Functional Testing for Psoriasis: What to Consider Beyond Standard Bloodwork

Psoriasis is more than a skin condition. It is an autoimmune disease, with inflammation and immune dysregulation driving the process. Standard medical care often relies on topical creams, immune-suppressing medication, or biologics. While these can help manage symptoms, they don’t explain why your immune system is reacting in the first place.

GP bloodwork – such as vitamin D, thyroid function, or inflammatory markers like ESR and CRP – can be useful starting points. But if you are still struggling with flares despite “normal” results, functional testing can provide a deeper look into the underlying drivers of your condition.

It’s important to be clear: functional testing is not about ordering every test available or casting the widest possible net. Instead, it is about considering which systems may be involved in your unique case of psoriasis, then using selected testing to validate clinical suspicions. In some cases, no additional testing is needed at all – a careful history and symptom review may already provide enough direction. The key is working with a skilled functional medicine practitioner who can help you prioritise wisely.

Why Functional Testing Matters in Psoriasis

Research highlights that people with psoriasis often experience:

• Gut dysbiosis (microbial imbalance) and intestinal permeability

• Nutrient deficiencies, particularly vitamin D, zinc, selenium, and omega-3 fatty acids

• Coexisting autoimmune conditions such as thyroid autoimmunity or coeliac disease

• Increased cardiovascular and metabolic risk from chronic systemic inflammation

• Environmental or immune triggers that go undetected with standard tests

Because psoriasis is rarely an isolated condition, understanding these root causes can make a profound difference to long-term health outcomes.

Stool Testing: Gut–Skin–Immune Connections

The gut is one of the most important areas to investigate in psoriasis. A stool test can reveal whether digestive or microbial factors may be fuelling inflammation.

A comprehensive analysis might look at:

• Microbiome diversity – reduced beneficial bacteria or overgrowth of inflammatory species.

• Digestive function – whether you are effectively breaking down fats, proteins, and carbohydrates.

• Pathogens or overgrowths – such as parasites, yeasts, or bacterial imbalance.

• Gut barrier function – signs of intestinal permeability that can drive autoimmune responses.

• Immune activity – markers like secretory IgA or calprotectin.

Not every psoriasis case requires stool testing, but if there are digestive complaints or signs of gut involvement, this can be one of the most revealing investigations.

Nutrient Analysis: Fuel for Skin Repair

Because psoriasis accelerates skin turnover, nutrient demand is high. If deficiencies are suspected, targeted nutrient analysis can highlight what needs to be corrected.

Examples include:

• Vitamin D – commonly low in psoriasis.

• B vitamins – needed for methylation and detoxification.

• Zinc and selenium – for antioxidant defence and healing.

• Magnesium – depleted by inflammation.

• Essential fatty acids – imbalances in omega-3 to omega-6 ratios can fuel inflammation.

Again, testing is most useful when there is clinical suspicion. Sometimes we can assume safe, evidence-based supplementation without testing, while in other cases lab data helps tailor dosage precisely.

Inflammatory and Immune Markers

Standard markers like ESR and CRP give only a broad sense of inflammation. Functional markers can offer more nuance when needed, for example:

• Oxidative stress markers – measuring cellular damage.

• Advanced lipid and metabolic markers – important in psoriasis, given increased cardiovascular risk.

These are not always essential, but they can be powerful tools to confirm whether systemic inflammation is ongoing and in what form.

Histamine and Mast Cell Activation

Histamine is often overlooked in psoriasis. Many people experience histamine-related symptoms alongside skin flares: itching, flushing, headaches, or digestive upset.

Functional testing may include:

• DAO enzyme activity – whether your body can break down histamine effectively.

• Plasma histamine – showing overall load.

• Mast cell activity markers – such as tryptase.

Histamine testing is not needed in every case, but where there are suggestive symptoms, it can help to guide dietary and therapeutic approaches.

Environmental Exposures and CIRS

For some, psoriasis is worsened by environmental triggers. Chronic Inflammatory Response Syndrome (CIRS), caused by exposure to mould and biotoxins in water-damaged buildings, is one possibility.

Relevant tests may include:

• HLA-DR genetic testing – to identify susceptibility.

• VCS testing – a simple screen for neuroinflammation.

• Specific inflammatory markers – such as TGF-beta1 or MMP-9.

• MARCoNS testing – to assess sinus colonisation.

These tests are only indicated when there is a clear history of exposure or suggestive symptoms. For some clients, addressing CIRS can be central to calming chronic inflammation, but it is not relevant in every case.

Beyond the Lab: Putting Results into Context

Testing should never replace a thorough history and clinical assessment. The role of functional testing is to confirm or rule out suspicions, not to create endless lists of abnormalities.

For example:

• If you have long-standing digestive symptoms, stool testing might be warranted.

• If you have persistent itching and flushing, histamine evaluation may be helpful.

• If you have lived or worked in a mouldy building, CIRS testing could be appropriate.

But in many cases, the most progress can be made without testing at all, simply by addressing diet, lifestyle, environment, and key nutrients.

Taking the Next Step

Functional testing can be a valuable tool in psoriasis care, but it is not about “testing everything and hoping something stands out.” It is about choosing the right tests at the right time, guided by practitioner expertise, to provide clarity where needed and to validate clinical reasoning.

At The Autoimmune Clinic, we use functional testing selectively, within the context of your history and symptoms, to help identify root causes and guide personalised care. Sometimes that means ordering a test. Other times, it means starting with targeted changes and only turning to testing if progress stalls.

Learn more about our framework for supporting individuals with autoimmune disease and psoriasis on our website, or book a discovery call with one of our practitioners to discuss how we can help you.

A Note on Functional Testing

Not every client needs every test. At The Autoimmune Clinic, we do not recommend ordering every test available. Functional testing is most valuable when it helps to confirm or rule out suspected drivers of inflammation. Sometimes no testing is needed at all, and meaningful progress can be made with history-taking, diet, lifestyle, and environmental adjustments.Your practitioner will help you decide:Which tests are relevant for your situationWhich can wait until laterWhether testing is necessary at allThe goal is not to collect data for the sake of it, but to use the right tools, at the right time, to guide your healing journey.