An update on thyroid disorders in the postpartum period.

PURPOSE: To review the pathophysiology, diagnosis and management of postpartum thyroid dysfunction, and related management of thyroid disorders during lactation. METHODS: We reviewed the literature on postpartum thyroid dysfunction and management of thyroid disorders during lactation. RESULTS: The postpartum period is characterized by a rebound from the immunotolerance induced by pregnancy. Routine thyroid function screening is not recommended for asymptomatic women in the postpartum period. Testing thyroid function should be considered at 6-12-week postpartum for high-risk populations, including women with a previous episode of postpartum thyroiditis, Graves' disease, or those with Hashimoto's thyroiditis on thyroid hormone replacement, known thyroid peroxidase antibody positivity, type 1 diabetes mellitus, other nonthyroidal autoimmune disease, or chronic hepatitis C. A serum TSH should also be checked in the setting of postpartum depression or difficulty lactating. If patients have thyrotoxicosis, new-onset or recurrent Graves' disease must be differentiated from postpartum thyroiditis, because the management differs. Periodic thyroid function testing is recommended following recovery from postpartum thyroiditis due to high lifetime risk of developing permanent hypothyroidism. Levothyroxine, and the lowest effective dose of antithyroid drugs, (propylthiouracil, methimazole, and carbimazole) can be safely used in lactating women. The use of radiopharmaceutical scanning is avoided during lactation and radioactive iodine treatment is contraindicated. CONCLUSIONS: Diagnosing postpartum thyroid dysfunction is challenging, because symptoms may be subtle. A team approach involving primary care providers, endocrinologists, and obstetricians is essential for transitioning thyroid care from the gestational to the postpartum setting.

Postpartum Thyroid Dysfunction in Women With Known and Newly Diagnosed Hypothyroidism in Early Pregnancy.

Background: Hypothyroidism in the first trimester of pregnancy (T1) has great adverse effects on mothers and foetuses. However, few studies have investigated the influence on postpartum thyroid dysfunction. This study aimed to evaluate their long-term effect on postpartum thyroid function within one year after delivery. Methods: In total, 151 women were recruited from 1496 participants and were classified as newly diagnosed subclinical hypothyroidism (SCH) in T1 (ND-SCH, n=50), previously known SCH before pregnancy (PK-SCH, n=51) and previously known overt hypothyroidism (PK-OH, n=50). Their thyroid functions were dynamically monitored from pre-conception to one-year postpartum. Results: During pregnancy, the first thyroid functions' test time in T1 were 5-8 gestational weeks. After delivery, the prevalence of postpartum thyroiditis (PPT) was comparable in women with previously known and newly diagnosed hypothyroidism [ND-SCH 62.0% vs PK-SCH 64.7% vs PK-OH 64.0%, P=0.96]. For the ND-SCH group, PPT was significantly related with thyroid-stimulating hormone (TSH) >4.0 mU/L occurring at <8 gestational weeks [OR=8.06, 95% CI, 2.08-31.29] and TSH levels outside 1.0-2.5 mU/L near childbirth [OR=3.73, 95% CI, 1.04-13.41]. For patients with known hypothyroidism before pregnancy (PK-SCH and PK-OH), TSH>2.5 mU/L in T1 [OR=3.55, 95% CI, 1.43-8.81] and TPOAb≥300 µIU/mL [OR=6.58, 95% CI, 2.05-21.12] were associated with PPT. Regardless of whether SCH was diagnosed before pregnancy or in T1, the levothyroxine (LT4) treatment was discontinued at delivery. More than 50% of the patients had to face the hypothyroidism phase of postpartum and restarted LT4 treatment in the first-year follow-up. The logistic regression analysis revealed that TSH elevation occurring at <8 gestational weeks [OR=2.48, 95% CI, 1.09-5.6], TSH levels outside 1.0-2.5 mU/L near childbirth [OR=3.42, 95% CI, 1.45-8.05], and TPOAb≥300 µIU/mL [OR=6.59, 95% CI, 1.79-24.30] were the risk factors. Conclusion: TSH elevation at <8 gestational weeks was associated with PPT after delivery in women with known and newly diagnosed hypothyroidism. Especially for SCH patients who stopped LT4 treatment at delivery, unsatisfactory TSH level at <8 gestational weeks and near childbirth, TPOAb≥300 µIU/mL were the risk factors for LT4 retreatment in one-year postpartum.

Post-pregnancy osteoporosis-related multiple vertebral fractures associated with post-partum thyroiditis: A CARE-compliant case report.

INTRODUCTION: Osteoporosis is a condition commonly observed in elderly and postmenopausal women. Pregnancy and lactation-induced osteoporosis are rare, and the development of severe vertebral fractures is uncommon. Postpartum thyroiditis (PPT) is a minor cause of osteoporosis. To the best of our knowledge, the development of osteoporosis associated with pregnancy has not yet been reported. PATIENT CONCERNS: Here, we report a rare case of post-pregnancy osteoporosis-related multiple vertebral fractures associated with PPT. A 25-year-old woman developed lower back pain after her first delivery. She was then admitted to our medical center because of aggravated back pain. DIAGNOSIS: On radiographic examination, she had multiple compressions of the lumbar spine. Bone mineral density was associated with osteoporosis. Laboratory tests, thyroid scans, and thyroid ultrasonography were performed. The patient was diagnosed with PPT. INTERVENTIONS: The patient stopped lactating immediately. She was administered bisphosphate at 3 mg/3 months intravenously, elementary calcium at 1000 mg/day, and calcitriol 0.5 µg/day. OUTCOMES: A month later, her pain was relieved by proper management and she could independently walk indoors. CONCLUSION: PPT might play a role in aggravating post-pregnancy osteoporosis. It should be considered as a differential diagnosis in patients presenting with postpartum osteoporosis-related multiple spine fractures.

Postpartum Thyroiditis in Women With Euthyroid and Hypothyroid Hashimoto's Thyroiditis Antedating Pregnancy.

CONTEXT: Postpartum thyroiditis (PPT) is defined as the occurrence of de novo autoimmune thyroid disease accompanied by thyroid dysfunction in the first year postpartum. However, hormonal changes resembling the typical pattern of PPT have been reported to occur even in women with pregestational Hashimoto's thyroiditis (HT) on levothyroxine (LT4). OBJECTIVE: To evaluate the risk of PPT in women with HT antedating pregnancy. DESIGN/SETTING: Retrospective chart review of pregnant women with HT antedating pregnancy seen in a university hospital (2008-2017), who were followed from preconception up to 1 year after delivery. PATIENTS: 167 women preconceptionally diagnosed with HT and classified as hypothyroid HT (hypo-HT; n = 98) or euthyroid HT (eu-HT; n = 69), according to their thyroid status at the time of diagnosis. OUTCOME MEASURES: PPT occurrence and associated clinical characteristics/risk factors. RESULTS: PPT occurred in 65/167 women, with a rate statistically greater in the eu-HT than in the hypo-HT group (68.1% vs 18.4%; odds ratio [OR] 9.49, 95% confidence interval [CI] 4.62-19.49). Most of the women experiencing PPT in both groups were euthyroid at the time of first-trimester evaluation (39/47 eu-HT [83%] and 16/18 hypo-HT [88.9%]). Multivariate regression analysis showed eu-HT group and first-trimester euthyroidism to be positively associated with PPT occurrence (ORs 10.71 and 3.89, respectively). CONCLUSION: PPT may occur in hypo-HT women on LT4 therapy, although significantly less frequently than in eu-HT women. The 4-fold higher risk of PPT in HT women maintaining euthyroidism at first -trimester of gestation suggests that the risk of PPT could be related to the amount of unaffected thyroid tissue.

Changes suggestive of post-partum thyroiditis in women with established hypothyroidism: incidence and predictors.

OBJECTIVE: Post-partum thyroiditis (PPT) is a common phenomenon in the general population. To date there have been few studies examining the incidence of PPT in women with hypothyroidism antedating pregnancy. This study aimed to assess the incidence and potential predictors of PPT in women with treated hypothyroidism antedating pregnancy. DESIGN: Retrospective cohort study. PATIENTS AND METHODS: We compiled a cohort of 97 women with previous hypothyroidism antedating pregnancy seen in the Endocrinology in Pregnancy clinic from 1999 to 2011, collecting data on thyroid function, antibodies and levothyroxine doses post-partum. The incidence of PPT and its predictors were analysed. RESULTS: A total of 66 (68%) women had fluctuations in thyroid function consistent with PPT. Of these, 22 (33%) had a hyperthyroid phase alone, 22 (33%) had a hypothyroid phase alone and 22 (33%) had both a hyper and hypo phase. The majority of women had their dose of thyroid medication adjusted during the PPT episode. Women who were on a full dose of thyroxine post-partum were significantly less likely to have a hypothyroid phase. In multivariable analysis, the only predictor of PPT was the presence of thyroid antibodies, with 83% of antibody positive women having PPT compared to 44% of antibody negative women (P = 0·0001). CONCLUSIONS: In our cohort, 2/3 of women had fluctuations in thyroid function consistent with PPT and most required adjustment of their thyroid dose. Women with hypothyroidism antedating pregnancy are at high risk for PPT and should be closely monitored during the first year post-partum.

Increased thyroid autoimmunity among women with multiple sclerosis in the postpartum setting.

BACKGROUND: Multiple sclerosis (MS) patients are predisposed to thyroid abnormalities, but the risk for pregnancy-related thyroid pathology among MS patients has not been evaluated. OBJECTIVES: The objectives of this research are to prospectively evaluate the prevalence of thyroid autoimmunity among MS patients in relation to pregnancy, and to investigate its impact on pregnancy outcome, postpartum depression and fatigue. METHODS: Forty-six pregnant MS patients underwent repeat testing for serum thyroid antibodies (Abs), clinical evaluation and thyroid hormone measurement. Results were compared to 35 age-matched healthy mothers. RESULTS: At six months postpartum 35.3% of MS patients presented elevated levels of thyroid Abs compared to 5.7% of controls, p = 0.01. Mean thyroid Ab concentrations among MS patients were significantly reduced during pregnancy and returned to maximal levels at six months postpartum. The proportion of individuals with postpartum thyroid dysfunction did not differ significantly between MS patients and healthy controls (3.4% vs 2.9%, p = 1.00). Elevated thyroid Ab levels did not increase the risk for adverse pregnancy outcome, fatigue or postpartum depression. CONCLUSIONS: Considering the tendency of MS mothers to develop thyroid autoimmunity postpartum and in association to treatments, we recommend screening MS patients for thyroid dysfunction (TSH) during early pregnancy and after delivery.

[Concept and management of postpartum thyroid dysfunction].

Postpartum thyroid dysfunction is found in 5-10% of women within one year after delivery. Dysfunction is developed from subclinical autoimmune thyroiditis through immune rebound mechanism and divided into 5 types. Most frequent one is destructive thyrotoxicosis, named as postpartum thyroiditis, which occur in early postpartum period and usually followed by transient hypothyroidism. Some of them progress into permanent hypothyroidism. Graves' disease is also developed mainly after 4 months postpartum and found in one out of 200 postpartum women in general population. Treatment of this dysfunction is principally the same as ordinal thyroid disease except for transient hypothyroidism.

Approach to the patient with postpartum thyroiditis.

Postpartum thyroiditis (PPT) is the occurrence of de novo autoimmune thyroid disease, excluding Graves' disease, in the first year postpartum. The incidence of PPT is 5.4% in the general population, and it is increased in individuals with other autoimmune diseases such as type 1 diabetes mellitus. The classic presentation of PPT of hyperthyroidism followed by hypothyroidism is seen in 22% of cases. The majority of women with PPT experience an isolated hypothyroid phase (48%), with the remainder experiencing isolated thyrotoxicosis (30%). Up to 50% of women who are thyroid antibody positive (thyroid peroxidase antibody and/or thyroglobulin antibody) in the first trimester will develop PPT. Symptoms are more common in the hypothyroid phase of PPT and include fatigue, dry skin, and impaired memory. Despite multiple studies exploring the relationship between PPT and postpartum depression, or postpartum depression in thyroid antibody-positive euthyroid women, the data are conflicting, and no firm conclusions can be reached. Long-term follow-up of women who had an episode of PPT reveals a 20-40% incidence of permanent primary hypothyroidism. In a single study, selenium administration significantly decreased the incidence of PPT, but replication of the findings is needed before the recommendation can be made that all pregnant thyroid peroxidase antibody-positive women receive selenium. The indication for treating the hyperthyroid phase of PPT is control of symptoms, whereas treatment of the hypothyroid phase of PPT is indicated for symptomatic relief as well as in women who are either breastfeeding or attempting to conceive.

[Thyroid dysfunctions and pregnancy]. / Dysthyroïdies et grossesse.

Advances in understanding the physiology of the thyroid function in normal pregnancy have highlighted the importance of the consequences of abnormal thyroid function on mother and fetal outcomes. Thyroid diseases are common in young women of childbearing age while management of thyroid diseases is relatively straightforward. For each thyroid dysfunction (hypothyroxinemia, hypothyroidism, hyperthyroidism, postpartum thyroiditis), the issues with the obstetric complications of the mother and the fetus are considered. Indeed, early recognition of thyroid diseases during pregnancy and appropriate management has the potential to improve outcome for the mother and the fetus.

Thyroid disease in pregnant women with systemic lupus erythematosus: increased preterm delivery.

Thyroid disease is common in pregnancy and is associated with miscarriage, preterm delivery and postpartum thyroiditis (PPT). Systemic lupus erythematosus (SLE) is associated with miscarriage and preterm delivery. The hypotheses of the study are (1) pregnant women with SLE will have a high prevalence of undiagnosed hypothyroidism and a high prevalence of PPT, and (2) women with SLE and thyroid disease will have an increased incidence of adverse pregnancy outcomes as compared with pregnant women with SLE who do not have thyroid disease. This was a retrospective study of the Hopkins Lupus Cohort. All women had thyroid-stimulating hormone and thyroid antibodies assayed on frozen sera. In total, 63 pregnant women who met the ACR classification for SLE were evaluated. Outcome measures were the prevalence of thyroid disease during pregnancy and postpartum, and pregnancy outcomes. Some 13% of the women were on thyroid hormone prior to becoming pregnant, 11% were diagnosed with hypothyroidism during pregnancy, and 14% developed PPT. The prevalence of preterm delivery was 67% in women with thyroid disease and 18% in women who were thyroid disease free (p = 0.002). The presence of thyroid antibodies was not correlated with preterm delivery. Pregnant women with SLE have an increased prevalence of thyroid disease. Women with SLE and thyroid disease have an increased prevalence of preterm delivery.

High rate of persistent hypothyroidism in a large-scale prospective study of postpartum thyroiditis in southern Italy.

CONTEXT: The incidence of postpartum thyroiditis (PPT) varies widely in the literature. Limited data exist concerning the hormonal status of women with PPT at the end of the first postpartum year. OBJECTIVE: Our aim was to conduct a large prospective study of the incidence and clinical course of PPT. DESIGN: A total of 4394 women were screened for thyroid function and thyroid autoantibodies at 6 and 12 months postpartum. Women were classified as being at high or low risk of having thyroid disease before any thyroid testing. SETTING: The study was conducted at two ambulatory clinics in southern Italy, an area of mild iodine deficiency. PATIENTS: A total of 4394 pregnant women were studied. INTERVENTION: There was no intervention. MAIN OUTCOME MEASURES: We measured incidence, clinical presentation, and course of postpartum thyroiditis. RESULTS: The incidence of postpartum thyroiditis was 3.9% (169 of 4384). Women classified as being at high risk for thyroid disease had a higher incidence of PPT than women classified as low risk (11.1 vs. 1.9%; odds ratio, 6.69; 95% confidence interval, 4.63, 9.68). Eighty-two percent of the 169 women with PPT had a hypothyroid phase during the first postpartum year. At the end of the first postpartum year, 54% of the 169 women had persistent hypothyroidism. CONCLUSIONS: One of every 25 women in southern Italy developed PPT. Women at high risk for thyroid disease have an increased rate of PPT. The high rate of permanent hypothyroidism at 1 yr should result in a reevaluation of the widely held belief that most women with PPT are euthyroid at the end of the first postpartum year.

[Incidence of postpartum thyroiditis and study of possible associated factors]. / Tiroiditis posparto: incidencia y estudio de los posibles factores asociados en las embarazadas de una zona de salud.

BACKGROUND AND OBJECTIVE: Our objective was to evaluate the presence of postpartum thyroiditis (PPT) in a group of pregnant euthyroid women. MATERIAL AND METHOD: This study was prospective and descriptive in nature and was carried out over the course of three years in an urban Health District in Toledo, Spain. Information recorded included height and weight, tobacco use, previous consumption of oral contraceptives, and numbers of pregnancies and abortions prior to the current gestation. Levels of Thyroid Stimulating Hormone (TSH), free Thyroxin (FT4) and thyroid peroxidase antibodies (TPOAb) were determined during the first trimester and 3 and 6 months postpartum. A urine sample was collected for determination of iodine levels. Thyroid ultrasonography was performed on all pregnant subjects concurrently with analytical sample collection at 3 months of pregnancy and 3 months postpartum. RESULTS: The sample contained 157 pregnant women, of whom 25 (15.9%) developed PPT. Of these, 44.0% were positive for TPO antibodies in the first trimester, compared to 4.5% of the subjects who did not develop PPT (P<.001). At the end of the first year, 5 (20%) were still afflicted with hypothyroidism. The complete study group of pregnant women displayed a median urinary iodine level of 135 microg/L. A minor BMI was found in the PPT subjects when compared with the rest of the study group (21.7 vs 24.5; P=.000). A greater frequency of PPT was found in Rh-negative women (33.3 vs 12.2%; P=.015). CONCLUSIONS: The incidence of PPT exceeded that previously reported. We have only found a significant correlation between PPT and BMI and Rh factor. Based on the high incidence rate detected in our Health District, an active search for cases of PPT might be justified.

Serum pituitary antibodies in normal pregnancy and in patients with postpartum thyroiditis: a nested case-control study.

OBJECTIVES: The aim of this study was to evaluate antipituitary antibody (APA) prevalence in a series of patients with postpartum thyroiditis (PPT) during pregnancy and in the postpartum. DESIGN: We conducted a nested case-control study on consecutive PPT and normal pregnant women at the Centre for Endocrine and Diabetes Sciences in Cardiff and at the Department of Endocrinology in Pisa. METHODS: We enrolled 30 women with PPT: 17 were hypothyroid (Hypo), 7 with hyperthyroidism (Hyper) and 6 with a transient hyperthyroidism followed by hypothyroidism (Biphasic). Twenty-one healthy pregnant women served as controls. APA (measured using indirect immunofluorescence), free thyroxine, free triiodothyronine, TSH, antithyroid autoantibodies, and thyroid ultrasound were performed during pregnancy and postpartum. The stored sera have been sent to Pisa, where serum APA, IGF1, and cortisol were measured. RESULTS: APA were found in 8 out of the 30 PPT patients (26.7%) and in one normal pregnancy (4.7%, P=0.063). Three out of the seventeen Hypo with PPT (17.6%), three out of the seven Hyper PPT (42.8%), and two out of the six Biphasic PPT (33.3%) were positive for APA. APA prevalence was not significantly different in the PPT subgroups (P=0.453). With one exception, APA all increased in the postpartum period (87.5%, P<0.016). Basal serum IGF1 and cortisol were in the normal range with the exception of two patients with positive APA who presented low serum IGF1 levels (36 and 45 ng/ml). CONCLUSIONS: APA are frequently present in the postpartum period in patients affected by PPT. Further studies are necessary to evaluate whether APA in PPT patients are associated with pituitary function impairment.

Prevalence of post-partum thyroiditis in Liguria (Italy): an observational study.

BACKGROUND: Post-partum thyroiditis (PPT) is an autoimmune disorder occurring within the first year following delivery. A variable prevalence has been reported in different surveys. We prospectively evaluated PPT prevalence and outcome in a cohort of pregnant women living in a well-defined geographic area. AIM: A subset from a group of healthy women consecutively evaluated for thyroid function and thyroid autoimmunity during pregnancy, referring to the same obstetric unit, were followed up at 4-6 months and 1 yr after delivery. MATERIALS/SUBJECTS AND METHODS: Follow-up for PPT was performed in 258 pregnant women. Control data were obtained in a comparable group of healthy non-pregnant women. Free T3 (fT3), free T4 (fT4), TSH thyroglobulin/thyroid peroxidase autoantibodies (TgAb/TPOAb), and urinary iodine excretion were measured. RESULTS: Autoantibody positivity was observed in 9.3% of pregnant, similar to control women. Forty-three out of 59 autoantibody-positive women were followed up; 23 showed PPT at the first control, 18 had hypothyroidism at 1 yr (5 had not shown PPT at the first control). Among 215 out of 584 autoantibody-negative women followed up, 27 developed PPT (15 of them without thyroid autoantibodies); 16 developed thyroid autoantibodies without PPT. After 1 yr, 9 women had hypothyroidism: only 1 of them was autoantibody-negative at the former control. Urinary iodine was increased in several pregnant women. CONCLUSIONS: An overall PPT prevalence of about 18% may be estimated. PPT was also observed in autoantibody- negative women. Differences with other surveys may be related to both study protocol and characteristics of the population studied.

Smoking and environmental iodine as risk factors for thyroiditis among parous women.

OBJECTIVE: To elucidate whether exposure to some environmental factors, i.e. cigarette smoking and iodine deficiency influence the risk of thyroiditis. METHODS: We identified a cohort of 874, 507 parous women with self-reported information on smoking during pregnancy registered in the Swedish Medical Birth Registry from September 1983 through December 1997. Hospital diagnoses of thyroiditis (n = 286) and hypothyroidism (n = 690) following entry into the cohort were identified by record-linkage with the national Inpatient Registry. The hazard ratio (HR) of smokers compared to non-smokers and the corresponding 95% confidence limits (CL) were estimated by Cox regression. RESULTS: Smoking was inversely associated with risk of overt thyroiditis (adjusted HR = 0.72; CL = 0.54-0.95), even when diagnoses of primary hypothyroidism were included. However, a diagnosis of thyroiditis within 6 months from a childbirth was positively associated with smoking (adjusted HR = 1.88; CL = 0.94-3.76). Being born in areas of endemic goiter was not associated to hospital admission for thyroiditis. Thyroiditis patients who were smokers had more often than non-smokers a co-morbidity with other autoimmune disorders. CONCLUSIONS: Smoking may increase the risk of thyroiditis occurring in the post-partum period and influence the clinical expression of other thyroiditis, especially when occurring as part of a polymorphic autoimmune disease.

Postpartum thyroiditis: long-term follow-up.

OBJECTIVE: To determine the incidence of persistent hypothyroidism (PH) after a long follow-up in 45 patients with postpartum thyroiditis (PPT) from a nonselected population of 641 pregnant women (PPT incidence 7.8%) and the clinical and biochemical factors associated with PPT evolution. DESIGN AND PATIENTS: The 45 women who developed PPT were followed for 8.1 +/- 2.2 years after delivery. MEASUREMENTS: Age at delivery, family and personal history, smoking, newborn gender, breast-feeding, and PPT course were recorded. Thyrotropin (TSH) and free thyroxine (T(4)) concentrations and antithyroid antibodies were evaluated at each visit. PH was considered when it persisted one year after being diagnosed. RESULTS: Fourteen of 45 patients with PPT developed PH with a probability of 56% after a PPT episode with hypothyroidism. None of the patients who developed hyperthyroidism alone during PPT evolved to PH. PH risk was higher if the newborn was a girl (relative risk [RR] 3.88) and increased for each additional TSH unit during PPT and for every additional year of the mother's age. CONCLUSIONS: The probability of developing PH after a PPT with hypothyroidism episode is 56%. PPT screening in all women permits us to establish levothyroxine treatment, if necessary, before a new pregnancy.

Follow up of patients with postpartum thyroiditis: a population-based study.

In this survey we studied the prevalence of permanent hypothyroidism and prognostic factors for its occurrence 3-5 yr after postpartum thyroiditis (PPT); 54 of 120 women with PPT and 50 of 920 healthy women from among 1,040 women followed 4-5 yr earlier for PPT were recalled. Demographic information, signs, and symptoms of thyroid disorders and results of physical exams were documented. Serum T3, T4, RT3U, TSH, and anti-thyroperoxidase (anti-TPO ab) and anti-thyro-gluboline (anti-Tg ab) antibodies were measured. Twenty-two percent of the cases and four percent of the control group had permanent hypothyroidism, p<0.01. Based on the TSH level we divided the case group into two subgroups: PPT-Hypothyroidism (PPT-Hypo) and PPT-Eutyhroidism (PPT-EU); PPT-Hypo had greater titer of anti-TPO ab than PPT-Eu (437+/-283 vs 126+/-221 IU/mL, p<0.001). Comparison of mean peak serum TSH level and anti-TPO ab during the postpartum thyroiditis phase between PPT-Hypo and PPT-Eu in the case group was significant (56+/- 24 vs 23+/- 28 mU/L, p<0.001, and 1960+/-1270 vs 640+/-959 IU/L, p<0.001, respectively). Results of this survey show a high prevalence of permanent hypothyroidism following PPT in Tehran. High titers of anti-TPOAb and TSH levels at postpartum period are prognostic factors for occurrence of permanent hypothyroidism.

High iodine intake is a risk factor of post-partum thyroiditis: result of a survey from Shenyang, China.

The aim of the present study is to obtain the epidemiological data on post-partum thyroiditis (PPT) firstly in Chinese women, and to tryto evaluate whether excessive intake of iodine in post-partum women imposes any danger of occurring PPT. Sixty hundred and ten pregnant women were involved in the cohort just before delivery. Four hundred and eighty-eight (80%) of them accepted taking part in follow-ups more than 6 months post-partum. A blood sample was taken from participants before delivery and every 3 months post-partum for testing of serum TSH, thyroid autoantibodies. Free T3 (FT3), free T4 (FT4) and TSH receptor antibody (TRAb) were detected if TSH was abnormal. The iodine nutrition was evaluated according to the mean level of the fasting urinary iodine excretions at different times during the studying period, and participants were subgrouped into 3 categories with low, adequate and high iodine intake. For those participants who had thyroid dysfunction within 6 months post-partum, the follow-up persisted for 1 yr. Of 488 pregnant women, PPT developed in 11.9% (58/488). Given overt and subclinical PPT, the prevalence was 7.17% (no.=35) and 4.71% (no.=23), respectively. There was a strong association between the presence of thyroid peroxidase antibody (TPOAb) at delivery and the risk of developing PPT [RR=6.76, 95% (CI) 4.42-10.34]. Overt cases had much higher titers of TPOAb than subclinical patients (all p<0.05). The median urinary iodine (MUI) of patients with PPT was significantly higher than that of healthy women (231.93 vs 199.88 microg/l p=0.00153). Both the prevalence of PPT and positive TPOAb rise with the increment of iodine intakes. Pregnant women with high iodine intake had more risk of developing PPT when compared with those with low iodine intake (RR=2.92, 95%CI 1.31-6.50). We concluded that positive TPOAb was of value for predicting the occurrence and severity of PPT, and a high iodine intake was a risk factor triggering PPT.