Different aetiologies in post-partum thyroiditis?

Implications of thyroid autoimmunity in infertile women with subclinical hypothyroidism in the absence of both goiter and anti-thyroid antibodies: lessons from three cases

There is a great deal of research interest regarding the underlying causes of slightly elevated TSH values in patients with subclinical hypothyroidism (SH) without abnormal findings on ultrasonography or anti-thyroid antibodies. Twelve infertile women with thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPOAb)-negative nongoitrous SH were referred to our department of endocrinology between September 2007 and September 2015. None had been diagnosed with autoimmune thyroid disease or had any possible causes of SH. In all cases, LT4 was prescribed to bring TSH value below 2.5 mIU/L. Among those with infertility treatments, six (50%) became pregnant and gave birth to infants. Here, we report three of these six women who successfully became pregnant with infertility treatments and were found to have thyroid autoimmunity on data obtained during the postpartum period. Two developed postpartum thyroiditis, and the remaining one woman was temporarily weakly positive for TPOAb at 9 months postpartum. We describe three infertile subclinically hypothyroid women without goiter or anti-thyroid antibodies with potential thyroid autoimmunity. Thyroid autoimmunity is one of the most important issues for management of pregnant women, and thus, our findings are noteworthy for the care of infertile women with SH. This report provides valuable insights into the presence of autoimmunity in nongoitrous thyroid-associated antibody-negative SH patients.

Prevalence of postpartum thyroid dysfunction: a quantitative review

Estimates of the prevalence of postpartum thyroid dysfunction (PPTD) vary widely because of variations in study design, populations, and duration of screening. Our objective was to estimate the prevalence of PPTD among general and high-risk women, across geographical regions and in women with antithyroid peroxidase antibodies (TPOAbs). We conducted a systematic review and pooled analysis of the published literature (1975-2004), simultaneously accounting for sample size, study quality, percentage follow-up, and duration of screening. Data sources were MEDLINE and the bibliography of candidate studies. Two reviewers independently extracted data. Of 587 studies identified, 21 articles (8081 subjects) met the study criteria. The pooled prevalence of PPTD, defined as an abnormal thyroid-stimulating hormone (TSH) level, for the general population was 8.1% (95% confidence interval [CI] 6.6%-10.0%). The risk ratios for the development of PPTD among women with TPOAbs compared to women without TPOAbs ranged between 4 and 97 with a pooled risk ratio of 5.7 (95% CI: 5.3-6.1). Global prevalence varied from 4.4% in Asia to 5.7% in the United States. Prevalence among women with type 1 diabetes mellitus was 19.6% (95% CI 19.5%-19.7%). PPTD occurs in 1 of 12 women in the general population worldwide, 1 of 17 women in the United States and is 5.7 times more likely to occur in women with TPOAbs. The high prevalence may warrant routine screening TPOAbs, but the benefits, cost, and risks related to subsequent therapy must be weighed.

Association between lithium use and thyrotoxicosis caused by silent thyroiditis

OBJECTIVE

To determine the incidence of silent thyroiditis in lithium users and characterize lithium-associated thyrotoxicosis.

DESIGN

Retrospective record review.

PATIENTS

400 consecutive patients (300 with Graves' disease and 100 with silent thyroiditis) who underwent radioiodine scanning of the thyroid.

MEASUREMENTS

Odds of lithium exposure.

RESULTS

The odds of lithium exposure were increased 4.7-fold in patients with silent thyroiditis compared with those with Graves' disease (95% CI: 1.3, 17). Lithium-associated silent thyroiditis occurred with an incidence rate of approximately 1.3 cases per 1000 person-years, and lithium-associated thyrotoxicosis occurred with an incidence rate of approximately 2.7 cases per 1000 person-years, higher than the reported incidence rates of silent thyroiditis (< 0.03-0.28 cases per 1000 person-years) and of thyrotoxicosis (0.8-1.2 cases per 1000 person-years) in the general population.

CONCLUSION

Thyrotoxicosis caused by silent thyroiditis might be associated with lithium use.

Aspectos ultra-sonográficos e prevalência da tireoidite pós-parto em gestantes sem disfunção tireóidea atendidas em hospital público de São Paulo

Avaliamos prospectivamente a função, as imagens ultra-sonográficas e a auto-imunidade tireóidea em grupo racial heterogêneo de 800 mulheres grávidas, primíparas ou multíparas (1 a 7 gestações prévias) atendidas em hospital universitário de São Paulo durante o pré-natal. Quarenta e seis pacientes foram excluídas do estudo por apresentarem diagnóstico confirmado de doença tireóidea anterior; das 754 restantes, 386 abandonaram o seguimento antes ou após o parto. Assim, a coorte avaliada no puerpério constituiu-se de 368 puérperas, examinadas aos 3, 6, 12 meses e no 2º ano pós-parto. Embora 29 pacientes tenham tido aumento transitório daqueles anticorpos antitireóideos, caracterizando reação de auto-imunidade, estes progressivamente declinaram ou tornaram-se negativos durante o puerpério. Entretanto, nenhuma destas evoluiu com disfunção tireóidea durante o acompanhamento. Quarenta e nove pacientes (13,3%) desenvolveram progressivamente alterações funcionais da tireóide (principalmente hipotireoidismo), provavelmente devido à TPP. Além disso, a continuação do seguimento mostrou que em 18 a 24 meses, 42 mostraram níveis séricos de anti-TPO mais elevados, em comparação aos valores do primeiro ano. Os fatores de risco para o desenvolvimento da TPP, presentes durante a gravidez, foram: (1) níveis relativamente baixos de anti-TPO, entre 60 e 100U/mL [risco relativo ou odds ratio de 3,1] e (2) alterações estruturais ultra-sonográficas da tireóide no primeiro trimestre [odds ratio de 6,4]. Concluímos que a prevalência de TPP em hospital público de São Paulo foi de 13,3%, considerando as 368 pacientes seguidas. Em 29 puérperas foi diagnosticada forma transitória de reação tireóidea auto-imune, caracterizada por elevação dos níveis séricos de anti-TPO, que posteriormente regrediram.

Clinical manifestations of postpartum thyroid disease

Postpartum thyroiditis (PPT) occurs in 5%-9% of unselected postpartum women; hyperthyroidism and hypothyroidism develop, the latter being permanent, in up to 25 %-30% of women. PPT is strongly associated with antithyroid peroxidase (anti-TPO) antibodies, but 50% of anti-TPO positive women do not develop thyroid dysfunction. Symptom analysis has shown that lack of energy and irritability were the most frequent hyperthyroid symptoms whereas lack of energy, aches and pains, poor memory, dry skin, and cold intolerance were the significant hypothyroid features. Some of these symptoms were more frequently observed than in antibody-negative controls even when these patients were euthyroid and in anti-TPOAb positive women who did not develop PPT at all. The diagnosis of PPT is based on the observation of abnormal thyroid function tests in a postpartum anti-TPOAb-positive woman: transient hyperthyroidism occurs at 14 weeks and hypothyroidism at 19 weeks postpartum. Diffuse or multifocal hypoechogenicity of the thyroid is seen on echography and a thyroid destructive process is evidenced by an increase in serum thyroglobulin and urinary iodine excretion. In addition to the 25%-30% of women who develop permanent hypothyroidism at 3 years, recent data indicate that 50% of women who have developed PPT will be hypothyroid 7-9 years later. The long-term risk is only 5% for those anti-TPOAb positive women not developing thyroid dysfunction postpartum. The risk of recurrent PPT is 70% if previous PPT was experienced and 25% if the patient was euthyroid after the first pregnancy.

Syndromes of thyrotoxicosis with low radioactive iodine uptake

It is very important to diagnose correctly the etiology of thyrotoxicosis, because the course and treatment of thyrotoxicosis with low radioactive iodine uptake differ significantly from that of hyperthyroidism due to Graves' disease or toxic nodular goiter. Many causes of subacute thyroiditis have been identified producing a characteristic course of transient hyperthyroidism, followed by hypothyroidism, and usually recovery. Ectopic hyperthyroidism includes factitious thyroid hormone ingestion, struma ovarii, and, rarely, large deposits of functioning thyroid cancer metastases. Iodine-induced hyperthyroidism may be associated with low radioiodine uptakes. Amiodarone-associated hyperthyroidism may be the result of subacute thyroiditis or iodine-induced hyperthyroidism; assessment and treatment can be quite challenging.

Postpartum thyroid dysfunction

Four disorders of the postpartum period are associated with thyroid dysfunction. The most common is PPT. Although recovery from thyroid dysfunction often occurs in PPT, many patients eventually develop permanent hypothyroidism. Postpartum Graves' Disease is less common than PPT, but it is not unusual. Whereas antithyroid drugs are indicated for postpartum Graves' Disease, they are not useful in PPT. Although they are rare, lymphocytic hypophysitis and postpartum pituitary infarction are important entities because they cause deficiencies of many critical hormones. The autoimmune nature of PPT, postpartum Graves' disease, and lymphocytic hypophysitis highlights the unique effects of pregnancy on the immune system.

The pathology of autoimmune thyroid disease: a review

Lymphocytic infiltration of the thyroid gland is the pathologic hallmark of autoimmune thyroid disease. Lymphoid cells are seen in the stroma of glands affected by Graves' disease. However, large lymphoid infiltrates are characteristic of that spectrum of diseases conveniently termed chronic lymphocytic thyroiditis. In this review, the pathology of the various subtypes of chronic thyroiditis is enumerated, including recently defined lesions, i.e., painless thyroiditis, thyroiditis associated with interleukin chemotherapy, and peritumor thyroiditis are reviewed. The unifying morphologic characteristics seen in these conditions are discussed.

Postpartum thyroid dysfunction and HLA status

Nine-hundred-and-one women presenting in an antenatal clinic at the 60th week of pregnancy were tested for antithyroid antibodies. A group of 113 antibody-positive women and 108 antibody-negative age-matched controls were HLA typed and followed prospectively at 6-weekly intervals through pregnancy and for 12 months postpartum. Forty-five of the women developed biochemical evidence of postpartum thyroid dysfunction (PPTD) of whom 36 were antibody positive. Compared with a local control population (n = 600), and using multiplex analysis, there was a significant increase in the combinations HLA B8, DR3 and HLA A1, B8, DR3 from 22.5% to 40.0% (P less than 0.02) and from 18.6% to 35.6% (P less than 0.01) respectively in the women who developed PPTD. The well-recognized association of these haplotypes with other organ-specific autoimmune diseases provides further support for autoimmune events being implicated in the development of PPTD.

[Postpartum thyroiditis. 31 cases]

Postpartum thyroiditis. 31 cases. Between 1977 and 1986, 29 women consulted in three internal medicine and endocrinology departments for clinical disorders which could be ascribed to 31 episodes of thyroiditis developed within 9 months of giving birth. Thyroiditis was diagnosed clinically on the basis of acute diffuse (11 cases) or nodular (7 cases) goitre formation, signs of dysthyroidism (16 cases) revealed by menstrual disturbances and/or galactorrhoea (11 cases). A thyrotoxic episode was observed in 9 patients; it was either without sequelae (5 cases) of followed by transient hypothyroidism (4 cases). In other patients transient hypothyroidism was observed in 11 cases and permanent hypothyroidism in 5 cases. Six patients showed no sign of dysthyroidism, and the diagnosis was made by immunological, cytological and/or histological examination of the thyroid gland. Circulating anti-thyroid antibodies were present in two-thirds of the patients. The results of radioisotope scanning varied according to the stage of the disease. In these patients, only the absence of goitre was predictive, in 4 out of 5 cases, of subsequent permanent hypothyroidism; in all other patients the prognosis was highly favourable, even without specific treatment.

Postpartum thyroiditis

The special characteristics of postpartum thyroid syndromes are summarized in Table 8. Many of the cases will pass unnoticed, although a higher detection rate is to be expected if postpartum thyroid disease becomes better known among physicians and the general public. Screening in early pregnancy of women with a previous or family history of thyroid disease and in women with other autoimmune disorders (such as diabetes mellitus type 1) may be worthwhile. The initial manifestation of postpartum thyroiditis, often appearing during the first three months postpartum, is a thyrotoxic phase characterized by a low RAIU ('painless thyroiditis' or 'destruction-induced thyrotoxicosis'). Subsequently, a transient hypothyroid phase supervenes. In a small proportion of women hypothyroidism becomes permanent. After a subsequent pregnancy recurrence is the rule. Women who are genetically disposed to Graves' disease may experience thyrotoxicosis with a high RAIU usually appearing later than three months postpartum. As the thyroid function abnormalities are usually mild and transient it is often appropriate to withhold treatment. However, in women with pronounced symptoms treatment should be started. When the postpartum period has passed gradual withdrawal of treatment should be attempted. In women who have experienced postpartum thyroid dysfunction, the risk of developing permanent thyroid disease in later life seems important and therefore long-term follow-up is recommended.

Thyroiditis

In this review, the major types of immune mediated thyroiditis are described and the etiology explained in the light of current theories of autoimmunity. Hashimoto's thyroiditis is a common autoimmune disease. The onset is gradual with patients presenting with symptoms of hypothyroidism, nonspecific symptoms of the autoimmune process itself, or symptoms relating to a goitre. The disease is usually relentless and, except in young patients, permanent replacement with thyroxine is eventually required. Silent thyroiditis is another autoimmune disease of more acute onset. The initial, thyrotoxic, phase lasting several weeks is due to release of thyroid hormone from damaged follicles, and radionuclidic scans show absent uptake. There often follows a hypothyroid phase with final recovery in most patients. Post partum thyroiditis is due to silent thyroiditis, or, less commonly, Hashimoto's thyroiditis, occurring three to six months after delivery. Subacute thyroiditis often follows a viral infection and is not thought to be an autoimmune disease. It presents with severe thyroid pain and tenderness with marked non-specific symptoms such as myalgia and fatigue. The initial, thyrotoxic, phase is also due to release of thyroid hormone, and radionuclidic scans show absent uptake. A hypothyroid phase often follows and recovery is complete. Hashimoto's thyroiditis appears to be due to a congenitally present, antigen specific, T suppressor lymphocyte defect. It is proposed that in silent thyroiditis there is a less severe Ts defect and a correspondingly greater decompensating factor. In post partum thyroiditis, this factor appears to be a general decline in T suppressor lymphocyte function after delivery. Subacute thyroiditis is not an autoimmune disease. The thyroid appears to be an "innocent bystander" in an immune mediated antiviral attack.

Influence of endogenous T3-autoantibodies on thyroid hormone measurements in a woman with transient postpartum thyroiditis

Unreliable estimates of serum total T3 due to the presence of autoantibodies against T3 were observed in a woman who developed thyrotoxicosis followed by transient hypothyroidism after childbirth (postpartum thyroiditis). The T3 autoantibody levels changed during the postpartum period in a similar way to the thyroid microsomal antibodies. The total T3 values were constantly low, whereas the measurement of free T3 by the Amerlex analogue method deviated from the expected only at the time of maximal antibody levels. Thus, evaluation of thyroid function may be complicated by the simultaneous presence of thyroid hormone autoantibodies and transient postpartum thyroiditis.

Post-partum hyperthyroidism

The importance of recognizing the frequent occurrence of the destructive (i.e. PPT) and stimulatory (i.e. PGD) causes of PH have been discussed. The estimated prevalence of PH in several geographical regions of Japan, North America and Europe ranges from 2.0-5%. Although the autoimmune basis for GD has been well-established, the clinical and laboratory features of PPT as well as the alterations of humoral and cellular thyroidal immune parameters, the typical needle biopsy evidence of lymphocytic infiltration, and the association with HLA and Gm allotypes associated with the PPT syndrome, favour the view that it is also likely a variant form of subclinical ATD which becomes transiently more active post-partum. Post-partum transient hyperthyroidism with or without transient or permanent hypothyroidism and relapse of GD thyrotoxicosis have been observed in patients with or without a previous history of GD. Hence, an RAIU test is the preferred diagnostic test in differentiating between these two entities, especially in the absence of associated stigmata of GD. When the RAIU test is suppressed, other causes such as thyrotoxicosis factitia and iodine exposure should be excluded. Without an RAIU test, only a rapid and spontaneous resolution of post-partum hyperthyroidism, accompanied by laboratory confirmation of a subsequent hypothyroid phase, can indirectly facilitate the differentiation between PGD and PPT. In the first trimester of pregnancy, an increased FT4I has been proposed as a risk factor for PGD and an increased AMA titre for PPT. Depending upon clinical manifestations, severity, patient and physician preferences, PGD can be treated by one of several choices of conventional therapy. The transient thyrotoxic phase of PPT when relatively asymptomatic may require no therapy, but when symptomatic, only conservative therapy with beta-adrenergic blockers, sedatives and/or tranquilizers is indicated. Close follow-up and long-term surveillance of mothers with PH due to PPT is essential for early detection and management of a possible subsequent hypothyroid phase, which may be symptomatic, but is seldom permanent. Treatment of recurrent episodes of PPT is controversial. Thyrotoxic symptoms are usually mild and transient and can best be managed by symptomatic therapy as indicated. In a few exceptional patients with recurrent episodes, prophylactic treatment with corticosteroid may be warranted but thyroidectomy and ablative radioactive iodine therapy is seldom justified.(ABSTRACT TRUNCATED AT 400 WORDS)