Establishment of reference intervals for serum thyroid-stimulating hormone, free and total thyroxine, and free and total triiodothyronine for the Beckman Coulter DxI-800 analyzers by indirect method using data obtained from Chinese population in Zhejiang

Abstract

Background In order to establish suitable reference intervals of thyroid‐stimulating hormone (TSH), free (unbound) T4 (FT4), free triiodothyronine (FT3), total thyroxine (T4), and total triiodothyronine (T3) for the patients collected in Zhejiang, China, an indirect method was developed using the data from the people presented for routine health check‐up. Methods Fifteen thousand nine hundred and fifty‐six person's results were reviewed. Box‐Cox or Case Rank was used to transform the data to normal distribution. Tukey and Box‐Plot methods were used to exclude the outliers. Nonparametric method was used to establish the reference intervals following the EP28‐A3c guideline. Pearson correlation was used to evaluate the correlation between hormone levels and age, while Mann‐Whitney U test was employed for quantification of concentration differences on the people who are younger and older than 50 years old. Results Reference intervals were 0.66–4.95 mIU/L (TSH), 8.97–14.71 pmol/L (FT4), 3.75–5.81 pmol/L (FT3), 73.45–138.93 nmol/L (total T4), and 1.24–2.18 nmol/L (total T3) in male; conversely, reference intervals for female were 0.72–5.84 mIU/L (TSH), 8.62–14.35 pmol/L (FT4), 3.59–5.56 pmol/L (FT3), 73.45–138.93 nmol/L (total T4), and 1.20–2.10 nmol/L (total T3). FT4, FT3, and total T3 levels in male and FT4 level in female had an inverse correlation with age. Total T4 and TSH levels in female were directly correlated. Significant differences in these hormones were also found between younger and older than 50 years old except FT3 in female. Conclusions Indirect method can be applied for establishment of reference intervals for TSH, FT4, FT3, total T4, and total T3. The reference intervals are narrower than those previously established. Age factor should also be considered.

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

“…However, various clinical laboratories use the RIs proposed by the manufacturer of these tests, which are mainly based on data from non-Chinese populations. In addition to ethnicity, the RIs for thyroid-associated hormones are influenced by several other factors, including the time of day, age, sex, iodine levels, and inter-assay differences [ 6 – 8 ]. Considering these facts, each laboratory should establish population-based and method-specific RIs, as recommended by the International Federation of Clinical Chemistry, Clinical & Laboratory Standards Institute (CLSI), and American Thyroid Association [ 9 – 11 ].…”

Reference intervals established using indirect method for serum ferritin assayed on Abbott Architect i2000SR analyzer in Chinese adults

“…Jones et al suggested that the standard parametric or non‐parametric statistical approach can be used in the indirect method for RIs when the data were collected at a community screening project or similar. In fact, the parametric approach has been used in the analysis of data from NHANES, and the non‐parametric approach has been used in a Chinese and a Turkish study, respectively . Of course, when the standard parametric approach is used, this will involve data transformation if the data are non‐normal or asymmetric distribution.…”

“…Parametric or non-parametric percentile statistical approach as described in the CLSI guidelines EP-A3 guidelines can be used to calculate RIs in indirect method. 21,24,25,33 For parametric approach, the 95% RIs (double-sided) was defined mean ± 1.96 SD; for nonparametric approach, the values of the 2.5th and 97.5th percentile were used as lower and upper limits of RIs following the guideline EP28-A3, 23 respectively. Meanwhile, the 90% confidence intervals (CI) for lower and upper limits were also calculated.…”

“…In fact, the parametric approach has been used in the analysis of data from NHANES, 21 and the non-parametric approach has been used in a Chinese and a Turkish study, respectively. 24,33 Of course, when the standard parametric approach is used, this will involve data transformation if the data are non-normal or asymmetric distribution. In this study, our data showed a significant skew distribution but were symmetrical or approximately normal distribution after transformation.…”

Optimization and validation of patient‐based real‐time quality control procedure using moving average and average of normals with multi‐rules for TT3, TT4, FT3, FT3, and TSH on three analyzers

“…Analyzers and analytes: Three Beckman Coulter DxI‐800 analyzers 11 (Beckman Coulter, S. Kraemer Boulevard) in Zhejiang Provincial People's Hospital in China were selected in our research and were named ZrmDxi_1, ZrmDxi_2, and ZrmDxi_3, respectively. Five analytes including thyrotropin (TSH), total thyroxine (TT4), total triiodothyronine (TT3), free thyroxine (FT4), and free triiodothyronine (FT3) were measured in the three analyzers every day from January 1st to September 20th in 2019.…”