The increase in haemoglobin (Hb)A₂ level is the most significant parameter in the identification of β thalassaemia carriers. However, in some cases the level of HbA₂ is not typically elevated and some difficulties may arise in making the diagnosis. For these reasons the quantification of HbA₂ has to be performed with great accuracy and the results must be interpreted together with other haematological and biochemical evidence. The present document includes comments on the need for accuracy and standardisation, and on the interpretation of the HbA₂ value, reviewing the most crucial aspects related to this test. A practical flow-chart is presented to summarise the significance of HbA₂ estimation in different thalassaemia syndromes and related haemoglobinopathies.

Background: The reference intervals for hemoglobin A_1c (Hb A_1c) in pregnant women without diabetes are not well defined, and few examples of reference intervals established by networks of different laboratories are available. Methods: Five Italian Diabetic Care Units were involved in the study. Data were collected from 445 pregnant women without diabetes, selected on the basis of glucose challenge test results, and from 384 nonpregnant control women. The Hb A_1c measurements were performed with HPLC systems aligned to the Diabetes Control and Complications Trial. Plasma glucose measurements were also performed locally. Both Hb A_1c and glucose measurements were harmonized by running appropriate external quality assessment schemes. The reference intervals were calculated in terms of nonparametric 2.5th to 97.5th percentiles with 0.90 confidence intervals. Results: The Hb A_1c measurements were reproducible (CV = 2.0%) and accurate [mean (SE) difference from the target values, −0.10 (0.06)%]. Glucose measurements were also reproducible (mean CV = 3.2%) and accurate [difference from the target values, −0.01 (0.04) mmol/L]. To calculate common reference intervals, we merged the data collected in the different centers. The Hb A_1c reference intervals were 4.0%–5.5% for pregnant nondiabetic women and 4.8%–6.2% for nonpregnant controls. Conclusions: Healthy pregnant women have lower Hb A_1c concentrations than nonpregnant women. The reference intervals for Hb A_1c in pregnant women should therefore be lower than those currently in use.

In clinical practice, glycemic control is generally assessed by measuring and interpreting glycated hemoglobin levels, however, this test should be run under standardized conditions. We focus here on the crucial steps to ensure IFCC standardized HbA_1c results, pointing out several residual weak points, mostly relating to the laboratory end-user (calibration, quality control materials, and EQAS). We also review the use of HbA_1c for diagnosing diabetes and the various indicators useful for assessing glucose variability because in some cases they seem to represent a patient’s glucose profile more accurately than one-off HbA_1c assays. Finally, the potential utility of glycated albumin and the glycation gap, the costs involved and the laboratory management issues are briefly discussed.

To evaluate the extent of interlaboratory variation and accuracy in hemoglobin A(2) (HbA(2)) assays, a pilot study of external quality assessment was organized among 48 Italian laboratories routinely measuring HbA(2). As part of the study, a survey was also performed by sending a questionnaire concerning some important analytical aspects related to the determination of HbA(2). The trial specimens consisted of three whole blood samples (A, B and C) with normal, pathological and borderline HbA(2) content, respectively. All laboratories used HPLC analyzers from the same manufacturer (Bio-Rad Laboratories). Normal and pathological samples were clearly differentiated by all laboratories, while data for the borderline sample partially overlapped those for the other samples. The overall interlaboratory coefficient of variation was 8.0%, 6.0% and 7.9% for samples with low, high and intermediate HbA(2) levels, respectively. To assign HbA(2) target values to the samples, the median of the laboratory group was used. The accuracy of HbA(2) results was evaluated on the basis of allowable total error. The proportion of laboratories reporting unacceptable results was 31.9% (15 out of 47) for sample A, 17.0% (8 out of 47) for sample B, and 31.9% (15 out of 47) for sample C. No abnormalities in the chromatographic separation pattern were reported by any of the laboratories. We conclude that quality in the measurement of HbA(2) should be improved.