Background: Standardization of laboratory tests can be a long process, and this is the case with regards to the methods used to measure hemoglobin A(2) (HbA(2)), an important marker for beta... Show moreBackground: Standardization of laboratory tests can be a long process, and this is the case with regards to the methods used to measure hemoglobin A(2) (HbA(2)), an important marker for beta-thalassemia and other thalassemic conditions. The IFCC standardization project started in 2004, and it took at least 15 years before developing a reference measurement procedure, defining and producing calibrators and certified reference materials.Methods: A series of steps have to be undertaken in order to promote the standardization in the field, a process involving a number of stakeholders (manufacturers, scientific societies, national health bodies, laboratory professionals, clinicians). In this work we describe some possible process indicators, in order to assure that the standardization will have internal and external validity and be effective for a long time. These indicators concern the inter-method studies, elaboration of External Quality Assessment Schemes, and the evaluation of the yearly distributions of HbA(2) measurements collected in selected laboratories.Results: Preliminary results are reported concerning the yearly distributions of HbA(2), collected in two different locations, and using different analytical methods. Median yearly values were found very constant over the years, but different between methods. On the other side, results obtained on the same specimens using two different techniques, proved that results by capillary electrophoresis in 2 out of the 3 years of observation, were significantly lower than those by HPLC.Conclusion: In this document we report what has been done so far, and what has to be done to achieve the standardization of the measurement of HbA(2) worldwide. Show less
BackgroundNon-equivalence in serum creatinine (SCr) measurements across Dutch laboratories and the consequences hereof on chronic kidney disease (CKD) staging were examined. MethodsNational data... Show moreBackgroundNon-equivalence in serum creatinine (SCr) measurements across Dutch laboratories and the consequences hereof on chronic kidney disease (CKD) staging were examined. MethodsNational data from the Dutch annual external quality organization of 2009 were used. 144 participating laboratories examined 11 pairs of commutable, value-assigned SCr specimens in the range 52–262 μmol/L, using Jaffe or enzymatic techniques. Regression equations were created for each participating laboratory (by regressing values as measured by participating laboratories on the target values of the samples sent by the external quality organization); area under the curves were examined and used to rank laboratories. The 10th and 90th percentile regression equation were selected for each technique separately. To evaluate the impact of the variability in SCr measurements and its eventual clinical consequences in a real patient population, we used a cohort of 82424 patients aged 19–106 years. The SCr measurements of these 82424 patients were introduced in the 10th and 90th percentile regression equations. The newly calculated SCr values were used to calculate an estimated glomerular filtration rate (eGFR) using the 4-variable Isotope Dilution Mass Spectrometry traceable Modification of Diet in Renal Disease formula. Differences in CKD staging were examined, comparing the stratification outcomes for Jaffe and enzymatic SCr techniques. ResultsJaffe techniques overestimated SCr: 21%, 12%, 10% for SCr target values 52, 73 and 94 μmol/L, respectively. For enzymatic assay these values were 0%, -1%, -2%, respectively. eGFR using the MDRD formula and SCr measured by Jaffe techniques, staged patients in a lower CKD category. Downgrading to a lower CKD stage occurred in 1-42%, 2-37% and 12–78.9% of patients for the 10th and 90th percentile laboratories respectively in CKD categories 45–60, 60–90 and >90 ml/min/1.73 m2. Using enzymatic techniques, downgrading occurred only in 2-4% of patients. ConclusionsEnzymatic techniques lead to less variability in SCr measurements than Jaffe techniques, and therefore result in more accurate staging of CKD. Therefore the specific enzymatic techniques are preferably used in clinical practice in order to generate more reliable GFR estimates. Show less
BackgroundNon-equivalence in serum creatinine (SCr) measurements across Dutch laboratories and the consequences hereof on chronic kidney disease (CKD) staging were examined. MethodsNational data... Show moreBackgroundNon-equivalence in serum creatinine (SCr) measurements across Dutch laboratories and the consequences hereof on chronic kidney disease (CKD) staging were examined. MethodsNational data from the Dutch annual external quality organization of 2009 were used. 144 participating laboratories examined 11 pairs of commutable, value-assigned SCr specimens in the range 52–262 μmol/L, using Jaffe or enzymatic techniques. Regression equations were created for each participating laboratory (by regressing values as measured by participating laboratories on the target values of the samples sent by the external quality organization); area under the curves were examined and used to rank laboratories. The 10th and 90th percentile regression equation were selected for each technique separately. To evaluate the impact of the variability in SCr measurements and its eventual clinical consequences in a real patient population, we used a cohort of 82424 patients aged 19–106 years. The SCr measurements of these 82424 patients were introduced in the 10th and 90th percentile regression equations. The newly calculated SCr values were used to calculate an estimated glomerular filtration rate (eGFR) using the 4-variable Isotope Dilution Mass Spectrometry traceable Modification of Diet in Renal Disease formula. Differences in CKD staging were examined, comparing the stratification outcomes for Jaffe and enzymatic SCr techniques. ResultsJaffe techniques overestimated SCr: 21%, 12%, 10% for SCr target values 52, 73 and 94 μmol/L, respectively. For enzymatic assay these values were 0%, -1%, -2%, respectively. eGFR using the MDRD formula and SCr measured by Jaffe techniques, staged patients in a lower CKD category. Downgrading to a lower CKD stage occurred in 1-42%, 2-37% and 12–78.9% of patients for the 10th and 90th percentile laboratories respectively in CKD categories 45–60, 60–90 and >90 ml/min/1.73 m2. Using enzymatic techniques, downgrading occurred only in 2-4% of patients. ConclusionsEnzymatic techniques lead to less variability in SCr measurements than Jaffe techniques, and therefore result in more accurate staging of CKD. Therefore the specific enzymatic techniques are preferably used in clinical practice in order to generate more reliable GFR estimates. Show less
