Diabetic Living Australia - July-August 2018

and “eat” glucose. This can

lower glucose levels, leading to

an inaccurate reading. Samples

should be kept in grey-top

tubes which block glucose

use, or in a tube that can

create a barrier between the

glucose and the blood cells.

HIGH PRESSURE LIQUID

CHROMATOGRAPHY

A medical scientist uses high

pressure liquid chromatography

(HPLC) to measure the

HbA1c in your blood. The

blood sample is mixed with

special liquids called reagents,

and then passed under

pressure through columns

filled with a material that

separates the blood into its

component molecules.

HbA1c occurs when glucose

binds to haemoglobin. These

molecules differ in size and

electrical charge from the

other blood molecules, so

they can be separated.

The machine then calculates

a percentage of how much

haemoglobin in the blood

is made up of HbA1c. This

process can be completed

within 30 seconds.

RESULTS AND REPORTING

The test results are reviewed,

and a report is prepared.

Patient details such as

age and sex are important

in deciding whether a test

result is normal.

Other health conditions

can also affect HbA1c results,

including pregnancy, severe

kidney and liver disease, as

well as iron deficiency and

certain blood disorders.

The possibility of medical

conditions that interfere with

test results must be considered

by the pathologist in all

patients with an unexpectedly

low HbA1c measurement.

With HbA1c results,

pathologists report two sets

of numbers; the traditional

percentages, plus the new

Systeme International (SI)

units, which are shown as

mmol/mol. These new units

were developed by the

International Federation of

Clinical Chemistry and

Laboratory Medicine (IFCC)

and are sometimes referred

to as IFCC units.

For people with diabetes,

the HbA1c target to aim for

is 48 mmol/mol (6.5 per cent).

This is a general target and

patients should be given an

individual target to aim

towards by their health team.

It is the pathologist’s duty

to oversee the entire testing

process and ensure it meets

Australia’s high quality

standards.

Although the results are

provided to the patient by

their doctor, pathologists are

always available to answer

doctors’ questions about test

results and advise on suitable

treatment options. ■

To learn more about diabetes tests,

visit Pathology Awareness Australia

at knowpathology.com.au

HIGH PRESSURE LIQUID

CHROMATOGRAPHY

RESULTS AND REPORTING

There is

no need to

fast before

having an

HbA1c test

WORDS & PHOTOGRAPHY

ASSOCIATE PROFESSOR GRAHAM JONES

ADDITIONAL PHOTOGRAPHY

GETTY IMAGES

116 JULY/AUGUST 2018 diabetic living

need to know