HbA1c Testing Post

HbA1c testing: Delivering HbA1c Test Results with Confidence

For efficient HbA1c testing, it is of paramount importance to deliver HbA1c test results with confidence.  In 2007, CAP began using accuracy grading with an acceptable limit of ±15% of a target value; this limit was lowered to ±12% in 2008 and future reductions are as follows:

• 2009 Surveys: ±10%
• 2010 Surveys: ±8%
• 2011 Surveys: ±6% (“educational grade”)

When laboratories participate in CAP surveys they are comparing the results obtained on their system to this target value.

Since grading criteria is dropping by 2% each year, it will be more difficult for laboratories to pass their CAP survey if they are using an analyzer which gives them results outside of the acceptable grading limit.

Tosoh Provides High Precision with Low CVs

Precision is a measure of the consistency of results in the entire customer installed base, and this in turn affects how well the 6% limit will be achieved in 2011. With CVs of <2%, Tosoh leads the industry in HbA1c precision. The typical industry performance is 1.5-3.5% CVs(JCCLM 2007; 45: 1083-1097). According to Tosoh HPLC Product Manager Ranka Milojkovic, “The instrument-reagent system utilizes the gold standard ion-exchange method for HbA1c level testing to effectively monitor diabetes.”

The Tosoh G8 provides direct determination of stable HbA1c. The system is used for in vitro diagnostic measurement of HbA1c in blood specimens. The G8 uses a non-porous column and microcomputer technology to quickly and accurately measure the stable portion of HbA1c as a percentage of the total amount of hemoglobin present in the sample. The G8 provides accurate and precise separation of HbA1c from other hemoglobin fractions. Off-line pretreatment is not required, and there is no interference from the labile portion of HbA1c.

The analyzer dilutes the whole blood specimen with Hemolysis & Wash Solution and then injects a small volume of the treated specimen onto the TSKgel Glyco HSi Variant Column. Separation is achieved by utilizing differences in ionic interactions between the cation exchange group on the column resin surface and the hemoglobin components in a step gradient elution. The hemoglobin fractions (designated as A1a, A1b, F, LA1c , SA1c, A0, and H-V0, H-V1, H-V2) are subsequently removed from the column material by performing a step-wise elution using Elution Buffers HSi Variant 1, 2, and 3 that have specific salt and pH concentrations.

The separated hemoglobin components pass through the LED photometer flow cell where changes in absorbance are measured at 415nm. The G8 software integrates and reduces the raw data, and then calculates the relative percentages of each hemoglobin fraction. The print-out consists of the numerical results and the chromatogram. This represents the changes in absorbance versus retention time for each peak fraction. An analysis requires only 1.6 minutes.
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