Thyroid function in cord blood

Objective: To determine the biochemical parameters of thyroid function in t he cord blood of Saudi infants. Methods: Cord blood samples sent to the Pathology Department for screening for congenital hypothyroidism were used to determine the reference ranges f or thyrotropin, free thyroxine, free triiodothyronine, thyroxine-binding gl obulin and thyroglobulin. All the measurements were carried out by immunoas say (Elisa, microparticle enzyme immunoassay or chemiluminescence immunoass ay). Reference ranges were calculated after exclusion of outliers. Results: Reference ranges for thyrotropin, free thyroxine and thyroxine-bin ding globulin were similar to published values, whereas those for free trii odothyronine and thyroglobulin were different. Conclusion: For correct interpretation of the parameters of thyroid functio n in cord blood it is essential to have reference ranges based on the labor atory's current methods and derived from the local population.