T(3)), thyroglobulin (Tg) and thyrotropin (TSH) in samples obtained from groups of newborns, children and adolescents.


METHODS
Blood samples collected from healthy children and teenagers (100 girls and 100 boys) of age groups ranging between 9-10, 11-14 and 15-17 years and selected randomly from a cohort representative of the Quebec population, were used. Samples from infants of age ranging between 1 day and 2 years (n = 99) were obtained from a hospital-based population with benign conditions unlikely to affect thyroid function. Variables were measured on the Access 2 immunosystem.


RESULTS
Free T(4), Tg and TSH levels declined significantly with age. However, Total T(3) level presented a nonlinear variation with age, being lower in the first month of life.
Djemli
Anissa
A
Department of Clinical Biochemistry, Ste-Justine Hospital, Montreal, Canada.
Van Vliet
Guy
G
Belgoudi
Jafaar
J
Lambert
Marie
M
Delvin
Edgard E
EE
D000293:Adolescent; D000375:Aging / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn / Q000097:blood*; D008297:Male; D011792:Quebec; D012016:Reference Values; D012727:Sex Characteristics; D013954:Thyroglobulin / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D014284:Triiodothyronine; D013972:Thyrotropin; D013954:Thyroglobulin