Comparative study on hemoglobin A1c, glycated albumin and glycosylated serum protein in aplastic anemia patients with Type 2 diabetes mellitus.

OBJECTIVE: To differentiate the value of hemoglobin A1c (HbA1c), glycated albumin (GA) and glycosylated serum protein (GSP) in monitoring blood glucose of patients with aplastic anemia. METHODS: 42 patients with aplastic anemia (AA) and 30 patients with AA and Type 2 diabetes mellitus (T2DM) were enrolled in the study, in comparison with 114 healthy subjects and 88 subjects with T2DM. HbA1c, GA, GSP, fasting plasma glucose (FPG), hemoglobin (Hb) and albumin (ALB) were measured, and group comparison and correlation analysis were carried out. RESULTS: Compared with the non-diabetes patients while ALB were <30 g/l or 30-40 g/l, the HbA1c and GSP values in AA, T2DM and AA+T2DM patients were significantly higher while the GA values were lower. Moreover, no differences in FPG levels. The AA+T2DM patients with ALB >40 g/l had higher HbA1c level, with no difference in GA, GSP and FPG levels. There was a positive correlation between HbA1c and GA in healthy group (ALB ≥ 40 g/l), AA patients (ALB 30-40 g/l and ≥40 g/l), T2DM patients (ALB 30-40 g/l and ≥40 g/l) and AA+T2DM patients (ALB 30-40 g/l and ≥40 g/l) but not in those with ALB < 30 g/l. CONCLUSION: The HbA1c results were affected by moderate-to-severe anemia, but not mild anemia. HbA1c is not recommended to detect blood glucose levels in AA patients (Hb < 90 g/l) or AA patients (ALB < 30 g/l). FPG and GSP are not suitable for AA patients.

Application of biological variation and six sigma models to evaluate analytical quality of six HbA1c analyzers and design quality control strategy.

Objective: To apply biological variation and six Sigma models to evaluate analysis performance of 6 HbA1c analyzers and design the new quality control strategy. Method: We collected data of imprecision and inaccuracy from routine internal quality control (June 2017-December 2017) and proficiency test of NGSP, respectively. The coefficient of variance (CV)% and bias% were plotted in the biological variation and six sigma models. The new quality control strategy was designed by the sigma value and OPSpecs. The quality improvement was guided by the QGI. Results: The analytical performance of 6 HbA1c analyzers in our laboratory were good in the routine model, However, 50% (3/6) and 67% (4/6) of the HbA1c analyzers reached the acceptable level in the biological variation and six Sigma model, respectively. We also design personalized control strategy and promote quality improvement by combining the sigma value, OPSpecs, and QGI. Conclusions: Biological variation model and six sigma model could visually display the performance of 6 HbA1c analyzers and personalized control strategy could be designed based on the sigma value, OPSpecs, and QGI.

False measurement of glycated hemoglobin in patients without hemoglobin A.

Background: Hemoglobin (Hb) A1c, a biochemical marker widely used in monitoring diabetes mellitus, can be quantitatively measured by various examining systems. However, significant errors still exist. In the present study, we evaluated the HbA1c level in five patients with compound heterozygotes by five different examining systems and our goal is to identify the existence of erroneous HbA1c measurement.Methods: Blood samples collected from normal (no hemoglobin variants) and abnormal (compound heterozygotes) patients were analyzed by capillary electrophoresis technique and sequence analysis. The samples without HbA expression via above methods were further analyzed for HbA1c by ion exchange HPLC Variant II/ Variant II Turbo 2.0 (VII and VII-T 2.0), boronate affinity HPLC, capillary electrophoresis, and Tinaquant immunoassay.Results: HbA1c expression were unexpectedly detected in the compound heterozygous samples by using additional examining systems: The HPLC VII and VII-T 2.0 detected HbA1c expression in two of five samples and failed to detect the abnormal HbA2 expression; the CE system detected HbA1c expression in one of five samples with abnormal HbA2 expression; the Ultra2 and PPI system detected the HbA1c expression of all samples without abnormal HbA2Conclusions: Five human samples without HbA expression were additionally detected with HbA1c expression with or without abnormal HbA2 expression by five analysis systems and the different examining assay potentially affected the test results. These results demonstrated that the limitations of current examining systems for monitoring patients with hemoglobin disorders highlighting the further improvement in the method of clinical HbA examination.

Effects of hemoglobin variants HbJ Bangkok, HbE, HbG Taipei, and HbH on analysis of glycated hemoglobin via ion-exchange high-performance liquid chromatography.

BACKGROUND: To explore the effects of HbJ Bangkok, HbE, HbG Taipei, and α-thalassemia HbH on the results of HbA1c assessment using ion-exchange high-performance liquid chromatography (IE-HPLC). METHODS: We enrolled five patients in which the results of the IE-HPLC HbA1c assay were inconsistent with the average levels of FBG. We performed hemoglobin capillary (Hb) electrophoresis using whole-blood samples. We also sequenced the genes encoding Hb using dideoxy-mediated chain termination and analyzed HbA1c using borate affinity HPLC (BA-HPLC) and turbidimetric inhibition immunoassay (TINIA). RESULTS: Two patients had the HbJ Bangkok variant. Hb genotypes of these patients were ß41-42 /ßJ Bangkok and ßN /ßJ Bangkok , and the content of HbJ Bangkok was 93.9% and 52.4%, respectively. The remaining three patients had the following: HbE (ßN /ßE Hb genotype, 23.6% HbE content), HbG Taipei (ßN /ßG Taipei Hb genotype, 39.4% HbG Taipei content), and α-thalassemia HbH (6.1% HbH content, 2.8% Hb Bart's content). In the patients with ß-thalassemia and HbJ Bangkok variants, the presence of the variants interfered with the results of HbA1c analyses using IE-HPLC and TINIA; in the remaining four patients, there was interference with the results of HbA1c IE-HPLC but not with the TINIA assay. There was no interference with BA-HPLC HbA1c results. CONCLUSIONS: HbJ Bangkok, HbE, HbG Taipei Hb, and α-thalassemia HbH disease cause varying degrees of interference with the analysis of HbA1c using IE-HPLC. In these patients, we suggest using methods free from such interference for the analysis of HbA1c and other indicators to monitor blood glucose levels.

Evaluation of the Interference of Hemoglobin Variant J-Bangkok on Glycated Hemoglobin (HbA1c) Measurement by Five Different Methods.

Objective The interference of the hemoglobin variant (Hb J-Bangkok) was evaluated on 4 different glycated hemoglobin assays and compared with a reference immuno assay. Methods An overall test of coincidence of 2 least-squares linear regression lines was performed to determine whether the presence of Hb J-Bangkok caused a statistically significant difference in HbA1c results compared with a reference immuno assay. Statistical analysis was performed on the difference of the estimated average glucose calculated from HbA1c values and fasting plasma glucose in the Hb J-Bangkok variant group using the different detection systems. Deming regression analysis was used to determinate whether Hb J-Bangkok had a significant interference on HbA1c results using an HbA1c±10% relative bias at 6% and 9% HbA1c as evaluation limits. Results Turbidimetric inhibition immunoassay method, and enzymatic methods were not affected by Hb J-Bangkok. However, Hb J-Bangkok showed statistically significant interference to the two ion-exchange high-performance liquid chromatography methods. Conclusion When performing HbA1c tests, clinical laboratory personnel should identify the Hb variant and select the appropriate methods or use alternative indicators.

Analytical performances and heart failure research of the BNP and NT-proBNP assays on the Cobas E601 and ADVIA Centaur.

BACKGROUND: The analytical performances of the NT-proBNP and BNP assays on the Cobas E601 and ADVIA Centaur were thoroughly evaluated. In addition, the values of BNP and NT-proBNP, which are heart failure markers, were compared in the diagnosis of HF patients with or without acute cerebral infarction since they could also be elevated in ischemic stroke. METHODS: Clinical and Laboratory Standards Institute (CLSI) documents were employed in the analytical evaluation of NT-proBNP and BNP assays on the Cobas E601 and ADVIA Centaur. Then 100 heart failure patients and 103 cerebral infarction complicated with heart failure patients, who had been diagnosed by clinical doctors blinded to NT-proBNP and BNP concentrations, were chosen to compare their values in the diagnosis of heart failure with or without acute cerebral infarction. RESULTS: The NT-proBNP and BNP methods are precise and accurate (total CV < 2.9%, deviation < 3.6%), have wide dynamic measuring ranges (8 pg/mL to 35 126 pg/mL and 2.0 pg/mL to 5094 pg/mL, respectively) with maximum dilutability of 1:2, and are free of common interferences. The most suitable sample types for NT-proBNP and BNP are serum and EDTA plasma, respectively, and both methods correlate well in simple-HF patients. Unlike BNP, the level of NT-proBNP is much higher in HF patients with acute cerebral infarction (p < 0.001). The Cobas E601 and ADVIA Centaur systems have good analytical performances. CONCLUSIONS: In HF patients with acute cerebral infarction, the NT-proBNP and BNP levels did not correlate and thus had implications for clinical diagnosis.