Your gut affects everything: energy, mood, immune function, skin, weight, and nutrient absorption. A blood test cannot map your microbiome, but it can reveal whether your gut is causing problems elsewhere in your body. Here is what it checks and why it matters.
A stool test looks at what is inside your gut. A blood test looks at what your gut is doing to the rest of your body. Both are useful. The blood test is usually the better starting point.
Your gut is where iron is absorbed. If full iron studies show low serum iron and low transferrin saturation despite adequate dietary intake or supplementation, the problem may be absorption rather than intake. Coeliac disease, inflammatory bowel conditions, H. pylori infection, and low stomach acid all impair iron absorption. Ferritin masked by inflammation makes this harder to detect without the full panel. Iron testing guide.
B12 absorption requires intrinsic factor produced by parietal cells in the stomach. Gastric atrophy, pernicious anaemia, H. pylori, and long-term PPI use all impair this process. Low B12 despite supplementation is a red flag for an absorption problem. The Signature panel includes intrinsic factor antibodies and gastric parietal cell antibodies to investigate further.
Anti-tissue transglutaminase (tTG) antibodies screen for coeliac disease, an autoimmune condition where gluten damages the small intestine lining. Coeliac affects approximately 1 in 100 people in the UK, but most are undiagnosed. Symptoms include bloating, fatigue, iron deficiency, and diarrhoea, but can also be silent. You must be eating gluten regularly for at least 6 weeks before testing. The Signature panel includes tTG antibodies.
Gut dysfunction is one of the most common drivers of chronic low-grade inflammation. A leaky gut barrier allows bacterial endotoxins into the bloodstream, triggering an immune response that elevates hs-CRP and alters immunoglobulin levels. Elevated hs-CRP with gut symptoms (bloating, irregular bowel habits, food intolerances) points toward gut-driven inflammation. TrueVitals includes hs-CRP in every panel and immunoglobulins (IgA, IgG, IgM) in the Ultimate panel.
Everything absorbed through your gut passes through the liver via the portal vein. A dysfunctional gut increases the toxic load on the liver. Elevated ALT, AST, or GGT alongside gut symptoms may indicate that gut permeability is driving liver stress. The liver markers in every TrueVitals panel provide this context.
Low albumin and total protein can indicate malabsorption. If you are eating adequate protein but blood markers are low, your gut may not be absorbing it efficiently. This is particularly relevant for people with chronic digestive complaints, inflammatory bowel conditions, or post-surgical patients.
Your FBC is an indirect window into gut health. Low MCV (small red cells) suggests iron malabsorption. High MCV (large red cells) suggests B12 or folate malabsorption. Low white cell counts can indicate chronic immune activation from gut permeability. These patterns are often the first clue that a gut problem exists before digestive symptoms become obvious.
The Advanced and Ultimate panels reveal the consequences of gut dysfunction through absorption markers, inflammation, and organ function. The Signature panel (200+ biomarkers, £799) adds direct digestive health markers processed by Randox Health.
Helicobacter pylori infects approximately 40% of the UK population. Most cases are asymptomatic, but it causes gastritis, peptic ulcers, impairs iron and B12 absorption, and is a risk factor for gastric cancer. Blood testing detects antibodies indicating current or past infection. Positive results warrant GP referral for eradication therapy.
Pepsinogens are produced by gastric cells. The PGI/PGII ratio is a non-invasive marker of gastric atrophy (thinning of the stomach lining). Low PGI with a low ratio suggests atrophic gastritis, which impairs acid production, nutrient absorption, and increases gastric cancer risk. This is the "gastropanel" approach used in Scandinavian screening programmes.
Gastrin regulates stomach acid production. Elevated gastrin can indicate low stomach acid (the body produces more gastrin to try to stimulate acid production), PPI overuse, or gastrinoma. Gastrin-17 adds specificity for antral gastric health. Together with pepsinogen ratios, these markers provide a comprehensive non-invasive gastric assessment.
Anti-tissue transglutaminase antibodies screen for coeliac disease. Intrinsic factor antibodies screen for pernicious anaemia (a cause of B12 deficiency). Gastric parietal cell antibodies detect autoimmune gastritis. Together, these cover the three most clinically significant autoimmune gut conditions.
Gut inflammation impairs T4-to-T3 conversion. Coeliac disease is associated with autoimmune thyroid disease. H. pylori infection can trigger Hashimoto's. If your thyroid markers are suboptimal, your gut may be contributing. Thyroid guide.
Over 90% of serotonin is produced in the gut. Gut dysfunction alters neurotransmitter production, drives inflammation that crosses the blood-brain barrier, and impairs absorption of B12, folate, magnesium, and iron, all of which affect mood and energy. Fatigue guide.
The gut metabolises and recirculates oestrogen via the estrobolome. Gut dysbiosis can cause oestrogen dominance by reducing excretion. This affects menstrual regularity, weight, mood, and cancer risk. Testing oestradiol alongside gut markers reveals the connection. Hormone guide.
The gut-skin axis is well established. Gut permeability drives systemic inflammation that manifests as eczema, acne, rosacea, and psoriasis. Elevated hs-CRP with skin complaints points toward gut-driven inflammation.
Approximately 70% of your immune system resides in the gut. Chronic gut dysfunction alters immunoglobulin production and impairs immune surveillance. Low IgA is particularly associated with mucosal immune dysfunction.
Gut dysfunction impairs insulin signalling, drives inflammation that causes leptin resistance, and alters nutrient absorption in ways that promote fat storage. If weight loss has stalled despite doing everything right, gut health may be the missing factor. Weight loss guide.
Reveals the systemic consequences of gut dysfunction: nutrient absorption, inflammation, immune activation, liver burden, coeliac screening, and H. pylori (Signature). Tests gut health alongside every other health system simultaneously. Better starting point because it identifies whether gut dysfunction is actually causing measurable harm and which downstream systems are affected.
Maps the microbiome composition, checks for parasites, bacterial overgrowth, yeast, and digestive enzyme output. More specific to what is happening inside the gut itself. Most useful when blood testing confirms gut-driven problems (malabsorption, inflammation) and you need to identify the specific cause within the gut. TrueVitals does not currently offer stool testing but can recommend providers if your blood results suggest it would be valuable.
A blood test reveals the consequences of gut dysfunction: iron and B12 malabsorption, coeliac antibodies, systemic inflammation, liver burden, protein malabsorption, and immune activation. The Signature panel adds direct digestive markers including H. pylori, pepsinogen ratios, and gastrin for deeper gastric assessment.
The Advanced (£269) and Ultimate (£349) panels reveal gut-related consequences through iron studies, B12, inflammation, liver function, and full blood count patterns. The Signature panel (£799) adds direct digestive markers: H. pylori, pepsinogen I/II, gastrin-17, and coeliac/autoimmune screening. If gut health is a primary concern, the Signature panel provides the deepest assessment. Compare all panels.
PPIs (omeprazole, lansoprazole) affect gastrin levels and pepsinogen ratios. For the most accurate Signature panel digestive results, stop PPIs 2 weeks before testing if medically safe to do so. Consult your prescribing doctor before stopping any medication. If you cannot stop, note your PPI use in the lifestyle quiz and your report will adjust interpretation accordingly.
Your report identifies which markers suggest gut involvement and recommends next steps. This may include GP referral for coeliac confirmation (gastroscopy), H. pylori eradication therapy, a targeted stool test for microbiome assessment, or dietary and lifestyle interventions. The data gives you and your GP a clear starting point for investigation.
IBS is a diagnosis of exclusion. A comprehensive blood test helps rule out conditions that mimic IBS: coeliac disease, thyroid dysfunction, iron deficiency, and inflammatory bowel disease (elevated hs-CRP and ESR). Ruling these out either confirms IBS or identifies a treatable alternative. Many people diagnosed with IBS actually have an undetected condition that a comprehensive blood test would catch.
Iron absorption, B12, inflammation, liver function, coeliac screening, and 100+ other markers. Add digestive depth with the Signature panel. From £269.
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