What blood tests might be linked with eczema or psoriasis?

If you’re living with eczema or psoriasis, you’ll know it’s not just about itchy, flaky skin; it can affect your sleep, confidence, and overall wellbeing. Both conditions can cause intense itching and inflammation that disrupts everyday life. 

Topical treatments and lifestyle changes can help manage symptoms, but for some people, flare-ups keep coming back without a clear cause, and with similar symptoms, it’s not always easy to know what you're dealing with.

Blood testing can help you look beneath the surface to find out what else might be going on.

In this blog, we go through:

• Why look beyond the skin?
• Inflammation and immune activity
• Allergies and sensitivities
• Could nutrient levels be affecting your skin?
• Skin and thyroid health

Why look beyond the skin?
 

Eczema and psoriasis are both inflammatory skin diseases, but they’re driven by different immune pathways.

Eczema is often linked to allergies and sensitivities, while psoriasis is an autoimmune condition where the body’s immune system speeds up the process that causes skin cells to grow and shed. In both cases, inflammation plays a central role, and it can affect more than just the skin.

People of all skin tones can be affected, though redness or red patches may be less visible on darker skin. You might also notice symptoms on your elbows and knees, scalp, or hands. Alongside itchy skin, these conditions can be linked with fatigue, brain fog, joint pain, or gut issues.

Blood tests can help uncover whether internal factors (like raised inflammation, nutrient deficiencies, or thyroid issues) might be playing a part.

Inflammation and immune activity
 

Your skin might be flaring up in response to something happening inside your body. Tests like C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) can detect low-level inflammation that may not show up in other ways.

In psoriasis, raised CRP levels are often linked with more severe symptoms and a higher risk of other health issues like high blood pressure and heart disease [1]. If your inflammation markers are raised, it might be a sign to look more closely at your treatment or overall health.

Allergies and sensitivities
 

For people with atopic eczema, allergies often play a role, especially in children. A raised total IgE level (an antibody involved in allergic reactions) can suggest your immune system is overreacting to environmental factors like pollen, pet dander, or certain foods [2].

Blood tests for specific allergens can help pinpoint your triggers, although they should be interpreted carefully alongside your eczema symptoms, history, and lifestyle.

View our range of antibody blood tests. 

Could nutrient levels be affecting your skin?
 

Healthy skin needs the right balance of vitamins and minerals. If you’re low in certain nutrients, your skin barrier may struggle to heal, and your immune system may become more reactive.

Some nutrients to consider testing include:

• Vitamin D — important for immune regulation and skin health. Low levels have been linked to both eczema and psoriasis severity [3].
• Iron and ferritin — low levels can affect energy, healing, and even the amount of blood your body can carry effectively to support skin repair.
• Vitamin B12 and folate — important for immune function and skin cell turnover. Some research suggests B12 may help reduce psoriasis symptoms [4].

If you’re struggling with persistent itchy skin and haven’t checked your nutrient levels in a while, it could be worth exploring. To learn more, read our blog on what a blood test can tell you about your skin.

Skin and thyroid health
 

Psoriasis and sometimes long-standing eczema can overlap with other autoimmune conditions, including thyroid disorders. If you’re experiencing fatigue, mood changes, or weight gain alongside skin issues, a thyroid test can help.

A thyroid blood test measures your TSH and free T4, and can include antibody checks to detect autoimmune conditions like Hashimoto’s thyroiditis.

Treatments beyond the surface
 

Some people benefit from treatments that work from the inside out. For example, light therapy is a common option for moderate to severe psoriasis, helping to reduce inflammation and slow skin cell growth. Identifying what’s happening inside your body through blood testing can help you decide if treatments like this are right for you.

References

1. Mehta NN, Yu Y, Pinnelas R, et al. (2011). Association of psoriasis with vascular inflammation measured by [18F]-fluorodeoxyglucose PET/CT. JAMA, 306(8), 897–903.
2. Spergel JM. (2010). From atopic dermatitis to asthma: the atopic march. Ann Allergy Asthma Immunol, 105(2), 99–106. 
3. Peroni DG, et al. (2011). Allergic diseases in children and adolescents: the role of the gut microbiota. World J Pediatr, 7(3), 213–218.
4. Ruedemann RA, Zeller J. (2020). Vitamin D and atopic dermatitis: a systematic review. Int J Mol Sci, 21(22), 8595.
5. Rueda MJ, et al. (2017). The potential role of vitamin B12 in the treatment of psoriasis. J Dermatol Treat, 28(3), 240–244.
6. Harvard Medical School. (2020). The inflammation theory of disease. Harvard Health Publishing. https://www.health.harvard.edu