Evaluation and comparison of Abbott Jaffe and enzymatic creatinine methods: Could the old method meet the new requirements?

BACKGROUND: The aim of this study is to evaluate and compare the analytical performance characteristics of the two creatinine methods based on the Jaffe and enzymatic methods. METHODS: Two original creatinine methods, Jaffe and enzymatic, were evaluated on Architect c16000 automated analyzer via limit of detection (LOD) and limit of quantitation (LOQ), linearity, intra-assay and inter-assay precision, and comparability in serum and urine samples. The method comparison and bias estimation using patient samples according to CLSI guideline were performed on 230 serum and 141 urine samples by analyzing on the same auto-analyzer. RESULTS: The LODs were determined as 0.1 mg/dL for both serum methods and as 0.25 and 0.07 mg/dL for the Jaffe and the enzymatic urine method respectively. The LOQs were similar with 0.05 mg/dL value for both serum methods, and enzymatic urine method had a lower LOQ than Jaffe urine method, values at 0.5 and 2 mg/dL respectively. Both methods were linear up to 65 mg/dL for serum and 260 mg/dL for urine. The intra-assay and inter-assay precision data were under desirable levels in both methods. The higher correlations were determined between two methods in serum and urine (r=.9994, r=.9998 respectively). On the other hand, Jaffe method gave the higher creatinine results than enzymatic method, especially at the low concentrations in both serum and urine. CONCLUSIONS: Both Jaffe and enzymatic methods were found to meet the analytical performance requirements in routine use. However, enzymatic method was found to have better performance in low creatinine levels.

Diagnostic value of glycemic markers HbA1c, 1,5-anhydroglucitol and glycated albumin in evaluating gestational diabetes mellitus.

BACKGROUND: The oral glucose tolerance test (OGTT) is the current established method performed worldwide to diagnose gestational diabetes mellitus (GDM). The purpose of this study was to assess the utility of the use of long- and short-term markers of glycemic status. METHODS: The study group was composed of 80 pregnant women, 40 with GDM and 40 with normal glucose tolerance. GDM was diagnosed with the American Diabetes Association criteria. Glycemic markers were measured in the OGTT blood samples of women at 24-28 weeks of gestation. RESULTS: HbA1c was significantly higher in the GDM group when compared with the controls, whereas 1,5-anhydroglucitol (1,5-AG) levels were significantly lower. There was not a significant difference between the groups for glycated albumin. Whereas HbA1c levels were correlated with fasting and 1 h glucose and negatively correlated with mean corpuscular volume, 1,5-AG was only negatively correlated with the first hour glucose. No difference was found for the diagnostic performances of HbA1c and 1,5-AG (receiver operating characteristic of the area under the concentration curve values were 0.756 and 0.722, respectively). CONCLUSION: HbA1c and 1,5-AG alone does not have sufficient diagnostic accuracy to diagnose GDM. 1,5-AG values were correlated with post-load glucose values in pregnant women so will improve the GDM management and be useful to predict complications.