Immunoturbidimetric assay of glycated hemoglobin.

We investigated the performances of HbA1c determination by a latex enhanced turbidimetric immunoassay using the specific monoclonal antibodies (Unimate, Roche) against the beta-N-terminal fragments. The coefficients of variation ranges from 1.7 to 3.8% within assay (n = 30) and from 3.9 to 4.9% between assay (n = 20). The assay was linear from 2.5 to 14.9% of HbA1c. No interferences was found from fetal, carbamylated, or variant (S) hemoglobins and from labile Schiff adduct with glucose. The following relationship was derived from fresh sample comparison between HPLC (Diamat-BioRad) (x) and immunoassay (y) method: y = 0.971 x + 0.87%, r=0.98, n = 115. The immunoassay provides a highly precise and specific method for HbA1c.