Pathology consultation on HbA(1c) methods and interferences

Microstrip isoelectric focusing with deep learning for simultaneous screening of diabetes, anemia, and thalassemia

BACKGROUND

Hemoglobin (Hb) is an important protein in red blood cells and a crucial diagnostic indicator of diseases, e.g., diabetes, thalassemia, and anemia. However, there is a rare report on methods for the simultaneous screening of diabetes, anemia, and thalassemia. Isoelectric focusing (IEF) is a common separative tool for the separation and analysis of Hb. However, the current analysis of IEF images is time-consuming and cannot be used for simultaneous screening. Therefore, an artificial intelligence (AI) of IEF image recognition is desirable for accurate, sensitive, and low-cost screening.

RESULTS

Herein, we proposed a novel comprehensive method based on microstrip isoelectric focusing (mIEF) for detecting the relative content of Hb species. There was a good coincidence between the quantitation of Hb via a conventional automated hematology analyzer and the one via mIEF with R2 = 0.9898. Nevertheless, our results showed that the accuracy of disease diagnosis based on the quantification of Hb species alone is as low as 69.33 %, especially for the simultaneous screening of multiple diseases of diabetes, anemia, alpha-thalassemia, and beta-thalassemia. Therefore, we introduced a ResNet1D-based diagnosis model for the improvement of screening accuracy of multiple diseases. The results showed that the proposed model could achieve a high accuracy of more than 90 % and a good sensitivity of more than 96 % for each disease, indicating the overwhelming advantage of the mIEF method combined with deep learning in contrast to the pure mIEF method.

SIGNIFICANCE

Overall, the presented method of mIEF with deep learning enabled, for the first time, the absolute quantitative detection of Hb, relative quantitation of Hb species, and simultaneous screening of diabetes, anemia, alpha-thalassemia, and beta-thalassemia. The AI-based diagnosis assistant system combined with mIEF, we believe, will help doctors and specialists perform fast and precise disease screening in the future.

Uncommon causes of hemoglobin E flags identified during measurement of hemoglobin A1c by ion-exchange high-performance liquid chromatography

We present 3 cases of discordant results from screening hemoglobin A1c (HbA1c) measured by ion-exchange high-performance liquid chromatography (HPLC) all due to various forms of interference and flagged by the instrument as "suspected hemoglobin E (HbE)." The first case was due to a rare hemoglobin variant, later confirmed to be hemoglobin Hoshida, the second due to "true" heterozygous HbE, and the third a result of analytical artifact causing splitting of the HbA1c peak without an underlying variant hemoglobin. We examine the similarities in these cases along with the laboratory work-up to classify each cause of interference to demonstrate the wide array of potential causes for the suspected HbE flag and why it warrants proper work-up. Because there is no standardized method of reporting out hemoglobin variant interference in HbA1c measurement, we discuss our laboratory's process of investigating discordant HbA1c measurements and reporting results in cases with variant interference as 1 possible model to follow, along with discussing the associated laboratory, ethical, and clinical considerations. We also examine the structure of hemoglobin Hoshida, HbE, and conduct a brief literature review of previous reports.

An incidental finding of a hemoglobin E variant in a diabetic patient with an abnormal glycated hemoglobin level: a case report

BACKGROUND

Glycated hemoglobin is a well-known marker for evaluating long-term glycemic control. However, the accuracy of glycated hemoglobin measurement can be affected by the presence of hemoglobin variants, which makes the determination and interpretation of glycated hemoglobin values in terms of glycemic control not only difficult but also misleading. Here we present the first ever case of a patient with type 2 diabetes with hemoglobin E from Nepal, diagnosed incidentally because of spurious glycated hemoglobin levels.

CASE PRESENTATION

A 45-year-old Hindu Mongolian female with a history of type 2 diabetes for around 9 years but not very compliant with follow-ups was referred to our facility for plasma fasting and postprandial blood glucose levels and glycated hemoglobin. Fasting and postprandial blood sugars were found to be high. A consistent very low glycated hemoglobin by two different high-performance liquid chromatography (HPLC) methods compelled us to call the patient for a detailed clinical history and for the records of investigations done in the past. The patient has been a known case of type 2 diabetes for around 9 years and presented irregularly for follow-up visits. Around 4 years ago, she presented to a healthcare facility with fatigue, severe headaches, pain in the abdomen, discomfort, and dizziness for a couple of months, where she was shown to have high blood glucose. She was referred to a tertiary-level hospital in Kathmandu, where she was prescribed metformin 500 mg once daily (OD). Due to her abnormal hemoglobin A1c reports, she was then sent to the National Public Health Laboratory for repeat investigations. Her blood and urine investigations were sent. Complete blood count findings revealed high red blood cell and white blood cell counts, a low mean corpuscular volume, and a high red cell distribution width-coefficient of variation. Other parameters, including serum electrolytes, renal function tests, liver function tests, and urine routine examinations, were within normal limits. A peripheral blood smear revealed microcytic hypochromic red cells with some target cells. Hemoglobin electrophoresis showed a very high percentage of hemoglobin E, a very low percentage of hemoglobin A2, and normal proportions of hemoglobin A and hemoglobin F. A diagnosis of homozygous hemoglobin E was made, and family screening was advised.

CONCLUSIONS

Clinicians should be aware of the limitations of glycated hemoglobin estimation by ion exchange high-performance liquid chromatography in patients with hemoglobin E and other hemoglobin variants. If the clinical impression and glycated hemoglobin test results do not match, glycated hemoglobin values should be determined with a second method based on a different principle, and glycemic status should be confirmed through alternative investigations, preferably those that are not influenced by the presence of hemoglobin variants (for example, boronate affinity chromatography, fructosamine test, glycated albumin test, the oral glucose tolerance test, continuous glucose monitoring, etc.). Consistent or even doubtful results should also raise the suspicion of a hemoglobin variant, which should be confirmed through further evaluation and investigations.

Interference of hemoglobin variants with HbA1c measurements: comparison of 6 commonly used HbA1c methods with the IFCC reference method

BACKGROUND

Glycated hemoglobin, or hemoglobin A1c (HbA1c), serves as a crucial marker for diagnosing diabetes and monitoring its progression. We aimed to assess the interference posed by common Hb variants on popular HbA1c measurement systems.

METHODS

A total of 63 variant and nonvariant samples with target values assigned by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference method were included. We assessed 6 methods for measuring HbA1c in the presence of HbS, HbC, HbD, HbE, and fetal hemoglobin (HbF): 2 cation-exchange high-performance liquid chromatography (HPLC) methods (Bio-Rad D-100 and HLC-723 G8), a capillary electrophoresis (CE) method (Sebia Capillarys 3 TERA), an immunoassay (Roche c501), an enzyme assay system (Mindray BS-600M), and a boronate affinity method (Primus Premier Hb9210).

RESULTS

The HbA1c results for nonvariant samples from the 6 methods were in good agreement with the IFCC reference method results. The Bio-Rad D-100, Capillarys 3, Mindray BS-600M, Premier Hb9210, and Roche c501 showed no interference from HbS, HbC, HbD, and HbE. Clinically significant interference was observed for the HLC-723 G8 standard mode. Elevated HbF levels caused significant negative biases for all 6 methods, which increased with increasing HbF concentration.

CONCLUSION

Elevated levels of HbF can severely affect HbA1c measurements by borate affinity, immunoassays, and enzyme assays.

Continuous glucose monitoring has an increasing role in pre-symptomatic type 1 diabetes: advantages, limitations, and comparisons with laboratory-based testing

Type 1 diabetes (T1D) is well-recognised as a continuum heralded by the development of islet autoantibodies, progression to islet autoimmunity causing beta cell destruction, culminating in insulin deficiency and clinical disease. Abnormalities of glucose homeostasis are known to exist well before the onset of typical symptoms. Laboratory-based tests such as the oral glucose tolerance test (OGTT) and glycated haemoglobin (HbA1c) have been used to stage T1D and assess the risk of progression to clinical T1D. Continuous glucose monitoring (CGM) can detect early glycaemic abnormalities and can therefore be used to monitor for metabolic deterioration in pre-symptomatic, islet autoantibody positive, at-risk individuals. Early identification of these children can not only reduce the risk of presentation with diabetic ketoacidosis (DKA), but also determine eligibility for prevention trials, which aim to prevent or delay progression to clinical T1D. Here, we describe the current state with regard to the use of the OGTT, HbA1c, fructosamine and glycated albumin in pre-symptomatic T1D. Using illustrative cases, we present our clinical experience with the use of CGM, and advocate for an increased role of this diabetes technology, for monitoring metabolic deterioration and disease progression in children with pre-symptomatic T1D.

Clinical Risk Assessment and Comparison of Bias between Laboratory Methods for Estimation of HbA1c for Glycated Hemoglobin in Hyperglycemic Patients

INTRODUCTION

Hemoglobin A1c (HbA1c), also known as glycated hemoglobin, is a blood test used to evaluate and track a patient's blood sugar levels over the previous 2-3 months. We have compared the analytical performance of the D10 hemoglobin (HPLC) testing system to that of the immunoturbidimetric technique, which is a light-scattering immunoassay.

OBJECTIVES

To assess the clinical risk assessment between two methods (Compare the two Immunoturbidometric methods (AU680) vs. HPLC method (D10)) in hyperglycemic patients and assess the acceptability of the respective methods in the Clinical biochemistry laboratory.

METHODS

The charge of the globins in Hb was used as the basis for the HPLC method used to measure HbA1c. HPLC detects and quantifies even the tiniest Hb fractions and the full spectrum of Hb variants. HbA1c was measured using the immunoturbidimetric (AU 680 Beckmann coulter analyzer) and high-performance liquid chromatography (HPLC) techniques. Experiments also made use of immunoturbidimetric techniques (using an AU 680 Beckmann coulter analyzer equipment).

RESULTS

There is no statistically significant difference in HbA1c readings between male and female patients, as measured by either the Immunoturbidimetric or HPLC techniques.

CONCLUSION

The immunoturbidimetric and high-performance liquid chromatography techniques for estimating HbA1c yielded identical results. From the results of this study, we may deduce that both techniques are valid for estimating HbA1c. As a result, it may be suggested that both approaches can be used to estimate HbA1c in diabetic individuals.

Evaluation of the Premier Hb9210 instrument for HbA1c determination

Background: Glycated hemoglobin measurements are a valuable tool for long-term blood glucose monitoring and the diagnosis of diabetes. Its widespread use has been made possible due to the development of new analytical methods with improved performances and standardization with reference materials. The aim of the present study was to evaluate the Trinity Biotech Premier Hb9210 analyzer for the measurement of HbA1c.Methods: The precision was assessed using the CLSI EP-15A3 and EP-10A3 protocols. The latter was also used to investigate linearity, carryover, and linear drift. The comparison study was performed between Premier Hb910 and Tosoh HLC-723 G8 through Passing-Bablok regression and the Bland-Altman plot. The Fleiss Kappa index was used to assess the degree of agreement. The interference of Hb variants was investigated using samples with Hb variants S, C, D, E, J, and Seville.Results: Within-run and between-run imprecision fell between 0.37% and 1.16%. No statistically significant nonlinearity, carry-over, and/or drift were observed. The resulting regression line of the Passing-Bablok analysis was y = 0.00 + 1.00x. The Pearson correlation coefficient was 0.997. In the Bland-Altman plot, the relative bias was 0.01%. The overall Fleiss Kappa index was 0.9. No interference from hemoglobin variants was observed.Conclusion: The Premier Hb9210 demonstrated a high degree of automation, reproducibility, good agreement, minimal carry-over effect, and excellent linearity across the wide range of HbA1c levels commonly found in diabetic patients and was not influenced by Hb variants.

Community-based diabetes prevention randomized controlled trial in refugees with depression: effects on metabolic outcomes and depression

Depression and antidepressant medications increase risk for type 2 diabetes. Cambodian-Americans have exceedingly high rates of both depression and diabetes. This paper reports outcomes of a diabetes prevention trial for Cambodian-Americans with depression. Primary outcomes were HbA1c, insulin resistance and depressive symptoms. Participants were aged 35-75, Khmer speaking, at risk for diabetes, and met study criteria for likely depression by either (a) antidepressant medication and/or (b) prolonged elevated depressive symptoms. Participants were randomized to one of three community health worker (CHW) interventions: (1) lifestyle intervention called Eat, Walk, Sleep (EWS), (2) EWS plus medication therapy management sessions with a pharmacist/CHW team to resolve drug therapy problems (EWS + MTM), or, (3) social services (SS; control). Assessments were at baseline, post-treatment (12 months), and follow-up (15 months). The n = 188 participants were 78% female, average age of 55 years, half had a household income < $20,000, and modal educational attainment was 7.0 years. Compared to the other arms, EWS + MTM showed a significant decrease in HbA1c and a trend for reduced inflammation and stress hormones. Depressive symptoms improved for EWS and EWS + MTM relative to SS. There was no change in insulin resistance. Cardiometabolic and mental health can be improved in tandem among immigrant and refugee groups.

The role of molecular diagnostic testing for hemoglobinopathies and thalassemias

Hemoglobin disorders are among the most common genetic diseases worldwide. Molecular diagnosis is helpful in cases where the diagnosis is uncertain and for genetic counseling. Protein-based diagnostic techniques are frequently adequate for initial diagnosis. Molecular genetic testing is pursued in some cases, particularly when a definitive diagnosis is not possible and especially for the purpose of assessing genetic risk for couples wanting to have children. The expertise available in the clinical hematology laboratory is essential for the diagnosis of patients with hemoglobin abnormalities. Initial diagnoses are made using protein-based techniques such as electrophoresis and chromatography. Based on these findings, genetic risk to an individual's offspring can be assessed. In the setting of β-thalassemia and other β-globin disorders, coincident α-thalassemia may be difficult to diagnose, which can have potentially serious consequences. In addition, unusual forms of β-thalassemia caused by deletions in the β-globin locus cannot be definitively characterized using standard techniques. Molecular diagnostic testing has an important role in the diagnosis of hemoglobin disorders and is important in the setting of genetic counseling. Molecular testing also has a role in prenatal diagnosis to identify fetuses affected by severe hemoglobinopathies and thalassemias.

Quantitation of hemoglobins using Sebia Capillarys-2 capillary electrophoresis (CE) for A1c: Comparison to results using CE for hemoglobins

Background

Measurement of A1c using the Sebia Capillarys-2 capillary electrophoresis (A1c CE) involves relative quantitative measurements of peaks for hemoglobins A1c, A, A2. We examined correlation of A1c CE results with results of CE analysis for hemoglobins (Hb CE) for homozygous A and S-trait patients. We specifically examined whether abnormalities in A2 or the A/S ratio by A1c CE alone would reasonably be the basis for recommendation of red cell indices for evaluation of possible thalassemia.

Methods

Selection of patients was from results for A1c CE, exhibiting either a normal pattern or a pattern consistent with S-trait. We then examined correlation of results of quantitation for A, S and A2 between A1c CE and Hb CE.

Results

%A2 by A1c CE (y) had high correlation with %A2 by Hb CE (x): y = 0.88 x; r = 0.948. %A2 in S-trait patients was right-shifted in comparison to normals by 0.5%. For S-trait patients, the A/S ratio by A1c CE (y) had high correlation with the A/S ratio by Hb CE (x): y = 1.02 x; r = 0.995.

Conclusions

Given high correlation of results between A1c CE and Hb CE, patent elevation of A2 by A1c CE for either normal or S-trait patients is a reasonable basis for recommendation of red cell indices for evaluation of possible beta thalassemia. For S-trait patients, patent abnormality in the A/S ratio by A1c CE is a reasonable basis for recommendation of red cell indices for evaluation of possible alpha or beta thalassemia.

Evaluation of interference from 16 hemoglobin variants on hemoglobin A1c measurement by five methods

Hb variants prevalent in China are different from those in other countries. We aimed to assess the interference from Hb variants found in China on HbA1c measurement. All Hb variants were confirmed using Sanger sequencing. HbA1c was measured using a capillary electrophoresis method (Capillarys 3 OCTA), two cation-exchange high-performance liquid chromatography methods (ADAMS HA-8180V and HLC-723 G8 standard mode), an immunoassay (Cobas c501), and a boronate affinity chromatography method (Premier Hb9210). Premier Hb9210 was used as a comparative method. A total of 16 species of Hb variants were identified in 102 variant carriers. The most common variant was Hb E, followed by Hb Q-Thailand, Hb New York and Hb J-Bangkok. Clinically significant interference was observed for the Capillarys 3 OCTA (two Hb variants), ADAMS HA-8180V (seven Hb variants), HLC-723 G8 (14 Hb variants), and Cobas c501 (two Hb variants). The proportion of unacceptable HbA1c results was 13.7% for Capillarys 3 OCTA, 52.9% for HA-8180V, 83.3% for HLC-723 G8, and 3.9% for Cobas c501. Hb variants in China severely affect the accuracy of some commonly used HbA1c methods.

The prevalence of hemoglobin Tacoma in Finland detected by HbA1c capillary electrophoresis

Previous studies have identified occasional cases of heterozygous Hb Tacoma in areas that have attracted Finnish immigrants, especially in Sweden and North America, but large studies of this slightly unstable beta variant in vitro have not been carried out. Here we determined the prevalence of hemoglobin variants across Finland. A total of 5059 samples from 11 different hospital districts were analyzed using HbA1c capillary electrophoresis and reviewed for atypical profiles (HbA1c, Capillarys 3 Tera, Sebia). 38 heterozygous Hb Tacoma cases were found (0.75%). The prevalence was highest in South Ostrobothnia (2.0%), located in western Finland, and second highest in the neighboring provinces (1.0-1.4%), but only two districts were devoid of variants. Heterozygous Hb Tacoma was confirmed by genetic testing (NM_000518.5(HBB):c.93G > T (p.Arg31Ser)). In addition, five other variants were found, suggestive of HbE, Hb Helsinki (two cases) and an alpha variant, as interpreted from the electropherograms. The fifth variant, belonging to the South Ostrobothnian cohort, remained unknown at the time of the initial analyses, but was later interpreted as homozygous Hb Tacoma and confirmed by hemoglobin fraction analysis (Hemoglobin(E), Capillarys 3 Tera). In a subsequent retrospective study of the electropherograms of routine HbA1c diagnostics, altogether nine homozygous Hb Tacoma cases were identified in South Ostrobothnia. While heterozygous Hb Tacoma is usually an incidental finding, it interferes with several HbA1c assays. The present study is the first demonstration of homozygous Hb Tacoma. The clinical presentations of homozygous Hb Tacoma are not known and need to be addressed in future studies.

SNAP participation moderates the association between household food insecurity and HbA1c among Cambodian Americans with depression

OBJECTIVES

We tested whether participation in the Supplemental Nutrition Assistance Program (SNAP) moderated the relation between household food insecurity and HbA1c among Cambodian Americans with depression enrolled in a diabetes prevention trial.

METHODS

Community health workers assessed household food insecurity and SNAP participation. HbA1c was ascertained using direct enzymatic assay.

RESULTS

Among the n = 189 respondents, 19% were food insecure, 41% received SNAP benefits, and mean HbA1c = 5.5%. There was a significant interaction between SNAP and food insecurity. HbA1c was highest among participants without SNAP who were food insecure. Simple effects analysis revealed a significant difference within the no SNAP group [Mean (SD): Secure = 5.38 (0.38), Insecure = 5.78 (0.36)] and no difference within the SNAP group [Secure = 5.61(0.44), Insecure = 5.61(0.55)]. Differences remained significant after controlling for demographic, socioeconomic, and clinical indicators.

CONCLUSIONS

SNAP may protect against the deleterious association between household food insecurity and HbA1c.

Exposure to Starvation: Associations with HbA1c, Anthropometrics, and Trauma Symptoms Four Decades Later Among Cambodians Resettled in the USA

BACKGROUND

Epidemiological data suggest that populations exposed to starvation show increased incidence of type 2 diabetes but these studies are limited by lack of person-level data. Cambodians resettled in the USA survived severe malnutrition during distinct historical eras. We examined the relationship of individual exposure to starvation with current HbA1c, anthropometrics, and trauma symptoms among Cambodian Americans.

METHODS

Participants were excluded for extant diabetes but all had elevated risk factors for type 2 diabetes and depression. Participants identified images on a 5-point scale that best depicted their body size during four distinct periods: before 1970 (peacetime), 1970-1975 (USA bombing campaign, widespread hunger), 1975-1979 (Pol Pot regime, mass starvation), and "now" (2016-2019, resettled in the USA). They reported trauma symptoms and provided anthropometrics and a blood sample.

RESULTS

The n = 189 participants were mean = 55 years old and had glycosylated hemoglobin (HbA1c) mean = 5.5%. Self-reported body size showed excellent validity by strong correlations between body thinness "now" and objectively measured waist circumference (r =  -0.35), weight (r =  -0.50), and body mass index (r =  -0.50). Whereas there was some variability, modal self-reported body size started as normal during peacetime, became thinner during the USA bombing campaign, became emaciated during the Pol Pot regime, and rebounded to normal/slightly heavy "now." Body size during Pol Pot showed the strongest associations with long-term outcomes; thinner body size (greater starvation) was associated with higher trauma symptoms and higher HbA1c even after controlling for age, current waist circumference, and current body mass index.

CONCLUSION

Greater degree of starvation was associated with higher HbA1c and trauma symptoms four decades later.

A Case of Mody 2 - Associated Hyperglycemia Diagnosed as Gestational Diabetes

Maturity-onset diabetes of the young (MODY) is the most common monogenic form of diabetes, accounting for 1-2% of all diabetes cases. At least 14 different MODY subtypes have been identified the most common of which is MODY 2 caused by mutations in the glucokinase (GSK) gene. The mild hyperglycemia of MODY 2 is often first detected during pregnancy. Patients with MODY are usually misdiagnosed as either idiopathic type 1 or type 2 diabetes. The recognition of MODY 2 during pregnancy has important clinical implications as the management of hyperglycemia may differ from the established algorithm in gestational diabetes. Fetus development could be seriously affected in case it has inherited the GSK mutation and maternal hyperglycemia is insulin treated to the pregnancy adopted glycemic targets. The case report describes the stepwise diagnostic approach to a 43-year-old woman with a history of gestational diabetes and persistent prediabetes who was found to be a carrier of a heterozygous pathogenic variant in GSK (c.184G>A) and discusses the possible genotype of her two children according to their birth weight.

Associations between HbA1c-derived estimated average glucose and fasting plasma glucose in patients with normal and abnormal hemoglobin patterns

Fasting plasma glucose (FPG) and HbA1c are well-known tests for monitoring short and long-term glycemic control, respectively. Estimated average glucose (eAG) is derived from the HbA1c for expression in the same units as FPG. The present study aimed to evaluate the association between eAG and FPG values. This retrospective study was performed on 1285 patients who measured the FPG and HbA1c (capillary electrophoresis method) values on the same day. They were initially divided into 3 hemoglobin-pattern groups, normal, HbE, and high HbA₂, and then these 3 groups were further subdivided into whole group, subgroup 1 (HbA1c ≤ 7%) and subgroup 2 (HbA1c >7%) for analytical comparisons. The eAG values were calculated using Nathan's equation. The differences, agreements, and correlations between eAG and FPG were evaluated. Good agreements and strong positive correlations between eAG and FPG values were observed in all 3 whole groups. In subgroup analysis, the degrees of agreement and correlation depended on the level of glycemic control, as all associations became stronger with better glycemic control. Additionally, the HbA1c levels and different eAG-FPG values between the normal and other groups were not significantly different in either whole group or subgroup comparisons. Our study found good agreements and strong positive correlations between eAG and FPG in all groups, indicating that high HbA₂ or HbE did not affect the HbA1c levels or thus the associations between eAG and FPG. Reporting the eAG together with the HbA1c value should help improve the understanding of glycemic status in patients, leading to improved blood glucose control.

Hemoglobin Fukuoka caused unexpected hemoglobin A1c results: A case report

BACKGROUND

Glycated hemoglobin (Hb) (HbA_1c) is an indicator that is used to diagnose and monitor the treatment of diabetes. Many factors can affect the detection of HbA_1c. One of the most important of these factors is the Hb variant. Here, we report a rare Hb variant and evaluate its effect on HbA_1c.

CASE SUMMARY

A 35-year-old man was suspected of harboring an Hb variant following the measurement of HbA_1c with the Variant II Turbo 2.0 Hb detection system during a routine examination. Subsequently, we used the Arkray HA-8160 and ARCHITECT c4000 system to reanalyze HbA_1c. Finally, the Hb variant was detected with a Capillary2FP analyzer that operates on the principle of capillary electrophoresis. We also used gene sequencing to investigate the mutation site. The value of HbA_1c detected with the Variant II Turbo 2.0 system was 52.7%. However, the Arkray HA-8160 system did not display a result while the ARCHITECT c16000 system showed a result of 5.4%. The Capillary2FP analyzer did not reveal any abnormal Hb zones. However, gene sequencing identified the presence of a mutation in the Hb β2 chain [CD2(CAC>TAC), His>Tyr, HBB: c.7C>T]; the genotype was Hb Fukuoka.

CONCLUSION

Hb variants could cause abnormal HbA_1c results. For patients with Hb variants, different methods should be used to detect HbA_1c.

Understanding and managing interferences in clinical laboratory assays: the role of laboratory professionals

The recently raised concerns regarding biotin interference in immunoassays have increased the awareness of laboratory professionals and clinicians of the evidence that the analytical phase is still vulnerable to errors, particularly as analytical interferences may lead to erroneous results and risks for patient safety. The issue of interference in laboratory testing, which is not new, continues to be a challenge deserving the concern and interest of laboratory professionals and clinicians. Analytical interferences should be subdivided into two types on the basis of the possibility of their detection before the analytical process. The first (type 1) is represented by lipemia, hemolysis and icterus, and the second (type 2), by unusual constituents that are not undetectable before analysis, and may affect the matrix of serum/plasma of individual subjects. Type 2 cannot be identified with current techniques when performing the pre-analytical phase. Therefore, in addition to a more careful evaluation and validation of the method to be used in clinical practice, the awareness of laboratory professionals should be raised as to the importance of evaluating the quality of biological samples before analysis and to adopt algorithms and approaches in the attempt to reduce problems related to erroneous results due to specific or non-specific interferences.

Impact of heterozygous hemoglobin E on six commercial methods for hemoglobin A1c measurement

Background

This study examined the impact of heterozygous HbE on HbA1c measurements by six commonly used commercial methods. The results were compared with those from a modified isotope-dilution mass spectrometry (IDMS) reference laboratory method on a liquid chromatograph coupled with tandem mass spectrometer (LC-MS/MS).

Methods

Twenty-three leftover samples of patients with heterozygous HbE (HbA1c range: 5.4–11.6%), and nineteen samples with normal hemoglobin (HbA1c range: 5.0–13.7%) were included. The selected commercial methods included the Tina-quant HbA1c Gen. 3 (Roche Diagnostics, Basel, Switzerland), Cobas B 101 (Roche Diagnostics, Basel, Switzerland), D100 (Bio-Rad Laboratories, Hercules, CA, USA), Variant II Turbo HbA1c 2.0 (Bio-Rad Laboratories, Hercules, CA, USA), DCA Vantage (Siemens Healthcare, Erlangen, Germany) and HbA1c Advanced (Beckman Coulter Inc., Brea, CA, USA).

Results

With the exception of Cobas B 101 and the Variant II Turbo 2.0, the 95% confidence intervals of the Passing–Bablok regression lines between the results from the six commercial methods and the IDMS method overlapped. The latter suggested no statistically significant difference in results and hence no impact on HbA1c result despite the presence of heterozygous HbE. The method of Cobas B 101 gave positive bias at the range of concentrations examined (5.4–11.6%), while that of Variant II Turbo 2.0 gave positive bias at concentrations up to approximately 9.5%. The finding of significant positive bias in the methods of Cobas B 101 and Variant II Turbo 2.0 agrees with the observations of some previous studies, but is contrary to manufacturer’s claim indicating the absence of interference by heterozygous HbE. Our results also clearly showed the impact of heterozygous HbE across a fairly broad measurement range using a laboratory method (the Variant II Turbo 2.0). Laboratory practitioners and clinicians should familiarize themselves with prevailing hemoglobin variants in the population they serve and select the appropriate methods for HbA1c measurement.

Association of hemoglobin H (HbH) disease with hemoglobin A1c and glycated albumin in diabetic and non-diabetic patients

OBJECTIVES

Hemoglobin A_1c (HbA_1c) and glycated albumin (GA) are glycemic control status indicators in patients with diabetes mellitus. Hemoglobin H (HbH) disease is a moderately severe form of α-thalassemia. Here we examine the usefulness of HbA_1c and GA in monitoring glycemic control in patients with HbH disease.

METHODS

HbA_1c, GA, and an oral glucose tolerance test were performed in 85 patients with HbH disease and 130 healthy adults. HbA_1c was measured using five methods, including two systems based on cation-exchange high-performance liquid chromatography (Variant II Turbo 2.0 and Bio-Rad D100), a capillary zone electrophoresis method (Capillarys 3 TERA), a boronate affinity HPLC method (Premier Hb9210), and an immunoassay (Cobas c501).

RESULTS

Significant lower levels of HbA_1c were observed in patients with HbH disease than in healthy adults. In contrast, GA showed no statistically significant differences between participants with and without HbH disease. A considerable number of diabetic patients with HbH disease would be missed if using HbA_1c as a diagnostic criterion for diabetes mellitus.

CONCLUSIONS

GA but not HbA_1c is suitable for monitoring glycemic control in patients with HbH disease that can modify the discriminative ability of HbA_1c for diagnosing diabetes.

Unexpected HbA1c results in the presence of three rare hemoglobin variants

Hemoglobin (Hb) variants, characterized by structural abnormalities in the globin chains, are among the most common inherited disorders. It has been shown that Hb variant remains an important cause of erroneous HbA_1c results. Thus, it is important to be aware of the extent of the interference of each Hb variant encountered to avoid reporting unreliable results. However, the effects of many types of Hb variants on the measurement of HbA_1c remain unclear. Here, we describe three rare Hb variants, Hb J-Tashikuergan [HBA2: c.59 C > A], Hb Pyrgos [HBB: c.251G > A], and Hb Hope [HBB: c.410 G > A], which lead to extremely high values (>25%) determined by Variant II Turbo 2.0. We further investigated their effects on HbA_1c measurement by an HPLC system (Bio-Rad D100), a CE system (Sebia Capillarys 3 TERA), a boronate affinity chromatography system (Premier Hb9210), and an immunoassay method (Roche Diagnostics), and found that these Hb variants severely interfered with HbA_1c measurement by Variant II Turbo 2.0 and Bio-Rad D100. This study demonstrates that patients with abnormally high HbA_1c levels should be highly suspected of carrying Hb variants. When the HbA_1c results are considered unreliable, other indicators such as glycated albumin may be a possible alternative to HbA_1c in diabetic patients.

The Interaction between Hb A1C and Selected Genetic Factors in the African American Population in the USA

BACKGROUND

The global prevalence of diabetes mellitus has been growing in recent decades and the complications of longstanding type 2 diabetes continue to place a burden on healthcare systems. The hemoglobin A1c (Hb A1c) content of the blood is used to assess an individual's degree of glycemic control averaged over 2 to 3 months. In the USA, diabetes is the seventh leading cause of death. Black, indigenous, people of color (BIPOC) are disproportionately affected by diabetes compared to non-Hispanic whites. There are many reports of interaction of Hb A1c and hematologic conditions that have a high prevalence in the Black population; some of these effects are contradictory and not easily explained. This review attempts to document and categorize these apparently disparate effects and to assess any clinical impact.

METHODS

Hb A1C can be determined by a variety of techniques including cation-exchange chromatography, electrophoresis, immunoassays, and affinity chromatography. The amount of Hb A1c present in a patient specimen depends not only on blood glucose but is strongly influenced by erythrocyte survival and by structural variations in the globin chains. Sickling hemoglobinopathies are well-represented in the USA in African Americans and the effects of these hemoglobin disorders as well as G6PD deficiency is examined.

CONCLUSION

Hb A1c measurement should always be performed with a cautious approach. The laboratory scientist should be aware of possible pitfalls in unquestioningly determining Hb A1c without a consideration of hematologic factors, both inherited and acquired. This presents a challenge as often times, the laboratory is not aware of the patient's race.

The Oral Glucose Tolerance Test: 100 Years Later

For over 100 years, the oral glucose tolerance test (OGTT) has been the cornerstone for detecting prediabetes and type 2 diabetes (T2DM). In recent decades, controversies have arisen identifying internationally acceptable cut points using fasting plasma glucose (FPG), 2-h post-load glucose (2-h PG), and/or HbA1c for defining intermediate hyperglycemia (prediabetes). Despite this, there has been a steadfast global consensus of the 2-h PG for defining dysglycemic states during the OGTT. This article reviews the history of the OGTT and recent advances in its application, including the glucose challenge test and mathematical modeling for determining the shape of the glucose curve. Pitfalls of the FPG, 2-h PG during the OGTT, and HbA1c are considered as well. Finally, the associations between the 30-minute and 1-hour plasma glucose (1-h PG) levels derived from the OGTT and incidence of diabetes and its complications will be reviewed. The considerable evidence base supports modifying current screening and diagnostic recommendations with the use of the 1-h PG. Measurement of the 1-h PG level could increase the likelihood of identifying high-risk individuals when the pancreatic ß-cell function is substantially more intact with the added practical advantage of potentially replacing the conventional 2-h OGTT making it more acceptable in the clinical setting.

Hb broomhill [α1 or α2 114(GH2) pro > ala;HBA1 or HBA2:c.343C > G]: a rare Hb variant found in a diabetic chinese individual

We report a clinically silent hemoglobin (Hb) variant, Hb Broomhill [α1 or α2 114(GH2) Pro > Ala;HBA1 or HBA2:c.343C > G] in a diabetic Chinese man. The Hb fractions of the subject were analyzed using various chromatographic and electrophoretic techniques. The glycated hemoglobin (HbA1c) levels measured using cation-exchange high-performance liquid chromatography (CE-HPLC) and the boronate affinity method showed nearly identical results. Analysis of the chromatogram of the CE-HPLC revealed an abnormal shoulder peak that appeared towards the end of the elution profile. Though the capillary electrophoresis method did not interpret the results, a manual examination revealed an abnormal shoulder on the HbA0 peak. Similarly, the electropherogram of the capillary zone electrophoresis also had an abnormal shoulder on the HbA peak. A missense mutation specific to the Hb Broomhill variant was found using Sanger sequencing.

Silent hemoglobin variant during capillary electrophoresis: A case report

Hemoglobin (Hb) North Manchester [β51(D2) Pro→His; HBB:c.155 C>A] is a rare Hb β-globin gene variant that affects glycated Hb measurement values, such as ion-exchange high-performance liquid chromatography, in patients with diabetes. This variant was first detected in the UK in 1998. Here, we describe the first case involving Hb North Manchester detected incidentally in a patient with type 2 diabetes in Northern China. The Hb variant was discovered by ion-exchange high-performance liquid chromatography, yet capillary electrophoresis of both glycated Hb program and Hb program failed to detect it. Subsequently, Sanger sequencing was carried out to help identify the Hb variant.

New Validated Method for Quantification of Glycated Hemoglobin by LC-QToF-MS: Is HRMS Able to Quantify Clinical Samples?

High-resolution mass spectrometry is a powerful tool in clinical analysis but remains less explored due to its lower dynamic range and sensitivity compared to triple quadrupoles. Glycated hemoglobin (HbA1c) is the current gold standard biomarker to monitor the control of diabetes, representing long-term plasma glycemic levels. Due to its clinical importance, several methods have been developed for HbA1c quantification, using different principles; however, the results obtained with these techniques may differ according to the method adopted. Hence, there is a great need to standardize the current methods to quantify glycated hemoglobin. A new UPLC-QToF-MS method was fully validated and tested to quantify HbA1c in human samples. The peptides VHLTPE m/z 695.373 and gly-VHLTPE m/z 857.426, obtained via Glu-C digestion, were the selected peptides for quantification of HbA1c (mmol/mol). Chromatographic separation was obtained in a C18 column, maintained at 40 °C. The mobile phase was composed of water and acetonitrile, both containing 0.02% TFA and 0.1% acetic acid, and eluted in gradient mode. The method was fully validated, being considered linear in the range of 25-107 mmol/mol of HbA1c, and was sensitive, selective, precise, accurate, and free of matrix and carryover effects. The method was successfully applied to real samples, reaching about 90% agreement with reference method results, providing accurate and precise information on peptide mass, without laborious sample preparation. These results support the use of HRMS to improve the quality of quantitative results of HbA1c in health services and demonstrate a possible application of peptide investigation for clinical analysis in the near future.

Association of Copeptin, a Surrogate Marker of Arginine Vasopressin, with Decreased Kidney Function in Sugarcane Workers in Guatemala

BACKGROUND

Vasopressin is elevated in response to heat and dehydration and has been postulated to have a role in the chronic kidney disease of unknown origin being observed in Central America. The aims of this study were to examine whether the vasopressin pathway, as measured by copeptin, is associated with the presence of kidney dysfunction, and to examine whether higher fluid intake is associated with lower circulating copeptin and thereby preserves kidney health among sugarcane workers exposed to hot conditions.

METHODS

Utilizing a longitudinal study of 105 workers in Guatemala, we examined relationships between hydration indices, plasma copeptin concentrations, and kidney function markers at 3 times during the 6-month harvest. We also examined whether baseline copeptin concentrations increased the odds of developing an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2.

RESULTS

Copeptin concentrations were positively associated with serum creatinine (β 1.41, 95% CI 0.88-2.03) and negatively associated with eGFR (β -1.07, 95% CI -1.43 to -0.70). In addition, as workers improved their hydration (measured by increases in fluid balance), copeptin concentrations were reduced, and this reduction was associated with an improvement in kidney function.

CONCLUSIONS

Results suggest that copeptin should be studied as a potential prognostic biomarker.

Separation detection of hemoglobin and glycated hemoglobin fractions in blood using the electrochemical microfluidic channel with a conductive polymer composite sensor

Separation and detection of hemoglobin (Hb) and glycated hemoglobin fractions (HbA1c, HbAld₁₊₂, HbAle, HbAld3a, HbAl_a+b, HbA2, and HbAld3b) was performed using an electrochemical AC field modulated separation channel (EMSC) coupled with a sensor probe. The sensor was fabricated based on immobilization of a redox mediator on the poly(2,2':5',5″-terthiophene-3'-p-benzoic acid, pTTBA) and N,S-doped porous carbon (NSPC) nanocomposite. The different types of catalytic redox mediators such as Nile Blue (NB), toluidine blue O (TBO), and Neutral Red (NR) were evaluated to achieve the efficient detection. Of these, the NB-based sensor showed the best analytical signal for Hb and HbA1c, thus it was characterized using various electrochemical and surface analysis methods. After that, the sensor was coupled with the EMSC to achieve the separation detection of the Hb family. The frequency and amplitude of the AC electrical field applied onto the EMSC walls were the main driving forces for the separation and sensitive detection of the analytes. Under optimized conditions, linear dynamic ranges for Hb and HbA1c among their fractions were obtained between 1.0 × 10^-6 to 3.5 mM and 3.0 × 10^-6 to 0.6 mM with the detection limit of 8.1 × 10^-7 ± 3.0 × 10^-8 and 9.2 × 10^-7 ± 5 × 10^-8 mM, respectively. Interference effects of other biomolecules were also investigated and the clinical applicability of the device was evaluated by the determination of total Hb and % HbA1c in real human blood samples.

Interpretation of hemoglobin A1C in primary care setting

Diagnostic tests for diabetes have evolved with the emphasis shifting from blood glucose levels and/or oral glucose tolerance test to measurement of hemoglobin A1c (HbA1c) levels. With the advent of modern and standardized methods assaying the percentage of glycosylated hemoglobin, clinicians are relying more and more on HbA1c for the management of diabetic patients. A brief review of literature shows, although HbA1c is an important tool in the diagnosis and management of diabetes, it is still far from being perfect. Clinicians need to be more aware about these limitations and take extra steps to avoid medical errors.

Hemoglobin A1c Levels Are Slightly but Significantly Lower in Normoglycemic Subjects With the Hemoglobin E Phenotype

Hb mutations can alter the structure, behavior, stability, or quantity of the globin chain produced. Some Hb variants shorten the erythrocyte life span, resulting in physiologically lower hemoglobin A1c (HbA1c) levels. The hemoglobin E (HbE) phenotype involves a single-nucleotide polymorphism that reduces β-globin chain synthesis. We compared the HbA1c levels of subjects with normal Hb (HbAA; N=131) and HbE (N=148) phenotypes, examining potential hematological and biochemical factors contributing to differences in HbA1c levels. All had normal fasting plasma glucose (<5.6 mmol/L), AST, ALT, and creatinine levels. Mean±SD HbA1c levels differed between HbAA and HbE subjects: 5.5±0.3% and 5.3±0.3% (P<0.001) according to an immunoassay, and 5.5±0.3% and 5.3±0.3% (P<0.001) according to cation-exchange HPLC, respectively. In multiple logistic regression, only mean corpuscular volume (P<0.001) contributed to the difference in HbA1c levels between groups. Although a 0.2% difference in HbA1c is relatively small and unlikely to alter clinical decisions, epidemiologically, this can lead to misclassification of a significant proportion of the population, especially since the threshold of non-diabetes HbA1c (≤5.6%) falls very close to the HbA1c median of the general population.

Similar burden of type 2 diabetes among adult patients with sickle cell disease relative to African Americans in the U.S. population: a six-year population-based cohort analysis

Conflicting evidence exists on the epidemiology of type 2 diabetes mellitus (T2DM) among patients with sickle cell disease (SCD). This study measured the prevalence, incidence and clinical outcomes associated with T2DM in a large US population of commercially-insured adults aged ≥20 years with SCD between 2009 and 2014. Among 7070 patients with SCD, the mean age (median) was 39 (37) years and 60·8% were female. The standardized prevalence of T2DM among patients with SCD showed a modest increase, from 15·7% to 16·5% (P trend = 0·026), and was comparable to African-American respondents to the National Health and Nutrition Examination Survey (18·2%). Over 17 024 person-years, the crude incidence rate for T2DM was 25·4 per 1000 person-years. Incident T2DM was associated with comorbid hypertension (hazard ratio [HR] = 1·45, 95% confidence interval [CI] 1·14-1·83), and dyslipidaemia (HR = 1·43, 95%CI 1·04-1·96). Compared to SCD patients without T2DM, more SCD patients with T2DM had diagnoses of nephropathy (28·0% vs. 9·5%; P < 0·001), neuropathy (17·7% vs. 5·2%; P < 0·001) and stroke (24·1% vs. 9·2%; P < 0·001). Prevalence of T2DM in SCD patients is similar to the general African American population with an increasing trend in recent years. These trends support routine screening for T2DM in aging patients with SCD, especially those with comorbid hypertension and/or dyslipidaemia.

Alarming increase in HbA1c and near misdiagnosis of diabetes mellitus resulting from a clinical laboratory instrument upgrade and haemoglobin variant

A 29-year-old woman was referred for new-onset diabetes mellitus after her glycosylated haemoglobin (HbA1c) was found to be 10.2%. Three years earlier, the patient's HbA1c-measured by the same clinical laboratory-had been 5.5%. The newer HbA1c was discordant with fasting glucose levels and a lack of diabetes-associated symptoms. The laboratory reported that their assay methodology remained unchanged and also that no haemoglobin variants were detected. Further investigation, however, revealed, first, that the patient carried a haemoglobin alpha chain mutation (Hb Wayne) that can sometimes cause assay interference and, second, that although the laboratory's assay methodology had not changed, their assay instrument had. Depending on assay methodology, haemoglobin variants can cause HbA1c assay interference and the presence of these variants may not be detected by the performing laboratory. Interference may not only be dependent on assay methodology but also on the assay instrument used.

Different strategies for detection of HbA1c emphasizing on biosensors and point-of-care analyzers

Measurement of glycosylated hemoglobin (HbA1c) is a gold standard procedure for assessing long term glycemic control in individuals with diabetes mellitus as it gives the stable and reliable value of blood glucose levels for a period of 90-120 days. HbA1c is formed by the non-enzymatic glycation of terminal valine of hemoglobin. The analysis of HbA1c tends to be complicated because there are more than 300 different assay methods for measuring HbA1c which leads to variations in reported values from same samples. Therefore, standardization of detection methods is recommended. The review outlines the current research activities on developing assays including biosensors for the detection of HbA1c. The pros and cons of different techniques for measuring HbA1c are outlined. The performance of current point-of-care HbA1c analyzers available on the market are also compared and discussed. The future perspectives for HbA1c detection and diabetes management are proposed.

Average glucose from hemoglobin A1c for altered red blood cell lifetimes: Predictions based on a model for hemoglobin A1c formation

BACKGROUND

A model for hemoglobin A_1c (HbA_1c) formation was used to predict the relationship between average glucose (AG) and %HbA_1c under conditions of altered red blood cell lifetime (RCL).

METHODS

Using a kinetic mass balance model for formation of HbA_1c in red blood cells as a function of age (time in circulation), whole blood %HbA_1c vs. glucose was calculated based on the nonlinear distribution of red blood cells as a function of age across RCL.

RESULTS

Model calculations provided a close fit to the standard relationship of estimated average glucose to %HbA_1c for normal RCL (r>0.999). Results for altered RCL were calculated assuming simple time-scale compression or expansion of the distribution of red blood cells as a function of RCL. For a given %HbA_1c, the operative average glucose needed to have achieved a given %HbA_1c was predicted to be altered by RCL according to average glucose×RCL=constant.

CONCLUSIONS

Model calculations estimate the extent to which standard reporting of AG vs. HbA_1c underestimates or overestimates AG under conditions of altered RCL. Conditions of altered RCL may often be operative in patients with certain hemoglobin variants.

Heterozygote Hemoglobin G-Coushatta as the Cause of a Falsely Decreased Hemoglobin A1C in an Ion-exchange HPLC Method

Glycated hemoglobin (HbA1c) is used for the assessment of glycemic control in patients with diabetes. The presence of genetic variants of hemoglobin can profoundly affect the accuracy of HbA1c measurement. Here, we report two cases of Hemoglobin G-Coushatta (HBB:c.68A>C) variant that interferes in the measurement of HbA1c by a cation-exchange HPLC (CE-HPLC) method. HbA1c was measured by a CE-HPLC method in a Tosoh HLC-723 G7 instrument. The HbA1c levels were 2.9% and 4%. These results alerted us to a possible presence of hemoglobinopathy. In the hemoglobin variant analysis, HbA2 levels were detected as 78.3% and 40.7% by HPLC using the short program for the Biorad Variant II. HbA1c levels were measured by an immunoturbidimetric assay in a Siemens Dimension instrument. HbA1c levels were reported as 5.5% and 5.3%. DNA mutation analysis was performed to detect the abnormal hemoglobin variant. Presence of Hemoglobin G-Coushatta variant was detected in the patients. The Hb G-Coushatta variants have an impact on the determination of glycated hemoglobin levels using CEHPLC resulting in a false low value. Therefore, it is necessary to use another measurement method.

Molecular Diagnosis of Thalassemias and Hemoglobinopathies: An ACLPS Critical Review

OBJECTIVES

To describe the use of molecular diagnostic techniques for patients with hemoglobin disorders.

METHODS

A clinical scenario is presented in which molecular diagnosis is important for genetic counseling. Globin disorders, techniques for their diagnosis, and the role of molecular genetic testing in managing patients with these disorders are described in detail.

RESULTS

Hemoglobin disorders, including thalassemias and hemoglobinopathies, are among the commonest genetic diseases, and the clinical laboratory is essential for the diagnosis of patients with these abnormalities. Most disorders can be diagnosed with protein-based techniques such as electrophoresis and chromatography. Since severe syndromes can result due to inheritance of combinations of globin genetic disorders, genetic counseling is important to prevent adverse outcomes. Protein-based methods cannot always detect potentially serious thalassemia disorders; in particular, α-thalassemia may be masked in the presence of β-thalassemia. Deletional forms of β-thalassemia are also sometimes difficult to diagnose definitively with standard methods.

CONCLUSIONS

Molecular genetic testing serves an important role in identifying individuals carrying thalassemia traits that can cause adverse outcomes in offspring. Furthermore, prenatal genetic testing can identify fetuses with severe globin phenotypes.

The Prevalence and Role of Hemoglobin Variants in Biometric Screening of a Multiethnic Population: One Large Health System's Experience

OBJECTIVES

To characterize and quantitate hemoglobin (Hb) variants discovered during biometric hemoglobin A1c (HbA1c) analyses in a large multiethnic population with a focus on the effect of variants on testing method and results.

METHODS

In total, 13,913 individuals had their HbA1c measured via ion-exchange high-performance liquid chromatography. Samples that had a variant Hb detected or HbF fraction more than 25% underwent variant Hb characterization and confirmation by gel electrophoresis. RBC indices were also evaluated for possible concomitant thalassemia.

RESULTS

Of the 13,913 individuals evaluated, 524 (3.77%) had an Hb variant. The prevalence of each variant was as follows: HbS trait (n = 396, 2.85%), HbSS disease (n = 4, 0.03%), HbC trait (n = 85, 0.61%), HbCC disease (n = 2, 0.01%), HbSC disease (n = 5, 0.04%), HbE trait (n = 18, 0.13%), HbD or G trait (n = 9, 0.06%), HbS β-thalassemia + disease (n = 1, 0.01%), hereditary persistence of HbF (n = 2, 0.01%), and HbMontgomery trait (n = 1, 0.01%). Concomitant α-thalassemia was detected in 20 (3.82%) of the 524 individuals with an Hb variant.

CONCLUSIONS

This study represents one of the largest epidemiologic investigations into the prevalence of Hb variants in a North American metropolitan, multiethnic workforce and their dependents and reinforces the importance of method selection in populations with Hb variants.

Comparison of four chromatographic methods used for measurement of glycated hemoglobin

This parameter’s results accuracy has a special importance in the management of diabetic patients since targets for optimal glycemic control are established using HbA1c values. Several error sources can influence the obtained value, some of them can be counteracted (ex. pipetting errors, storage), and others should be taken into consideration at the interpretation of the result (ex. presence of hemoglobin variants). The aim of this study was to compare four chromatographic methods regarding the costs and the influence of certain error sources on the accuracy of the result. Materials and methods: Samples and controls were analyzed using Variant I, Micromat II and In2it (Bio-Rad) systems, and the BIOMIDI reagent kit for HbA1c measurement. Results: Positive correlation could be observed comparing the results obtained using different methods, except the patients presenting elevated HbF. Pipetting errors modify the results up to 5% in case of Variant I, and up to 10% in case of Micromat II in the tested range. One day of improper storage at room temperature causes 3% deviation from the actual value using the Variant I analyzer and 5% in case of Micromat II and In2it equipment. As a conclusion, depending on the number of samples, automated chromatographic analyzers are the most appropriate equipments for the determination of HbA1c.

Hb Melusine and Hb Athens-Georgia: potentially underreported in the Belgian population? Four cases demonstrating the lack of detection using common CE-HPLC methods either for glycated hemoglobin (HbA1C) analysis or Hb variant screening

OBJECTIVE AND IMPORTANCE

Suspected hemoglobin (Hb) variants, detected during HbA_1C measurements should be further investigated, determining the extent of the interference with each method.

CLINICAL PRESENTATION

This is the first report of Hb Melusine and Hb Athens-Georgia in Caucasian Belgian patients. Intervention & Technique: Since common CE-HPLC methods for HbA_1C analysis or Hb variant screening are apparently unable to detect these Hb variants, their presence might be underestimated. HbA_1C analysis using CZE, however, alerted for their presence. Moreover, in case of Hb Melusine, even Hb variant screening using CZE was unsuccessful in its detection.

CONCLUSION

Fortunately, carriage of Hb Melusine or Hb Athens-Georgia variants has no clinical implications and, as shown in this report, no apparent difference in HbA_1C should be expected.

Erroneous HbA1c results in a patient with elevated HbC and HbF

BACKGROUND

HbA1c is used in the diagnosis and monitoring of diabetes mellitus (DM). Interference from hemoglobin variants is a well-described phenomenon, particularly with HPLC-based methods. While immunoassays may generate more reliable HbA1c results in the presence of some variants, these methods are susceptible to negative interference from high concentrations of HbF. We report a case where an accurate HbA1c result could not be obtained by any available method due to the presence of a compound hemoglobinopathy.

METHODS

HbA1c was measured by HPLC, immunoassay, and capillary electrophoresis. Hemoglobinopathy investigation consisted of a CBC, hemoglobin fractionation by HPLC and electrophoresis, and molecular analysis.

RESULTS

HbA1c analysis by HPLC and capillary electrophoresis gave no result. Analysis by immunoassay yielded HbA1c results of 5.9% (Siemens DCA 2000+) and 5.1% (Roche Integra), which were inconsistent with other markers of glycemic control. Hemoglobinopathy investigation showed HbC with the hereditary persistence of fetal hemoglobin-2 Ghana deletion.

CONCLUSION

Reliable HbA1c results may be unobtainable in the presence of some hemoglobinopathies. HPLC and capillary electrophoresis alerted the laboratory to the presence of an unusual hemoglobinopathy. Immunoassays generated falsely low results without warning, which could lead to missed diagnoses and under treatment of patients with DM.