title: Serum Thyroglobulin Concentration Is a Weak Marker of Iodine Status in a Pregnant Population with Iodine Deficiency.
abstract: OBJECTIVE
  To assess the reliability of thyroglobulin (Tg) as a marker of iodine status during pregnancy.
  
  
  METHODS
  299 women aged 30.5 ± 4.8 years (mean ± SD) were studied.
  
  
  METHODS
  In every subject, we measured urinary iodine concentration (UIC), serum thyrotropin (TSH), Tg, free thyroxine (fT4), Tg autoantibodies (TgAbs) and human chorionic gonadotropin (hCG) levels. We excluded samples with increased TgAbs from the analysis.
  
  
  RESULTS
  According to WHO criteria, the study population was iodine deficient in every trimester. Serum Tg levels did not differ during the three trimesters of pregnancy. Serum hCG levels fell significantly as pregnancies advanced. A weak, significantly negative correlation (limited to the 3rd trimester) was found between Tg and UIC (ρ = -0.187, p = 0.039). Serum fT4 decreased as pregnancies advanced and TSH increased. Serum fT4 was negatively correlated with TSH (ρ = -0.161, p = 0.006) and positively with hCG (ρ = +0.165, p = 0.005). The multiple regression equation of Tg based on hCG, TSH, UIC and trimester of pregnancy was significant but weak (F = 4.057, p = 0.003; R(2) = 0.055), with hCG as a significant predictor Tg (p for log hCG = 0.041).
  
  
  CONCLUSIONS
  Tg cannot be considered as a valid marker of iodine deficiency in pregnancy, at least in a mildly iodine-deficient environment. Further studies in a larger patient cohort with differences in iodine status, as well as studies on Tg changes after improving iodine status in pregnant women, are needed in order to corroborate these results.
authors: Department of Endocrinology, E Venizelou Maternity Hospital, Athens, Greece.
authors: Eftychia
authors: E
authors: Koukkou
authors: Department of Endocrinology, E Venizelou Maternity Hospital, Athens, Greece.
authors: Ioannis
authors: I
authors: Ilias
authors: Departments of Endocrinology, University of Patras Medical School, Patras, Greece.
authors: Irene
authors: I
authors: Mamalis
authors: Departments of Obstetrics and Gynecology, University of Patras Medical School, Patras, Greece.
authors: Georgios G
authors: GG
authors: Adonakis
authors: Departments of Endocrinology, University of Patras Medical School, Patras, Greece.
authors: Kostas B
authors: KB
authors: Markou
keywords: Human chorionic gonadotropin; Iodine; Iodine deficiency; Pregnancy; Thyroglobulin