The TDG Five-Test Programme

Your tests
are normal.
That's the problem.

You've had blood tests. You've been told everything is fine. You still feel exhausted, foggy, and unwell — and nobody has a satisfying explanation. The issue isn't you. It's the tests. Standard medical testing is designed to find disease. The TDG programme is designed to find dysfunction — years before it becomes disease.

Book Your Discovery Consultation → See the five tests
900+ Data points per
client investigation
170+ Validated clinical
patterns assessed
5 Integrated
functional tests
37 Years of clinical
pattern recognition
Scroll to explore
Why standard testing fails you

The gap between
"not diseased"
and optimal

Standard medical reference ranges are built from population averages — wide enough to include the vast majority of people, including many who are chronically unwell. When your results fall within these ranges, you're told you're normal. But normal is not the same as optimal. And optimal is where you need to be to actually feel well.

Take TSH, the standard thyroid test. The NHS reference range runs from 0.5 to 5.0. The functional optimal range is 1.0 to 2.0. At 3.5 — technically normal — many people experience the full constellation of hypothyroid symptoms: fatigue, weight gain, cold intolerance, brain fog, hair loss. They're told their thyroid is fine. Their thyroid is not fine. We're just not looking at the right range.

The same gap exists across blood sugar, iron, vitamin D, hormones, and dozens of other markers. Standard testing finds disease. Functional testing finds the dysfunction that precedes disease — at the stage when it's still fully reversible.

"I've had everything checked. They said it's all normal. But I feel terrible and nobody can tell me why."

The exhausted professional

Wakes up tired, runs on caffeine, crashes mid-afternoon, can't switch off at night. "Adrenal fatigue" is dismissed as not a real thing. It is real. It's HPA axis dysfunction — and it shows on testing.

The woman with hormonal chaos

Heavy periods, severe PMS, weight that won't shift, mood swings. Told it's "just stress" or offered the pill. The actual drivers — oestrogen metabolism, gut dysbiosis, cortisol — are never investigated.

The gut symptom sufferer

Bloating, IBS, food intolerances, constipation. Told to try a different diet, referred to a gastroenterologist who finds nothing structurally wrong. The infections and dysbiosis causing the symptoms are never looked for.

The person who's tried everything

Supplements, diets, exclusions, functional medicine protocols from books and podcasts. Some things helped briefly. Nothing stuck. Because without knowing which specific things are wrong in this specific body, you're guessing.

The investigation framework

Test, Don't Guess —
a complete investigation,
not a consultation

TDG stands for Test, Don't Guess. It's not a philosophy — it's a methodology. Five validated functional tests, interpreted using optimal clinical ranges rather than population averages, synthesised into a single coherent picture of what is actually happening in your body.

The five tests are not chosen arbitrarily. Each one investigates a different layer of function — metabolic, gut, hormonal, cellular, and immune — and each reveals information the others cannot. The diagnostic power is in reading them together, not in isolation. A pattern visible only when GI-MAP findings are cross-referenced against DUTCH hormone results and OAT organic acids data would be invisible to any single test.

This approach is built on 37 years of clinical practice, training with the founders of Functional Diagnostic Nutrition and Metabolic Typing, co-founding Omnos laboratory software now integrated with Regenerus Labs, and the review of thousands of client test panels. It is documented in the book Test, Don't Guess — the clinical framework in print.

Principle 1
Measure accurately
Optimal ranges, not population averages. DNA-based stool analysis, not culture. Diurnal hormone patterns, not single-point snapshots.
Principle 2
Interpret correctly
170+ validated patterns. 40+ cross-test conflict resolutions. Pattern reading, not individual marker reading.
Principle 3
Intervene systematically
The sequence matters as much as the intervention. HPA axis, then blood sugar, then gut, then thyroid, then sex hormones. Always upstream before downstream.
Principle 4
Track progress objectively
Retest at defined intervals. Evidence of improvement in markers, not just symptoms. Protocol adjusted based on data, not assumption.
The investigation

Five tests.
One complete picture.

Each test investigates a different layer of function. Together they produce 900+ data points covering the systems most responsible for chronic symptoms.

1
Randox Health — GP3 Advanced / Signature Prestige
Comprehensive Blood Chemistry
The metabolic foundation — where every investigation begins
+

150 markers on the standard panel; 300 on the Signature Prestige for complex presentations. Interpreted using functional optimal ranges rather than the wide population-average reference ranges used in standard GP testing. The first thing we look at is hydration — sodium-potassium balance, BUN-to-creatinine ratio, haematocrit — before any other marker. Without cellular hydration, nothing else works properly.

What this test reveals
  • Full thyroid cascade: TSH, Free T4, Free T3, Reverse T3, and antibodies — not just TSH
  • Fasting insulin and HOMA-IR: insulin resistance 10–15 years before glucose elevates
  • Ferritin (optimal 70–100 ng/mL): below 50 impairs thyroid conversion, dopamine production, and energy
  • Vitamin D (optimal 75–150 nmol/L): UK average is 25–50 nmol/L
  • Homocysteine: methylation dysfunction and cardiovascular inflammation
  • GGT: earliest liver stress marker, reflects detoxification capacity
  • hs-CRP (optimal below 1.0 mg/L): systemic inflammatory burden
Why standard testing misses this
  • Standard TSH range (0.5–5.0) misses dysfunction that shows at 2.5–4.9
  • Fasting insulin is almost never tested in standard care
  • Ferritin "normal" range starts at 15 ng/mL — 55 points below what is functionally adequate
  • Free T3 and Reverse T3 are rarely requested, yet reveal thyroid conversion failure
  • Homocysteine is not standard — methylation dysfunction is systematically invisible

Results in 2–3 days. Blood draw arranged through Randox or coordinated through Direct Labs for US-based clients.

2
Diagnostic Solutions Laboratory
GI-MAP Stool Analysis
DNA-based gut microbiome mapping — finds what standard stool tests miss
+

Quantitative PCR technology — the same DNA-based detection used in the most sophisticated medical laboratories. A standard NHS stool culture detects 20–30 organisms under ideal conditions. The GI-MAP identifies hundreds simultaneously, including parasites, fungi, and bacteria that do not grow on culture media and would be completely invisible to standard testing.

What this test reveals
  • H. pylori with virulence factor typing (CagA, VacA) — not just presence but pathogenicity
  • Parasites: Blastocystis, Cryptosporidium, Giardia, Dientamoeba — routinely missed by standard testing
  • Secretory IgA: mucosal immune defence depleted by cortisol
  • Beta-glucuronidase: the bacterial enzyme that drives oestrogen dominance via reabsorption
  • Zonulin: intestinal permeability (leaky gut) — the mechanism behind systemic inflammation
  • Pancreatic elastase: exocrine function; below 200 µg/g indicates enzyme insufficiency
  • Calprotectin: active intestinal inflammation
Why standard testing misses this
  • Blastocystis hominis — one of the most common drivers of chronic IBS — is not found on NHS stool culture
  • Beta-glucuronidase (explaining oestrogen dominance through gut dysbiosis) is not tested anywhere in standard care
  • Zonulin and intestinal permeability are functional medicine concepts; mainstream medicine does not routinely test for leaky gut
  • Secretory IgA, the single most important gut immune marker, is essentially unknown outside functional medicine

Single stool collection. 2–4 week turnaround. Home collection kit posted to you.

3
Precision Analytical
DUTCH Plus Hormone Panel
Patterns, not snapshots — the complete 24-hour hormonal picture
+

Standard blood hormone tests give you one number at one moment. DUTCH gives you patterns across 24 hours — how hormones fluctuate, how they're metabolised, what pathways they take through your body. The oestrogen metabolite profile alone — 2-OH vs 4-OH vs 16-OH — reveals cancer risk information that a standard blood oestrogen reading cannot approach.

What this test reveals
  • Cortisol awakening response — the morning surge indicating HPA axis competence (or failure)
  • Full diurnal cortisol curve: four time points revealing whether you're wired, flat, or inverted
  • Oestrogen metabolite ratios: 2-OH (protective), 4-OH (genotoxic), 16-OH (proliferative)
  • Methylation capacity: ability to clear oestrogen metabolites through the 2-methylation pathway
  • 6-OH melatonin sulphate: nighttime melatonin production — sleep quality and cancer protection
  • Neurotransmitter metabolites: serotonin (5-HIAA), dopamine (HVA), noradrenaline (VMA)
  • DHEA-S: stress resilience buffer; depleted by chronic HPA axis activation
Why standard testing misses this
  • A single morning blood cortisol tells you nothing about the evening cortisol driving your insomnia
  • Standard oestrogen testing reveals levels — not how oestrogen is being metabolised; the 4-OH pathway can be active with "normal" oestrogen levels
  • No standard test measures the cortisol awakening response — the clearest single indicator of HPA axis health
  • Melatonin production is never tested in standard care despite being critical for sleep, immunity, and cancer prevention

Four urine collections across one day. Home collection. 2–4 week turnaround.

4
Great Plains / Mosaic Diagnostics
Organic Acids Test (OAT)
Under the hood — cellular metabolism, neurotransmitters, and gut toxins
+

The OAT measures organic acid metabolites in urine — byproducts of cellular metabolism that reveal what is happening inside your cells. Blood chemistry shows you the dashboard warning lights. The OAT shows you what's malfunctioning in the engine. It connects the dots between symptoms that appear unrelated: fatigue, anxiety, brain fog, weight resistance — all visible simultaneously in the metabolic picture the OAT produces.

What this test reveals
  • Krebs cycle intermediates: mitochondrial function and cellular energy production efficiency
  • HPHPA (Clostridia metabolite): directly inhibits dopamine-beta-hydroxylase — the mechanism behind dopamine disruption, anxiety, and behavioural symptoms
  • 5-HIAA (serotonin metabolite): gut serotonin production underpinning mood and sleep
  • HVA (dopamine metabolite): motivation, focus, drive — low HVA explains the ADHD-like presentation in gut dysbiosis
  • Arabinose and tartaric acid: Candida overgrowth confirmation
  • Pyroglutamic acid: glutathione depletion — Phase II detoxification capacity
  • B vitamin functional status: identifies functional insufficiency even when serum levels appear normal
Why standard testing misses this
  • Mitochondrial function is never assessed in standard care — the OAT provides the only practical clinical window into cellular energy production
  • HPHPA, the Clostridia metabolite disrupting dopamine metabolism, is unknown in standard medicine — yet explains presentations routinely labelled as anxiety, ADHD, or depression
  • Glutathione status, the master antioxidant and Phase II detoxification indicator, is not tested in standard panels
  • B vitamin functional status (as opposed to serum levels) identifies insufficiency that serum testing misses

Single first-morning urine collection. Home collection. Approximately 2-week turnaround.

5
Biolab / Lorisian
Food Sensitivity Panel
IgG reactions — the delayed immune triggers invisible to allergy testing
+

IgG food sensitivity testing — not IgE allergy testing. The distinction is clinically fundamental. IgE reactions are immediate and obvious: eat peanuts, throat swells. IgG reactions are delayed by hours to days, producing chronic low-grade inflammation that drives symptoms with no obvious connection to the causative food. You eat eggs on Monday. You feel terrible on Wednesday. The connection is invisible without testing.

What this test reveals
  • 200+ food IgG antibody reactivity — identifies the specific foods driving immune reactions
  • Reaction class grading (Class 1–4) — distinguishes background exposure from clinically significant reactions
  • Often reveals reactivity to foods eaten daily and considered "healthy" — eggs, almonds, chicken are common unexpected findings
  • Used in context of GI-MAP intestinal permeability data to determine whether sensitivities are driving the dysfunction or are a consequence of leaky gut
Clinical caveats applied in interpretation
  • Sequencing: food sensitivities are often a consequence of intestinal permeability, not a primary cause — gut must be addressed concurrently
  • Multiple high reactions often indicate leaky gut rather than true permanent sensitivity to all reactive foods
  • Reintroduction is the goal: temporary elimination during gut healing, with structured reintroduction after barrier repair
  • Not used as a standalone test — always interpreted in context of GI-MAP findings

Fingerprick or venepuncture blood sample. Home collection kit. 2-week turnaround.

Is this right for you?

The TDG programme is built for people
who are done guessing

Pattern 1
The Exhausted Professional

Wakes up exhausted despite sleeping. Dependent on multiple coffees. Crashes mid-afternoon. Can't switch off at night. Has tried everything — supplements, diets, better sleep hygiene. Nothing sticks. Standard tests came back normal. Nobody has investigated the HPA axis, cortisol rhythm, or thyroid conversion.

Pattern 2
The Digestive Sufferer

Bloating, IBS, food intolerances, reflux, constipation, or alternating bowel habits. Has been told it's stress, or given antispasmodics, or told to try a low-FODMAP diet. The infections, dysbiosis, and intestinal permeability driving the symptoms have never been properly investigated.

Pattern 3
The Hormonally Chaotic

Heavy periods, severe PMS, perimenopausal symptoms, low testosterone, or thyroid symptoms with a "normal" TSH. Offered the pill, antidepressants, or HRT without investigation. The oestrogen metabolism, gut estrobolome, cortisol-thyroid interaction, and nutrient deficiencies driving the hormonal picture have never been mapped.

Pattern 4
The Weight-Resistant

Caloric restriction and exercise produce no meaningful change. Has been told it's a willpower problem. Insulin resistance, cortisol-driven visceral fat accumulation, thyroid conversion failure, gut-derived metabolic endotoxaemia, and sleep deprivation as metabolic drivers have never been addressed because they've never been identified.

Pattern 5
The Brain Fog Sufferer

Difficulty concentrating, word-finding struggles, poor memory, cognitive fatigue. Told it's stress or depression. Clostridia metabolites disrupting dopamine, mitochondrial dysfunction limiting cellular energy to the brain, neuroinflammation from gut dysbiosis — the biochemical drivers of cognitive symptoms are invisible to standard testing.

Pattern 6
The Post-Viral / Long-Hauler

Symptoms that began or dramatically worsened after a significant viral illness. Post-exertional malaise. Fatigue disproportionate to activity. Cognitive symptoms. The mitochondrial dysfunction, HPA axis dysregulation, gut microbiome disruption, and immune dysregulation of post-viral presentations are addressable — but only if they're correctly identified and sequenced.

Who the TDG programme is not right for: Anyone seeking a quick fix, a single supplement recommendation, or who has not yet ruled out conditions requiring urgent medical attention. The programme requires active engagement with a systematic process over 3–6 months. It is an investigation, not a treatment, and it produces a protocol to be implemented — not a prescription to be passively received.

Programme deliverables

What you receive — the complete investigation package

🔬

Five validated functional tests

All five test kits coordinated and arranged. Randox blood chemistry, GI-MAP stool analysis, DUTCH Plus hormone panel, Organic Acids Test, and food sensitivity panel. All interpretation uses functional optimal ranges, not population-average reference ranges.

📊

Comprehensive interpretation session

A detailed review of all five panels simultaneously — 900+ data points cross-referenced against 170+ validated clinical patterns. Findings explained in clinical plain language. Pattern identification and root cause hierarchy established.

📋

Personalised clinical protocol

A sequenced, phased intervention plan based on your specific results — not a generic functional medicine protocol. Sequenced correctly: addressing causes before consequences, upstream before downstream, with clear priorities and timelines.

📚

TDG Resource Manual — 13 modules

Access to the complete TDG client education resource: 13 modules covering every body system, every test, every intervention category, and the clinical framework for reading your own results. Built so you understand the reasoning behind every recommendation, not just what to take.

💊

Targeted supplement protocol

Supplement recommendations specific to your deficiencies and patterns — not generic recommendations. Professional-grade products through Fullscript at practitioner pricing. Dosed therapeutically, sequenced correctly, with clear timelines for each intervention.

🔄

Follow-up and protocol support

Ongoing support as you implement the protocol. Questions answered. Protocol adjusted based on response. Retest recommendations at defined intervals to confirm that markers are improving — not just symptoms. Evidence of progress in data, not just in how you feel.

How it works

The investigation step by step

1
First step
Discovery Consultation — 45 minutes
A detailed conversation about your health history, current symptoms, previous investigations, and goals. This is not a sales call. It's a clinical conversation to establish whether the TDG programme is appropriate for your situation and to ensure you understand what the process involves. £145 (£95 for book or Starter Kit holders). Fee credited against the programme if you proceed.
Book online → receive confirmation → consult via video
2
Weeks 1–2
Test kits dispatched and blood draw arranged
All five test kits coordinated. Randox blood draw arranged at your nearest clinic (or through Direct Labs for US clients). Home collection kits for GI-MAP, DUTCH, OAT, and food sensitivity posted to you with clear collection instructions. All returned to the relevant laboratories.
Randox blood results: 2–3 days. Other panels: 2–4 weeks
3
Weeks 3–6
Results reviewed and pattern analysis completed
All five panels reviewed simultaneously once all results are received. 900+ data points cross-referenced. Pattern hierarchy established — what is primary, what is secondary, what is a downstream consequence of something else. The clinical picture built from evidence, not assumption.
Typically 3–4 weeks after all samples are received
4
Results session
90-minute comprehensive review and protocol delivery
A full walkthrough of all results, what they mean, how they connect, and what the evidence shows. The personalised protocol delivered — supplement recommendations, dietary adjustments, lifestyle sequencing, and timing. Everything explained so you understand the reasoning, not just the instructions. Recorded for your reference.
Video consultation — recorded and sent to you
5
Ongoing — months 2–6+
Protocol implementation and follow-up support
Implementation of the phased protocol with support as needed. Questions answered. Protocol adjusted as the picture develops. Retest recommendations at appropriate intervals — because you cannot know if an intervention worked without confirming it in data. The 120-day RBC rule: some markers take 3–4 months to fully reflect change. Long enough timelines to see genuine evidence of improvement.
Retesting at 8–12 weeks for blood chemistry; 3–4 months for OAT and hormones
Stephen Duncan BSc (Hons) MSc FDN-P — Detective Health Edinburgh
Stephen Duncan BSc (Hons) MSc FDN-P · Edinburgh
About the practitioner

Stephen Duncan

FDN-P · MSc · Advanced Metabolic Typing Advisor · Edinburgh

I started working with the human body at 18 as an athletics and boxing coach. Over the next two decades, I accumulated an MSc, trained in Functional Diagnostic Nutrition with Reed Davis, worked through the Metabolic Typing system under Bill Wolcott at Healthexcel, studied blood chemistry interpretation with Dr Bryan Walsh, and trained with Paul Chek, Michael McEvoy, and the Institute for Functional Medicine.

In 2012, I co-founded Omnos — laboratory software for functional medicine practitioners integrating with major diagnostic labs across Europe. That platform is now part of Regenerus Labs. Building it required reviewing thousands of test panels, identifying where interpretation was failing, and understanding what the data could and couldn't tell you when read in isolation versus in combination.

That experience, combined with clinical practice over 37 years and the development of the test interpretation framework documented in my book Test, Don't Guess, is what the TDG programme is built on. Not a methodology borrowed wholesale from someone else's training. A clinical framework developed through direct observation of what actually produces measurable, lasting results in real people with real complexity.

I practise from Edinburgh. I work with clients across the UK and internationally, coordinating testing through appropriate laboratories in each territory. I walk my dog Dexter every morning. I am still, after 37 years, surprised and interested by the patterns that emerge in test results — and what they reveal about what is actually driving a presentation that conventional medicine has dismissed as unexplained.

MSc FDN-P Advanced Metabolic Typing Advisor CHEK Institute 37 Years Clinical Practice Co-Founder, Omnos / Regenerus
The investment

What a complete investigation
actually costs

The five tests in the TDG programme cost £800–1,200 depending on the Randox panel selected. The balance of the programme investment covers interpretation — which is the part that takes 37 years to develop and cannot be automated, delegated, or replaced with a dashboard.

A private GP consultation costs £200–300 for 45 minutes and a standard panel that tells you your bloods are normal. A private specialist appointment is £300–500 and will investigate one system in isolation, without reference to the others. The TDG programme investigates five interconnected systems simultaneously, synthesises 900+ data points into a single coherent clinical picture, and delivers a sequenced intervention protocol.

The goal is to do this once, properly, and then maintain rather than repeat. Most clients who have been around the NHS and private medicine circuit have spent more than £3,500 on consultations, supplements, and investigations that produced nothing actionable.

Programme investment
£3,500
Complete five-test programme · All-inclusive
  • Randox comprehensive blood chemistry (150+ markers, functional ranges)
  • GI-MAP stool analysis — DNA-based quantitative PCR
  • DUTCH Plus — full diurnal hormone panel with metabolites
  • Organic Acids Test (OAT) — cellular metabolism and neurotransmitters
  • Food sensitivity panel — 200+ IgG antibody reactivity
  • Discovery consultation (45 min) — clinical history and programme planning
  • Comprehensive results interpretation session (90 min, recorded)
  • Personalised phased protocol with supplement recommendations
  • TDG Resource Manual — 13-module clinical education resource
  • Follow-up support during protocol implementation
  • Retest recommendations at defined intervals
Book Your Discovery Consultation → £145 discovery consultation · credited against programme if you proceed
Flexible testing option

Not ready for the full five-test programme? A flexible three-test option (blood chemistry + GI-MAP + DUTCH) is available for presentations where symptoms clearly point to specific systems. Discuss at the discovery consultation.

Common questions

Frequently asked

Do I need a GP referral?
No. The TDG programme is a private functional medicine investigation and does not require GP referral. However, if results indicate a condition requiring urgent medical attention (severely abnormal thyroid, significant diabetes markers, signs of serious pathology), you will be advised to discuss these findings with your GP alongside the functional medicine work.
Can I do this if I'm already on medication?
Yes. A significant proportion of clients are on prescribed medications. The testing and protocol work alongside medication. If results indicate that medication may be driving dysfunction (PPIs causing nutrient deficiency, statins depleting CoQ10, contraceptives affecting test interpretation), this will be flagged — but working with your prescriber to address it is always the appropriate route.
I'm outside the UK — can I still do the programme?
Yes. US clients coordinate blood draws through Direct Labs. All other tests use home collection kits. The interpretation and protocol sessions are conducted via video. International shipping applies to some test kits. Discuss your location at the discovery consultation and testing logistics will be confirmed.
How long does the full programme take?
Testing typically takes 3–6 weeks from test kit dispatch to all results received. The interpretation session follows shortly after. Genuine physiological improvement from protocol implementation is measured in months: blood sugar stabilises in weeks; gut restoration takes 3–6 months; HPA axis recovery from significant burnout takes 6–12 months. The investigation is fast. The body requires time.
What if my results are complicated or I have a diagnosis?
Complex cases with existing diagnoses (Hashimoto's, PCOS, ME/CFS, IBD, fibromyalgia) are specifically what the TDG programme is designed for. These diagnoses describe symptom patterns — they do not identify causes. The programme investigates the root causes driving the diagnosed condition. Complexity is not a contraindication; it's the reason for comprehensive testing rather than less of it.
Can children do the TDG programme?
The standard TDG programme is designed for adults. For children and young people, a tailored approach is available — discuss at the discovery consultation. Neurodivergent presentations (ADHD, autism, learning differences) in children are an area where functional investigation can be particularly valuable, as gut dysbiosis, nutrient deficiencies, and mitochondrial markers are frequently significant contributors to presentation severity.
Start the investigation

Stop guessing.
Start knowing.

The Discovery Consultation is a 45-minute clinical conversation. No obligation to proceed. A chance to establish whether this investigation is right for your situation — and to start getting answers.

Book Your Discovery Consultation → Read the blog first
Discovery Consultation: £145 · £95 for book or Starter Kit holders · Credited against programme investment if you proceed