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Postpartum thyroid dysfunction (PPTD) occurs in 5% of women, with hypothyroidism developing in 23% of these after 3-5 yr. We have determined the prognostic significance of thyroid peroxidase antibody (TPOAb), thyroid ultrasound morphology (U/S), human leukocyte antigen haplotype, and postpartum thyroid status on the development of thyroid dysfunction 77-81 months after PPTD. Ninety-eight TPOAb-positive [48 who had developed PPTD (group 1) and 50 without PPTD (group 2)] and 70 TPOAb-negative (group 3) women (derived from 145 TPOAb-positive and 229 TPOAb-negative cohorts at the index pregnancy), with comparable ages, parity, pregnancies after index pregnancy, and follow-up duration, were studied. Thyroid dysfunction occurred in 46% of group 1 vs. 4% of group 2 (P<0.001) and 24.5% of groups 1 and 2 vs. 1.4% of group 3 (P<0.001). Factors predictive of thyroid dysfunction included a hypothyroid form of PPTD, TSH more than 20 mU/L, and higher TPOAb levels (213.8 kIU/L in group 1 vs. 131.8 kIU/L in group 2; P<0.002) during the postpartum period. Although TPOAb was higher in group 1 than in group 2 at follow-up (166 vs. 97.7 kIU/L; P<0.03), there was no significant fall in TPOAb levels within either group during the period of follow-up. The prevalence of ultrasound hypoechogenicity was higher in group 1 than in group 2 at follow-up (76% vs. 52%; P<0.006), but U/S improved in 62.5% of group 1 during the period of follow-up. Human leukocyte antigen DR10 was lower in those who developed late thyroid dysfunction. These data, representing the longest follow-up of PPTD women, clearly show that the hypothyroid form of PPTD, high TPOAb levels, and a hypoechogenic U/S pattern lead to a high risk (relative risk, 32) of long term thyroid dysfunction. This compares with a relative risk of 12.9 for TPOAb- and PPTD-positive women, who remained euthyroid at the end of the first postpartum year, and 2.8 for TPOAb-positive but PPTD-negative women, all compared to TPOAb-negative women. Therefore, long term surveillance of TPOAb- and PPTD-positive women (group 1) is indicated.

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Objective: To study the evolution of thyroid autoimmunity, in relation to the change in goitre prevalence, during 3 years of iodine prophylaxis in Sri Lanka. Methods: Two groups of Sri Lankan schoolgirls between the ages of 10.8 and 17.5 years were studied in 1998 (401 girls) and 2001 (282 girls). A prospective study was performed in 42 schoolgirls who were thyroid autoantibody (Ab)-positive (þ ve) in 1998. Anthropometric measures, urinary iodine excretion (UIE), thyroid volume, free thyroxine, free tri-iodothyronine, TSH, and thyroglobulin (Tg) and thyroid peroxidase (TPO) Ab were evaluated in all 683 girls. Results: Goitre prevalence was significantly lower in 2001 compared with 1998 related to age (2.9% compared with 20.2%) and body surface area (11.6% compared with 40.8%), although UIE was Conclusions: This study demonstrates that: (1) in 2001, goitre prevalence and thyroid autoimmunity rates were significantly lower than in 1998; (2) the pattern of thyroid Ab was different in the two surveys; (3) in 2001 alone, the occurrence of hypothyroidism was correlated with the presence of thyroid autoimmunity. These results indicate an evolution of thyroid autoimmune markers during the course of iodine prophylaxis, which has not been described before.