Functional Testing: Deeper Insights to Support Your Health
You've had blood tests. The GP says everything looks fine. But something clearly isn't — the fatigue, the bloating, the skin that won't settle, the hormones that feel off. "Normal" on a standard test and normal in terms of how you actually feel are not always the same thing.
Functional testing looks at what standard NHS panels aren't designed to catch: mineral balance, gut microbiome patterns, hormone rhythms, metabolic by-products, nutrient status. Not to diagnose conditions - to understand what's contributing to how you feel, and where to focus.
Below are the tests I use in practice. Each one is explained plainly: what it measures, when it's worth considering, and what it can and can't tell you.
The Tests
Comprehensive Functional Blood Panel
A broader screen than standard NHS testing. Looks at thyroid markers including antibodies, full iron studies including ferritin, active B12, vitamin D, blood sugar regulation, inflammation, liver and kidney function, and lipid patterns. Useful when you're symptomatic but nothing has shown up - or when you've only had one or two markers tested and want the fuller picture.
Comprehensive Stool Testing
An in-depth look at how your gut is actually functioning - digestion and absorption markers, gut microbiome diversity and balance, inflammation indicators, and screening for parasites, yeasts and pathogenic bacteria. Most useful when gut symptoms have been going on for a while and haven't shifted with the obvious dietary changes.
DNA & Nutrigenomic Testing
A cheek swab that looks at genetic variations affecting how you process nutrients, metabolise hormones, respond to caffeine, handle stress and regulate blood sugar. Because your genes don't change, the insights have long-term value - a reference point for decisions about food, supplements and lifestyle, not a one-off exercise. I work with Lifecode Gx as a registered Nutrigenomics Practitioner.
DUTCH Hormone Test
A dried urine test completed at home that looks at cortisol patterns across the day, oestrogen and how it's being cleared, progesterone, androgens and sometimes melatonin. The diurnal rhythm - how cortisol rises and falls over 24 hours - can't be captured in a single blood test. This can. Particularly useful when standard hormone bloods have come back normal but something still feels hormonally driven.
Hair Mineral Analysis (HTMA)
A small hair sample - cut from the back of the head, no blood draw - that reflects mineral patterns over the previous three months rather than a single point in time. Looks at essential minerals, their ratios to each other, and toxic metals. Most useful when symptoms could plausibly relate to mineral imbalances and blood tests haven't offered a clear picture. Works best as an additional perspective, not a first-line test.
Iodine Testing
A urine-based assessment of iodine status, most relevant if you avoid dairy and fish, are pregnant or planning pregnancy, or have thyroid symptoms that remain unexplained despite normal blood tests. Iodine is one of several nutrients that affect thyroid function - alongside selenium, zinc, iron and vitamin D. This test is most meaningful when interpreted alongside thyroid markers and your diet, not in isolation.
Organic Acids Test (OAT)
A first-morning urine sample that looks at metabolic by-products linked to cellular energy production, B-vitamin-dependent pathways, gut microbial activity, neurotransmitter metabolism and oxidative stress. Most useful when symptoms span multiple systems and conventional testing has drawn a blank. The value is in reading the overall pattern - not individual markers in isolation.
SIBO Breath Testing
A non-invasive breath test that detects hydrogen and methane gases produced when bacteria ferment carbohydrates in the small intestine - where they shouldn't be. Can identify both SIBO (hydrogen) and intestinal methanogen overgrowth (methane), which tend to present differently and respond to different approaches. Most useful when bloating, gas and unpredictable bowels haven't responded to standard dietary changes.
Do you actually need a test?
Not always. Plenty of clients make real progress through a thorough consultation, a careful look at diet and lifestyle, and some targeted changes. Testing earns its place when symptoms are persistent, multi-system, or haven't shifted with the obvious first steps - or when you want clarity rather than educated guesswork.
If you're not sure whether testing is the right next move, that's exactly what the free call is for. We'll talk through what you're experiencing, what's already been checked, and whether testing is likely to add something — or whether a different starting point makes more sense.
Let's Talk
If you'd like personalised support interpreting your symptoms without all the background noise of social media trends and must-take supplements then let's talk.
Book a free introductory call with me. We can have a chat about how you are feeling now and what your main concerns are. But most importantly we can talk about what you'd like to get out of working together and how you'd like to feel.
There is no obligation to work with me following this call but it's a great opportunity to have an informal chat and ask any questions about my Nutritional Therapy programme before committing.
Book in using the calendar shown and if there aren't any dates or times that suit you drop me an email to louise@louisegouldingnutrition.co.uk