Thyroid hormones and iodine status in Sudanese pregnant women with goitre

Thyroid hormones in relation to iodine status were studied in a group of Sudanese pregnant women with goitre (n = 66). These women were compared with a healthy, non-pregnant control group from the same area (n = 40). Twenty-four-hour urine samples and serum samples were collected during weeks 10-13, 20-24 and 32-39 of pregnancy. The goitrous group had a significantly lower mean urinary iodine concentration (UIC) than the non-pregnant group during weeks 20-24 and 32-39 (P < 0.003 and P < 0.001), respectively. The thyroid-stimulating hormone (TSH) and T3 levels in the pregnant group showed a stable pattern with the progression of pregnancy. TSH values in all the pregnant women were within the reference range. The mean FT4 levels of the goitrous pregnant group, in weeks 20-24 and 32-39 of pregnancy, were significantly lower than that of the non-pregnant control group (P < 0.003 and P < 0.05), respectively. The proportions of the pregnant women with FT4 below the reference range were 31, 50 and 40% in weeks 10-13, 20-24 and 32-39 of pregnancy, respectively. There was no correlation between UIC and TSH, UIC and FT4 and between TSH and FT4 during pregnancy. By virtue of the proportion of subjects falling below and above the reference range, this study indicates that in this particular study area, UIC and FT4 are better indicators of iodine status than TSH.