Visual Explainers · Stephen Duncan FDN-P MSc

Clinical Diagrams

Six bespoke mechanism diagrams built for the way the body actually works — not the way it’s usually taught. Each one maps a clinical pattern your lab results are pointing to. Open the diagram. Read the article. Understand what’s driving your results.

Why diagrams?  People understand their bodies differently. Some learn by reading. Some by seeing mechanisms laid out visually. These exist for the second group — and they’re built to the same clinical standard as everything else here.
Jump to: Stress & Hormones Gut Health Metabolism & Energy
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Mechanism, not metaphor
Each diagram maps the actual biochemical pathway — the enzyme, the conversion step, the organ involved. Not a cartoon. Not stock art.
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Tied to your test results
Every diagram corresponds to one or more of the five TDG functional tests. The diagram shows what the test is actually measuring and why it matters.
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Paired with an article
Each diagram has a companion blog post for those who prefer reading the mechanism in full. Visual and textual, side by side.
3 diagrams
HYPOTHALAMUS · CRH PITUITARY · ACTH ADRENALS · CORTISOL NEGATIVE FEEDBACK Measured by DUTCH Plus
Stress · HPA Axis DUTCH Plus
Diurnal cortisol
The HPA Axis Cascade
Hypothalamus to pituitary to adrenals — the three-step stress hormone relay that governs your cortisol pattern, waking energy, immune function, and sleep quality. Covers the negative feedback loop and what happens when it breaks down under chronic stress.
OESTRADIOL (E2) 2-OH PATHWAY ✓ PROTECTIVE 4-OH PATHWAY ⚠ GENOTOXIC 16-OH PATHWAY ✗ PROLIFERATIVE 2:16 ratio — measured on DUTCH Plus Blood test shows level only — not metabolic fate
Hormones · Oestrogen DUTCH Plus
Oestrogen metabolites
Oestrogen Metabolism Pathways
Two women. Same blood oestrogen level. One feels well; one doesn’t. The difference is where the oestrogen goes after — the 2-OH, 4-OH, and 16-OH metabolic pathways, the 2:16 ratio, and why a standard blood test completely misses this picture.
CHOLESTEROL PREGNENOLONE ⚡ CHRONIC STRESS SEX HORMONES ↓ CORTISOL ↑ THE STEAL
Hormones · Stress DUTCH Plus
Pregnenolone steal
The Pregnenolone Steal
Under chronic stress, the body diverts pregnenolone — the raw material for all steroid hormones — toward cortisol production and away from sex hormones. Low testosterone, low progesterone, oestrogen dominance: this is often the upstream cause. And you can’t supplement your way out of it without addressing the steal first.
1 diagram
INTACT BARRIER Nutrients pass · Toxins blocked LEAKY BARRIER LPS · Antigens · Toxins leak 5R PROTOCOL: REMOVE · REPLACE · RE-INOCULATE · REPAIR · REBALANCE
Gut Health · Barrier GI-MAP
Zonulin · sIgA · Calprotectin
Gut Barrier Integrity & the 5R Protocol
The gut barrier is one cell thick. When tight junctions break down, lipopolysaccharides, undigested antigens, and pathogens cross into systemic circulation — driving inflammation that appears as skin conditions, joint pain, brain fog, and autoimmunity. This diagram maps the barrier structure, what the GI-MAP measures, and the sequenced repair protocol.
2 diagrams
GLUCOSE RESPONSE OVER TIME OPTIMAL EARLY IR ESTABLISHED IR Insulin: Normal Insulin: ↑↑ Glucose: ↑↑↑ HOMA-IR detects this years before glucose rises · Randox blood chemistry
Metabolic Health Blood Chemistry
HOMA-IR · Fasting insulin
Insulin Resistance Cascade
Your fasting glucose is normal. Your fasting insulin — which isn’t on the standard panel — tells a different story. This diagram maps the progression from optimal insulin sensitivity through compensatory hyperinsulinaemia to established resistance, and why HOMA-IR catches the pattern years before your GP would.
OPTIMAL ATP ⚡⚡⚡ OAT: Krebs acids normal DYSFUNCTION ATP ⚡ OAT: Succinic · Fumaric ↑ Measured by OAT Krebs · Neurotransmitters · Gut · B-vitamins · Detox
Energy · Cellular Health Organic Acids Test
Krebs cycle markers
Mitochondrial Function & the Organic Acids Test
Fatigue that doesn’t respond to rest, brain fog, poor exercise tolerance — these often have a cellular origin. This diagram maps optimal versus dysfunctional Krebs cycle activity, what the backed-up OAT markers reveal, and why the OAT is the only test that shows neurotransmitter production, B-vitamin status, gut overgrowth, and mitochondrial function in one panel.
Open Diagram → ● Article coming soon

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