Reference Intervals For Thyroid Hormones Research Articles

Calculation of reference intervals for thyroid hormones using an indirect approach

Calculation of reference intervals for thyroid hormones using an indirect approach

Calculation of reference intervals for indicators of thyroid hormones and cortisol in horses

The article discusses the results of calculating reference intervals for thyroid hor mones and cortisol in adult horses. The study included the results of a laboratory study of the concentrations of total triiodothyronine, total and free thyroxine and cortisol from 50 horses aged 3 to 29 years, including 17 mares, 13 stallions and 20 geldings. All animals underwent an extensive biochemical blood test, the results of which revealed no pathological changes.To calculate the normative limits of fluctuations for each hormone, calculations were carried out using the Tukey method, which is used to determine the reference limits in the case of a small number of variants in the group and the absence of a normal distribution. Microsoft Excel was used for calculations. The conducted studies made it possible to clarify the reference intervals for thyroid hormones and cortisol in horses, which were: total triiodothyronine (T3) - 1.13-4.04 nmol/l, total thyroxine (T4) - 20.97-57.42 nmol/l, free thyroxine (fT4) 7.38-23.07 pmol/l, cortisol – 39.42-227.02 nmol/l. The results obtained can be recommended for use not only for the clinical and biochemical laboratory of St. Petersburg State University of Medicine, but also for all veterinary laboratories using diagnostic test systems for enzyme immunoassay of Vital Development Corporation.

Thyroid Hormone Reference Intervals among Healthy Individuals In Lanzhou, China.

The common reference intervals (RIs) for thyroid hormones currently used in China are provided by equipment manufacturers. This study aimed to establish thyroid hormone RIs in the population of Lanzhou, a city in the subplateau region of northwest China, and compare them with previous reports and manufacturer-provided values. In total, 3,123 individuals (1,680 men, 1,443 women) from Lanzhou, an iodine-adequate area of China, perceived as healthy were selected. The Abbott Architect analyzer was used to determine the serum concentration of thyroid hormones. The 95% RI was estimated using the 2.5th and 97.5th percentiles as the lower and upper reference limits, respectively. The serum levels of thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), antithyroglobulin (ATG) antibody, and antithyroid peroxidase (ATPO) antibody levels were significantly correlated with sex (P<0.05). TSH, total thyroxine (TT4), and ATPO levels were significantly correlated with age (P<0.05). The serum levels of TSH, ATG, and ATPO in men were significantly lower than in women; in contrast, the serum TT3 level was significantly higher in men than in women (P<0.05). Serum TSH, TT3, TT4, and ATG levels differed across age groups (P<0.05), but no such variation was observed for ATG levels (P>0.05). The established RIs of TSH, ATG, and ATPO in this study differed between sexes (P<0.05). The thyroid hormone RIs established herein were inconsistent with the manufacturer-provided values. The RIs of thyroid hormones in the healthy population of Lanzhou were inconsistent with those in the manufacturer's manual. Validated sex-specific values are required for diagnosing thyroid diseases.

Reference Intervals for Thyroid Hormones and Thyroid Volume in Children Aged 7 ~ 13 Years from Iodine-Sufficient Areas in Tianjin, China.

Reference intervals (RIs) for serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) suitable for local children are urgently needed in northern China. The reference interval for thyroid volume (Tvol) in Chinese children also differed greatly from that recommended by the WHO. This study aimed to establish TSH, FT3, FT4, and Tvol RIs suitable for children in northern China. A total of 1070 children aged 7 ~ 13 were recruited from iodine nutrition-sufficient areas in Tianjin, China, from 2016 to 2021. Four hundred fifty-eight children aged 7 ~ 13years, and 815 children aged 8 ~ 10years were eventually included to study RIs for the thyroid hormones and Tvol. RIs for thyroid hormones were established in accordance with the Clinical Laboratory Standards Institute (CLSI) document C28-A3 guidelines. Quantile regression was used to analyze the influencing factors of Tvol. RIs for TSH, FT3, and FT4 were 1.23 (1.14 ~ 1.32) to 6.18 (5.92 ~ 7.26) mIU/L, 5.43 (5.29 ~ 5.52) to 7.89 (7.66 ~ 7.98) pmol/L, and 13.09 (12.85 ~ 13.73) to 22.22 (21.61 ~ 22.51) pmol/L. There was no need to establish RIs by age and gender. Our RIs could increase the prevalence of subclinical hyperthyroidism (P < 0.001) and reduce the prevalence of subclinical hypothyroidism (P < 0.001). Body surface area (BSA) and age are correlated with the 97th percentile of Tvol (both P < 0.001). Our reference interval could increase the goiter rate in children from 2.97 to 4.96% (P = 0.007). The thyroid hormones' reference intervals suitable for local children should be established. In addition, BSA and age should be considered when establishing Tvol reference interval.

Thyroid hormone status during pregnancy in Bangladesh

ABSTRACT Background: Pregnancy is a physiological condition where early detection of any pathological change of thyroid hormone is very important to prevent complications. Population-specific thyroid hormone reference intervals are a key to this. Since Bangladesh is yet to develop such reference intervals, the aim of this study was to establish trimester-specific reference intervals addressing the physiological changes of thyroid hormone during pregnancy for Bangladeshi women. Materials and Methods: One thousand nine hundred and thirty-seven women with singleton pregnancy consuming iodinated salt were selected for this cross-sectional study. Participants having a history of thyroid disorder (TD), any illness influencing thyroid function, presence of goiter, recent history of consumption of thyroid status-altering medications, family history of TDs, and presence of thyroid antibodies were excluded from the study. 1038 pregnant women with thyroid-stimulating hormone (TSH) level within normal (nonpregnant) laboratory reference value (0.35–5.5 μIU/mL) were considered eligible for the study. Results: The mean age of the eligible cases was 28.06 ± 4.633 years ranging from 18 years to 42 years. The mean gestational ages of the study population while checking thyroid function were 8.83 ± 2.344 weeks, 19.99 ± 4.824 weeks, and 31.77 ± 2.123 weeks during 1st, 2nd, and 3rd trimesters, respectively. TSH level raised significantly from 1st trimester to 2nd trimester (1.85 ± 1.00 vs. 2.03 ± 1.02; P = 0.018) but the decline in 3rd trimester comparing to 2nd trimester (2.03 ± 1.02 vs. 1.90 ± 0.90; P = 0.071) was not statistically significant. The 2.5th–97.5th percentiles of TSH level of the study population were 0.440–4.050 μIU/mL, 0.531–4.570 μIU/mL, and 0.622–3.917 μIU/mL in 1st, 2nd, and 3rd trimesters, respectively. Conclusion: Reliance on nonpregnant reference intervals or any generalized gestational reference interval can hinder the desired progression of pregnancy influencing diagnosis and management for TDs in case of certain populations. Establishment of individual reference intervals for thyroid hormone in pregnancy bears great clinical importance for every population.

The reference intervals for thyroid hormones: A four year investigation in Chinese population.

The reference intervals (RIs) are of great importance for physicans to determine whether or not an individual is healthy. However, many clinical laboratories in China still adopted the default RI provided by the manufacturers; and these "uncalibrated" RIs might lead to the misdiagnosis of diseases. In the present study, we enroll reference people with the purpose of determining the RIs of serum triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) in Chinese population, and explore the possible roles of age and sex on the levels of biomarkers. Serum samples from 66,609 individuals who met the inclusion criteria were analyzed using an Roche Cobas E 601 hormone analyzer. The dynamic trends of biomarker were visually assessed by their concentrations over age and sex. Specific partitions were determined by the method of Harris and Boyd. RIs, corresponding to the 2.5th and 97.5th percentiles, as well as the 0.5th, 25th, 50th, 75th and 99.5th percentiles were calculated for each reference partition using a non-parametric rank approach. The serum level of T3, T4, FT4 or TSH showed a right-skewed distribution in both males and females while FT3 presented an approximate normal distribution. Females had a higher mode value of serum T3 or T4, but a lower mode value of serum TSH, FT3 or FT4. All five biomarkers did not need age partitioning according to the approach of harris and boyd, while T3 and FT3 need sex partitioning. The present study not only determined the age- and sex-specific trends of the five thyroid hormones, but provided sex-stratified RIs for T3 and FT3, valuably contributing to the current literature and timely evaluation of thyroid health and disease.

Reference Intervals of Thyroid Hormones During Pregnancy Established by Three Statistical Methods.

Monitoring the thyroid hormones during pregnancy is of great importance for fetal growth and development. Throughout the whole pregnancy, there is constant fluctuation in the thyroid hormone reference intervals (RIs). The purpose of this study is to determine method- and trimester-specific RIs for thyroid-stimulating hormone, free thyroxine, and free triiodothyronine in pregnant women in China. In this study, 2,167 women with normal pregnancies (first trimester, n = 299; second trimester, n = 1,032; third trimester, n = 836) and 4,231 healthy nonpregnant women subjects were recruited. Serum thyroid-stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) concentrations were measured using electrochemiluminescence immunoassays in Abbott Alinity i analyzer. Following the exclusion of outliers, the RIs were determined using three statistical techniques: the non-parametric method, the Hoffmann method, and the Q-Q plot method. Pregnant women's levels of these three thyroid hormones differ markedly from those of healthy non-pregnant women. In addition, the concentrations of these three hormones change considerably over the course of the three phases of pregnancy. The Q-Q plot method offered more comparable RIs with the non-parametric method in healthy non-pregnant women than the Hoffmann method. Three statistical techniques were used to construct the trimester-specific RIs of thyroid hormones in pregnant women, and there was little difference between them all. The RIs by the non-parametric and Q-Q plot methods indicated closer RIs, and the RIs by the Hoffmann approach were higher and wider than those by the other two methods. For thyroid hormones, trimester-specific RIs are required. The RIs determined by non-parametric and Q⁃Q plot indirect calculation could be used as the alternative method.

The Significance of Trimester-Specific Thyroid Hormones Reference Intervals in Iraqi Pregnant Women

In Iraq, there is no obvious considerable data regarding trimester-specific reference intervals of thyroid hormones despite documented multiple physiological hormonal changes during pregnancy. Thus, this study aimed to determine trimester-specific reference intervals for serum TSH, FT3, and FT4 and assess the incidence of thyroid function test misinterpretation and misdiagnosis among pregnant women using non-pregnant reference intervals. A thyroid function test was performed for 774 enrolled pregnant women. Reference intervals of TSH, FT3, and FT4 were ascertained in each pregnancy trimester. It was then compared to the adult non-pregnant values, and the incidence of misinterpretation was later calculated. TSH and FT4 reference interval values were lower than non-pregnant reference interval values. The application of non-pregnant women references values in pregnant women caused a serious misinterpretation and misdiagnosis in 66 (8.5%) pregnant women regarding TSH, and 34 (4.4%) pregnant women regarding FT4, while no misdiagnosis was noticed regarding FT3. The trimester-specific reference interval values of TSH, FT3, and FT4 in Iraqi pregnant women showed an obvious variation from non-pregnant reference intervals and the urgent advice to use the trimester-specific reference intervals to avoid misclassification of thyroid dysfunction during pregnancy.

Validation and comparison of five data mining algorithms using big data from clinical laboratories to establish reference intervals of thyroid hormones for older adults

AimTo establish Reference intervals (RIs) of thyroid-related hormones in older adults using five data mining algorithms and to assess the applicability of each algorithm. MethodsRIs for thyroid-related hormones in older adults were established using five data mining algorithms based on physical examination and patient data. The results of these algorithms were compared to those of RIs established using healthy older adults recruited following strict inclusion and exclusion criteria. The bias ratio (BR) matrix was used to compare the limits of RIs established using different algorithms. ResultsConsistency across different algorithms in physical examination data was found to be greater than that of outpatient data. The transformed Hoffmann, transformed Bhattacahrya, kosmic and refineR algorithms showed good performance in calculating RIs from physical examination data. The RIs of Thyroid Stimulating Hormone (TSH) established using Expectation maximization (EM) and patient data were highly consistent with the RIs established using data from healthy older adults. ConclusionThis study recommends the use of transformed Hoffmann, transformed Bhattacahrya, kosmic, and refineR algorithms which are based on physical examination data to establish RIs for thyroid-related hormones in older adults. However, if patient data is used, then an EM algorithm combined with Box-Cox transformation is recommended for data with obvious skewness.

Preterm to term infant postmenstrual age reference intervals for thyroid-stimulating hormone and free thyroxine.

Infants born preterm are affected by a hypothalamic-pituitary-thyroid axis that is immature and still developing as they progress closer to corrected term gestation. Multiple risk factors place preterm infants at risk for a hypothyroid state. However, there is variability in thyroid-stimulating hormone cutoff values and limited data on free thyroxine reference intervals to guide clinicians. 1584 thyroid-stimulating hormone and 1576 free thyroxine laboratory samples that were originally collected to screen hospitalized infants for delayed-onset of hypothyroidism were retrospectively evaluated from a group of 1087 infants who ranged in postmenstrual age from 25 to 43 weeks gestation at the time of laboratory sample collection. Median thyroid hormone values and reference intervals were established using R and the mixtools package. Thyroid-stimulating hormone reference intervals remained similar across gestational ages from 0.340-9.681 µIU/mL in 25-27 6/7-week infants to 1.090-7.627 µIU/mL in 40-43-weeks infants. For the same age groups, free thyroxine reference intervals increased from 0.42-0.91 ng/dL to 0.87-1.32 ng/dL. The reference intervals identified suggest that infants <31 weeks gestation have a higher thyroid-stimulating hormone and lower free thyroxine level at baseline than previously anticipated. The increasing free thyroxine values in preterm to term infants indicate a maturing hypothalamic-pituitary-thyroid axis. Clinicians need thyroid hormone reference intervals that also vary by postmenstrual age to aid the evaluation of sick preterm infants who are at risk of a delayed hypothyroidism diagnosis that can be missed on the initial newborn screen. This study provides one of the largest samples of thyroid-stimulating hormone and free thyroxine data to establish reference intervals in preterm infants. Clinicians may utilize the identified postmenstrual age-based reference intervals to inform follow-up thyroid testing in preterm infants at several weeks postnatal age.

Age- and sex-specific reference intervals for thyroid hormones in a Chinese pediatrics: a prospective observational study of 1,279 healthy children.

BackgroundThyroid hormones are essential for early neurocognitive development and growth and development in childhood and adolescence. However, the reference intervals (RIs) for thyroid hormones in Chinese pediatric individuals remain unclear. This study aimed to establish thyroid hormone RIs for a Chinese pediatric population according to appropriate age- and sex-specific partitioning.MethodsIn this prospective observational study, a total of 1,279 healthy children (singletons, aged from 1 day to 12 years) were recruited, and serum samples were analyzed on a Mindray automated chemiluminescence immunoassay analyzer CL-6000i for thyroid hormone detection, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), total triiodothyronine (T3), and total thyroxine (T4). Age and sex-specific RIs were established, and the corresponding 95% confidence intervals (CIs) were calculated in accordance with the Clinical Laboratory Standards Institute (CLSI) document C28-A3 guidelines.ResultsQuantile testing revealed that the median (P50) and RIs [2.5th percentile (P2.5)–97.5th percentile (P97.5)] for TSH, FT3, T3, and T4 of males differed significantly from those of females (P<0.05), except for FT4 (P=0.483). For FT3 and T3, the RIs of males were higher than that of females, and the RI of T4 for males was narrower and higher than that of females [P2.5–P97.5: 72.33–171.60 vs. 72.31–176.27 nmol/L; P50: 116.75 vs. 113.47 nmol/L, P=0.011]. RIs for TSH, FT3, FT4, T3, and T4 showed sex- and age-specific properties and displayed a wide variation during the first month of life but gradually narrowed and concentrated with increasing age. In addition, RIs of TSH, FT3, FT4, and T3 in males differed significantly from females in the first month of life (TSH: 1.46–10.87 vs. 1.08–11.35 mIU/L; FT3: 2.96–7.08 vs. 2.35–7.27 pmol/L, FT4: 13.34–28.65 vs. 13.82–31.83 pmol/L; T3: 0.83–2.33 vs. 0.72–2.46 nmol/L). The RI of T4 also exhibited a difference between males and females in the 9- to 12-year age group (59.31–150.72 vs. 63.29–146.94 pmol/L for males and females, respectively).ConclusionsPediatric RIs of thyroid hormones display age- and sex-specific trends. The RIs established in this study will improve the accuracy of TSH assay result interpretations and clinical decision-making in clinical laboratories that utilize the Mindray analytical platform.

Correction: Reference Intervals for Thyroid Hormones During the First Trimester of Gestation: A Report from an Area with a Sufficient Iodine Level.

Correction: Reference Intervals for Thyroid Hormones During the First Trimester of Gestation: A Report from an Area with a Sufficient Iodine Level.

Reference Intervals for Thyroid Hormones During the First Trimester of Gestation: A Report from an Area with a Sufficient Iodine Level.

A concern was raised 1 regarding the number of pregnant women in the analysis of reference range for the thyroid hormones in pregnancy 2, where we reported 185 cases and it was believed to be 145 cases.

Importance of Setting Up Reference Intervals and Multiple of Medians (MoM).

I was interested in the article of Kianpour et al. on reference intervals for thyroid hormones during the first trimester of gestation from an area with sufficient iodine level 1. The unavailability of data in this population had triggered this study where 436 pregnant and 444 non-pregnant women were recruited. I appreciate the great effort taken by the authors to recruit such a large population for the study. Following screening as per exclusion criteria 291 pregnant women were eliminated and thus the data of 145 pregnant was included for analysis. However, the article mentions the analysis of samples of 185 patients. The authors have also calculated the multiples of medians (MoM) to unitise different laboratory reports.

Method-dependent variation in TSH and FT4 reference intervals in pregnancy: A systematic review.

Gestational TSH and FT4 reference intervals may differ according to assay method, but the extent of variation is unclear and has not been systematically evaluated. We conducted a systematic review of published studies on TSH and FT4 reference intervals in pregnancy. Our aim was to quantify method-related differences in gestation reference intervals, across four commonly used assay methods, Abbott, Beckman, Roche and Siemens. We searched the literature for relevant studies, published between January 2000 and December 2020, in healthy pregnant women without thyroid antibodies or disease. For each study, we extracted trimester-specific reference intervals (2.5-97.5 percentiles) for TSH and FT4 as well as the manufacturer-provided reference interval for the corresponding non-pregnant population. TSH reference intervals showed a wide range of study-to-study differences with upper limits ranging from 2.33 to 8.30 mU/L. FT4 lower limits ranged from 4.40 to 13.93 pmol/L, with consistently lower reference intervals observed with the Beckman method. Differences between non-pregnant and first trimester reference intervals were highly variable, and for most studies, the TSH upper limit in the first trimester could not be predicted or extrapolated from non-pregnant values. Our study confirms significant intra- and intermethod disparities in gestational thyroid hormone reference intervals. The relationship between pregnant and non-pregnant values is inconsistent and does not support the existing practice in many laboratories of extrapolating gestation references from non-pregnant values. Laboratories should invest in deriving method-specific gestation reference intervals for their population.

First Estimation of Reference Intervals for Thyroid-Stimulating Hormone and Thyroid Hormones in Slovenian Population

For thyroid function estimation and clinical decision making, use of appropriate reference intervals for thyroid-stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) is crucial. For each laboratory, establishment of own reference intervals is advised. For the first Slovenian estimation of reference intervals for thyroid hormones a large group of 1722 healthy individuals without thyroid disease was established retrospectively. Hormone analyses were performed on automated analyser Advia Centaur XP Immunoassay System (Siemens Healthineers), which reference intervals for TSH, fT4 and fT3 were 0.55-4.78 mIU/L, 11.5-22.7 pmol/L, and 3.5-6.5 pmol/L, respectively. Statistical analysis followed non-parametric percentile method. Our laboratory reference intervals for TSH, fT4 and fT3 are mostly narrower than intervals given by manufacturer. Median value, lower and upper limit for TSH, fT4 and fT3 were 1.98 (0.59-4.23) mIU/L, 14.5 (11.3-18.8) pmol/L and 4.82 (3.79-6.05) pmol/L, respectively. Most likely, an inclusion of a high number of healthy individuals without thyroid disease was a reason for such results.

Establishment of assay method- and trimester-specific reference intervals for thyroid hormones during pregnancy in Chengdu, China.

BackgroundThe reference intervals of thyroid hormone will change at different stages of pregnancy because of physiological alterations. On the other hand, the reference intervals of thyroid hormone will also change in different detection systems due to the manufacturer's methodology as well as a different race. The objective of this study was to establish the assay method‐ and trimester‐specific reference intervals for thyroid‐stimulating hormone, free thyroxine and free triiodothyronine for pregnant women in Chengdu.MethodsA prospective, population‐based cohort study involved 23,701 reference samples of pregnant women during the three trimesters and 8646 non‐pregnant women with pre‐pregnancy clinical and laboratory tests. The 2.5th and 97.5th percentiles were calculated as the reference intervals for thyroid‐stimulating hormone, free thyroxine and free triiodothyronine at each trimester of pregnant women according to ATA Guidelines.ResultsThe reference interval of thyroid‐stimulating hormone in the 2.5th and 97.5th percentiles has a significant increasing trend from the first trimester, to second trimester and to third trimester, which was 0.08–3.79 mIU/L for the first trimester, and 0.12–3.95 mIU/L for the second trimester and 0.38–4.18 mIU/L for the third trimester, respectively (p < 0.001). However, the reference intervals of free thyroxine and free triiodothyronine in the 2.5th and 97.5th percentiles have significant decreasing trends from the first trimester, to second trimester and to third trimester, which were 11.87–18.83 pmol/L and 3.77–5.50 pmol/L for the first trimester, and 11.22–18.19 pmol/L and 3.60–5.41 pmol/L for the second trimester, and 10.19–17.42 pmol/L and 3.37–4.79 pmol/L for the third trimester, respectively (both p < 0.001).ConclusionIt is necessary to establish assay method‐ and trimester‐specific reference intervals for thyroid‐stimulating hormone, free thyroxine, and free triiodothyronine because the reference intervals of these thyroid hormones are significantly different at different stages of pregnancy.

Establishment of Early Pregnancy Related Thyroid Hormone Models and Reference Intervals for Pregnant Women in China Based on Real World Data.

Thyroid hormone reference intervals are crucial for diagnosing and monitoring thyroid dysfunction during early pregnancy, and the dynamic change trend of thyroid hormones during pregnancy can assist clinicians to assess the thyroid function of pregnant women. This study aims to establish early pregnancy related thyroid hormones models and reference intervals for pregnant women. We established two derived databases: derived database* and derived database#. Reference individuals in database* were used to establish gestational age-specific reference intervals for thyroid hormones and early pregnancy related thyroid hormones models for pregnant women. Individuals in database# were apparently healthy non-pregnant women. The thyroid hormones levels of individuals in database# were compared with that of individuals in database* using nonparametric methods and the comparative confidence interval method. The differences in thyroid stimulating hormone and free thyroxine between early pregnant and non-pregnant women were statistically significant (p<0.0001). The reference intervals of thyroid stimulating hormone, free thyroxine and free triiodothyronine for early pregnant women were 0.052-3.393 μIU/ml, 1.01-1.54 ng/dl, and 2.51-3.66 pg/ml, respectively. Results concerning thyroid stimulating hormone and free thyroxine reference intervals of early pregnancy are comparable with those from other studies using the same detection platform. Early pregnancy related thyroid hormones models showed various change patterns with gestational age for thyroid hormones. Early pregnancy related thyroid hormones models and reference intervals for pregnant women were established, so as to provide accurate and reliable reference basis for the diagnosing and monitoring of maternal thyroid disfunction in early pregnancy.

Validation of an approach using only patient big data from clinical laboratories to establish reference intervals for thyroid hormones based on data mining

BackgroundWhile many studies have established reference intervals (RIs) for thyroid hormones using patient data, this approach has not been validated. Therefore, in this study, we aimed to validate an approach for establishing RIs for thyroid hormones only using patient data from clinical laboratories. MethodsWe established two derived databases: derived database* and derived database#. Reference individuals in derived database* were selected using strict exclusion criteria, and the RIs established by the database were considered standard RIs (RIs*). Individuals in derived database# were the physical examination population, whose information was downloaded directly from the Laboratory Information System, and RIs established from this database were evaluated (RIs#). The comparative confidence interval (CI) method and consistency of the decision results based on external databases were used to compare RIs* and RIs#. ResultsRIs# and RIs* for the thyroid hormones tested were similar. The 90% CIs of the upper and lower limits of RIs for most thyroid hormones overlapped between RIs# and RIs*, and the limit of RIs# was within the 90% CI of RIs*. The consistency rates for the results of the RIs* and RIs# in the external database were greater than 98% for all thyroid hormones tested. ConclusionIt was possible to establish RIs for thyroid hormones using only patient data from clinical laboratories after adopting appropriate statistical methods.

Reference intervals for thyroid-stimulating hormone and thyroid hormones using the access TSH 3rd IS method in China.

BackgroundTo calculate the reference intervals for thyroid‐stimulating hormone (TSH) and thyroid hormones using the Access TSH 3rd IS method and evaluate the differences between age and genders in Chinese populations.MethodsThis study collected 349 serum samples of healthy subjects were from Shengli Oilfield Central Hospital in China. Subjects who tested positive for thyroid peroxidase antibody or thyroglobulin antibody were excluded. Accordingly, 313 subjects were included for establishing reference intervals for the thyroid hormones. The serum concentrations of TSH, total and free thyroxine (TT4 and FT4), and total and free triiodothyronine (TT3 and FT3) were measured using the Access TSH 3rd IS method. The 2.5th and 97.5th percentiles or mean with standard deviation were calculated as the reference interval as appropriate.ResultsThe reference intervals for TSH, FT4, FT3, TT4, and TT3 calculated in present study were 0.61‐4.16 mIU/L, 0.67‐1.11 ng/dL, 2.63‐4.33 pg/mL, 5.56‐11.33 μg/dL, and 0.72‐1.32 ng/mL, respectively. The FT3, TT4, and TT3 levels in males were significantly higher than in females (P < .05), while TSH levels in males were significantly lower than in females (P < .05). The levels of FT3 in subjects with the age of less than 30 years were significantly higher than other groups (P < .05).ConclusionThe present study provided a valid basis for the reference intervals for TSH, FT4, FT3, TT4, and TT3 in Chinese populations. In addition, this present study indicated that age and gender should be considered in diagnostic evaluation of thyroid diseases.