Forgive me, but I was a biochemist before becoming a doctor and biochemists love to test! Functional lab testing has revolutionised my practice and been a powerful tool to help me show patients the effect of the nutrition and environment (including stress) on their health.

When do I use it? Just imagine a patient comes in with fatigue, mood issues, digestive troubles, behavioural issues, joint pain, or just not feeling like themselves.

This could be due to underlying:

• digestive issues

• nutrient deficiencies

• hormone issues

• inflammation

• toxicity

• detoxification issues


• some or all of the above.

This leads to the obvious question: where to start? This is where functional testing comes in, as it helps guide us to the most likely cause of patients symptoms. I really feel for my GP colleagues in the public sector, because it’s challenging to work out a diagnosis in the brief time they have with a patient.

I’m privileged as a private GP to be able to spend 60-90 minutes in initial appointments and 30-60 minutes in follow up appointments with my patients. This gives me time to determine the likely underlying causes (avoiding unnecessary and risky temporary suppression of symptoms with medications) and to decide which testing is likely to reveal these causes.

I particularly have a love affair with functional tests as they reveal an extraordinary amount of information compared to standard local lab testing. All functional tests are useful but to reduce costs I usually recommend two to three as a good start. These tests are generally performed by USA based labs but some are available in Australia.

The process involves giving the patient a kit to do the test at home. This is because most of the tests involve collecting urine, stool or saliva samples. Food antigen testing is usually a blood spot but can be performed with a standard lab blood draw at local labs.

So what testing is available? There are many, and all provide many more markers than are usually available through standard public sector laboratories. As a fully registered GP, I do still do public sector lab testing in addition to functional labs because it provides more pieces of a patients’ health ‘puzzle’. The more pieces I have the better the picture and the more I can help a patient.

Current functional lab tests include:

• gut microbiome and function

• stress and sex hormones and metabolites (with some organic acids)

• organic acids for indicators of metabolism, toxin, pathogen, nutrient, neurotransmitter

• body chemical load

• urine toxics metals and essential minerals

• body mould toxin load

• genetic SNPs: e.g. Vitamin D receptor (which could explain why a patients vitamin D levels aren’t increasing on therapy)

• food antigen testing: food reactions (most also do complement levels for the degree of inflammation they cause).

I will cover these tests in more detail in future opinion pieces but I strongly feel we owe it to our patients to at least make them aware of these other researched testing options.

These tests would have helped me recover from my own health issues much sooner if I had known about them then. I also have seen the benefits for my patients.

Ask the laboratories that offer them for a kit for yourself so you can see the benefits for yourself. The results might surprise you!