Biomarkers associated with coronary high-risk plaques.

Vascular inflammation, lipid metabolism, and thrombogenicity play a key role not only in atherogenesis but also in the development of acute coronary syndromes. Biomarkers associated with coronary high-risk plaques defined according to intravascular imaging have not been systematically studied. A total of 69 patients with coronary artery disease who underwent both optical coherence tomography and intravascular ultrasound imaging, and who provided blood specimens were included. Comprehensive biomarkers for inflammation, lipid, and coagulation were analyzed. Composite models sought biomarker patterns associated with thin-cap fibroatheroma (TCFA) and "high-risk plaques" (TCFA and large plaque burden). Two different composite models were developed for TCFA, based on the finding that high sensitivity C-reactive protein (hsCRP), plasminogen activator inhibitor-1, fibrinogen, IL-6, homocysteine and amyloid A levels were elevated, and high-density lipoprotein cholesterol (HDL) and bile acid levels were decreased in these patients. Both composite models were highly accurate for detecting patients with TCFA (area under curve [AUC]: 0.883 in model-A and 0.875 in model-B, both p < 0.001). In addition, creatinine, hsCRP, fibrinogen, tumor necrosis factor-α, IL-6, homocysteine, amyloid A, HDL, prothrombin, and bile acid were useful for detecting patients with "high-risk plaques". Two composite models were highly accurate for detection of patients with "high-risk plaques" (AUC: 0.925 in model-A and 0.947 in model-B, both p < 0.001). Biomarkers useful for detection of patients with high-risk coronary plaques defined according to intravascular imaging have been identified. These biomarkers may be useful to risk stratify patients and to develop targeted therapy.Clinical Trial Registration https://www.umin.ac.jp/ctr/ , UMIN000041692. Biomarkers and high-risk plaques hsCRP, PAI-1, fibrinogen, IL-6, homocysteine, amyloid A, HDL, and bile acid were useful for detecting patients with TCFA. hsCRP, fibrinogen, IL-6, homocysteine, amyloid A, creatinine, TNFα, HDL, prothrombin, and bile acid were useful for detecting patients with "high-risk plaques" (plaque which has both TCFA and large plaque burden). White arrowhead denotes TCFA. Red and green dashed lines denote lumen area and external elastic membrane area, respectively.

[The Present State of Inter-Laboratory Differences in Setting and Practicing Critical Values -Results of a Questionnaire Survey Performed to the Laboratories of Keio University-Associated Hospitals].

Presently we, Keio Endocrine and Metabolite Survey (KEMS) study group conducted a questionnaire sur- vey with respect to panic values in the laboratories belonging to Keio University-associated hospitals. As to the initial setting, most of the laboratories answered to play a leading role in preparing the necessary matters to implementation of panic values and revise them corresponding to physician's request on each occasion. In almost all laboratories, they did not verify whether the notification procedure does work to exert appropriate clinical action. The numbers of critical values answered by the 18 laboratories distributed widely in the test items (8-39) and their critical limits (10-68). As to the critical limits, the lower limits of serum K and blood glucose converged among the laboratories, however, the limits of other test items diverged. The results of the present survey regarding to critical values, although being in small scale, may submit the im- portant issue to be solved in near future. [Short Communication].

[The Issues and Prospects of Pharmacy-Based Laboratory Testing -From the Perspective of a Clinical Laboratory Technician -].

The promotion of self-medication was announced in the "strategy for the reconstruction of Japan", which was approved in June 2013 by the cabinet, with the concepts of "extending healthy life expectancy" and estab- lishing "pharmacy-based laboratory testing services". In April 2014, the "guideline for pharmacy-based laboratory testing" was published, and approximately 1,000 pharmacies were registered as service providers as of the end of May 2015. Issues of providing pharmacy-based laboratory testing services were as follows: 1) appropriate techniques for fingertip blood sampling, 2) quality control including the maintenance and management of devices and reagents, 3) infection prevention, and 4) provision of information on examination results and factors affecting the examination to examinees. The improvement of health screening rates remains to be resolved in order to achieve "extension of healthy life expectancy" and reduce medical costs. The involvement of clinical testing specialists is essen- tial to resolve the above issues for the appropriate management of pharmacy-based laboratory testing ser- vices. [Review].

[Quality Management and Quality Specifications of Laboratory Tests in Clinical Studies--Challenges in Pre-Analytical Processes in Clinical Laboratories].

The cost, speed, and quality are the three important factors recently indicated by the Ministry of Health, Labour and Welfare (MHLW) for the purpose of accelerating clinical studies. Based on this background, the importance of laboratory tests is increasing, especially in the evaluation of clinical study participants' entry and safety, and drug efficacy. To assure the quality of laboratory tests, providing high-quality laboratory tests is mandatory. For providing adequate quality assurance in laboratory tests, quality control in the three fields of pre-analytical, analytical, and post-analytical processes is extremely important. There are, however, no detailed written requirements concerning specimen collection, handling, preparation, storage, and shipping. Most laboratory tests for clinical studies are performed onsite in a local laboratory; however, a part of laboratory tests is done in offsite central laboratories after specimen shipping. As factors affecting laboratory tests, individual and inter-individual variations are well-known. Besides these factors, standardizing the factors of specimen collection, handling, preparation, storage, and shipping, may improve and maintain the high quality of clinical studies in general. Furthermore, the analytical method, units, and reference interval are also important factors. It is concluded that, to overcome the problems derived from pre-analytical processes, it is necessary to standardize specimen handling in a broad sense.

[Introduction of the NGSP value in clinical practice and later].

Currently, the NGSP value for HbA1c is widely used as the global standard. In Japan, the JDS value was replaced with the NGSP value in clinical practice on April 1, 2012. From April 2013, the NGSP value will also be used in health examinations. In April 2014, the HbA1c value will be consolidated into the NGSP value. Since the JDS did not finalize the timeline for the replacement until the last moment, clinical laboratories and manufacturers were left behind with little time for preparation; however, introduction of the NGSP value caused little confusion in clinical practice. It is speculated that the reason for the lack of confusion was either because dissemination of the NGSP replacement among clinicians, patients, and co-medicals was effective, or JDS and NGSP values were listed side by side in current clinical practice. Real confusion might occur when consolidation of the NGSP value becomes effective in April 2014. The final goal of international standardization of the HbAlc value will be achieved by enabling the measurement of HbA1c, which will be traced back to SI units in the future.

Usefulness of HbA1c Measurements by HPLC- and Immuno-Assay for Screening Unstable Hemoglobinopathy.

OBJECTIVE: Unstable hemoglobinopathy (UH), red blood cell membrane disease (MD), and red blood cell enzymopathy are known as major congenital hemolytic anemias. Specialized examinations are needed for their differential diagnosis. We hypothesized that simultaneous measurements of HbA1c levels using high-performance liquid chromatography (HPLC) by fast mode (FM) and immunoassay [HPLC (FM)-HbA1c and IA-HbA1c, respectively] are useful for the differential diagnosis of UH from other congenital hemolytic anemias and verified this hypothesis in this study. METHODS: HPLC (FM)-HbA1c and IA-HbA1c levels were simultaneously measured in 5 variant hemoglobinopathy (VH) patients with ß-chain heterozygous mutation, 8 MD patients, 6 UH patients, and 10 healthy controls. None of the patients had diabetes mellitus. RESULTS: In VH patients, HPLC-HbA1c levels were low, whereas IA-HbA1c levels were within the reference range. In MD patients, HPLC-HbA1c and IA-HbA1c levels were similarly low. In UH patients, both HPLC-HbA1c and IA-HbA1c levels were low, but HPLC-HbA1c levels were significantly lower than IA-HbA1c levels. The HPLC-HbA1c/IA-HbA1c ratio was 90% or more in all MD patients and control subjects. This ratio was, however, less than 90% in all VH patients and UH patients. CONCLUSION: The HPLC (FM)-HbA1c/IA-HbA1c ratio calculated using simultaneous measurements of HPLC (FM)-HbA1c and IA-HbA1c levels is useful for the differential diagnosis of VH, MD, and UH.

[The significance of high sensitive C reactive protein as a risk factor for cardiovascular diseases].

Chronic inflammation is involved in the pathogenesis of cardiovascular diseases (CVD). Several prospective studies have indicated that an elevated high sensitive C-reactive protein (hs-CRP) level is a risk factor for CVD. These results were also confirmed by prospective studies in Japan both for primary and secondary prevention. A randomized control study using statins also revealed that lower levels of both LDL cholesterol and hs-CRP were independently related to the incidence of CVD. Recent meta-analysis revealed that hs-CRP was a risk factor not only for CVD but for other diseases including cancers. It revealed that the absolute value of hs-CRP varied among the study populations. The mechanism of how hs-CRP is associated with the pathogenesis of CVD is not fully understood. Generally, inflammation in the vascular wall and the release of inflammatory cytokines from macrophages was considered to the main mechanism, but infection with such as chlamydia or Helicobacter pylori, and periodontal disease have been postulated as the causes of systemic inflammation. Recently, visceral fat accumulation and its cross-interaction with inflammatory cells have been proposed as the cause of systemic inflammation as "innate inflammation". Our original cross sectional studies also showed the correlations of hs-CRP with BMI and triglyceride. Although there is no specific therapy for the reduction of hs-CRP, we have to consider hs-CRP as a risk factor for CVD which complements other classical risk factors.

A case of α-chain variant hemoglobin (Hb Chad) with falsely high HbA1c levels measured by immunoassay.

Variant hemoglobin is often detected during the diagnosis and treatment of diabetes mellitus. We here describe a case of α2-chain variant hemoglobin (Hb Chad) that was identified as a result of differences in HbA1cs values determined by different assays. HbA1c measured by immunoassay was thus falsely high, whereas that measured by high-performance liquid chromatography (HPLC) was slightly low. Sequencing analysis revealed a heterozygous GAG (glutamic acid) → AAG (lysine) mutation at amino acid position 23 of the α2-globin gene. This residue is located at the surface of the α-chain in the crystal structure of hemoglobin. The high HbA1c value determined by immunoassay might have been the result of increased antigenicity of the variant hemoglobin, whereas the low value measured by HPLC reflected differential fractionation of the variant relative to the wild-type protein. Hb Chad has been reported in only three cases to date, and HbA1c was measured for the first time. This is the first case where falsely high HbA1c measured by immunoassay due to increased antigenicity in α-chain variant hemoglobin. This case highlights the importance of comparison with other parameters related to plasma glucose such as glycated albumin if an HbA1c abnormality is suspected. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13340-021-00529-y.

Gut Microbiota and Coronary Plaque Characteristics.

Background The relationship between gut microbiota and in vivo coronary plaque characteristics has not been reported. This study was conducted to investigate the relationship between gut microbiota and coronary plaque characteristics in patients with coronary artery disease. Methods and Results Patients who underwent both optical coherence tomography and intravascular ultrasound imaging and provided stool and blood specimens were included. The composition of gut microbiota was evaluated using 16S rRNA sequencing. A total of 55 patients were included. At the genus level, 2 bacteria were associated with the presence of thin-cap fibroatheroma, and 9 bacteria were associated with smaller fibrous cap thickness. Among them, some bacteria had significant associations with inflammatory/prothrombotic biomarkers. Dysgonomonas had a positive correlation with interleukin-6, Paraprevotella had a positive correlation with fibrinogen and negative correlation with high-density lipoprotein cholesterol, Succinatimonas had positive correlations with fibrinogen and homocysteine, and Bacillus had positive correlations with fibrinogen and high-sensitivity C-reactive protein. In addition, Paraprevotella, Succinatimonas, and Bacillus were also associated with greater plaque volume. Ten bacteria were associated with larger fibrous cap thickness. Some were associated with protective biomarker changes; Anaerostipes had negative correlations with trimethylamine N-oxide, tumor necrosis factor α, and interleukin-6, and Dielma had negative correlations with trimethylamine N-oxide, white blood cells, plasminogen activator inhibitor-1, and homocysteine, and a positive correlation with high-density lipoprotein cholesterol. Conclusions Bacteria that were associated with vulnerable coronary plaque phenotype and greater plaque burden were identified. These bacteria were also associated with elevated inflammatory or prothrombotic biomarkers. Registration URL: https://www.umin.ac.jp/ctr/; Unique identifier: UMIN000041692.

[Attempt to standardize clinical tests for the purpose of quality management in the field of clinical studies and clinical trials].

The purpose of this study was to contribute to the quality management in the fields of clinical studies and clinical trials. To accomplish this purpose we tried to make guidelines for nationwide standardization of clinical tests. This study was performed by multidisciplinary personnel such as medical doctors, medical technologist, CRC, and representatives of pharmaceutical companies and/or clinical laboratory testing companies. The study was also focused on two fields of clinical tests such as pre-analytical and post-analytical phase. Each member shared various incidents and tried to make solutions. In post-analytical area in particular, further discussion concerning CDISC and SS-MIX was done. Based on these efforts, a tentative guideline was made.

HbA1c levels Measured by Enzymatic Assay and Immunoassay during Off-Site Health Checkups Are Both Lower than Those Measured by On-Site HPLC Assay.

It has already been reported that HbA1c levels measured by immunoassay (IA) (IA-HbA1c) during off-site health checkups present falsely lower results. We also reported that HbA1c levels measured by enzymatic assay (EA) (EA-HbA1c) during off-site health checkups are lower. In the present study, we compared IA-HbA1c levels or EA-HbA1c levels during off-site health checkups with on-site high-performance liquid chromatography (HPLC)-HbA1c levels using the same samples. Subjects were 88 non-diabetic individuals who had health checkups in Nishinomiya Municipal Central Hospital. Subjects with a history of diabetes mellitus and those with HPLC-HbA1c ≥ 6.5% were excluded. IA-HbA1c levels (Study 1) or EA-HbA1c levels (Study 2) in the health checkups were compared with on-site HPLC-HbA1c levels using the same samples. Both IA-HbA1c levels and EA-HbA1c levels had positive correlations with HPLC-HbA1c levels (p <0.0001 for both), although both were significantly lower than HPLC-HbA1c levels (p <0.0001 for both). The degrees of reductions in the IA-HbA1c levels and EA-HbA1c levels compared with HPLC-HbA1c levels were almost same to each other. Similarly to IA-HbA1c levels, EA-HbA1c levels during the health checkups were lower than HPLC-HbA1c levels. It was demonstrated that HbA1c levels decrease similarly if measured by either EA or IA during off-site health checkups.

Non-mercaptalbumin is significantly associated with the coronary plaque burden and the severity of coronary artery disease.

Human non-mercaptalbumin (HNA), oxidized form of serum albumin, has been reported as a useful marker in oxidative stress-related diseases; however, few reports have examined the association between HNA and the severity of coronary artery disease (CAD). The present study evaluated whether the HNA fraction is correlated with coronary artery stenosis in 140 patients considered to have a high risk of CAD or who were suspected of having acute coronary syndrome. The severity of CAD was defined by the number of stenotic coronary vessels and a severity score system (the Gensini score). HNA measurements were performed using our newly established high-performance liquid chromatography methodology. The results had shown that HNA was significantly increased in patients with three-vessel disease, compared with those without CAD or with single-vessel disease (p = 0.025), and was positively correlated with the Gensini score (ρ = 0.421, p < 0.001). A multivariate analysis showed that the number of stenotic vessels was an independent and significant factor associated with HNA (ρ = 1.246, p = 0.012). A logistic regression analysis showed that HNA was a strong predictor of multivessel CAD (odds ratio, 1.12; 95% confidence interval, 1.020-1.229; p = 0.017). These findings indicate that the measurement of HNA could be clinically practical for predicting the severity of coronary artery stenosis.

A survey of the reactivity of in vitro diagnostic bilirubin reagents developed in Japan using artificially prepared bilirubin materials: A comparison of synthetic delta, unconjugated, and taurine-conjugated bilirubin.

BACKGROUND: In vitro diagnostic bilirubin reagents based on oxidation with bilirubin oxidase or vanadic acid for total and direct-reacting bilirubin are widely used in Japan; however, their reactivity to unconjugated and conjugated bilirubin and delta bilirubin has not been completely disclosed by manufacturers. We used artificially prepared bilirubin materials to investigate the reactivity with four in vitro diagnostic bilirubin reagents. METHODS: Porcine unconjugated bilirubin solution, chemically synthesized ditaurobilirubin solution, and chemically synthesized delta bilirubin solution were used as surrogates of naturally occurring unconjugated bilirubin, conjugated bilirubin, and delta bilirubin, respectively. The total bilirubin and direct-reacting bilirubin concentrations were measured by three bilirubin oxidase methods and one vanadic acid method, and the observed concentrations were compared with those obtained by the diazo-based reference measurement procedure. RESULTS: The unconjugated bilirubin and delta bilirubin concentrations were similar when any of the four in vitro diagnostic bilirubin reagents were used during total bilirubin measurement. This was consistent with reference measurement procedure and exhibited a converged inter-method variation. Compared with reference measurement procedure, significantly low ditaurobilirubin concentrations were observed by the in vitro diagnostic bilirubin reagents despite the converged inter-method variation. In delta bilirubin measurement, some reagents reacted doubtfully with unconjugated bilirubin, while showed lower ditaurobilirubin concentrations than its corresponding total bilirubin concentration. Reactivity with delta bilirubin was different for each method including reference measurement procedure. Some reagents were developed to react less with delta bilirubin and others to strongly react with delta bilirubin. CONCLUSIONS: We revealed the reactivity of IVD-TB and IVD-DB reagents to artificially prepared bilirubin materials, and their consistency with reference measurement procedure. The delta bilirubin data results vary depending on the reagents used.

Sample transport and/or storage can cause falsely low HbA1c levels in blood cells measured by enzymatic assay.

Although HbA1c measurement by enzymatic assay (EA-HbA1c) is widely used in health-screening settings in Japan, recent studies have suggested lower EA-HbA1c levels as compared with HbA1c levels measured by high-performance liquid chromatography (HPLC-HbA1c). Hypothesizing that falsely low levels of EA-HbA1c are attributable to hemolysis caused by sample transport and/or storage, we measured EA-HbA1c in blood cells and whole blood after sample transport and compared them with HPLC-HbA1c levels. Blood samples were collected from ten non-diabetic individuals into sodium fluoride-containing blood collection tubes and immediately measured for EA-HbA1c in blood cells. After transport, the blood samples were again subjected to measurement of EA-HbA1c levels in blood cells and whole blood the following day. These EA-HbA1c levels were compared with HPLC-HbA1c levels. EA-HbA1c levels in blood cells measured immediately after sample collection did not significantly differ from HPLC-HbA1c levels. Transported blood samples showed hemolysis and significantly lower EA-HbA1c levels in blood cells, as compared with HPLC-HbA1c levels, whereas no significant difference was observed between EA-HbA1c levels in whole blood and HPLC-HbA1c levels. Transported blood samples showed hemolysis and falsely low EA-HbA1c levels in blood cells. Hemolysis caused by sample transport and/or storage might be responsible for the falsely low EA-HbA1c levels. This should be kept in mind, because falsely low HbA1c levels may lead to a false-negative diagnosis of diabetes.

Two cases with Hb Andrew-Minneapolis showing high or low-normal HbA1c levels depending on the measurement method.

We experienced two cases of Hb Andrew-Minneapolis with high or low-normal HbA1c levels depending on the measurement method. Case 1 was a 25-year-old male, and case 2 was a 32-year-old pregnant woman. Both cases showed normal glucose tolerance levels and glycated albumin within the reference range. In both cases, the high-performance liquid chromatography (HPLC) method (standard mode) showed high HbA1c levels of 6.8% and 6.5%, respectively, while the HbA1c levels measured by immunoassay were low normal at 4.6% in both cases. Globin gene analysis detected heterozygous ß-chain mutations (ß144Lys → Asn) in both cases, which resulted in the diagnosis of Hb Andrew-Minneapolis. In case 1, a high-resolution HPLC chromatogram showed multiple abnormal peaks; two unknown peaks in addition to variant hemoglobin (HbX0) and glycation products of variant hemoglobin (HbX1c) were observed after in vitro glycation reaction. Although the details of unknown peaks were not identified, those might be modified hemoglobin associated with variant hemoglobin. The presence of unknown peaks could cause high HbA1c levels measured by HPLC (standard mode). Furthermore, the HbA1c level measured by immunoassay was increased to 4.9% within the reference range after adjustment for modified hemoglobin in case 1. Consequently, the high HbA1c levels measured by HPLC (standard mode) and the low-normal HbA1c level measured by immunoassay might be due to modified hemoglobin associated with variant hemoglobin.

HbA1c levels measured by enzymatic assay during off-site health checkups are lower than those measured by on-site HPLC assay.

HbA1c is widely used as a therapeutic target marker and as a diagnostic marker for diabetes mellitus. This has led to an increasing frequency of HbA1c measurements in current health checkups throughout Japan. In the present study, we compared the HbA1c levels measured by an enzymatic assay (EA-HbA1c) off-site during health checkups with the HbA1c levels measured by on-site ion-exchange high-performance liquid chromatography (HPLC; HPLC-HbA1c) in a hospital. A total of 96 individuals (53 males and 43 females; age, 68.9 ± 8.4 years old; 70 diabetic and 26 non-diabetic individuals) whose HbA1c levels were measured by both the methods listed above were included in the study. Since no HPLC-HbA1c levels were measured on the day of the health checkup, HPLC-HbA1c levels were estimated using HPLC-HbA1c levels measured before and after the health checkup. A significant correlation of HbA1c levels was observed between the two groups (R = 0.973; p < 0.001). However, EA-HbA1c levels measured off-site during health checkups are lower than estimated HPLC-HbA1c levels measured on-site (6.37 ± 0.75% vs. 6.69 ± 0.75%; p < 0.001). Since lower EA-HbA1c levels measured during health checkups, which diverged from on-site measurements, may lead to underestimating diabetes mellitus, accurate measurement of HbA1c is required irrespective of the measuring method. Further investigation of the cause of falsely low EA-HbA1c levels and the strategy for reconciling HbA1c to reflect plasma glucose accurately are warranted.

A case of variant hemoglobin (Hb Agenogi) with type 2 diabetes mellitus showed high HbA1c levels measured by immunoassay due to enhanced antigenicity.

HbA1c is a widely utilized biomarker for the management of diabetes mellitus. The presence of variant hemoglobins might interfere with HbA1c measurement using different methods. We herein describe Hb Agenogi (ß90Glu → Lys) with type 2 diabetes mellitus whose HbA1c measured by immunoassay (IA) showed falsely high levels while HbA1c measured by high-performance liquid chromatography (HPLC) in the standard mode (SM) showed falsely low levels. To clarify the cause of the falsely high-IA-HbA1c levels, HbA1c was measured by various methods. Glycated albumin was slightly higher than the reference range. HbA1c measured by HPLC in the variant mode, affinity assay and enzymatic assay showed the range (mean ± 2SD: 6.0-6.8%) in this case. However, HbA1c measured by several HPLC-SMs showed falsely low levels (4.1-4.4%). IA-HbA1c using an antibody manufactured by Fujirebio Inc. showed falsely high levels (7.3-8.2%); whereas, IA-HbA1c using an antibody manufactured by Roche Ltd. showed the expected range (6.2-6.5%). In the case of Hb Agenogi, IA-HbA1c using an antibody manufactured by Fujirebio yielded falsely high levels. The mutation at codon 90 of the ß-globin chain might enhance antigenicity of the N-terminal peptide region and, therefore, lead to falsely high-HbA1c levels in IA-HbA1c.

A case of monoclonal gammopathy of undetermined significance with abnormal low levels of plasma glycated albumin by M protein.

BACKGROUND: It is known that an immunoglobulin abnormality affects various clinical laboratory measurements and leads to abnormal values. We experienced a case of monoclonal gammopathy of undetermined significance (MGUS) showing a falsely low plasma glycated albumin (GA) level. CASE REPORT: The patient was a 75-y-old male who visited our hospital for thrombocytosis identified during a medical checkup. Based on further examinations, he was diagnosed with MGUS (IgM-κ type). Laboratory examinations revealed that the plasma GA level was significantly low at -1.3% but the serum GA level was reasonable at 15.5%. We investigated the cause of the falsely low plasma GA level. RESULTS: The patient's plasma became turbid after mixing with the first reagent for GA measurement. The plasma GA level was increased by dilution of the plasma. The plasma GA level was falsely decreased only at the time of measurement on a sample collected using a blood-collecting tube with heparin sodium. The GA level was decreased by adding heparin sodium to the patient's serum, whereas the GA level was increased by neutralization of the patient's plasma with protamine sulfate. The GA level was increased after adding polyethylene glycol to the patient's plasma. Serum GA levels in healthy controls were decreased by adding purified M protein from the patient's serum. CONCLUSIONS: We report a patient with MGUS whose plasma GA concentration was falsely decreased by M protein when blood was drawn in a heparin sodium-containing tube.

Collaborative derivation of reference intervals for major clinical laboratory tests in Japan.

OBJECTIVES: Three multicentre studies of reference intervals were conducted recently in Japan. The Committee on Common Reference Intervals of the Japan Society of Clinical Chemistry sought to establish common reference intervals for 40 laboratory tests which were measured in common in the three studies and regarded as well harmonized in Japan. METHODS: The study protocols were comparable with recruitment mostly from hospital workers with body mass index ≤28 and no medications. Age and sex distributions were made equal to obtain a final data size of 6345 individuals. Between-subgroup differences were expressed as the SD ratio (between-subgroup SD divided by SD representing the reference interval). Between-study differences were all within acceptable levels, and thus the three datasets were merged. RESULTS: By adopting SD ratio ≥0.50 as a guide, sex-specific reference intervals were necessary for 12 assays. Age-specific reference intervals for females partitioned at age 45 were required for five analytes. The reference intervals derived by the parametric method resulted in appreciable narrowing of the ranges by applying the latent abnormal values exclusion method in 10 items which were closely associated with prevalent disorders among healthy individuals. Sex- and age-related profiles of reference values, derived from individuals with no abnormal results in major tests, showed peculiar patterns specific to each analyte. CONCLUSION: Common reference intervals for nationwide use were developed for 40 major tests, based on three multicentre studies by advanced statistical methods. Sex- and age-related profiles of reference values are of great relevance not only for interpreting test results, but for applying clinical decision limits specified in various clinical guidelines.

Committee on Diabetes Mellitus Indices of the Japan Society of Clinical Chemistry-recommended reference measurement procedure and reference materials for glycated albumin determination.

BACKGROUND: Glycated albumin is an intermediate glycaemic control marker for which there are several measurement procedures with entirely different reference intervals. We have developed a reference measurement procedure for the purpose of standardizing glycated albumin measurements. METHODS: The isotope dilution liquid chromatography/tandem mass spectrometry method was developed as a reference measurement procedure for glycated albumin. The stable isotopes of lysine and fructosyl-lysine, which serve as an internal standard, were added to albumin isolated from serum, followed by hydrogenation. After hydrolysis of albumin with hot hydrochloric acid, the liberated lysine and fructosyl-lysine were measured by liquid chromatography/tandem mass spectrometry, and their concentrations were determined from each isotope ratio. The reference materials (JCCRM611) for determining of glycated albumin were prepared from pooled patient blood samples. RESULTS: The isotope dilution-tandem mass spectrometry calibration curve of fructosyl-lysine and lysine showed good linearity (r = 0.999). The inter-assay and intra-assay coefficient of variation values of glycated albumin measurement were 1.2 and 1.4%, respectively. The glycated albumin values of serum in patients with diabetes assessed through the use of this method showed a good relationship with routine measurement procedures (r = 0.997). The relationship of glycated albumin values of the reference material (JCCRM611) between these two methods was the same as the relationship with the patient serum samples. CONCLUSION: The Committee on Diabetes Mellitus Indices of the Japan Society of Clinical Chemistry recommends the isotope dilution liquid chromatography/tandem mass spectrometry method as a reference measurement procedure, and JCCRM611 as a certified reference material for glycated albumin measurement. In addition, we recommend the traceability system for glycated albumin measurement.