Behind the scenes

What pathologists do with your tests

There are more than 500 pathology laboratories nationwide, but few people know what goes on inside them. These labs process tests for the 1.25 million Australians living with diabetes. For every diabetes test performed, at least 10 people are involved, including collectors, couriers, medical scientists, technicians, IT specialists, registrars and pathologists.

“Diabetes is defined by pathology tests,” says Pathology Awareness Australia ambassador, Associate Professor Graham Jones.

“We have no other tools to see if we’re winning against the condition. Trying to manage diabetes without pathology is like trying to drive a car without a steering wheel!”

It is recommended that people with diabetes have regular haemoglobin A1c blood tests, which indicate the level of long-term blood sugar control. The term haemoglobin A1c (HbA1c) refers to glycated haemoglobin. This develops when haemoglobin, a protein within red blood cells, joins with glucose in the blood, becoming ‘glycated’.

By measuring HbA1c, clinicians can get an overall picture of the average blood glucose levels over a threemonth period.

Understanding your HbA1c levels can help you to manage diabetes by choosing the best treatments to optimise your blood glucose levels.

Taking proactive action on regular HbA1c results can also help reduce your risk of health complications.

Unlike the fasting glucose test, there is no need to fast before a HbA1c test. The ingestion of glucose before the test has no impact on the result, and there is no waiting time involved. The convenience and reliability of HbA1c testing makes it easier to screen those at risk of diabetes and provides the opportunity for early diagnosis and intervention.

Here, Jones explains the journey of an HbA1c test.

SAMPLE COLLECTION

This is the only part of pathology that is seen by the public. Phlebotomists, more commonly known as collectors, are trained to accurately collect and store patients’

samples and to provide the correct paperwork with each one. Speed is essential given how many people can attend a collection centre at any one time. Collectors outside of hospitals often work to courier schedules, so processing the samples to get them to the lab quickly is vital.

SPECIMEN DELIVERY

A special courier transports your test sample to the lab, making sure it is kept at the right temperature and that it arrives within a suitable timeframe. On arrival in the lab the staff at specimen reception ensure it is distributed to the correct department. Due to the high volume of samples delivered daily, staff at reception can be on duty 24/7.

SORTING

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

There is no need to fast before having an HbA1c test

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.