The essentials

An autoimmune disease happens when the immune system attacks the body's own healthy cells. There are more than 80 of them, from thyroid disease to lupus, and together they affect about 1 person in 10. No single blood test detects them all: doctors combine symptoms with targeted antibody tests, such as ANA, and inflammation markers.

What is an autoimmune disease, at a glance?

  • Definition: the immune system, which normally fights germs, makes antibodies or cells that damage the body's own tissues[1].
  • Number: more than 80 types are known[1]. Some target one organ, such as the thyroid in Hashimoto's thyroiditis; others affect the whole body, such as lupus.
  • How common: in a study of 22 million people in the UK, 19 common autoimmune diseases affected 10.2% of the population: 13.1% of women and 7.4% of men[4]. In the United States, more than 23.5 million people live with one[3].
  • Key blood tests: the ANA test for the body-wide diseases, a disease-specific antibody (thyroid, celiac, rheumatoid arthritis, type 1 diabetes) and inflammation markers such as CRP and ESR.

What are the symptoms of autoimmune disease?

Symptoms depend on the organ under attack, and many other illnesses cause the same ones[1]. Signs that often come first:

  • Lasting tiredness, low-grade fever and feeling unwell.
  • Joint pain, swelling and stiffness; muscle weakness[2].
  • Skin rashes, redness, warmth or swelling, the classic signs of inflammation[1][2].
  • Symptoms that come and go: periods of worse symptoms are called flares; calmer periods are called remissions[1].

Some patterns point to a specific organ:

  • Thyroid: weight change, feeling cold or hot, a racing heart (Hashimoto's thyroiditis or Graves' disease).
  • Joints: painful, swollen small joints of the hands, worse in the morning (rheumatoid arthritis).
  • Gut: diarrhea, bloating, weight loss or iron deficiency (celiac disease, Crohn's disease).
  • Pancreas: thirst, frequent urination and weight loss (type 1 diabetes)[2].
  • Nerves and muscles: vision problems, numbness, drooping eyelids or weakness that worsens during the day (multiple sclerosis, myasthenia gravis).
  • Dry eyes and mouth: Sjögren's disease.

When should you see a doctor?

When to see a doctor

  • Emergency: call 911 for fruity-smelling breath with vomiting, deep fast breathing or drowsiness, which can reveal type 1 diabetes for the first time[16]; for severe trouble breathing or swallowing in someone with muscle weakness[17]; or for chest pain, sudden confusion or one-sided weakness.
  • Within 24 to 48 hours for a hot, swollen joint with fever, a new rash with fever, foamy or dark urine, or a known autoimmune disease that is flaring fast.
  • At your next appointment for tiredness, joint pain or a rash that lasts several weeks, or a positive antibody result found by chance. Bring a symptom diary and your family history.

What causes autoimmune diseases, and who is at risk?

The exact cause is unknown. Doctors think certain genes make some people prone, and a trigger then sets off the disease[1]. Known risk factors:

  • Sex: women are affected much more often, frequently during their childbearing years[3][4].
  • Family history: a parent, brother or sister with an autoimmune disease raises the risk[1][2].
  • Infections: some viruses, such as Epstein-Barr virus and COVID-19, are linked to the start of autoimmune diseases[2].
  • Smoking and chemicals: tobacco use and some environmental exposures[2].
  • Having one already: autoimmune diseases cluster. Children with type 1 diabetes had much higher rates of celiac disease, thyroid disease and Addison's disease than the general population[4].

How are autoimmune diseases diagnosed? The blood tests and how to read them

There is usually no single test for a given autoimmune disease, and the diagnosis can take several visits[1]. The doctor starts from your symptoms and orders the tests that fit them: a complete blood count, inflammation markers, then antibodies. A fictitious example of a report for joint pain, rash and tiredness:

Fictitious example of an autoimmune blood test report (United States format)
TestResultReference rangeFlag
ANA screen, IFA (HEp-2)PositiveNegativeA
ANA titer1:320<1:80H
ANA patternHomogeneous (AC-1)
Anti-dsDNA48 IU/mL0-29H
Complement C372 mg/dL90-180L
Complement C48 mg/dL10-40L
C-reactive protein (CRP)0.5 mg/dL<0.9
Sed rate (ESR)38 mm/h0-20H
  1. ANA positive at 1:320: the titer is the last dilution at which antibodies are still seen. Healthy people can be positive too: 13.3% at 1:80 and 5% at 1:160 in an international study[6]. A high titer counts more, but it is never a diagnosis on its own[5].
  2. Pattern: the lab describes how the antibodies light up the cells; 29 patterns are defined, and each one suggests which follow-up antibody to test[7].
  3. Anti-dsDNA high, C3 and C4 low: both findings carry weight in the classification criteria for lupus, which require a positive ANA of at least 1:80 to start with[8].
  4. ESR high, CRP normal: the ESR shows inflammation but cannot tell its cause[15]. Reference ranges vary by lab: use those printed on your report.

Antibodies, titers, patterns and inflammation markers on several pages? BloodSense explains each line of your full report in plain words and helps you list the questions to ask your doctor.

Explain my lab results
Blood tests often ordered when an autoimmune disease is suspected
TestLinked diseasesHow to read it
ANALupus, Sjögren's disease, scleroderma, autoimmune hepatitis[5]A screening test: negative makes lupus very unlikely; positive needs follow-up antibodies[6][8]
Anti-dsDNA, C3 and C4Lupus[8]High anti-dsDNA (H) and low complement (L) support active lupus
Rheumatoid factor and anti-CCPRheumatoid arthritis[9]Anti-CCP is found in most people with the disease and almost never without it; both positive makes it probable[10]
Anti-TPO, TgAb, TSI or TRAbHashimoto's thyroiditis, Graves' disease[11]Read with TSH: high anti-TPO points to Hashimoto's, high TSI to Graves'
tTG-IgA with total IgACeliac disease[12]Valid only if you still eat gluten; a low total IgA can hide a positive result[12][13]
Islet autoantibodies (insulin, GAD, IA-2, ZnT8)Type 1 diabetes[14]Can be found before any symptom (presymptomatic stage); screening is offered to people with a family history[14]
CRP and ESRAny inflammation[15]Show how active the inflammation is, not its cause

Three traps: a positive ANA is common in healthy adults, especially women over 65, and after some infections or medicines[5]; stopping gluten before a celiac test can make it falsely negative[12]; and a normal CRP does not rule out an autoimmune disease. A biopsy or imaging is sometimes needed to confirm the diagnosis[2][13].

How are autoimmune diseases followed over time?

Follow-up tests depend on the disease and on the treatment:

  • Rheumatoid arthritis and lupus: CRP, ESR and blood counts track inflammation; in lupus, urine tests and kidney function are checked too.
  • Thyroid disease: TSH guides the dose of thyroid hormone.
  • Type 1 diabetes: HbA1c measures average blood sugar.
  • Celiac disease: repeat celiac antibodies check that the diet without gluten works; no special preparation is needed for monitoring[12].
  • Immune-suppressing medicines: regular blood counts and liver and kidney tests watch for side effects.

How are autoimmune diseases treated?

Most are long-term conditions, and treatment aims to calm the immune system and reduce inflammation and pain; some people need it for life[1]. No doses are given here.

  • Pain relievers and anti-inflammatory medicines, including corticosteroids[2].
  • Immunosuppressants and other medicines that slow down the immune system[1][2].
  • Replacing what the organ no longer makes: insulin for type 1 diabetes[2], thyroid hormone for an underactive thyroid.
  • A strict diet with no gluten at all for celiac disease[13].
  • Physical and occupational therapy, and intravenous immunoglobulin in some diseases[2].

Can you prevent autoimmune disease or live well with it?

No proven way prevents most autoimmune diseases, but you can lower some risks and catch flares early:

  • Do not smoke, or get help to quit[2].
  • Write down your family's health history, including grandparents and cousins, and share it with your doctor[3].
  • Keep a symptom diary: what appears, when, and what makes it better or worse[3].
  • Learn the early signs of your flares and who to call when they start.
  • Keep copies of all your antibody results: they rarely need repeating, and the next specialist will ask for them.
  • Do not stop a prescribed treatment, even when you feel well, without medical advice.

Questions to ask your doctor

  1. Which autoimmune disease do my symptoms suggest, and which tests confirm or rule it out?
  2. Is my ANA titer meaningful, and what does the pattern point to?
  3. Do I need to see a specialist, and which one?
  4. Which blood tests will we repeat, and how often?
  5. Which signs of a flare mean I should call you right away?

Frequently asked questions

Can one blood test rule out all autoimmune diseases?

No. A negative ANA makes lupus very unlikely, but it does not rule out thyroid disease, celiac disease, type 1 diabetes or multiple sclerosis, which have their own tests[1].

Is autoimmune disease hereditary?

Partly. Families share genes that raise the risk, often for different autoimmune diseases, but most relatives never develop one[1].

Is an autoimmune disease contagious?

No. It comes from your own immune system and cannot be passed to others, even if an infection may act as a trigger[2].

Can autoimmune diseases be cured?

Most cannot be cured, but treatment often controls them well. Some, like celiac disease, go quiet as long as the trigger is avoided[1][13].

  1. MedlinePlus. Autoimmune diseases. US National Library of Medicine, 2024. medlineplus.gov (accessed October 30, 2026)
  2. Cleveland Clinic. Autoimmune diseases. 2024. clevelandclinic.org (accessed October 30, 2026)
  3. Office on Women's Health, US Department of Health and Human Services. Autoimmune diseases. 2026. womenshealth.gov (accessed October 30, 2026)
  4. Conrad N, Misra S, Verbakel JY, et al. Incidence, prevalence, and co-occurrence of autoimmune disorders over time and by age, sex, and socioeconomic status: a population-based cohort study of 22 million individuals in the UK. Lancet. 2023;401(10391):1878-1890. doi:10.1016/S0140-6736(23)00457-9 (accessed October 30, 2026)
  5. MedlinePlus. ANA (antinuclear antibody) test. US National Library of Medicine, 2025. medlineplus.gov (accessed October 30, 2026)
  6. Tan EM, Feltkamp TE, Smolen JS, et al. Range of antinuclear antibodies in "healthy" individuals. Arthritis Rheum. 1997;40(9):1601-1611. doi:10.1002/art.1780400909 (accessed October 30, 2026)
  7. Damoiseaux J, Andrade LEC, Carballo OG, et al. Clinical relevance of HEp-2 indirect immunofluorescent patterns: the International Consensus on ANA patterns (ICAP) perspective. Ann Rheum Dis. 2019;78(7):879-889. doi:10.1136/annrheumdis-2018-214436 (accessed October 30, 2026)
  8. Aringer M, Costenbader K, Daikh D, et al. 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus. Arthritis Rheumatol. 2019;71(9):1400-1412. doi:10.1002/art.40930 (accessed October 30, 2026)
  9. Aletaha D, Neogi T, Silman AJ, et al. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010;62(9):2569-2581. doi:10.1002/art.27584 (accessed October 30, 2026)
  10. MedlinePlus. Cyclic citrullinated peptide (CCP) antibody test. US National Library of Medicine, 2024. medlineplus.gov (accessed October 30, 2026)
  11. MedlinePlus. Thyroid antibodies. US National Library of Medicine, 2026. medlineplus.gov (accessed October 30, 2026)
  12. MedlinePlus. Celiac disease screening. US National Library of Medicine, 2025. medlineplus.gov (accessed October 30, 2026)
  13. Rubio-Tapia A, Hill ID, Semrad C, et al. American College of Gastroenterology guidelines update: diagnosis and management of celiac disease. Am J Gastroenterol. 2023;118(1):59-76. doi:10.14309/ajg.0000000000002075 (accessed October 30, 2026)
  14. American Diabetes Association Professional Practice Committee. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes-2025. Diabetes Care. 2025;48(Suppl 1):S27-S49. doi:10.2337/dc25-S002 (accessed October 30, 2026)
  15. MedlinePlus. Erythrocyte sedimentation rate (ESR). US National Library of Medicine, 2024. medlineplus.gov (accessed October 30, 2026)
  16. MedlinePlus Medical Encyclopedia. Diabetic ketoacidosis. US National Library of Medicine, 2025. medlineplus.gov (accessed October 30, 2026)
  17. NHS. Myasthenia gravis. 2023. nhs.uk (accessed October 30, 2026)

This page is general information. It does not replace the advice of a doctor, who interprets your results with your symptoms, history, medicines and examination.