Reference Intervals for Thyroid-Associated Hormones and the Prevalence of Thyroid Diseases in the Chinese Population.

BACKGROUND: Thyroid diseases are highly prevalent worldwide, but their diagnosis remains a challenge. We established reference intervals (RIs) for thyroid-associated hormones and evaluated the prevalence of thyroid diseases in China. METHODS: After excluding outliers based on the results of ultrasound screening, thyroid antibody tests, and the Tukey method, the medical records of 20,303 euthyroid adults, who visited the Department of Health Care at Peking Union Medical College Hospital from January 2014 to December 2018, were analyzed. Thyroid-associated hormones were measured by the Siemens Advia Centaur XP analyzer. The RIs for thyroid-associated hormones were calculated according to the CLSI C28-A3 guidelines, and were compared with the RIs provided by Siemens. The prevalence of thyroid diseases over the five years was evaluated and compared using the chi-square test. RESULTS: The RIs for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyroxine (TT4), and total triiodothyronine (TT3) were 0.71-4.92 mIU/L, 12.2-20.1 pmol/L, 3.9-6.0 pmol/L, 65.6-135.1 nmol/L, and 1.2-2.2 nmol/L, respectively. The RIs of all hormones except TT4 differed significantly between males and females. The RIs of TSH increased with increasing age. The prevalence of overt hypothyroidism, overt hyperthyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism was 0.5% and 0.8%, 0.2% and 0.6%, 3.8% and 6.1%, and 3.3% and 4.7% in males and females, respectively, which differed from those provided by Siemens. CONCLUSIONS: Sex-specific RIs were established for thyroid-associated hormones, and the prevalence of thyroid diseases was determined in the Chinese population.

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.

New trimester-specific reference intervals for clinical biochemical tests in Taiwanese pregnant women-cohort of TMICS.

BACKGROUND: Because there are no published biochemical reference intervals (RI) for pregnant Taiwanese women, we used an established islandwide birth cohort, the Taiwan Maternal and Infant Cohort Study, to establish RIs for important biochemical parameters in women during their 3rd trimester in Taiwan. Additionally, we compared the differences in these biochemical parameters between early third trimester (weeks 28 to 31) and late third trimester (weeks 37 to 40) of pregnant women as well as the differences in them between the third trimester and after delivery. METHODS: Between 2012 and 2015, we recruited a total of 2,136 pregnant women from nine hospitals located in northern (n = 3), central (n = 3), southern (n = 2), and eastern Taiwan (n = 1) to receive regular prenatal health examinations during their third trimester (weeks 28 to 40). After exclusion, samples obtained from 993 eligible pregnant women were analyzed. RESULTS: There were increases in both lower and upper normal limits for blood neutrophil, thyroid profile (triiodothyronine (T3) and thyroxine (T4)), testosterone, estradiol, and progesterone and decreases for RBC, hemoglobin (Hb), alanine aminotransferase (ALT) and creatinine (Cr) during their third trimesters. Women in their late third trimester (n = 378) had higher median RBC, Hb, aspartate aminotransferase (AST), Cr, thyroid-stimulating hormone (TSH), testosterone, estradiol, and progesterone and lower median platelet and insulin, compared with those in their early third trimester (n = 490). Twenty-three of the women had both third trimester and post-pregnancy data. After delivery, the women had lower median AST, ALT, insulin, T3, T4, testosterone, estradiol, and progesterone and higher median Cr, free T4, FSH, and luteinizing hormone (LH), compared to their third trimesters. CONCLUSIONS: Gestation-related changes in important biochemical parameters should be considered when evaluating clinical laboratory values in pregnant women.

Associations Between Thyroid Hormones Within the Euthyroid Range and Indices of Obesity in Obese Chinese Women of Reproductive Age.

Background: A number of researches have reported that thyroid hormones are associated with obesity. However, the relationship of serum levels of thyroid hormones in the normal range with obesity and parameters of obesity in women of childbearing age remains controversial. The purpose of this study was to examine serum levels of thyroid hormones within the normal range in obese Chinese women of reproductive age and to investigate the relationship between concentration of thyroid hormones and indices of obesity, including body mass index (BMI), waist-to-hip ratio (WHR), insulin resistance, blood glucose, blood lipids, and blood pressure. Methods: One hundred fifty-one obese women of reproductive age and 160 nonobese women of reproductive age were enrolled in this study. Serum levels of thyroid-stimulating hormone (TSH) of all subjects were within the normal reference range (0.35-4.94 mIU/L). The serum levels of free triiodothyronine (FT3), free thyroxine (FT4), and TSH, height, body weight, BMI, waist and hip circumferences, WHR, fasting blood glucose (FBG), fasting insulin (FI), homeostasis model assessment of insulin resistance (HOMA-IR), total triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured in all subjects. Quantile regression analysis was used to analyze the associations of serum levels of FT3, FT4, and TSH with values of BMI, WHR, FBG, FI, HOMA-IR, TG, TC, LDL-C, HDL-C, SBP, and DBP. Results: In the group of obese women, serum levels of FT4 were lower (P < 0.001) and serum levels of TSH were higher (P < 0.001) compared with nonobese controls. After adjusting for covariables, quantile regression analysis showed that serum levels of FT4 were inversely associated with BMI values between the quantile levels of 0.29 and 0.60 of BMI (i.e., BMI level of 22.49 and 28.31 kg/m2, respectively). Meanwhile, we found that serum levels of TSH positively correlated with BMI values after the quantile level of 0.51 (i.e., BMI level of 27.06 kg/m2), positively associated with TC after the quantile level of 0.6 (i.e., TC level of 4.86 mM), and positively associated with LDL-C after the quantile level of 0.39 (i.e., LDL level of 1.96 mM). No significant associations were found between serum levels of thyroid hormones and values of WHR, FBG, FI, HOMA-IR, TG, HDL-C, SBP, and DBP. Conclusions: FT4 and TSH play an important role in regulating the weight in women with normal thyroid function during their reproductive years. Women with decreased serum FT4 or increased serum TSH levels have a higher risk of developing obesity. Besides, TSH has a significant influence on metabolism of blood lipids. Women with higher serum levels of TSH have a higher risk of incidence of lipid metabolism disorders.

Comparison of method-related reference intervals for thyroid hormones: studies from a prospective reference population and a literature review.

Introduction Reference intervals are dependent on the reference population, the analytical methods and the way the data are handled statistically. Individual method-related differences have been studied but the comparative differences in reference intervals have not. Methods We studied a reference population of healthy adult subjects and measured free thyroxine and thyroid-stimulating hormone by the four most commonly used analytical platforms used in the UK. Subjects were excluded if they were > 65 years or had positive thyroid peroxidase antibodies. We also performed a systematic literature review of thyroid hormone reference interval studies in non-pregnant adults. Results In total, 303 subjects were recruited and 42 excluded. The central 95th centile values for thyroid-stimulating hormone (mIU/L) were Abbott Architect (0.51-3.67); Beckman Unicel DxI (0.57-3.60); Roche Cobas (0.60-4.31) and Siemens Advia Centaur XP (0.63-4.29). The 95th centile values for thyroxine (pmol/L) were Abbott Architect (10.6-15.5); Beckman Unicel DxI (7.9-13.0); Roche Cobas (12.5-19.6) and Siemens Advia Centaur XP (11.8-19.0). We identified 55 papers describing thyroid reference intervals in male and non-pregnant female adults. The values for upper and lower reference intervals by manufacturer varied but were not significantly different for thyroid-stimulating hormone but were for thyroxine. Discussion Our study demonstrates clearly that there are marked variations in the reference intervals for thyroid hormones between analytical platforms. There is an urgent need for standardization of thyroid hormone assays to permit transferability of results. Until then, guidelines will need to reflect this method-related difference.

Efectos del deporte sobre la glándula tiroides / Effects of sport on the thyroid gland

La tiroides es una glándula situada en el cuello, encargada de producir dos hormonas que son esenciales para el metabolismo y el crecimiento de las personas: la triyodotironina (T3) y la tiroxina (T4). La producción en exceso o la falta de estas hormonas provoca hipertiroidismo en el primer caso e hipotiriodismo en el segundo. Ambas disfunciones de la tiroides se tratan con fármacos. En este trabajo de revisión se mostrarán los efectos del ejercicio físico en las personas que sufren bien de hipertiroidismo o de hipotiroidismo, siendo un complemento al tratamiento médico(AU)

The thyroid is a gland located in the neck, responsible for producing two hormones that are essential for the metabolism and growth of people: triiodothyronine (T3) and thyroxine (T4). The excess production or the lack of these hormones causes hyperthyroidism in the first case and hypothyroidism in the second. Both thyroid dysfunctions are treated with drugs. This review will show the effects of physical activity in people who suffer from hyperthyroidism or hypothyroidism, being a complement to medical treatment(AU)

Development of gestation-specific reference intervals for thyroid hormones in normal pregnant Northeast Chinese women: What is the rational division of gestation stages for establishing reference intervals for pregnancy women?

BACKGROUND: A laboratory- and region-specific trimester-related reference interval for thyroid hormone assessment of pregnant women was recommended. Whether the division by trimester is suitable requires verification. Here, we tried to establish appropriate reference intervals of thyroid-related hormones and antibodies for normal pregnant women in Northeast China. METHODS: A total of 947 pregnant women who underwent routine prenatal care were grouped via two methods. The first method entailed division by trimester: stages T1, T2, and T3. The second method entailed dividing T1, T2, and T3 stages into two stages each: T1-1, T1-2, T2-1, T2-2, T3-1, and T3-2. Serum levels of TSH, FT3, FT4, Anti-TPO, and Anti-TG were measured by three detection systems. RESULTS: No significant differences were found in TSH values between T1-1 group and the non-pregnant women group. However, the TSH value of the T1-1 group was significantly higher than that of T1-2 group (P<0.05). The TSH values in stage T3-2 increased significantly compared to those in stage T3-1 measured by three different assays (P<0.05). FT4 and FT3 values decreased significantly in the T2-1 and T2-2 stages compared to the previous stage (P<0.05). The serum levels of Anti-TPO and Anti-TG were not having significant differences between the six stages. CONCLUSION: The diagnosis and treatment of thyroid dysfunction during pregnancy should base on pregnancy- and method-specific reference intervals. More detailed staging is required to assess the thyroid function of pregnant women before 20 gestational weeks.

Early pregnancy thyroid hormone reference ranges in Chilean women: the influence of body mass index.

OBJECTIVE: Thyroid dysfunction and obesity during pregnancy have been associated with negative neonatal and obstetric outcomes. Thyroid hormone reference ranges have not been established for the pregnant Hispanic population. This study defines thyroid hormone reference ranges during early pregnancy in Chilean women and evaluates associations of body mass index (BMI) with thyroid function. DESIGN, PATIENTS, MEASUREMENTS: This is a prospective observational study of 720 healthy Chilean women attending their first prenatal consultation at an outpatient clinic. Thyroid function [TSH, Free T4, Total T4 and antithyroid peroxidase antibodies (TPOAb)] and BMI were assessed at 8·8 ± 2·4 weeks of gestational age. RESULTS: Median, 2·5th percentile (p2·5), and 97·5th percentile (p97·5) TSH values were higher, while median, p2·5, and p97·5 free T4 values were lower in obese patients compared with normal weight patients. Obesity was associated with a median TSH 16% higher (P = 0·035) and a median free T4 6·5% lower (P < 0·01) than values from patients with normal weight. BMI had a small, but statistically significant effect on TSH (P = 0·04) and free T4 (P < 0·01) when adjusted by maternal age, TPO antibodies, parity, sex of the newborn, gestational age and smoking. In all TPOAb (-) patients, median (p2·5-p.97·5) TSH was 1·96 mIU/l (0·11-5·96 mIU/l) and median (p2·5-p.97·5) free T4 was 14·54 pmol/l (11·1 - 19·02 pmol/l). Applying these reference limits, we found a prevalence of overt and subclinical hypothyroidism of 0·9% and 3·05% respectively. CONCLUSIONS: TSH distributes at higher values and free T4 at lower values in obese pregnant women compared to normal weight pregnant women. Thyroid hormone reference ranges derived from Chilean patients with negative TPOAb are different from the fixed internationally proposed reference ranges and may be used in the Hispanic population.

Establishment of trimester-specific reference intervals for thyroid hormones in Korean pregnant women.

BACKGROUND: Establishment of trimester- and assay-specific reference intervals for every population is recommended. The aim of this study was to establish a trimester- and assay-specific reference interval for thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in Korean pregnant women. METHODS: From April 2012 to December 2012, 531 pregnant women receiving prenatal care and 238 age-matched, non-pregnant women were enrolled in this study. After excluding patients with pregnancy-associated complications or thyroid-specific autoantibody, 465 pregnant and 206 non-pregnant women were included. Non-parametric analysis (2.5-97.5th percentile) was performed to determine the reference interval. Levels of TSH and FT4 were determined by electrochemiluminescence immunoassay (Elecsys thyroid tests, Roche Diagnostics, Germany). RESULTS: The TSH reference intervals were 0.01-4.10, 0.01-4.26, and 0.15-4.57 mIU/L for the first, second, and third trimester, respectively. From the first trimester to the third trimester, the median TSH levels showed a significantly increasing trend (P<0.0001). The FT4 reference intervals were 0.83-1.65, 0.71-1.22, and 0.65-1.13 ng/dL for the first, second, and third trimester, respectively, showing a significantly decreasing trend (P<0.0001). CONCLUSIONS: Establishing trimester-specific reference intervals in pregnant women is essential for accurate assessment of thyroid function. Our population-specific and method-specific reference intervals will be useful for screening Korean pregnant women for thyroid disease.

Indirect estimation of reference intervals for thyroid parameters.

BACKGROUND: The aim of this work was to determine indirect reference intervals from patients' results obtained during routine laboratory work. This could be an accurate alternative to the laborious and expensive job of producing reference intervals for populations according to international recommendations. METHODS: All the results for thyrotropin (TSH), total and free thyroxine, and triiodothyronine (T4, fT4, T3, and fT3) stored in our laboratory information system between 2008 and 2011 were included in this study. We used logarithmic transformation of the raw data to exclude outliers. After visual observation of the data distribution, we estimated non-parametric reference intervals. A standard normal deviation test was performed to test the significance of differences between subgroups. RESULTS: There was no significant difference in the serum levels of the analyzed thyroid parameters, so we calculated combined reference values. However, we found a significant difference in TSH values between ambulatory and hospitalized patients, but only in 2011. Indirect reference values for TSH, T4, fT4, T3 and fT3 were 0.42 - 3.67 mIU/L, 66.0 - 136.10 nmol/L, 10.20 - 18.40 pmol/L, 1.10 - 2.39 nmol/L, and 3.17 - 5.59 pmol/L, respectively. CONCLUSIONS: The indirect determination of laboratory-specific reference intervals using patients' laboratory data is a relatively easy and inexpensive method. Also, indirect reference limits will be more precise and true if skewness and kurtosis of the distribution are not too large.

The children reference range of thyroid hormones in Northern Iran.

Hypothyroidism is associated with mental and growth abnormality in children. The aim of this study was to determine the reference range of thyroid stimulating hormone (TSH). Thyroxin (T4) and triodothyronine (T3) of children in Northern Iran. The sample population for this study consists of subjects of 4 age groups up to 21 years. The subjects were selected randomly from people referred to Danesh Medical Diagnostic Laboratory in Gorgan Northern Iran. Thyroid hormone level were investigated with Radio immunoassay. The mean concentration for T4, T3, TSH for the sample population of 4 groups were as follow (113.5, 107.4, 102.9, 99.2 nmol L(-1)), (1.9, 1.7, 1.9, 1.6 nmol L(-1)) and (2.1,3.5, 2.9, 2.7 mIu L(-1)). The mean value of T3, TSH were higher for females but the mean value of T4 was slightly higher in males. The findings of this investigation indicated that there is an inverse age correlation in particular for T4 in all age groups. On the bases of the results from this study, we conclude that reference range, in all age groups and lower, upper limits of our reference range are not universally similar; therefore determination of reference range in each region is a critical need for clinical practice.

Does normal thyroid gland by ultrasonography match with normal serum thyroid hormones and negative thyroid antibodies?

Few papers have shown that a hypoechoic appearance of the thyroid gland at ultrasonography (US) is related to a hypofunction and serum positivity of thyroid antibodies (T-Ab). However, it is not ascertained if normal thyroid appearance at US correspond to normal thyroid laboratory tests. The aim of this study was to assess the value of normal thyroid at US in predicting normal thyroid hormones and negative T-Ab in a cohort of 48 adult patients. All patients (37 females and 11 males) were referred to our hospital to undergo their first thyroid US examination, followed by a thyroid function evaluation. All subjects had normal thyroid gland at US. As a control group 65 patients with hypoechoic and inhomogeneous thyroid gland were enrolled. All 48 patients had normal free-T (3) and free-T (4) levels. While 41 patients (85.4%) showed normal TSH, in 7 subjects (14.6%) TSH was elevated and a significant (p < 0.001) difference was recorded between the two groups in mean TSH value. Positive T-Ab value was found in 5 patients (10.4%) and the remaining 43 patients (89.6%) had negative T-Ab. TSH was not significantly correlated with age, thyroid volume or BMI. The multivariate model showed that only BMI was significantly correlated to thyroid volume (p < 0.01, r(2)=0.31). These results showed that normal thyroid recorded by US matches with normal thyroid laboratory assessment to a large degree. These preliminary data need to be confirmed in a prospective study and in a larger series and should suggest the evaluation of thyrotropin and thyroid antibodies in subjects with normal thyroid gland as assessed by US.

Stability of serum thyroid hormones following 8-11 years of cold storage.

BACKGROUND: Ethnic differences necessitate a need for local reference intervals (RI), but establishing these can be challenging in some cultures that are reluctant to donate blood. Frozen sera are an alternative, but results can be questionable. Between 1998 and 2001, we collected blood samples from 343 healthy pregnant Chinese women (5-41 weeks' gestation), and in 2001 published gestational RI for thyrotropin thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) using the ACS180, now obsolete. As a pilot to re-establishing RI, TSH, FT4 and FT3 were re-assayed in archived specimens using contemporary assays. METHODS: Thirty archived specimens (-80 degrees C) with ACS180 TSH concentrations ranging from 0.25 to 3.7 mIU/L were measured using the Roche E170, Advia Centaur and Architect i2000 TSH, FT4 and FT3 assays, along with 10 newer contemporary samples. Results were compared to the original, and examined in context of past and present methodological performances in an external quality assurance (EQA) program. RESULTS: All contemporary assays detected significantly lower TSH and increased FT4 and FT3 concentrations in the stored samples. CONCLUSIONS: With reference to methodological performances in EQA, the results obtained with contemporary assays suggest analyte deterioration in specimens and thus their unsuitability for re-establishing RI.

Towards the certification of the purity of calibrant reference materials for thyroid hormones: a chicken and egg dilemma.

The certification of the purity of CRMs intended for calibration, where no other certified material already exists for comparison, raises principle questions on how to determine the purity of a "first" calibrant in the calibration hierarchy. We developed and certified two calibration CRMs for their purity in thyroid hormones taking into consideration inorganic residues, residual solvents and organic impurities detectable by HPLC-UV and HPLC-MS. IRMM-468 was certified for a thyroxine (T(4)) mass fraction of 98.6+/-0.7% and IRMM-469 was certified for a 3,3',5-triiodothyronine (T(3)) mass fraction of 97.1+/-0.7%. The approach we used aims to determine the purity of these two CRMs to the best of our knowledge and taking all scientific aspects properly into account for the estimation of an uncertainty related to the stated purity.

Reference intervals for thyroid hormones on the architect analyser.

The objective of this study was to establish reference intervals for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyronine (TT4) and total triiodothyronine (TT3) on the Architect i2000 analyser (Abbott). Serum samples were obtained from apparently healthy adults (n=217, age 18-90 years) excluding individuals taking oral contraceptives or under hormone replacement therapy. The second group were ambulatory euthyroid patients (n=323) excluding those with a history of thyroid disorders. We also investigated thyroid hormones in sera from euthyroid hospitalised patients (n=490) excluding those with severe non-thyroidal illness. The reference intervals for the healthy adults were for TSH 0.17-4.23 mIU/l, for FT4 11.24-26.86 pmol/l, for FT3 2.56-6.36 pmol/l, for TT4 55.8-155.1 nmol/l and for TT3 0.90-2.54 nmol/l. TSH and TT3 concentrations were similar in males and females. However, FT4, FT3 and TT4 levels exhibited significant differences between females and males. No significant differences were observed between the concentrations of TSH, FT3, TT3, FT4 and TT4 in healthy subjects and in euthyroid ambulatory patients aged 18-90 years. TSH levels in healthy subjects were the same in younger and older individuals. In contrast, in outpatients and in hospitalised patients TSH concentrations were significantly lower (20%) in subjects older than 50 years compared to those younger than 50 years. For FT3 and TT3 we consistently observed in all three study groups 6-7% and 8-12% higher concentrations in the younger (< 50 years) compared to the older (> 50 years) subjects. For FT4 and TT4 no consistent pattern of correlation with age was detectable when the three study groups were analysed independently. The reference intervals for thyroid hormones determined in this study differ considerably from values found in other European and non-European countries. This underlines the need for population-specific reference ranges.

A model for a multicentre approach to the derivation of reference intervals for thyroid hormones and testosterone for laboratories using identical analysers.

Ideally, every laboratory should derive their own reference intervals for all analytes, but this is difficult in practice. A survey, by questionnaire, of UK laboratories using the Chiron Diagnostics ACS:180 (Chiron Diagnostics Limited, Halstead, Essex, UK), for thyroid function tests, showed that 10% of laboratories derived their own reference intervals, 60% quoted values "adapted" from intervals for previous methods, whilst the remaining 40% quoted (often incorrectly) reference intervals supplied by the manufacturer. In addition only 13% of respondent laboratories derived their own reference intervals for testosterone. As a result of this survey, a study was devised to enable the users of the Chiron Diagnostics ACS:180 immunoassay system to develop and use within-method, between-laboratory reference intervals for thyroid hormones and testosterone. Laboratory collaboration provided the recommended minimum number of data points by establishing a reference sample group. This sample group was used for the calculation of appropriate reference intervals for each hormone according to the guidelines published by the IFCC. We propose this approach as a model for laboratories using identical instrumentation to produce, through collaboration, within-method, between laboratory reference intervals.

Can chemiluminescent immunoanalysis of thyroid hormones stand for a reference method?

Some analytical properties of chemiluminescent immunoassays (ChLIA) for the estimation of total triiodothyronine (T3), total thyroxine (T4) and thyrotropine (TSH) in serum were studied and compared with radioimmunoanalysis (RIA) as a reference method. Measurement range of ChLIA for T3 is lower, for T4 is equivalent and for TSH is greater than by RIA methods. Analytical sensitivity of ChLIA is better for all three analytes. Also precision of ChLIA is much better. ChLIA method seems to be more resistant to lipaemia. When compared to secondary reference materials, i.e. to commercial control sera, higher accuracy can be evaluated. However, adjustment of the control sera and analytical methods to different primary standards and calibrators, resulting in disagreement of results with asigned values, seems to be evident. With respect to the accuracy of ChLIA further study should be performed involving primary standards. Other interferences except of lipaemia, which we refer to in our work, and problems of specificity also need to be elucidated.