title: Postpartum thyroiditis and long-term thyroid status: prognostic influence of thyroid peroxidase antibodies and ultrasound echogenicity.
abstract: 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.
authors.affiliation: Department of Medicine, University of Wales College of Medicine, Cardiff, United Kingdom.
authors.forename: L D
authors.initials: LD
authors.lastname: Premawardhana
authors.forename: A B
authors.initials: AB
authors.lastname: Parkes
authors.forename: F
authors.initials: F
authors.lastname: Ammari
authors.forename: R
authors.initials: R
authors.lastname: John
authors.forename: C
authors.initials: C
authors.lastname: Darke
authors.forename: H
authors.initials: H
authors.lastname: Adams
authors.forename: J H
authors.initials: JH
authors.lastname: Lazarus
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006650:Histocompatibility Testing; D020249:Hormone Replacement Therapy; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology*; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy; D011379:Prognosis; D013960:Thyroid Function Tests; D013966:Thyroiditis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014463:Ultrasonography
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D007453:Iodide Peroxidase; D013974:Thyroxine