Reference Intervals of Alpha-Fetoprotein and Carcinoembryonic Antigen in the Apparently Healthy Population

Establishment of tumor marker reference intervals for different age and gender groups in the healthy population of South China

To establish age- and sex-specific reference intervals (RIs) for serum tumor markers (AFP, CEA, CA125, CA199, CA153, HE4, CA724, CYFRA21-1, PSA, and NSE) among a cohort of healthy individuals in South China, a retrospective analysis was conducted on 51,353 samples collected from 2015 to 2020, during health assessments at Guangdong Provincial People's Hospital. The influence of age and gender on serum tumor markers was investigated. New RIs were determined using non-parametric rank-based methods per CLSI EP28-A3C guidelines. Significant differences were detected across age groups for AFP, CEA, CA125, CA199, HE4, CYFRA21-1, PSA, and NSE (p < 0.05). The upper reference limits (URLs) for CA153 and HE4 are significantly lower compared to our current laboratory standards. The URL for CA125 exceeds these limits in individuals under 50 but decreases in those aged 50 and above. For CA199, CEA, and PSA, the URLs are below current standards in individuals younger than 60 but exceed them in those aged 60 and older. Noteworthy elevations were observed in CA724, CYFRA21-1, and NSE levels. Our study establishes age- and sex-specific RIs for ten serum tumor markers among healthy individuals from South China, providing a fundamental resource for the prevention, early detection, and management of tumor-related disorders.

Development of next-generation reference interval models to establish reference intervals based on medical data: current status, algorithms and future consideration

Evidence derived from laboratory medicine plays a pivotal role in the diagnosis, treatment monitoring, and prognosis of various diseases. Reference intervals (RIs) are indispensable tools for assessing test results. The accuracy of clinical decision-making relies directly on the appropriateness of RIs. With the increase in real-world studies and advances in computational power, there has been increased interest in establishing RIs using big data. This approach has demonstrated cost-effectiveness and applicability across diverse scenarios, thereby enhancing the overall suitability of the RI to a certain extent. However, challenges persist when tests results are influenced by age and sex. Reliance on a single RI or a grouping of RIs based on age and sex can lead to erroneous interpretation of results with significant implications for clinical decision-making. To address this issue, the development of next generation of reference interval models has arisen at an historic moment. Such models establish a curve relationship to derive continuously changing reference intervals for test results across different age and sex categories. By automatically selecting appropriate RIs based on the age and sex of patients during result interpretation, this approach facilitates clinical decision-making and enhances disease diagnosis/treatment as well as health management practices. Development of next-generation reference interval models use direct or indirect sampling techniques to select reference individuals and then employed curve fitting methods such as splines, polynomial regression and others to establish continuous models. In light of these studies, several observations can be made: Firstly, to date, limited interest has been shown in developing next-generation reference interval models, with only a few models currently available. Secondly, there are a wide range of methods and algorithms for constructing such models, and their diversity may lead to confusion. Thirdly, the process of constructing next-generation reference interval models can be complex, particularly when employing indirect sampling techniques. At present, normative documents pertaining to the development of next-generation reference interval models are lacking. In summary, this review aims to provide an overview of the current state of development of next-generation reference interval models by defining them, highlighting inherent advantages, and addressing existing challenges. It also describes the process, advanced algorithms for model building, the tools required and the diagnosis and validation of models. Additionally, a discussion on the prospects of utilizing big data for developing next-generation reference interval models is presented. The ultimate objective is to equip clinical laboratories with the theoretical framework and practical tools necessary for developing and optimizing next-generation reference interval models to establish next-generation reference intervals while enhancing the use of medical data resources to facilitate precision medicine.

Reference intervals: past, present, and future

Clinical laboratory test results alone are of little value in diagnosing, treating, and monitoring health conditions; as such, a clinically actionable cutoff or reference interval is required to provide context for result interpretation. Healthcare practitioners base their diagnoses, follow-up treatments, and subsequent testing on these reference points. However, they may not be aware of inherent limitations related to the definition and derivation of reference intervals. Laboratorians are responsible for providing the reference intervals they report with results. Yet, the establishment and verification of reference intervals using conventional direct methods are complicated by resource constraints or unique patient demographics. To facilitate standardized reference interval best practices, multiple global scientific societies are actively drafting guidelines and seeking funding to promote these initiatives. Numerous national and international multicenter collaborations demonstrate the ability to leverage combined resources to conduct large reference interval studies by direct methods. However, not all demographics are equally accessible. Novel indirect methods are attractive solutions that utilize computational methods to define reference distributions and reference intervals from mixed data sets of pathologic and non-pathologic patient test results. In an effort to make reference intervals more accurate and personalized, individual-based reference intervals are shown to be more useful than population-based reference intervals in detecting clinically significant analyte changes in a patient that might otherwise go unrecognized when using wider, population-based reference intervals. Additionally, continuous reference intervals can provide more accurate ranges as compared to age-based partitions for individuals that are near the ends of the age partition. The advantages and disadvantages of different reference interval approaches as well as the advancement of non-conventional reference interval studies are discussed in this review.

Evaluation of Analytical Performances of Magnetic Force-Assisted Electrochemical Sandwich Immunoassay for the Quantification of Carcinoembryonic Antigen

Carcinoembryonic antigen (CEA) is a biomarker indicated in different cancers, targeted for quantitative analysis via immunoassay. Here we introduce a new technique called magnetic force-assisted electrochemical sandwich immunoassay (MESIA) for determination of CEA level in a drop of human serum using a fully automated point-of-care testing (POCT) device. The analytical performances of the assay are assessed based on precision, accuracy, limit of blank (LoB), limit of detection (LoD) and limit of quantitation (LoQ), linearity, Hook effect, interference, cross-reactivity, and method comparison following the guidelines of the Clinical Laboratory Standards Institute (CLSI). The LoD is 0.50 ng/ml. A linear relationship is shown in the range of 0.5–200 ng/ml. A high dose effect is not seen up to approximately 500,000 ng/ml. The recovery range is from 94.7 to 108.9%. The %CV of run-to-run and within-lab variations are less than 2.04 and 4.41% across the CEA concentrations, respectively, whereas reproducibility is 4.45–6.24%. Method comparison shows that the assay correlates well with the reference device (R² = 0.9884). The assay demonstrates acceptable precision, accuracy, LoB, LoD and LoQ, hook effect, linearity, interference, cross-reactivity, and high correlation with its reference device. Thus, the system is suitable for the quantification of CEA in clinical practices with a POCT manner.

Reference interval for urinary neutrophil gelatinase-associated lipocalin in healthy adults in Jiangsu region in Eastern China: a multicenter study

Aim: We explored the concentrations of urinary neutrophil gelatinase-associated lipocalin (NGAL) in healthy adults in the Jiangsu region in Eastern China and established a reference interval using latex-enhanced immunoturbidimetry to provide important guidelines for the interpretation and application of urinary NGAL in clinical practice. Methods: In total, 1970 eligible subjects from four regions were included in this study. The urinary NGAL levels were measured using an AU5800 automatic biochemical analyzer with its matched reagents. The urinary NGAL reference interval was established using the one-sided percentile method (95th percentile). Results: The urinary NGAL data were non-normally distributed. The urinary NGAL levels were not significantly different by sex or age. Therefore, the urinary NGAL reference interval in healthy adults in the Jiangsu region in Eastern China was <87.5 ng/ml (95th percentile of the upper limit). Conclusion: Urinary NGAL reference interval will play an important role in promoting the clinical value of urinary NGAL.

Distribution of urinary N-acetyl-beta-D-glucosaminidase and the establishment of reference intervals in healthy adults

BACKGROUND

Urinary N-acetyl-beta-D-glucosaminidase (NAG) plays an important role in the early diagnosis and progression of diseases related to renal tubular injury. We detected the urinary NAG concentration, assessed the preliminary statistics of its distribution, and established reference intervals for healthy adults in China using the rate method.

METHODS

A total of 1,095 reference individuals (aged 20 to 79 years) met the requirements for inclusion in this study. Urinary NAG concentrations were detected using an AU5800 automatic biochemical analyzer with its matched reagents. The Kolmogorov-Smirnov test was used to analyze the normality of the data. According to the guidelines of C28-A3 and WS/T 402-2012, the reference intervals of urinary NAG were established using the nonparametric percentile method (unilateral 95th percentile).

RESULTS

The urinary NAG data showed a non-normal distribution. The distribution of urinary NAG was significantly different by sex and age. Therefore, the reference intervals of urinary NAG were established using the rate method: males (aged 20-59 years) <19.4 U/L (90% CI: 18.0-20.3 U/L); males (aged 60-79 years) <22.3 U/L (90% CI: 20.2-22.6 U/L); females (aged 20-59 years) <15.7 U/L (90% CI: 15.2-16.5 U/L); and females (aged 60-79 years) <21.4 U/L (90% CI: 20.3-22.3 U/L).

CONCLUSIONS

We established preliminary reference intervals of urinary NAG for healthy adults in China to provide guidance for health screening, auxiliary diagnosis, and treatment monitoring of renal tubule-related diseases.

Minimal increases of serum alpha-foetoprotein herald HCC detection in Caucasian HBV cirrhotic patients under long-term oral therapy

BACKGROUND & AIMS

In Caucasian patients with compensated cirrhosis caused by hepatitis B virus (HBV), the risk of hepatocellular carcinoma (HCC) developing persist despite long-term nucleos(t)ide analogs (NUC) treatment. In the surveillance of this population with persistently normal transaminases because of NUCs, the added value of serum alpha-foetoprotein (AFP) monitoring is poorly defined.

METHODS

Two hundred and fifty-eight Caucasian HCC-free patients with HBV-compensated cirrhosis who started tenofovir or entecavir while having normal serum AFP levels (≤7 ng/mL) at baseline or within the first year of treatment underwent HCC surveillance by semiannual ultrasound evaluation and serum AFP determination.

RESULTS

During 96 (18-120) months of antiviral therapy, 3947 AFP values were collected, median AFP level was 2 ng/mL. Thirty-five patients developed an HCC at an overall 8-year crude cumulative incidence of 14% (annual incidence of 2%). HCC incidence increased in parallel with increasing AFP thresholds: 24%, 36%, 64% and 92% for AFP levels after exceeding 2, 4, 6 and 7 ng/mL for the first-time. Of the 12 patients who experienced an AFP rise > 7 ng/mL, 11 developed an HCC and one had liver metastases of lung cancer. Overall, an AFP > 7 ng/mL had 99.6% specificity, 31.4% sensitivity, 91.7% PPV, 90.2% NPV, LR+ 70.1 and LR- 0.69 for HCC; this excellent specificity was maintained up to 18 months before HCC detection.

CONCLUSIONS

In Caucasian patients with HBV-compensated cirrhosis on long-term NUC, an increase in AFP over 7 ng/mL shows excellent specificity, heralding HCC development within 1 year.

Reference intervals for gastrointestinal tumor markers (AFP, CEA, CA199 and CA724) in healthy adults of Han nationality in Chongqing by Roche ECLIA system

The aim of this study is to establish the reference intervals (RIs) for serum gastrointestinal tumor markers (AFP, CEA, CA199 and CA724) in healthy adults of Han nationality in Chongqing by Roche ECLIA system. According to CLSI EP28-A3, the appropriate statistical analysis method was selected and the RIs were determined using the indirect method based on the analysis results. All the test data of the four research projects showed a skewness distribution (p < .05). Gender and age are two important factors influencing the level of detection value. According to the analysis results, the data of the four research projects were grouped by gender and age, and the non-parametric percentile method (95%, double-sided) was used to establish the RIs of each group. The established RIs were validated using the method of Reference Change Value (RCV). The relative deviations between the upper limit value of reference interval in each group of AFP and CEA and that provided by the manufacturer is all smaller than the RCV of eath, so the RIs established by this study is proved to be reliable. While, the relative deviation of the group CEA (male > 40 years old, female > 60 years old) and CA724 is higher than each RCV, which indicates that the RIs provided by the manufacturer is not applicable to the test population and test system of the laboratory. We established RIs of serum gastrointestinal tumor markers (AFP, CEA, CA199 and CA724) in healthy adults of Han nationality in Chongqing by Roche ECLIA system. Furthermore, our study suggests that it is necessary to establish the age-specific and sex-specific RIs for gastrointestinal tumor markers in different detection systems.

Comparison of Four Automated Carcinoembryonic Antigen Immunoassays: ADVIA Centaur XP, ARCHITECT I2000sr, Elecsys E170, and Unicel Dxi800

Background

Carcinoembryonic antigen (CEA) is one of the tumor markers available for evaluating disease progression status after initial therapy and monitoring subsequent treatment modalities in colorectal, gastrointestinal, lung, and breast carcinoma. We evaluated the correlations and differences between widely used, automated CEA immunoassays at four different medical laboratories.

Methods

In total, 393 serum samples with CEA ranging from 3.0 to 1,000 ng/mL were analyzed on ADVIA Centaur XP (Siemens Diagnostics, Tarrytown, NY, USA), ARCHITECT i2000sr (Abbott Diagnostics, Abbott Park, IL, USA), Elecsys E170 (Roche Diagnostics, Indianapolis, IN, USA), and Unicel DxI800 (Beckman Coulter, Fullerton, CA, USA), and the results were compared. Deming regression, Passing-Bablok regression, and Bland-Altman analyses were performed to evaluate the data correlation and % differences among these assays.

Results

Deming regression analysis of data from Elecsys E170 and UniCel DxI800 showed good correlation (y=3.1615+0.8970x). According to Bland-Altman plot, no statistically significant bias (−1.78 ng/mL [95% confidence interval: −4.02 to 0.46]) was observed between Elecsys E170 and UniCel DxI800. However, the relative differences of CEA concentrations between assays exceeded the acceptable limit of 30%. Regarding the agreement of positivity with cut-off value 5.0 ng/mL, ARCHITECT i2000sr and Elecsys E170 showed the highest agreement (95.2%), whereas ADVIA Centaur XP and ARCHITECT i2000sr showed the lowest agreement (70.7%).

Conclusions

Agreements between automated CEA immunoassays are variable, and individual CEA concentrations may differ significantly between assays. Standardization of serum CEA concentrations and further harmonization are needed.

Reference intervals of carbohydrate antigen 19-9 in the apparently healthy adult population

BACKGROUND

To establish reference intervals of carbohydrate antigen 19-9(CA 19-9) according to the CLSI CA28-A3 guideline and to evaluate age- and gender-related variations.

METHODS

Serum CA 19-9 values of 10 149 healthy subjects (from 20 years old to 60 years old) were measured from location health checkups. The relationship between CA 19-9 and age was analyzed using Spearman's approach. The reference intervals of CA19-9 were established using Q_2.5 and Q_97.5 , and the 90% confidence intervals of upper limits were calculated.

RESULTS

The reference intervals of CA 19-9 were 1.98-25.12 U/mL for males (1.97-25.06 U/mL for 20-50 years old and 2.31-26.13 U/mL for 50-60 years old) and 2.36-29.29 U/mL for adult (20-60 years old) females. The upper limit of reference intervals for all individuals was 26.45 U/mL; the level of CA 19-9 is higher in females than males. Carbohydrate antigen (CA) 19-9 is significantly associated with aging in adult males(r = .0930, P < .0001), but not in females (P = .4734).

CONCLUSIONS

Establishing reference intervals for CA19-9 and giving age-related reference intervals of CA19-9 using a big data of healthy adult, we first discovered that CA19-9 tends to increase with age in adult males but not in females.

Serum reference interval of ARCHITECT alpha-fetoprotein in healthy Chinese Han adults: Sub-analysis of a prospective multi-center study

OBJECTIVES

Alpha-fetoprotein (AFP) has been widely used in clinical practice for decades. However, large-scale survey of serum reference interval for ARCHITECT AFP is still absent in Chinese population. This study aimed to measure serum AFP levels in healthy Chinese Han subjects, which is a sub-analysis of an ongoing prospective, cross-sectional, multi-center study (ClinicalTrials.gov Identifier: NCT03047603).

METHODS

This analysis included a total of 530 participants (41.43±12.14years of age on average, 48.49% males), enrolled from 5 regional centers. Serum AFP level was measured by ARCHITECT immunoassay. Statistical analysis was performed using SAS 9.4 and R software.

RESULTS

AFP distribution did not show significant correlation with age or sex. The overall median and interquartile range of AFP was 2.87 (2.09, 3.83) ng/mL. AFP level did not show a trend of increasing with age. The new reference interval was 2.0-7.07ng/mL (LOQ- 97.5th percentiles).

CONCLUSIONS

The reference interval for ARCHITECT AFP is updated with the data of adequate number of healthy Han adults. This new reference interval is more practical and applicable in Chinese adults.