Autoimmune Blood Test: Screening for Autoimmune Conditions

Autoimmune conditions affect more than 4 million people in the United Kingdom, making them one of the most significant categories of chronic disease. The defining feature of autoimmune disease is that the immune system — designed to protect the body from infections and foreign invaders — mistakenly attacks the body's own tissues. This misdirected immune response can target virtually any organ or system, producing a bewildering range of symptoms that often takes years to diagnose correctly.

The average time to diagnosis for an autoimmune condition in the UK is 4.5 years, spanning visits to 3 or more different doctors. This diagnostic delay is driven by several factors: symptoms are often vague and fluctuating, overlap between different autoimmune conditions is extensive, and many GPs lack the time or resources to perform comprehensive screening panels. Blood tests cannot diagnose every autoimmune condition, but a well-chosen panel can significantly narrow the field and accelerate the path to the correct diagnosis.

Understanding Autoimmune Disease

There are more than 80 recognised autoimmune conditions. Some of the most common in the UK include:

• Hashimoto's thyroiditis: Autoimmune destruction of the thyroid — the most common cause of hypothyroidism
• Graves' disease: Autoimmune stimulation of the thyroid — the most common cause of hyperthyroidism
• Rheumatoid arthritis (RA): Chronic inflammatory arthritis affecting approximately 400,000 people in the UK
• Coeliac disease: Gluten-triggered autoimmune damage to the small intestine — affecting 1 in 100 people
• Type 1 diabetes: Autoimmune destruction of insulin-producing beta cells in the pancreas
• Systemic lupus erythematosus (SLE/lupus): A multi-system condition affecting joints, skin, kidneys, and other organs
• Sjogren's syndrome: Autoimmune attack on moisture-producing glands, causing dry eyes and dry mouth
• Psoriasis and psoriatic arthritis: Autoimmune skin and joint disease

A critical point is that autoimmune conditions cluster. If you have one, your risk of developing a second is significantly higher. For example, people with Hashimoto's have an increased prevalence of coeliac disease, type 1 diabetes, and pernicious anaemia. This clustering means comprehensive screening across multiple markers is more informative than testing for a single condition in isolation.

Key Blood Markers for Autoimmune Screening

Antinuclear Antibodies (ANA)

ANA is the broadest screening test for systemic autoimmune conditions. These antibodies target components of the cell nucleus and are present in several autoimmune diseases:

• Systemic lupus erythematosus (SLE): ANA is positive in approximately 95% of lupus patients — making it an excellent screening test (a negative ANA largely excludes lupus)
• Sjogren's syndrome: Positive in 60-70%
• Scleroderma (systemic sclerosis): Positive in 60-80%
• Mixed connective tissue disease: Positive in nearly 100%

The important caveat with ANA is specificity. A positive ANA does not confirm autoimmune disease. Low-titre positive ANAs (1:80 or below) are found in up to 15% of healthy individuals, particularly women over 40. The titre (dilution) and pattern (homogeneous, speckled, nucleolar, centromere) matter — higher titres and certain patterns are much more suggestive of true autoimmune disease. A positive ANA should always be interpreted alongside symptoms and other markers.

Anti-TPO and Anti-Thyroglobulin (Anti-Tg) Antibodies

These are the antibodies that target the thyroid gland:

• Anti-TPO (anti-thyroid peroxidase): Present in approximately 90% of Hashimoto's thyroiditis patients and 75% of Graves' disease patients. This is the primary screening test for autoimmune thyroid disease.
• Anti-Tg (anti-thyroglobulin): Present in 60-70% of Hashimoto's patients. Occasionally positive when anti-TPO is negative, so testing both improves sensitivity.

Autoimmune thyroid disease is the single most common autoimmune condition in the UK. Anti-TPO antibodies can be elevated for years before thyroid function becomes measurably abnormal, providing an early warning window. People with positive anti-TPO and a TSH in the upper normal range (3-5 mIU/L) should be monitored annually, as progression to overt hypothyroidism occurs at a rate of approximately 5% per year.

Rheumatoid Factor (RF) and Anti-CCP

These markers are used in the assessment of rheumatoid arthritis:

• Rheumatoid factor (RF): An antibody found in approximately 70-80% of RA patients. However, RF is not specific to RA — it can be positive in other autoimmune conditions, chronic infections, and even in 5-10% of healthy elderly people.
• Anti-CCP (anti-cyclic citrullinated peptide): Far more specific for RA than RF, with a specificity exceeding 95%. Anti-CCP can be positive years before RA symptoms appear, making it a powerful predictive marker. Patients who are both RF-positive and anti-CCP-positive tend to have more aggressive disease.

Early diagnosis of RA matters enormously. Joint damage begins within the first two years and is largely irreversible. Early treatment with disease-modifying anti-rheumatic drugs (DMARDs) can prevent or significantly reduce joint destruction. If you have persistent joint pain and stiffness — particularly in the small joints of the hands and feet, worse in the morning — RF and anti-CCP testing should be a priority.

Tissue Transglutaminase IgA (tTG IgA)

The standard screening test for coeliac disease. tTG IgA has a sensitivity and specificity both exceeding 95%, making it one of the best-performing antibody tests in medicine. Coeliac disease affects 1 in 100 people in the UK, but roughly 70% remain undiagnosed. The most common presenting symptoms are fatigue, bloating, diarrhoea, and iron deficiency — but coeliac disease can also present with neurological symptoms, skin rashes (dermatitis herpetiformis), osteoporosis, or infertility. Total IgA must be measured alongside tTG IgA, as IgA deficiency (present in 2-3% of coeliac patients) renders the test unreliable.

CRP and ESR (Inflammatory Markers)

C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are non-specific markers of systemic inflammation:

• CRP: Produced by the liver in response to inflammatory cytokines. Rises within 6-8 hours of an inflammatory stimulus and falls rapidly when inflammation resolves. Very sensitive for acute inflammation.
• ESR: Measures the rate at which red blood cells settle in a tube. Rises more slowly than CRP and stays elevated for longer. Particularly useful in conditions like polymyalgia rheumatica and giant cell arteritis, where ESR is often dramatically elevated (above 50-100 mm/hr).

In the context of autoimmune screening, persistently elevated CRP or ESR supports the presence of an active inflammatory or autoimmune process, even when specific antibody tests may be inconclusive.

Full Blood Count (FBC)

The FBC provides several clues to autoimmune conditions:

• Lymphopenia (low lymphocytes): Common in active SLE — part of the diagnostic criteria
• Anaemia: Seen in many autoimmune conditions due to chronic inflammation (anaemia of chronic disease), autoimmune haemolytic anaemia, or nutritional deficiencies from malabsorption (coeliac)
• Thrombocytopenia (low platelets): Can occur in SLE (immune thrombocytopenia) and other autoimmune conditions
• Raised white cells or eosinophils: May point toward specific autoimmune or allergic processes

Immunoglobulins (IgG, IgA, IgM)

Immunoglobulin levels can be informative in autoimmune screening. Elevated IgG is common in autoimmune hepatitis and SLE. Elevated IgA is seen in IgA nephropathy and coeliac disease. IgA deficiency, as mentioned, is the most common primary immunodeficiency in the UK and is associated with an increased risk of coeliac disease and other autoimmune conditions. Low overall immunoglobulins may indicate common variable immunodeficiency (CVID), which can mimic autoimmune disease.

No Single Test Does It All

This is worth emphasising: there is no single blood test that screens for all autoimmune conditions. Each antibody test targets a specific condition or group of conditions. A comprehensive panel increases the probability of identifying the correct condition — or at least narrowing the differential diagnosis enough to guide specialist referral. Some autoimmune conditions (such as psoriasis and ankylosing spondylitis) are primarily clinical diagnoses where blood markers play a supporting rather than diagnostic role.

When to Consider Autoimmune Screening

• Persistent fatigue that does not respond to rest or lifestyle changes
• Joint pain and stiffness, particularly morning stiffness lasting more than 30 minutes
• Unexplained skin rashes, mouth ulcers, or hair loss
• Recurrent miscarriages or unexplained infertility
• Family history of autoimmune conditions (first-degree relatives)
• Multiple vague symptoms affecting different body systems (fatigue plus joint pain plus skin changes plus dry eyes, for example)
• Already diagnosed with one autoimmune condition and experiencing new symptoms

Testing With Lola Health

Our Peak Insights 70 test (£185) provides the most comprehensive baseline for autoimmune screening, including anti-TPO antibodies, CRP, a full blood count, thyroid function, liver and kidney function, and a broad metabolic panel. For a targeted autoimmune panel, rheumatoid factor (RF), anti-CCP, ESR, tTG IgA, and ANA are available as add-on biomarkers, allowing you to build a customised investigation tailored to your symptoms.

All results are reviewed by qualified clinicians who provide written commentary explaining the significance of any positive findings. If your results suggest an autoimmune condition, our team will recommend the appropriate specialist referral — whether that is rheumatology, gastroenterology, endocrinology, or another discipline — so you can access treatment without further delay.

Early Detection Changes Outcomes

The 4.5-year average diagnostic delay for autoimmune conditions is not merely an inconvenience — it represents years of preventable tissue damage. Joint erosion in RA, villous atrophy in coeliac disease, thyroid destruction in Hashimoto's, and kidney damage in lupus all progress during the interval between symptom onset and diagnosis. Blood testing is the most accessible and cost-effective first step toward closing that gap. If you recognise the patterns described above, comprehensive screening is one of the most impactful investments you can make in your long-term health.