Glycated haemoglobins or HbA1c

Glycated haemoglobins

POCT Test Name

Glycated haemoglobin or HbA₁C.

There are three major types of haemoglobin (Hb): HbA1, HbA2, and HbF. In addition, over 400 variants or haemoglobinopathies are known. All of the types react with hexose sugars to give products known as glycated haemoglobins.

It is known that the condensation reaction between glucose and haemoglobin occurs throughout the typical 120 day life-span of erythrocytes, and the extent of glycosylation depends on the circulating concentration of glucose. Thus the glycated haemoblobin concentration in a given blood sample can reflect the mean blood-glucose concentration of the preceding 120 days.

Blood glucose level is a spot check and reveals information only on the day of the blood glucose test. Information on glycated haemoglobin informs the clinician on how well a patient has managed to control blood glucose with diet and/or insulin injection. This information may help the clinician to decide if it is necessary to increase or decrease the dose of insulin to provide more effective control.

Instruments

Siemens DCA2000+

Location within CDHB

There are seven within the CDHB. They are located in:

Diabetes Centre (3 units)
Christchurch Womens' School of Medicine Research (1)
Paediatric Outpatients (2)
Special Chemistry, CHLabs (1)

Tests measured

Glycated haemoglobin or HbA₁C.

Microalbumin (Christchurch Womens' School of Medicine Research)

Sample and volume requirements

A single drop of capillary blood is all that is required. Capillary action will draw the required volume (1µL) into the cartridge.

Microalbumin: 40uL of clear MSU. A special sample holder is required.

Consumables

Please contact the POCT Coordinator for details.

Controls

Quality Controls are available for the DCA2000 and must give expected results before the analyser is used for patient samples. Alternatively, QC must be analysed if the lot number of cartridges changes.
Controls check the ability of the operator to deliver the sample correctly to the meter and the ability of the meter to determine the correct result.
Controls do not check the quality of the patient capillary sample before it is delivered to the meter.
A monthly whole blood correlation is analysed between the laboratory method and each of the DCA2000's. Results are available from the POCT Coordinator.
Regular correlations of microalbumin are made between DCA2000 and CHLabs 8200i Architect analysers.

Reference Range

All reference ranges can be found in the CHLabs test database. Click on the left hand menu link to Canterbury Health Laboratories home page, then click on "Tests".

Sources of Error

Failure to analyse QC samples
Continued use of analyser when QC fails.
Incorrect capillary sampling technique.
Expired cartridges

Competencies

Available. Please contact the POCT Coordinator.