Reference ranges for analytes of thyroid function in children.

Promptly detecting pediatric thyroid dysfunction requires age-appropriate reference ranges for serum thyroid-stimulating hormone (TSH), serum free thyroxine (FT4), and serum free triiodothyronine (FT3). We sought to establish such ranges, employing the widely-used Immulite® 2000 automated immunoluminometric assays in a large population. We assayed the analytes according to manufacturer's instructions in serum samples from 359 male and 297 female university hospital patients, aged between newborn to 18 years, without evidence of thyroid or pituitary dysfunction. As data were not normally distributed, the reference ranges were assumed to lie between the 2.5th and 97.5th percentiles. Curves for age-related changes in the reference ranges were calculated using the linearity, median and skewness method. TSH, FT4, and FT3 reference ranges showed a wide spread immediately after birth, rapidly decreasing within the first 2 years of life. Reference range width was fairly stable after about age 4 years. However, from that time, the ranges' lower and upper limits steadily declined, essentially reaching (FT3) or approximating (TSH, FT4) healthy adult values by age 18 years. Age-specific reference ranges should be used when measuring TSH, FT4, and FT3 in children. During very early life, values of these analytes range widely, making it challenging to interpret measurements in infants, and, especially, newborns.

Verburg FA ，Kirchgässner C ，Hebestreit H ，Steigerwald U ，Lentjes EG ，Ergezinger K ，Grelle I ，Reiners C ，Luster M ... -  《-》

Maternal thyroid function at 11-13 weeks of gestation.

To establish normal ranges of maternal serum thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) at 11-13 weeks of gestation. Maternal serum concentrations of FT3, FT4, TSH, anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) antibodies were measured at 11-13 weeks. Normal ranges were constructed from the data of singleton pregnancies with no anti-thyroid antibodies resulting in live births after 34 weeks of phenotypically normal neonates with birth weight above the 5th percentile. Adjustments were made for maternal characteristics found by multiple regression analysis to affect the levels of TSH, FT3 and FT4. 3,592 of the 4,318 pregnancies examined were antibody negative, and in this group serum TSH increased whereas FT3 and FT4 decreased with gestation, and all three were lower in black than in white women. Serum FT3 and FT4 decreased but TSH did not change significantly with maternal age; TSH and FT3 increased whereas FT4 decreased with body mass index; TSH decreased whereas FT3 and FT4 increased with serum free beta-hCG. In the antibody-positive group, compared to the negative group, median TSH was higher and median FT3 and FT4 were lower. The study established normal ranges for maternal thyroid function at 11-13 weeks.

Ashoor G ，Kametas NA ，Akolekar R ，Guisado J ，Nicolaides KH ... -  《-》

Effects of age and health on the euthyroid reference ranges for serum free thyroxine and free triiodothyronine.

Midgley JE ，Gruner KR 《NUKLEARMEDIZIN-NUCLEAR MEDICINE》

Increases in thyrotropin within the near-normal range are associated with increased triiodothyronine but not increased thyroxine in the pediatric age group.

Karavani G ，Strich D ，Edri S ，Gillis D ... -  《-》

Reference intervals from birth to adulthood for serum thyroxine (T4), triiodothyronine (T3), free T3, free T4, thyroxine binding globulin (TBG) and thyrotropin (TSH).

Elmlinger MW ，Kühnel W ，Lambrecht HG ，Ranke MB ... -  《CLINICAL CHEMISTRY AND LABORATORY MEDICINE》