Functional Diagnostic Nutrition
in the United Kingdom

The DUTCH Plus is widely regarded as the most advanced dried urine hormone test available. It covers the full HPA axis including diurnal cortisol and cortisone patterns, DHEA-S, all major sex hormones and their metabolites, oestrogen detoxification pathways (2-OH, 4-OH, 16-OH), melatonin, and secretory IgA as an immune marker. Available through Regenerus Labs with UK postal collection kits — no clinic visit required. This is a genuine direct equivalent to the FDN Stress and Hormones Profile, and in several respects more comprehensive.

The FDN Metabolic Wellness Profile is a targeted organic acids panel covering protein digestion (Indican), liver detoxification (Urinary Bile Acids), and oxidative stress (8-OHdG). The full OAT available through Regenerus covers all of these markers and extends significantly further — including mitochondrial function, neurotransmitter metabolism, B-vitamin status, and yeast and bacterial markers. UK postal collection kit, dried urine. Clinically, the OAT provides everything the Metabolic Wellness Profile does and considerably more.

The FDN Mucosal Barrier Assessment measures Zonulin, Histamine, and DAO as markers of intestinal permeability and histamine metabolism. The Precision Point Diagnostics Advanced Intestinal Barrier Assessment, available through Regenerus Labs, measures Zonulin, DAO, and LPS (lipopolysaccharide) — a near-direct equivalent with a meaningful clinical addition. LPS is an endotoxin released by gram-negative bacteria that crosses a compromised gut barrier and drives systemic inflammation; its presence as a standalone marker makes this panel arguably more clinically informative than the original FDN test. Available as a home blood collection kit posted to UK clients. This closes what was previously the most significant gap in UK FDN lab implementation. In the TDG framework, findings from this test are interpreted alongside GI-MAP sIgA, calprotectin, lactoferrin, and Zonulin for a full mucosal barrier picture.

The GI-MAP is the same test in the UK as in the US — Diagnostic Solutions Laboratory produces it, and Regenerus Labs distribute it to UK practitioners with postal stool collection kits. No substitution is required. The GI-MAP uses quantitative PCR DNA analysis to identify pathogens, parasites, H. pylori, opportunistic bacteria, beneficial microbes, and intestinal immune markers including sIgA, calprotectin, and lactoferrin. This is the most straightforward of the five tests for UK implementation — clinically identical in every respect.

The FDN programme uses the Mediator Release Test (MRT) — a US-only test measuring functional immune reactivity across 176 foods and chemicals via mediator release rather than antibody measurement. MRT is not available to UK clients. The TDG framework uses the IgG Food MAP with Candida and Yeast via Mosaic Diagnostics — a dried blood spot collection kit available to UK clients covering 190+ foods, food chemicals, and Candida species. The mechanism differs from MRT: IgG measures antibody-mediated memory responses rather than immediate mediator release. Both tests identify inflammatory food triggers; the clinical interpretation approach is adjusted accordingly. The Candida and yeast inclusion in the Mosaic panel is a meaningful addition not present in MRT.

The FDN programme incorporates Metabolic Typing® as developed by Bill Wolcott — a questionnaire-based assessment determining optimal macronutrient ratios by metabolic type. The TDG framework extends this through the Metabolic Natures model: six constitutional types (Kinetic, Grounded, Catalyst, Endurance, Adaptive, Calibrated) derived from the integration of functional test findings with metabolic phenotype assessment. This moves beyond the questionnaire-only approach by cross-referencing lab data — DUTCH hormone patterns, OAT mitochondrial markers, GI-MAP findings — to identify metabolic type with greater clinical precision.

Comprehensive blood chemistry is not part of the standard FDN five-test suite. The TDG framework adds Randox Health blood chemistry as a fifth integrated layer — covering full metabolic panel, thyroid (TSH, free T4, free T3, reverse T3, TPO antibodies), iron studies (ferritin, serum iron, TIBC, transferrin saturation), cardiovascular markers, inflammatory markers (CRP, homocysteine), liver function, and kidney function. All markers are interpreted at functional optimal ranges rather than standard NHS reference ranges — the difference between a ferritin of 18 (normal) and 18 (critically low for functional health) being a central example. This is the layer that makes TDG an advanced implementation of FDN methodology rather than a direct replica.