Valores de referencia y estudio de la variabilidad de hormonas tiroideas en gestantes de El Bierzo

Background and objectivesEl Bierzo area is characterized by low urinary iodine levels in the pregnant population. Guidelines recommend that local reference values are established for the diagnosis of thyroid dysfunction in pregnancy. Our objectives were to establish reference values for thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) in women in the first trimester of pregnancy and to explore the factors influencing variability in these hormones.Patients and methodsA retrospective study of 412 women in the first trimester of pregnancy who were measured serum levels of TSH, FT4, and FT3; 163 women with conditions with a potential influence on thyroid function were excluded. Thirty smoking pregnant women were also excluded from the study of reference values. Factors examined in the variability study included age, body mass index (BMI), and smoking. A multifactorial analysis of covariance was performed.ResultsReference values in first-trimester pregnant women were: TSH: 0.497-3.595 mIU/L; FT4: 0.90–1.42 ng/dL; FT3: 2.49–3.56 pg/mL. TSH levels depended on mother age and on interaction between age and smoking. FT3 levels depended on the mother's BMI and smoking, and there was also an interaction between both factors.ConclusionThe reference values found may be used to assess thyroid dysfunction in pregnant women from El Bierzo. TSH and FT3 levels are influenced by age and BMI of the mother and by smoking, in addition to the interaction of these factors.     

Is there a link between blastomere contact surfaces of day 3 embryos and live birth rate?

Background

Limitations in our current knowledge of normative physiologic changes in thyroid function during the periconception window narrow our ability to establish an optimal approach to screening and diagnosis of thyroid disease in pregnant women. The objective of this study was to characterize changes in thyroid function during the transition from the pre-pregnant to pregnant state in normal fertile women.

Methods

Women (N = 60) ages 30-42 years without a history of thyroid disease, who were planning pregnancy, were observed prospectively before and during early pregnancy. Thyroid function (thyroid stimulating hormone, TSH and free thyroxine, FT4) was measured before conception and between 6 and 9 weeks gestation. Pre-pregnancy samples were analyzed for thyroid antibodies. Bivariate analyses and longitudinal curves (general estimating equation models) were used to analyze changes in thyroid function during the periconception window by antibody status.

Results

Pre-pregnancy TSH values were significantly higher than early pregnancy TSH (p < 0.001), but FT4 values did not differ (p = 0.53). TSH declined as gestational age increased (P < 0.01). Thyroid antibody positive women had a higher pre-pregnancy TSH compared to antibody negative women (p < 0.01). Periconceptional change in thyroid function was more variable among women with antibodies (p < 0.001). 50% of women with elevated pre-pregnancy TSH values (TSH > 3.0 mIU/L) had normal TSH values (TSH < 2.5 mIU/L) in pregnancy.

Conclusions

TSH values decline during the transition from pre-pregnancy to early pregnancy. The change in TSH appears to be less predictable in women with thyroid antibodies. Periconceptional changes in thyroid function should be considered in formulating prenatal thyroid screening guidelines.     

Reference values and the effect of clinical parameters on thyroid hormone levels during early pregnancy

Objective: Thyroid dysfunction is a common endocrine problem during pregnancy; correct diagnosis and appropriate treatments are essential to avoid adverse pregnancy outcomes. Besides, it is vital to identify and quantify the major risk factors for gestational thyroid dysfunction, including thyroid autoimmunity, human chorionic gonadotropin (HCG) concentration, body mass index (BMI) and parity. The study objective was to establish reference ranges during early pregnancy and to explore the relationship between risk factors and thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyroxine (FT3).Design, patients and measurements: To establish the reference ranges of thyroid hormone during early pregnancy in China and to identify the risk factors for thyroid dysfunction, woman in the first trimester of pregnancy (4–12 weeks gestation) were recruited. After excluding thyroid peroxidase antibody (TPO-Ab) positive and/or thyroglobulin antibody (TG-Ab) positive women, previous thyroid disease, a lack of iodine intake, reference values were calculated by 2.5th to 97.5th percentiles.Results: After exclusion of TPO-Ab and/or TG-Ab positive women, reference values were as follows: TSH, 0.11–3.67 mIU/l; FT3, 3.19–5.91 pmol/l; FT4 10.95–16.79 pmol/l. Higher BMI was associated with lower FT4 concentrations (P=0.005). In multiple regression analysis, TSH was significantly and positively associated with TG (P=0.03). Maternal parity and maternal age may be risk factors for the abnormal thyroidal response to hCG concentrations.Conclusions: Our study defined first trimester-specific reference ranges for serum TSH, FT4, FT3 in a Chinese population, and demonstrated that BMI ≥23kg/m², maternal parity ≥3 and maternal age ≥30 years may increase the risk of thyroid dysfunction.     

Thyroid Physiology in Pregnancy

ObjectiveVarious physiological changes occur in maternal thyroid economy during pregnancy. This review focuses on the events taking place during gestation that together strongly influence maternal thyroid function.MethodsScientific reports on maternal thyroid physiology in pregnancy.ResultsDuring the 1^st trimester, human chorionic gonadotropin (hCG) induces a transient increase in free thyroxine (FT4) levels, which is mirrored by a lowering of thyroid-stimulating hormone (TSH) concentrations. Following this period, serum FT4 concentrations decrease of approximately 10 to 15%, and serum TSH values steadily return to normal. Also starting in early gestation, there is a marked increase in serum thyroxine-binding globulin (TBG) concentrations, which peak around midgestation and are maintained thereafter. This event, in turn, is responsible for a significant rise in total T4 and triiodothyronine (T3). Finally, significant modifications in the peripheral metabolism of maternal thyroid hormones occur, due to the expression and activity of placental types 2 and 3 iodothyronine deiodinases (D2 and D3, respectively).ConclusionIn line with these variations, both free thyroid hormone and TSH reference intervals change throughout pregnancy, and most scientific societies now recommend that method-and gestation-specific reference ranges be used for interpreting results in pregnancy.The maternal iodide pool reduces during pregnancy because of increased renal clearance of iodine and transfer of iodine to the feto-placental unit. This results in an additional requirement of iodine during pregnancy of ~ 100% as compared to nonpregnant adults. In accordance, the recommended iodine intake in pregnancy is 250 μg/day. A daily iodine intake below this threshold poses risks of various degrees of thyroid insufficiency for both the mother and the fetus. (Endocr Pract. 2014;20:589-596)     

Normal intellectual development in children born from women with hypothyroxinemia during their pregnancy

Proper maternal thyroid function is known to be essential for neural differentiation and migration in the fetus during the first half of pregnancy. The objectives of this study were to assess the relationship between thyroxin levels, in pregnant women with no thyroid disease and the intellectual development of their offspring in a non-iodine-deficient area, and to know specifically whether or not isolated hypothyroxinemia during pregnancy was associated with a lower intelligence in the offspring.Previously we had publicated values TSH, FT4, free T3 (FT3), anti-thyroid peroxidase antibodies (TPO Abs) and urinary iodine concentration (UIC) in 1322 pregnant women in our hospital area. Now we presented results of intelligence quotient in children born from these pregnancies. We assessed 455 children at one year of age using Brunet-Lezine scale. Of these, 289 children were evaluated again at 6–8 years of age using the WISC-IV. From the total group of children recruited, we established as control subgroup, children born of rigorously normal pregnancies (women with UIC > 150 μg/L, FT4 > 10th percentile and TPO-Ab negative in both trimesters). The remaining children were divided into two subgroups: those born to mothers with FT4 below the 10th percentile and the rest. No correlation was found between FT4 maternal levels, in either of trimesters studied, and the intellectual scores of offspring. No differences were found in intellectual scores comparing children born to mothers with hypothyroxinemia and those whose mothers were euthyroxinemic in both trimesters, or with the control subgroup.As conclusions we did not find any association between the levels of maternal FT4 during pregnancy and the subsequent intellectual development the offspring from these pregnancies. We attribute this result to the fact that all the pregnant women included had normal thyroid function.     

Iodine in early pregnancy--is there enough?

Aims: To evaluate the iodine status of patients in early pregnancy and its dependence on level of thyroid-stimulating hormone (TSH). Methods: Between June 2005 and December 2006, 168 patients with a confirmed vital pregnancy (up to 10(th) week of pregnancy) were included in the study. The entry criteria were no prior thyroid disease, did not take any other medication, had not undergone radio-iodine therapy and did not take multivitamins containing iodine. The iodine status was measured as the amount of iodine in urine over 24 hours. The TSH level was determined from the blood using chemiluminescence. Results: The average ioduria value in patients was found to be 3.04 micromol/24 hr, with the norm 0.6-2.4 micromol/ 24 hr, median 2.9, SD 1.5. None of the patients had a value lower than 0.9 micromol/24 hr. The average TSH value was 1.98 mIU/l, median was 1.31, SD 0.98. The laboratory limits were set to 0.25-3 mIU/l for pregnant women in the first trimester. Three pregnancies ended in miscarriage by week 12, 1 miscarriage occurred in week 22 and the other pregnancies concluded in delivery between weeks 38-41. Fourteen patients had TSH levels above 3 mIU/l with normal levels od free thyroxine (T4) : 10.3-25 pmol/l. Conclusions: The results of this study did not reveal any iodine deficit in any of the patients. However 14 patients had elevated TSH levels signalling subclinical or incipiently clinical hypothyroidism. These pacients underwent levothyroxine therapy after endocrinologist's consultations.     

Association of Thyroid Function During Pregnancy With the Risk of Pre-eclampsia and Gestational Diabetes Mellitus

ObjectiveTo estimate the association of maternal thyroid dysfunction with the risk of gestational hypertension and diabetes. Whether the association was affected by gestational age at diagnosis and thyroid autoimmunity was further explored.MethodsA cohort study of 41 647 participants was conducted. Thyroid function (ie, thyroid-stimulating hormone [TSH] and free thyroxine [FT4]) was measured by electrochemiluminescence immunoassay. Thyroid antibody positivity (eg, thyroperoxidase, thyroglobulin, and TSH receptor antibody) was indicated if the values of these antibodies exceeded the upper targets of the reference range. The relationship between maternal thyroid dysfunction and the risk of pre-eclampsia (PE) and gestational diabetes mellitus (GDM) was assessed by multivariate logistic regression.ResultsIsolated hypothyroxinemia (defined as 5th ≤ TSH ≤ 95th percentile, FT4 < 5th percentile) was associated with the risk of PE (odds ratio [OR], 1.32; 95% CI, 1.10-1.58). Overt hypothyroidism (TSH > 95th percentile; FT4 < 5th percentile) was related to the risk of severe PE (OR, 2.59; 95% CI, 1.05-6.37). Being positive for TSH receptor antibody was associated with a decreased risk of GDM (OR, 0.49; 95% CI, 0.35-0.70). A marginally significant association between overt hypothyroidism detected at the first trimester and the risk of GDM was found (OR, 1.60; 95% CI, 1.00-2.83). The association of thyroid dysfunction with the risk of PE and GDM was stronger among pregnant women who were negative for autoantibodies.ConclusionSome types of thyroid dysfunction during pregnancy were associated with the risk of PE and GDM. The associations varied by gestational age at diagnosis and by thyroid autoantibody status.     

Correlation Between Iodine Intake and Thyroid Function in Subjects with Normal Thyroid Function

Excessive iodine intake is known to induce hypothyroidism in people who have underlying thyroid disorders. However, few studies have been performed on subjects with normal thyroid function without a history of autoimmune thyroid disease. We hypothesized that high iodine intake may cause a subtle change in thyroid function even in subjects with normal thyroid function. We analyzed 337 subjects (64 men and 273 women; mean age, 49 years) who showed normal levels of thyroid peroxidase antibodies (TPO-Ab) and thyroglobulin antibodies (Tg-Ab) by measuring the urinary iodine excretion, free T4 (FT4), and thyroid-stimulating hormone (TSH). The results showed urinary iodine excretion had negative correlation with FT4 (γ = −0.11, p = 0.043) and showed a positive trend with TSH (γ = 0.10, p = 0.068). We found that 61.7% of subjects had circulating TPO-Ab within normal reference range. In all subjects, TPO-Ab levels were negatively correlated with FT4 (γ = −0.17, p = 0.002) and positively with TSH (γ = 0.13, p = 0.021). In conclusion, high iodine intake can negatively affect thyroid hormone levels in subjects with normal thyroid function. Population-based study will be helpful for further clarification.     

Ingesta de yodo durante el embarazo: efectos en la función tiroidea materna y neonatal

IntroductionRecent studies in Spain have shown an inadequate iodine intake in a significant proportion of pregnant women. Pregnancy increases thyroid hormone requirements, and adequate iodine intake is therefore needed.Material and methodsOne hundred and forty-seven women in their third trimester (week 37) of pregnancy provided a blood sample and a 24-hour urine sample to test serum and urine iodine levels and completed a food frequency questionnaire to assess iodine intake during pregnancy. Serum TSH levels were measured in the babies born to the 140 mothers in the postpartum group.ResultsOnly 10.9% of pregnant women consumed more than 250 μg iodine daily, and 24.4% of them consumed less than 100 μg daily. Mean free T4 levels were 9.37 pmol/L, and 74 women (54.41%) had levels below the hypothyroxinemia threshold. TSH levels were normal in 135 newborns (96.4%), while 5 (3.6%) had levels higher than 5 μU/mL.     

Urinary iodine and thyroid function in a population of healthy pregnant women in the North of Spain

BackgroundIodine is an essential trace element for the synthesis of thyroid hormones, which are keys in maternal metabolism during pregnancy as well as in neurological development during fetal and postnatal life. This was a prospective study on iodine status and thyroid function in women during pregnancy in the Basque country to assess whether there was any relationship among maternal urinary iodine, maternal thyroid function and thyrotropin (TSH) in newborns, and to explore any difference in women experiencing miscarriages.MethodsWe analyzed TSH, free T₄ (FT₄), free T₃ (FT₃), thyroid peroxidase antibody (TPO-Ab) titers in serum and urinary iodine concentrations (UIC) in 2104 women in the first trimester of pregnancy and in 1322 of them in their second trimester. We obtained neonatal TSH levels in 1868 cases.ResultsIn the first (T1) and second trimesters (T2), the median UICs were 88.5 μg/L and 140 μg/L, respectively. No relationship was found between UIC and FT₄, or maternal and neonatal TSH. In T1 and T2, 9.7% and 7.5% of women were TPO-Ab positive, respectively. The total miscarriage rate was 10%. The percentage of miscarriages in healthy women was 8.9%, lower than in women with overt hypothyroidism (21.2%; p < 0.001) and than in women with subclinical hypothyroidism (15.6%; p < 0.025). The miscarriage rate was not higher in TPO-Ab-positive women.ConclusionsIn this study most women had iodine deficiency during pregnancy. Neonatal TSH is not correlated with maternal UIC during pregnancy. Pregnant women with hypothyroidism have a higher rate of miscarriages.     

Thyroid Function and Serum Copper,Selenium, and Zinc in General U.S. Population

Association of the levels of serum selenium (Se), zinc (Zn), and copper (Cu) with thyroid function was assessed by analyzing data from National Health and Nutrition Examination Survey for the cycle 2011–2012. Thyroid function variables analyzed were as follows: thyroid-stimulating hormone (TSH), free and total triiodothyronine (FT3, TT3), free and total thyroxine (FT4, TT4), and thyroglobulin (TGN). Regression models with log-transformed values of thyroid hormones as independent variables and age, race/ethnicity, smoking and iodine sufficiency status, respondents’ education, and levels of Se, Zn, and Cu as dependent variables were fitted. For males, levels of Zn were associated with decreased levels of FT4 and TT4, and levels of Cu were associated with increased levels of FT4 and TT4. For females, levels of Cu were associated with increased levels of TT3 and TT4. Smoking was found to be associated with lower levels of TSH and higher levels of TGN in males. Smoking was found to be associated with lower levels of TT4 in females. Males had about 5–10 % higher levels of both Se and Zn, but as much as 20 % lower levels of Cu than females. Smoking was associated with lower levels of Zn, but higher levels of Cu in males.     

Valoración de la función tiroidea durante la gestación: intervalos de referencia de tirotropina y tiroxina no unida a proteína durante el primer trimestre

Background and objectivesThe physiological changes that occur during pregnancy affect the physiology of the thyroid gland. Consequently, interpretation of thyroid function markers during pregnancy requires trimester-specific reference intervals. The aims of our study were to: 1) establish first-trimester reference intervals for biochemical markers of thyroid function [thyroid-stimulating hormone (TSH) and free thyroxine (T4)] and 2) to establish the prevalence of autoimmune thyroid disease in pregnant women resident in Cartagena (Murcia, Spain).Patients and methodA total of 441 women between weeks 11 and 13 of pregnancy were included in this study. A blood sample was extracted from all women to measure TSH, free T4 and antithyroid antibodies. Reference intervals for TSH and free T4 were determined in 400 pregnant women without autoimmune thyroid disease or known thyroid disease.ResultsAutoimmune thyroid disease was detected in 23 pregnant women (5.2%) who showed TSH levels higher than those in pregnant women without thyroid autoimmunity. First-trimester reference intervals were as follows: TSH: 0.130–3.710 mUI/L; free T4: 0.89–1.50 ng/dL. These reference intervals differed from the non-pregnant reference intervals used in our laboratory.ConclusionsThe reference intervals established are useful to evaluate thyroid function in women between 11 and 13 weeks of pregnancy. Interpretation of thyroid function requires intervals established in a reference population without autoimmune thyroid disease and with the methodology usually used to analyze these markers.     

Iodine, Selenium, and Other Trace Elements in Urine of Pregnant Women

The purpose of this work was to determine trace element levels in urine and evaluate possible associations between urinary iodine concentration (UIC), other trace elements (Cr, Cu, Fe, Mn, Na, Se, Zn), toxic elements (Cd, Pb), anthropometrical measures (body weight and height), glycemic indices (serum insulin and glucose), and several parameters related to thyroid function (thyroid stimulating hormone, free thyroxine, antithyroid peroxidase antibodies, thyroid volume, and thyroid echogenicity) in pregnant women. One hundred sixty-nine participants were recruited. The whole study group, originating from Krakow region, comprised three subgroups belonging to three trimesters: I trimester (n?=?28), II trimester (n?=?83), and III trimester (n?=?58). Trace elements were determined using inductively coupled plasma mass/(atomic emission) spectrometry. Partial least square model was used to reveal correlation structure between parameters investigated, as well as a possible causal relationship between dependent parameters and potentially explanatory parameters. Results obtained for trace and toxic elements in urine were comparable with results of other authors, although the study group was not homogenous. We confirmed (1) low iodine excretion in pregnant women, (2) the existence of statistically significant correlation between UIC and urinary selenium, and (3) lack of correlation between latter parameter and typical indices of thyroid function. Urinary selenium correlated with other urinary trace elements, but physiological significance of this finding remains uncertain. The fact that a large number of pregnant women fail to meet dietary recommendations for iodine is the major reason for concern.     

Maternal thyroid function in early and late pregnancy.

Thyroid function was investigated during and after pregnancy in 12 healthy euthyroid women. During pregnancy, serum total T4 (TT4) levels were significantly elevated and nearly stable, while thyroxine-binding globulin (TBG) levels progressively increased till the 7th month. A slight elevation, though not significant, of free T4 (fT4) was recorded in early pregnancy. In the following months, fT4, free T3 (fT3) and the T4/TBG ratio progressively diminished, reaching a plateau at the 7th month. Serum TSH levels, measured by an ultrasensitive immunofluorometric assay, were comparable to postpartum values during the first trimester and showed a moderate upward trend with the progression of pregnancy. The evaluation of 24-hour TSH profiles was performed in 5 women during the first trimester of pregnancy. In all women, the circadian rhythm of TSH was present with a normal nocturnal surge, though anticipated in 1 case. In summary (1) during the first trimester of pregnancy, the increased thyroid activity does not seem to be only sustained by pituitary TSH which remains unmodified; the negative correlation between TSH and hCG levels might suggest that hCG also stimulates the gland to increase thyroid hormone output, and the presence of a normal TSH circadian rhythm indicates that the central mechanism of neuroregulation of the pituitary-thyroid axis is preserved in early pregnancy, and (2) in late pregnancy, a marked decrease in free thyroid hormone fractions is accompanied by serum TSH levels still in the normal range, indicating a modification of thyroid homeostasis which might recognize various etiological factors.     

甲状腺功能5 项检测在妊娠期妇女中的应用

目的:分析甲状腺功能5项检测在妊娠期妇女中的应用价值,为制定妊娠期妇女的甲状腺功能指标的参考值范围提供依据。方法:选取2013年8月~2014年12月我院收治的826例健康妊娠妇女(实验组)与794例非妊娠育龄妇女(对照组)为研究对象。采用电化学发光法检测甲状腺功能5项指标,即三碘甲腺原氨酸(TT3)、甲状腺素(TT4)、促甲状腺激素(TSH)、游离三碘甲腺原氨酸(FT3)、游离甲状腺素(FT4),比较两组甲状腺功能异常率,并比较5项指标在妊娠早、中、晚期妇女与对照组中的差异。结果:(1)实验组甲状腺功能异常的发生率(39.10%)显著高于对照组(17.63%),差异有统计学意义(P0.05);(2)实验组FT4、TT4水平随着妊娠期的进展逐渐降低,TSH水平逐渐升高,且均低于对照组水平,差异有统计学意义(P0.05);而各妊娠期FT3、TT3水平比较差异无统计学意义,但均略低于对照组(P0.05)。结论:甲状腺功能5项指标检测应作为妊娠期妇女的孕期必查项目之一,且制定早、中、晚期妊娠期妇女的甲状腺功能5项指标参考值范围十分必要。     

Effect of Environmental Perchlorate on Thyroid Function in Pregnant Women from Córdoba,Argentina, and Los Angeles,California

ObjectiveTo determine whether environmental perchlorate exposure adversely affects thyroid function in women in the first trimester of pregnancy.MethodsFirst-trimester pregnant women were recruited from prenatal clinics in the Los Angeles County Hospital, Los Angeles, California, and in the Hospital Universitario de Maternidad dependent Universidad Nacional de Córdoba, Córdoba, Argentina, between 2004 and 2007. Spot urine and blood specimens were obtained during the clinic visit. Urinary perchlorate, iodine, and creatinine were measured, and thyroid function tests were performed.ResultsThe study included 134 pregnant women from Los Angeles, California (mean gestational age ± SD = 9.1 ± 2.2 weeks), and 107 pregnant women from Córdoba, Argentina (mean gestational age = 10.0 ± 2.0 weeks). Median urinary iodine values were 144 mg/L in California and 130 mg/L in Argentina. Urinary perchlorate levels were detectable in all women (California: median, 7.8 mg/L [range, 0.4-284 mg/L] and Argentina: median, 13.5 mg/L [range, 1.1-676 mg/L]). Serum thyroperoxidase antibodies were detectable in 21 women from California (16%) and in 17 women from Argentina (16%). Using Spearman rank correlation analyses, there was no association between urinary perchlorate concentrations and serum thyrotropin, free thyroxine index, or total triiodothyronine values, including within the subset of women with urinary iodine values less than 100 mg/L. In multivariate analyses using the combined Argentina and California data sets and adjusting for urinary iodine concentrations, urinary creatinine, gestational age, and thyroperoxidase antibody status, urinary perchlorate was not a significant predictor of thyroid function.ConclusionsLow-level perchlorate exposure is ubiquitous, but is not associated with altered thyroid function among women in the first trimester of pregnancy. (Endocr Pract. 2011;17:412-417)     

Thyroid function and obesity in children and adolescents

The aim of this retrospective study was to investigate the frequency of thyroid dysfunction as assessed by TSH, T3 and T4 in a large cohort of 290 obese and 280 healthy children. In addition, thyroid autoantibodies were measured in random subgroups of 123 obese and 80 control children, iodine excretion in 50 and thyroid volume in 23 of the obese children. Elevated TSH levels (>4 U/l) were found in 22 obese children (7.5%), but only in one control (0.3%). The medians of TSH and T3 concentrations were normal, but significantly higher in the obese group than in the controls, while T4 levels did not differ. The prevalence of positive thyroid autoantibodies was increased in the obese children, for the most part in those with elevated TSH. There was no evidence for iodine deficiency as a cause of the average increase of TSH. We conclude that in childhood obesity TSH and T3 levels are significantly increased; in most cases, however, these increases are not accounted for by thyroid autoimmunity or iodine deficiency. As a consequence, TSH elevations with normal thyroid hormone levels in obese children don't need any thyroxine treatment, if thyroid disorders were definitely excluded beforehand.     

Iron Deficiency,a Risk Factor for Thyroid Autoimmunity During Second Trimester of Pregnancy in China

ObjectivePrevious studies have reported an association between iron deficiency (ID) and increased thyroid peroxidase antibody (TPO-Ab) during early pregnancy. The objective of this study was to explore the relationship between ID and thyroid dysfunction, as well as thyroid autoantibodies, during the second trimester of pregnancy.MethodsA total of 1,592 pregnant women (13 to 28 weeks gestation) were enrolled in this cross-sectional study. According to serum ferritin (SF) concentrations, they were divided into ID (SF <20 μg/L) or non-ID (SF ≥20 μg/L) groups. Logistic regression analysis was used to evaluate the association between ID and subclinical hypothyroidism (thyroid-stimulating hormone [TSH] >4.0 mIU/L and free thyroxine [FT4] within the reference range) and thyroid autoimmunity.ResultsThe prevalence of ID was 23.43% (373/1,592). Compared with the non-ID group, the ID group had lower FT4 levels (13.94 pmol/L [8.91 to 29.82 pmol/L] versus 14.63 pmol/L [8.22 to 47.24 pmol/L]; P<.001]) and higher TSH levels (1.85 mIU/L [0.01 to 7.84 mIU/L] versus 1.69 mIU/L [0.01 to 10.2 mIU/L]; P<.05). Logistic regression analysis confirmed ID as a risk factor for increased thyroglobulin antibody (TG-Ab) (odds ratio 1.974; 95% confidence interval 1.065, 3.657; P<.05), but not for subclinical hypothyroidism or increased TPO-Ab.ConclusionID is associated with increased TG-Ab during the second trimester of pregnancy.     

Selenium Status Is Positively Associated with Bone Mineral Density in Healthy Aging European Men

ObjectiveIt is still a matter of debate if subtle changes in selenium (Se) status affect thyroid function tests (TFTs) and bone mineral density (BMD). This is particularly relevant for the elderly, whose nutritional status is more vulnerable.ResultsThe overall Se status in our population was low normal with only 0.5% (2/387) of subjects meeting the criteria for Se deficiency. SePP and Se levels were not associated with thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroxine (T4), triiodothyronine (T3) or reverse triiodothyronine (rT3) levels. The T3/T4 and T3/rT3 ratios, reflecting peripheral metabolism of thyroid hormone, were not associated with Se status either. SePP and Se were positively associated with total BMD and femoral trochanter BMD. Se, but not SePP, was positively associated with femoral neck and ward''s BMD. Multivariate linear analyses showed that these associations remain statistically significant in a model including TSH, FT4, body mass index, physical performance score, age, smoking, diabetes mellitus and number of medication use.ConclusionOur study demonstrates that Se status, within the normal European marginally supplied range, is positively associated with BMD in healthy aging men, independent of thyroid function. Thyroid function tests appear unaffected by Se status in this population.     

Trimester-specific thyroid hormone reference ranges in Sudanese women

Background

Trimester-specific reference ranges for T3, T4, and TSH need to be established in different communities. Neither Sudan nor other African countries have established trimester-specific reference ranges for TSH, free T3 (FT3), and free T4 (FT4) in healthy pregnant women. This study aimed to establish trimester-specific reference ranges for TSH, FT3, and FT4 in healthy pregnant Sudanese women.

Results

We performed a longitudinal study, which included 63 women with singleton pregnancies who were followed since early pregnancy until the third trimester. The study was performed in Saad Abu-Alela Hospital, Khartoum, Sudan, during January to October 2014. An equal number of age- and parity-matched non-pregnant women were enrolled as a control group. Basic clinical and obstetrics data were gathered using questionnaires. TSH, FT3, and FT4 levels were measured. Median (5th–95th centile) values of TSH, FT3, and FT4 were 1.164 IU/ml (0.079–2.177 IU/ml), 4.639 nmol/l (3.843–6.562 nmol/l), and 16.86 pmol/l (13.02–31.48 pmol/l) in the first trimester. Median values of TSH, FT3, and FT4 were 1.364 IU/ml (0.540–2.521 IU/ml), 4.347 nmol/l (3.425–5.447 nmol/l), and 13.51 pmol/l (11.04–31.07 pmol/l) in the second trimester. These values were 1.445 IU/ml (0.588–2.460 IU/ml), 4.132 nmol/l (3.176–5.164 nmol/l), and 12.87 pmol/l (9.807–23.78 pmol/l) in the third trimester, respectively. TSH levels increased throughout the trimesters. FT3 and FT4 levels were significantly higher in the first trimester compared with the second and third trimesters. TSH, FT3, and FT4 levels were significantly lower in pregnant women compared with non-pregnant women (P?<?0.001).

Conclusions

The present study is the first to establish trimester-specific reference ranges of TSH, FT3, and FT4 in Sudanese women with normal pregnancies. Our results suggest that pregnancy is likely to suppress TSH, T3, and T4 levels in healthy women.