Thyroid Size and Iodine Intake in Iodine-Repleted Pregnant Women in Isfahan, Iran

Abstract

To evaluate the goiter and iodine intake status of pregnant women in Isfahan, after 8 years of iodized salt distribution in Iran. Thyroid staging was assessed by clinical examination, thyroid volume was determined by sonography, and urinary iodine (UI) excretion was assessed by the digestion method in 90 healthy pregnant women (30 in each trimester) and 90 age-matched nonpregnant women selected by random sampling in prenatal and primary health-care clinics. The data were reported as mean +/- standard deviation; P values <0.05 were considered statistically significant. The mean age of the pregnant and the nonpregnant women was 25.3 and 27.5 years, respectively-no significant difference (P = NS). The clinical goiter prevalence in the pregnant and the nonpregnant groups was 37% and 32%, respectively (P = NS). The mean thyroid volume in the pregnant and nonpregnant women was 7.8 +/- 3.2 and 7.8 +/- 2.8 mL, respectively (P = NS). Urinary iodine (UI) excretion was 20.7 +/- 6.9 mg/dL in pregnant women and 23.7 +/- 7.6 mg/dL in nonpregnant women (P = NS). The prevalence of goiter assessed by sonography was 29% in pregnant women and 21% in nonpregnant women (P = NS). The mean thyroid size in 26 of 90 pregnant women with goiter (thyroid volume >9.2 mL) was 11.8 +/- 2.73 mL and in 19 of 90 nonpregnant women with goiter was 12.36 +/- 1.6 mL (P = NS). The mean thyroid volume was 6.0 +/- 1.7, 9.9 +/- 1.7, 11.8 +/- 2.2, and 18.9 +/- 2.4 mL in the pregnant women with or without goiter at thyroid stages 0, Ia, Ib, and II, respectively. A strong correlation between goiter staging assessed by clinical examination and thyroid volume determined by sonography was found in pregnant (r = 0.77) and nonpregnant (r = 0.78) women (both P<0.000001). Mean UI excretion was 20.9 +/- 7.0, 19.9 +/- 6.8, 20.6 +/- 7.5, and 25.9 +/- 2.3 mg/dL in the pregnant women at thyroid stages 0, Ia, Ib, and II, respectively. In the pregnant and the nonpregnant women, no correlation was found between thyroid stage and UI excretion or between thyroid volume and UI excretion. No iodine deficiency was found in Isfahani pregnant women. Thus, as in most iodine-sufficient areas, thyroid size did not increase during pregnancy. Despite sufficient iodine intake, a moderate prevalence of goiter was noted in pregnant and nonpregnant women. This study also revealed that careful physical examination of the thyroid had diagnostic accuracy similar to sonography.