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I am frequently asked ‘what exactly is functional testing’ and ‘how does this differ from the test my GP ran?’.

Functional testing aims to evaluate a range of physiological processes within the body rather than simply looking at individual specific markers of ‘disease’ and determining whether the suspected disease is present or not.  A disease is simply a collection of symptoms that have been classified with a particular name and, within the conventional medicine paradigm, if you fall into this category the solution typically is to prescribe one or more pills that will hopefully suppress the symptoms.   If you are lucky this prescribed medication wont have any side effects.  It is a very linear, reductionist process and does not look to find out WHY the disease or collection of symptoms is there in the first place.

Diseases don’t suddenly appear out of nowhere but are a result of a move away from homeostasis or  balance over a period of time, frequently years, and many clients come knowing something is wrong but have been told by their GP that they ‘are fine’.  A further reason conventional tests may not have picked anything up is that ranges they use are based on a ‘normal’ or ‘average’ population and you may not fall into these ‘normal’ ranges.   We are all biochemically unique and just because you have not reached the outright definition of a disease does not mean everything is working as you may hope or expect – picking up on these moves away from more optimum ranges early on is a key part of being preventative.  You know your body better than anyone else and if you don’t think everything is fine, the chances are you are right.

Functional tests offer a range of options to evaluate different physiological processes using a range of analytes (such as stool, urine or dried saliva) to look at, for example, gastrointestinal function, hormone balance including adrenal function, metabolic function, presence of pathogens and immune function.  Ranges provided in many of these tests are based on optimal physiology and as a result are often much narrower.  Patterns in a range of markers are looked at to build up an overall picture of which systems in your body may be out of balance and why.   Looking at the results in conjunction with your case history which will go back to conception, any beyond, helps us to connect the dots and target a nutritional intervention more finely, removing some time-consuming guess work.

One of my favourite tests is one called an Organic Acids Test (or OAT) which uses a urine sample to give indications on potential blocks in energy production, certain potential nutrient deficiencies, amino-acid status, potential yeast overgrowth, neurotransmitter imbalance and oxidative stress.  This is a non-invasive test and can be done at home which is another great advantage.

Functional tests allow  you to look at nutritional bio-markers that can determine how well you are using a specific nutrient, whether it can actually get into the cells, not whether it just present in the blood serum.   For various reasons specific to each vitamin, it is possible to have normal serum levels of a vitamin while showing signs of deficiency due to the lack of ability for it to be used intra-cellularly.  A good example of where this is helpful is B12 – serum B12 is not the best indicator of functional B12 status but a substance known as methylmalonic acid is believed to offer better clinical guidance (1,2).  Methylmalonic acid needs B12 to be broken down so an elevation in its status (tested via urine) is an indicator that more B12 is required for optimal function in the body.  Looking at a range of marker such as these allows a picture to be built  up.  Most essential nutrients play fundamental roles in cellular metabolism and thus can affect the whole body and in chronic diseases we will frequently find that there are multiple nutrient deficiencies involved.

Other tests that are used frequently in practise are functional blood chemistry panels and stool testing for more targeted detection of potential gut pathogens which can have far reaching effects on your body’s physiology.   Stool tests also provide information on the make-up of your gut microbiome, your digestive function, inflammatory markers and potential yeast overgrowth.  However, no tests are infallible and must always be looked at in conjunction with your symptoms and case history and interpretation of any tests you have done will be included in your package.

If you want more information on specific tests and whether they may be of relevance or use to you, please send me an email at or use the form below.



    1. Allen, R. H., Stabler, S. P., Savage, D. G., & Lindenbaum, J. (1990). Diagnosis of cobalamin deficiency I: Usefulness of serum methylmalonic acid and total homocysteine concentrations. American Journal of Hematology, 34(2), 90–98.
    2. Klee, G. G. (2000). Cobalamin and Folate Evaluation: Measurement of Methylmalonic Acid and Homocysteine vs Vitamin B 12 and Folate Biochemical Features Beckman Conference. Clinical Chemistry (Vol. 46). Retrieved from