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Free access

HB Shahbazian, F Sarvghadi, and F Azizi

OBJECTIVE: To determine the prevalence of postpartum thyroiditis (PPT), one of the autoimmune disorders of the thyroid which usually occurs in women in the first year after parturition. PPT presents with periods of transient thyrotoxicosis and hypothyroidism, in many cases resulting in permanent hypothyroidism. DESIGN: The study involved 1040 mothers who had contacted five health centers in Tehran for vaccination of their children. METHODS: Signs and symptoms of hypothyroidism and thyrotoxicosis, and the presence of goiter (using the World Health Organization classification), were sought. Serum T3, T4, TSH, anti-TPO and anti-Tg antibodies were measured at 3, 4.5, 6 and 9 months after parturition. In those with hypothyroidism or thyrotoxicosis and a matched group of normal women, thyroid sonography was performed. RESULTS: The prevalence of thyroiditis was 11.4%. Hypothyroidism and thyrotoxicosis occurred in 68 and 42 mothers respectively. Nine had thyrotoxicosis followed by hypothyroidism. There was one case of Graves' disease. Out of 68 hypothyroid patients, 33 women underwent treatment with levothyroxine (because of the severity of symptoms) for 12 months. Six women showed increased TSH at 6 weeks after discontinuation of thyroxine. Stage II goiter (World Health Organization classification) were observed in 21.8% of patients and in 6.7% of pospartum euthyroid women (P<0.001). Positive anti-TPO was found in 61.5% of patients and in 19% of the control group; positive anti-Tg was found in 58% of patients and in 6% of the control group (P<0.001). Sonographic changes were observed in 96% of the patients and in 7% of the control group (P<0.001). There was no significant correlation between the occurrence of thyroiditis and parity, the age of the mother, a previous history of thyroid disease in the patient or family, breast-feeding, or the gender of the child. CONCLUSION: The results of this study show a high prevalence of PPT in Tehranian women. This may be due to the length and frequency of follow-up and/or the transition from low to adequate iodine intake. The major difference with respect to other studies is the low frequency of the biphasic form of PPT.

Free access

Allan Carlé, Nils Knudsen, Inge Bülow Pedersen, Hans Perrild, Lars Ovesen, Lone Banke Rasmussen, and Peter Laurberg

Objective

To characterize thyroid hormone levels at the time of diagnosis in the nosological types of thyrotoxicosis diagnosed in the population and to analyze determinants for serum thyroxine (T4) and tri-iodothyronine (T3).

Design

Population-based study of thyrotoxicosis at disease onset.

Methods

In the period 1997–2000, we prospectively identified all patients diagnosed with incident primary overt thyrotoxicosis in a Danish population cohort and classified patients into ten well-defined nosological types of disease (n=1082). Untreated levels of serum T3, T4, and T3:T4 ratio were compared and related to sex, age, level of iodine deficiency, smoking status, alcohol intake, iodine supplement use, co-morbidity, and TSH receptor antibodies (TRAbs) in multivariate models.

Results

Graves' disease (GD) patients had much higher levels of T3 and higher T3:T4 ratio at diagnosis compared with other thyrotoxic patients, but with a profound negative association between hormone levels and age. In GD, patients diagnosed in the area with more severe iodine deficiency had lower levels of T3 and T4. TRAb-negative GD patients had biochemically mild thyrotoxicosis. Higher age was also associated with lower degree of biochemical thyrotoxicosis in nodular toxic goiter. We found no association between serum T3 and T4 and sex, smoking habits, iodine supplements, alcohol intake, or co-morbidity in any type of thyrotoxicosis.

Conclusions

The study gives new insight into the hormonal presentation of thyrotoxicosis and showed that young age, positive TRAb levels, but also residency in the area with higher iodine intake was positively associated with biochemical disruption in GD.

Free access

L Druetta, H Bornet, G Sassolas, and B Rousset

Thyroglobulin (Tg) present in the serum of normal individuals and patients with thyroid disorders could be partly newly synthesized non-iodinated Tg and partly Tg containing iodine and hormone residues originating from the lumen of thyroid follicles. With the aim of examining the contribution of the latter source of Tg to the elevation of serum Tg concentration in thyroid pathophysiological situations, we devised a procedure to identify thyroxine (T4) and tri-iodothyronine (T3) residues on Tg from unfractionated serum. A two-step method, basedon (i)adsorption of Tg on an immobilized anti-human Tg (hTg) monoclonal antibody (mAb) and (ii)recognition of hormone residues on adsorbed Tg by binding of radioiodinated anti-T4 mAb and anti-T3 mAb, was used to analyze serum Tg from patients with either Graves' disease (GD), subacute thyroiditis (ST) or metastatic differentiated thyroid cancer (DTC). Purified hTg preparations with different iodine and hormone contents were used as reference. Adsorption of purified Tg and serum Tg on immobilized anti-hTg mAb ranged between 85 and 90% over a wide concentration range. Labeled anti-T4 and anti-T3 mAbs bound to adsorbed purified Tg in amounts related to its iodine content. Tg adsorbed from six out of six sera from ST exhibited anti-T4 and anti-T3 mAb binding activities. In contrast, significant mAb binding was only observed in one out of eight sera from untreated GD patients and in 1 out of 13 sera from patients with DTC. The patient with DTC, whose serum Tg contained T4 and T3, represented a case of hyperthyroidism caused by a metastatic follicular carcinoma. In conclusion, we have identified, for the first time, T4 and T3 residues on circulating Tg. The presence of Tg with hormone residues in serum is occasional in GD and DTC but is a common and probably distinctive feature of ST.

Free access

J Rojano, S Sasian, I Gavilan, M Aguilar, L Escobar, and JA Giron

The distribution of peripheral blood CD16/56 cytotoxic T and natural killer (NK) cells in Graves' disease patients is analyzed in order to correlate them with disease activity and with prognosis. Eighteen patients with Graves' disease, twenty-four patients with Hashimoto's thyroiditis and thirty-two sex- and age-matched healthy control subjects were studied. Peripheral blood CD16/56 (cytotoxic T and NK) cells were analyzed by cytofluorometry. A decreased proportion of CD16/56+ and CD16/ 56+CD3+ cells were detected in Graves' disease patients when compared with thyroiditis patients and healthy control groups. No correlation was detected with serum free thyroxine. On diagnosis, patients who would require a radical treatment for thyrotoxicosis control showed a significant decrease of cytotoxic CD56+ T (CD3+) and NK (CD3-) cells compared with those who would maintain the euthyroid state after methimazole. These results suggest that the cytotoxic compartment, both T and NK cells, of the immune system is altered in patients with Graves' disease, independently of the functional thyroid status. Changes in peripheral blood lymphocytes in Graves' disease patients could be useful as predictive markers of an unfavorable outcome.

Free access

J Tani, K Mori, S Hoshikawa, T Nakazawa, J Satoh, Y Nakagawa, S Ito, and K Yoshida

OBJECTIVE: Interferon regulatory factor-1 (IRF-1) is a critical regulator of interferon-gamma(IFNgamma)-mediated immune responses. To determine whether IRF-1 is involved in the pathogenesis of thyroiditis in animal models, we evaluated the incidence of iodide-induced lymphocytic thyroiditis (LT) in non-obese diabetic (NOD) mice lacking IRF-1 as well as IRF-1 +/+ and +/- mice. DESIGN: IRF-1 +/+, +/- and -/- NOD mice at 6 weeks of age were fed water (group 1) or iodide water (group 2) for 8 weeks. METHODS: Thyroids were examined histopathologically and intrathyroidal lymphocytic infiltration was arbitrarily graded. Serum thyroxine (T(4)) and anti-mouse thyroglobulin antibody (anti-mTgAb) levels were measured. Spleen cell population was analyzed by flow cytometry, and IFNgamma and interleukin-10 produced by splenocytes were measured by enzyme-linked immunosorbent assay. RESULTS: In group 1, only 4.3% of NOD mice developed LT. In contrast, 67.6% of mice in group 2 developed the disease. Iodide treatment induced LT in more than 80% of IRF-1 +/+ and +/- mice. However, no IRF-1 -/- mice in group 2 developed LT. There was no difference in both serum anti-mTgAb and T(4) levels among the three IRF-1 genotypes of NOD mice. Numbers of splenic CD8(+) T cells and IFNgamma production by Concanavalin A-stimulated splenocytes were markedly decreased in IRF-1-deficient NOD mice. CONCLUSIONS: IRF-1 is involved in the development of iodide-induced LT in NOD mice.

Free access

Anthony J O’Sullivan, Mridula Lewis, and Terrance Diamond

Objective: Amiodarone-induced thyrotoxicosis (AIT) is a challenging management problem, since patients treated with amiodarone invariably have underlying heart disease. Consequently, thyrotoxicosis can significantly contribute to increased morbidity and mortality. The aim of this study was to compare the clinical outcome and hormone profiles of patients with AIT (n = 60) with those with Graves’ thyrotoxicosis (n = 49) and toxic multinodular goitre (MNG, n = 40).

Design: A retrospective study of patients with AIT in a single institution was conducted.

Methods: Data from patients with AIT over 12 years were collected.

Results: Mean TSH levels were significantly suppressed in all three groups. However, there was no intergroup significant difference. Free thyroxine (T4) levels were significantly higher in AIT (45.6 ± 3.5 pmol/l) and Graves’ disease (44.6 ± 4.0 pmol/l) compared with toxic MNG (31.5 ± 5.1 pmol/l, P < 0.05). In contrast, free triiodothyronine (T3) levels were only significantly higher in Graves’ disease (14.7 ± 1.5 pmol/l, P = 0.002) compared with AIT (8.6 ± 0.7 pmol/l) and toxic MNG (7.4 ± 0.5 pmol/l). Six deaths occurred in the patients with AIT (10.0%, P < 0.01) and no deaths occurred in the other groups. Amiodarone treatment (P = 0.002) was the most significant predictor of death, whereas free T4, free T3 and age did not affect outcome. Within the amiodarone-treated group severe left ventricular dysfunction (P = 0.0001) was significantly associated with death.

Conclusions: (i) AIT differs from other forms of thyrotoxicosis, and (ii) severe left ventricular dysfunction is associated with increased mortality in AIT.

Free access

LH Duntas, E Mantzou, and DA Koutras

OBJECTIVE: Selenium (Se) in the form of selenocysteine is an essential component of the family of the detoxifying enzymes glutathione peroxidase (Gpx) and of the iodothyronine selenodeiodinases that catalyse the extrathyroidal production of tri-iodothyronine (T(3)). Thus, Se deficiency may seriously influence the generation of free radicals, the conversion of thyroxine (T(4)) to T(3) and the autoimmune process. Therefore, we performed a randomised, placebo-controlled prospective study to investigate the effects of Se treatment on patients with autoimmune thyroiditis (AIT). DESIGN AND METHODS: Sixty five patients aged 22-61 years (median age 48 years) with AIT were recruited into two groups. Group I (Gr I) (n=34) was treated with selenomethionine (Seme) 200 microg, plus L-thyroxine (LT(4)) to maintain TSH levels between 0.3-2.0 mU/l, whereas group II (Gr II) (n=31) received LT(4) plus placebo over a period of 6 months. Moreover, the pharmacokinetics of Seme were studied in 10 patients and eight volunteers at baseline and 2 h, 4 h, 6 h and 24 h after oral administration of a 200 microg tablet of Seme. Finally, Se levels were measured at the end of the study in some patients of both groups and their results were correlated with thyroid hormone levels. RESULTS: In the pharmacokinetics study, basal serum concentration of Se (75+/-6 microg/l) was within the reference range (70-125 microg/l), it promptly increased at 2 h, peaked at 4 h (147+/-17 microg/l; P<0.0001) and it was abundant in serum at 24 h. In Gr I, antibodies against thyroid peroxidase (anti-TPO) levels showed an overall decrease of 46% at 3 months (from 1875+/-1039 U/l to 1013+/-382 U/l; P<0.0001) and of 55.5% at 6 months. In Gr II the overall decrease of anti-TPO amounted to 21% at 3 months and to 27% at 6 months (from 1758+/-917 U/l to 1284+/-410 U/l; P<0.005). There were no significant changes of antibodies against thyroglobulin levels between the groups. At the end of this study Se levels were found to be statistically significantly increased in Gr I (n = 9/34) compared with Gr II (n=11/31) (97+/-8.4 vs 79+/-8; P<0.01) but no correlation with thyroid hormone was found. CONCLUSIONS: Seme is proven to be rapidly absorbed by the gastrointestinal tract. It appears to be useful as adjunctive therapy with LT(4) in the treatment of AIT. The exact mechanism(s) is not very well determined, it might enhance the activity of detoxifying enzymes and enforce the defense against oxidative stress.

Free access

P Biassoni, G Ravera, J Bertocchi, F Schenone, and P Bourdoux

OBJECTIVE: In contrast with the endemic goiter reported in several African countries, the nomadic Bororos of the Central African Republic have an unexpectedly low prevalence of goiter. This study was conducted to elucidate this puzzling observation. DESIGN: Thyroid function and iodine and thiocyanate intakes were evaluated in Bororos and inhabitants of the same area and compared with an Italian population. RESULTS: Urinary iodine concentrations indicated moderate iodine deficiency in the rural people and the Bororos. In the latter, no individual with clinical hypothyroidism was observed. Compared with the reference population, the Bororos had slightly lower thyroxine (T4) and free thyroxine (FT4), slightly increased tri-iodothyronine (T3) and T3/T4 ratio, slightly higher TSH, normal serum thyroglobulin, a prevalence of goiter of 17.1% and a higher urinary thiocyanate. The rural people showed striking differences: lower T4 and FT4, increased T3/T4 ratio, markedly increased TSH and thyroglobulin, a prevalence of goiter of 76.9% and a high urinary thiocyanate, indicating frequent consumption of cassava. A dietary survey indicated that the Bororos ingest large amounts of milk and related products but infrequently eat cassava. CONCLUSION: A minute difference in iodine deficiency between two populations induces totally different patterns of goiter and thyroid function. The reason for such a contrast probably involves differences in diet.

Free access

M Rotondi, G Mazziotti, F Sorvillo, M Piscopo, M Cioffi, G Amato, and C Carella

OBJECTIVE: To compare the effects of pregnancy on the serum free thyroxine (FT4) levels in two cohorts of primary hypothyroid women treated with different levothyroxine (L-T4) doses before gestation. DESIGN AND METHOD: Twenty-five women with compensated hypothyroidism of different aetiology (thyroidectomized and Hashimoto's thyroiditis) were enrolled in this prospective study. The women were receiving substitutive doses of L-T4 and were anticipating pregnancy. They were assigned to two groups: 14 patients (group I) were switched to partially suppressive treatment while 11 patients (group II) continued the same therapeutic regimen. RESULTS: Pre-conceptional thyroid function evaluation demonstrated significantly higher FT4 and lower TSH in group I (P<0.001, for both hormones) and comparable free 3,5,3'-triiodothyronine (FT3) levels. The first post-conception thyroid function evaluation occurred at a median time of 6 (5-8) and 7 (5-9) weeks of gestation, for groups I and II respectively (P<0.05); all women in group I showed adequate serum FT4 levels while three patients in group II showed low-normal FT4 levels and one case was below normal levels. Statistical analysis demonstrated significantly higher frequencies (0% vs 36.4%; P<0.05) of low-normal FT4 levels in patients receiving substitutive doses of L-T4. None of the Hashimoto's-affected patients showed low or low-normal serum FT4 levels regardless of their therapeutic regimen. CONCLUSION: Our results suggest that in hypothyroid women anticipating pregnancy (with serum TSH in the lower quartile of normal range), the pre-conception adjustment of L-T4 doses may result in adequate maternal thyroid function up to the first post-conception evaluation. The procedure seems safe and inexpensive; it may be a worthwhile treatment, at least in thyroidectomized women, in view of the well-known potential effects of even marginal maternal thyroid hypofunction on the subsequent IQ of the progeny.

Free access

Nitash Zwaveling-Soonawala, M Emma Witteveen, Jan Pieter Marchal, Femke C C Klouwer, Nadine A Ikelaar, Anne M J B Smets, Rick R van Rijn, Erik Endert, Eric Fliers, and A S Paul van Trotsenburg

Objective

The hypothalamus–pituitary–thyroid (HPT) axis set point develops during the fetal period and first two years of life. We hypothesized that thyroxine treatment during these first two years, in the context of a randomized controlled trial (RCT) in children with Down syndrome, may have influenced the HPT axis set point and may also have influenced the development of Down syndrome-associated autoimmune thyroiditis.

Methods

We included 123 children with Down syndrome 8.7 years after the end of an RCT comparing thyroxine treatment vs placebo and performed thyroid function tests and thyroid ultrasound. We analyzed TSH and FT4 concentrations in the subgroup of 71 children who were currently not on thyroid medication and had no evidence of autoimmune thyroiditis.

Results

TSH concentrations did not differ, but FT4 was significantly higher in the thyroxine-treated group than that in the placebo group (14.1 vs 13.0 pmol/L; P = 0.02). There was an increase in anti-TPO positivity, from 1% at age 12 months to 6% at age 24 months and 25% at age 10.7 years with a greater percentage of children with anti-TPO positivity in the placebo group (32%) compared with the thyroxine-treated group (18.5%) (P = 0.12). Thyroid volume at age 10.7 years (mean: 3.4 mL; range: 0.5–7.5 mL) was significantly lower (P < 0.01) compared with reference values (5.5 mL; range: 3–9 mL) and was similar in the thyroxine and placebo group.

Conclusion

Thyroxine treatment during the first two years of life led to a mild increase in FT4 almost 9 years later on and may point to an interesting new mechanism influencing the maturing HPT axis set point. Furthermore, there was a trend toward less development of thyroid autoimmunity in the thyroxine treatment group, suggesting a protective effect of the early thyroxine treatment. Lastly, thyroid volume was low possibly reflecting Down-specific thyroid hypoplasia.