Blood Tests Used in the Diagnosis of Lupus
Antibodies form in the body as a response to infection. When an invader (antigen) enters the body, white blood cells known as B lymphocytes react by making special types of proteins called antibodies. Antibodies are your body’s way of remembering an antigen; if it enters the body again, the antibodies will recognize it, combine with it, and neutralize it to prevent you from becoming infected. However, with autoimmune diseases such as lupus, the immune system can produce antibodies (auto-antibodies) that attack your body’s cells as though they were invaders, causing inflammation, damage, and even destruction. Several blood tests can be performed to detect specific auto-antibodies and help make the diagnosis of lupus. These blood tests are not conclusive by themselves, but combining the tests with certain physical findings can help to corroborate a diagnosis.
Anti-Nuclear Antibody (ANA) Test
Anti-nuclear antibodies (ANA) are autoantibodies to the nuclei of your cells. 98% of all people with systemic lupus have a positive ANA test, making it the most sensitive diagnostic test for confirming diagnosis of the disease. The test for anti-nuclear antibodies is called the immunofluorescent antinuclear antibody test. In this test, a blood sample is drawn and sent to a laboratory. Serum from the blood sample is then added to a microscopic slide prepared with specific cells (usually sections of rodent liver/kidney or human tissue culture cell lines) on the slide surface. If the patient has antinuclear antibodies, their serum will bind to the cells on the slide. Then, a second antibody tagged with a fluorescent dye is added so that it attaches to the serum antibodies and cells that have bound together. Lastly, the slide is viewed using a fluorescence microscope, and the intensity of staining and pattern of binding are scored at various dilutions. The test is read as positive if fluorescent cells are observed.
Usually, the results of the ANA test are reported in titers and patterns. The titer gives information about how many times the lab technician diluted the blood plasma to get a sample of ANAs. Each titer involves doubling the amount of test fluid, so that the difference between a titer of 1:640 and 1:320 is one dilution. A titer above a certain level then qualifies as a positive test result. ANA titers may increase and decrease over the course of the disease; these fluctuations do not necessarily correlate with disease activity. Thus, it is not useful to follow the ANA test in someone already diagnosed with lupus.
The pattern of the ANA test can give information about the type of autoimmune disease present and the appropriate treatment program. A homogenous (diffuse) pattern appears as total nuclear fluorescence and is common in people with systemic lupus. A peripheral pattern indicates that fluorescence occurs at the edges of the nucleus in a shaggy appearance; this pattern is almost exclusive to systemic lupus. A speckled pattern is also found in lupus. Another pattern, known as a nucleolar pattern, is common in people with scleroderma.
It is important to realize that even though 98% of people with lupus will have a positive ANA, ANAs are also present in healthy individuals (5-10%) and people with other connective tissue diseases, such as scleroderma and rheumatoid arthritis. Moreover, about 20% of healthy women will have a weakly positive ANA, and the majority of these people will never develop any signs of lupus. One source cites that some ten million Americans have a positive ANA, but fewer than 1 million of them have lupus. Therefore, a positive ANA test alone is never enough to diagnosis systemic lupus. Rather, a physician will order an ANA test if the patient first exhibits other signs of lupus. This is because by itself, the test has low diagnostic specificity for systemic lupus, but its value increases as a patient meets other clinical criteria. It is possible for people with lupus to have a negative ANA, but these instances are rare. In fact, only 2% of people with lupus will have a negative ANA. People with lupus who have a negative ANA test may have anti-Ro/SSA or antiphospholipid antibodies.
Other Diagnostic Tests
In people with a positive ANA, more tests are usually performed to check for other antibodies that can help to confirm the diagnosis. Certain autoantibodies and substances in the blood can give information about which autoimmune disease, if any, is present. To check for these antibodies, doctors usually order what is called an ANA panel, which checks for the following antibodies: anti-double-stranded DNA, anti-Smith, anti-U1RNP, anti-Ro/SSA, and anti-La/SSB. Some laboratories also include other antibodies in their panel, including antinucleoprotein, anticentromere, or antihistone.
Anti-dsDNA Antibody
The anti-double-stranded DNA antibody (anti-dsDNA) is a specific type of ANA antibody found in about 30% of people with systemic lupus. Less than 1% of healthy individuals have this antibody, making it helpful in confirming a diagnosis of systemic lupus. [The absence of anti-dsDNA, however, does not exclude a diagnosis of lupus.] The presence of anti-dsDNA antibodies often suggests more serious lupus, such as lupus nephritis (kidney lupus). When the disease is active, especially in the kidneys, high amounts of anti-DNA antibodies are usually present. However, the anti-dsDNA test cannot be used to monitor lupus activity, because anti-dsDNA can be present without any clinical activity. Three tests are currently used to detect anti-dsDNA antibodies, namely enzyme-linked immunosorbent assay (ELISA), the Crithidia luciliae immunofluorescence test, and a test called radioimmunoassay.
Anti-Smith Antibody
An antibody to Sm, a ribonucleoprotein found in the nucleus of a cell, is found almost exclusively in people with lupus. It is present in 20% of people with the disease (although the incidence varies among different ethnic groups), but it is rarely found in people with other rheumatic diseases and its incidence in healthy individuals is less than 1%. Therefore, it can also be helpful in confirming a diagnosis of systemic lupus. Unlike anti-dsDNA, anti-Sm does not correlate with the presence of kidney lupus. Prospective studies have been performed as to whether anti-Sm correlates with lupus flares and disease activity, although evidence seems to suggests that it does not. The anti-Sm antibody is usually measured by one of four methods: ELISA, counterimmunoelectrophoreses (CIE), immunodiffusion, or hemagglutination.
Anti-U1RNP Antibody
Anti-U1RNP antibodies are commonly found along with anti-Sm antibodies in people with SLE. The incidence of anti-U1RNP antibodies in people with lupus is approximately 25%, while less than 1% of healthy individuals possess this antibody. However, unlike anti-dsDNA and anti-Sm antibodies, anti-U1RNP antibodies are not specific to lupus; they can be found in other rheumatic conditions, including rheumatoid arthritis, systemic sclerosis, Sjogren’s syndrome, and polymyositis.
Anti-U1RNP has shown to be associated with features of scleroderma, including Raynaud’s phenomenon; it has also been linked to other conditions, such as Jaccoud’s arthropathy, a deformity of the hand caused by arthritis. Levels of anti-U1RNP may fluctuate in individuals over time, but this fluctuation has not proven to be a significant indicator of disease activity.
Anti-Ro/SSA and Anti-La/SSB Antibodies
Anti-Ro/SSA and Anti-La/SSB are antibodies found mostly in people with systemic lupus (30-40%) and primary Sjogren’s syndrome. They are also commonly found in people with lupus who have tested negative for anti-nuclear antibodies. Anti-Ro and anti-La can also be found in other rheumatic diseases, such as systemic sclerosis, rheumatoid arthritis, and polymyositis, and are present in low titers in about 15% of healthy individuals. These antibodies are not highly specific for systemic lupus, but they are associated with certain conditions, including extreme sun sensitivity, a clinical subset of lupus called subacute cutaneous lupus erythematosus (SCLE), and a lupus-like syndrome associated with a genetic deficiency of a substance called complement (a system of proteins that helps mediate your body’s immune response). In addition, babies of mothers with anti-Ro and anti-La antibodies are at an increased risk of neonatal lupus, an uncommon condition that produces a temporary rash and can lead to congenital heart block. Therefore, women with lupus who wish to become pregnant should be tested for these antibodies.
Anti-Histone Antibodies
Antibodies to histones, proteins that help to lend structure to DNA, are usually found in people with drug-induced lupus (DIL), but they can also be found in people with systemic lupus. However, they are not specific enough to systemic lupus to be used to make a concrete diagnosis.
Serum (blood) Complement Test
A serum complement test measures the levels of proteins consumed during the inflammatory process. Thus, low complement levels reflect that inflammation is taking place within the body. Variations in complement levels exist in different individuals simply due to genetic factors.
Sources
- “ANA.” 8 April 2009. Lab Tests Online. 8 April 2009. American Association for Clinical Chemistry. 6 July 2009. – Link
- “Blood Tests.” The Lupus Site. 6 July 2009. – Link
- “Laboratory Tests.” Lupus Foundation of America. 6 July 2009. – Link
- Wallace, Daniel J. The Lupus Book: A Guide for Patients and Their Families. 1st ed. New York: Oxford University Press, 1995.
- Wallace, Daniel J., and Bevra Hannahs Hahn, eds. Dubois’ Lupus Erythematosus. 7th ed. Philadelphia: Lippincott Williams & Wilkins, 2007.
FAQs
Are blood tests for lupus accurate? ›
98% of all people with systemic lupus have a positive ANA test, making it the most sensitive diagnostic test for confirming diagnosis of the disease. The test for anti-nuclear antibodies is called the immunofluorescent antinuclear antibody test. In this test, a blood sample is drawn and sent to a laboratory.
What do lab results look like for lupus? ›An examination of a sample of your urine may show an increased protein level or red blood cells in the urine, which may occur if lupus has affected your kidneys. Antinuclear antibody (ANA) test. A positive test for the presence of these antibodies — produced by your immune system — indicates a stimulated immune system.
What test confirms you have lupus? ›Your doctor will look for rashes and other signs that something is wrong. Blood and urine tests. The antinuclear antibody (ANA) test can show if your immune system is more likely to make the autoantibodies of lupus. Most people with lupus test positive for ANA.
What is the gold standard test for lupus? ›The 'gold standard' is the anti-dsDNA antibody test, which has been used as a marker of disease activity by clinicians in SLE for over 35 years.
What is borderline lupus? ›A doctor may use the phrase "borderline lupus" when symptoms or blood test results suggest lupus, but there is not enough information for a definite diagnosis.
What level of ANA indicates lupus? ›The initial requirement of the criteria for lupus diagnosis is a positive ANA test with a titer of at least 80. The numerical value of the titer refers to the ratio of blood serum being evaluated to a dilution agent.
What is included in a lupus panel? ›A LUPUS blood test includes: Antinuclear Antibodies (ANA) Direct, Complete Blood Count with Differential and Platelets (CBC), Urinalysis Complete, Rheumatoid Arthritis (RA) Factor, Sedimentation Rate (ESR), C-Reactive Protein (CRP) High Sensitivity Cardiac Risk, Comprehensive Metabolic Panel - 14 tests, Prothrombin ...
How does a rheumatologist diagnose lupus? ›The most important blood screening test is ANA. If ANA is negative, you don't have lupus. However, if ANA is positive, you might have lupus and will need more specific tests. These blood tests include antibodies to anti-dsDNA and anti-Sm, which are specific to the diagnosis of lupus.
What are the top 5 signs of lupus? ›- Fatigue.
- Fever.
- Joint pain, stiffness and swelling.
- Butterfly-shaped rash on the face that covers the cheeks and bridge of the nose or rashes elsewhere on the body.
- Skin lesions that appear or worsen with sun exposure.
Common signs and symptoms of lupus
Extreme fatigue (feeling tired all the time) Pain or swelling in the joints. Swelling in the hands, feet, or around the eyes. Headaches.
What are the 11 criteria for lupus diagnosis? ›
- Butterfly (malar) rash on cheeks.
- Rash on face, arms, neck, torso (discoid rash)
- Skin rashes that result from exposure to sunlight or ultraviolet light (photosensitivity)
- Mouth or nasal sores (ulcers), usually painless.
- Joint swelling, stiffness, pain involving two or more joints (arthritis)
According to a lot of clinicians, normal values of CRP are 0-0.5 mg/dl (0-5 mg/L) and ESR between 12-20 mm. Levels over 15 mg/L (1.5 mg/dl) are found with 4 SLE patients (5 SLE relapses), and 2 patients with infections (3 cases of infection).
Will lupus show up on MRI? ›In general, a brain MRI will show more lesions with MS ("black holes and bright spots") but sometimes the brain lesions found with lupus or MS can be indistinguishable.
Which test is the most specific and sensitive test for SLE? ›The antinuclear antibody (ANA) test is the most sensitive test for SLE and is therefore the best screening assay for ruling out its presence.
What does Mild lupus look like? ›A tell-tale sign of lupus is a butterfly-shaped rash across the cheeks and bridge of the nose. Other common skin problems include sensitivity to the sun with flaky, red spots or a scaly, purple rash on various parts of the body, including the face, neck, and arms. Some people also develop mouth sores.
What is lupus pain like? ›Muscle and joint pain.
You may experience pain and stiffness, with or without swelling. This affects most people with lupus. Common areas for muscle pain and swelling include the neck, thighs, shoulders, and upper arms.
Types of lupus
Symptoms range from mild to severe, and many people will have long periods with few or no symptoms before experiencing a sudden flare-up, where their symptoms are particularly severe. Even mild cases can be distressing and have a considerable impact on a person's quality of life.
A positive result on an ANA test means that antinuclear antibodies were found in your blood. A positive result may be a sign of: Systemic lupus erythematosus (SLE) A different type of autoimmune disease.
What is a high ANA test result? ›A ratio of 1:640 or greater indicates a high possibility of autoimmune disorder, but results will need to be analyzed by a doctor and additional tests performed to draw a conclusion. However, a positive result doesn't always mean that you have an autoimmune disease.
What is considered a high titer? ›The antibody titer score is generated by the number of times the scientist can dilute a patient's serum and still be able to detect the presence of antibodies. Titers of 1:80 and 1:160 were categorized as low titers; 1:320 moderate; and 1:960 or ≥ 1:2880 were high.
What labs are abnormal in lupus? ›
Low C3 and C4 levels (below 60 for C3 and below 15 for C4 in the usual American measure), occur in active lupus, especially when the kidneys are affected or there is immune breakdown of blood cells (autoimmune hemolytic anemia, AIHA).
What does it mean when your blood test shows inflammation? ›Blood tests known as 'inflammatory markers' can detect inflammation in the body, caused by many diseases including infections, auto-immune conditions and cancers. The tests don't identify what's causing the inflammation: it might be as simple as a viral infection, or as serious as cancer.
What drugs can cause lupus? ›- Isoniazid.
- Hydralazine.
- Procainamide.
- Tumor-necrosis factor (TNF) alpha inhibitors (such as etanercept, infliximab and adalimumab)
- Minocycline.
- Quinidine.
Lupus symptoms can also be unclear, can come and go, and can change. On average, it takes nearly six years for people with lupus to be diagnosed, from the time they first notice their lupus symptoms.
What should you not do if you have lupus? ›- (1) Sunlight. People with lupus should avoid the sun, since sunlight can cause rashes and flares. ...
- (2) Bactrim and Septra (sulfamethoxazole and trimethoprim) Bactrim and Septra are antibiotics that contain sulfamethoxazole and trimethoprim. ...
- (3) Garlic. ...
- (4) Alfalfa Sprouts. ...
- (5) Echinacea.
Conclusions: The prevalence of chronic low back pain in individuals with systemic lupus erythematosus was 26%. The maximal voluntary isometric contraction of the back muscles was 63% predicted by five variables of interest, however, only the handgrip strength was a statistically significant predictive variable.
Why is it so hard to get a lupus diagnosis? ›Lupus is a disease that is known for being difficult to diagnose because the symptoms are different from person to person, they mimic the symptoms of many other diseases, and they can come and go. It can sometimes take several years to receive an official diagnosis.
Who is the best doctor to treat lupus? ›Rheumatologist. This specialist is an expert on joints and muscle, and some autoimmune diseases. They're typically your go-to doctor for lupus.
What does a lupus flare feel like? ›Painful, swollen joints. An increase in fatigue. Rashes. Sores or ulcers in the mouth or nose.
Can lupus affect your bowels? ›Lupus can slow the digestive process, and this can cause a wide variety of GI issues. Digestive problems may be the direct result of an attack by the immune system or from medications to treat lupus. These digestive difficulties include nausea, vomiting, diarrhea, or constipation.
What are the first signs of a lupus flare? ›
- Feeling more tired.
- Pain.
- Rash.
- Fever.
- Stomach ache.
- Severe headache.
- Dizziness.
Lupus and the central nervous system
Symptoms include: Confusion and trouble concentrating (sometimes called lupus brain fog) Seizures (sudden, unusual movements or behavior) Stroke (blocked blood flow in the brain that causes brain cells to die)
No single test can diagnose lupus. Instead, a doctor must look for signs of systemic inflammation, which indicates that the immune system may be attacking the body. To help with diagnosis, doctors may: take a complete medical history, including a log of all symptoms and how they have changed over time.
Can I have lupus without the rash? ›While the butterfly rash (also called a malar rash or lupus rash) is one of the most commonly known symptoms people associate with lupus, it does not need to be present to be diagnosed with lupus.
Does lupus cause weight gain? ›Weight changes — Lupus can sometimes cause weight loss or weight gain. Weight loss may be unintentional and due to decreased appetite or problems with the digestive system (see 'Digestive system' below). It can also be a side effect of some medications used to treat lupus.
What is the first line of treatment for lupus? ›Hydroxychloroquine is first-line treatment unless contraindicated and is useful in almost all manifestations of lupus. Other treatments are titrated against type and severity of organ involvement. Monoclonal antibodies have a limited role in the management of lupus.
How do I know if I have lupus or rheumatoid arthritis? ›No one test can tell if you have RA or lupus. Instead, your doctor will ask about your symptoms and family history, do a physical exam, and order some lab and imaging tests. During the physical exam, your doctor will feel your joints to see if the swelling feels hard. If it does, it could mean you have osteoarthritis.
Where is the best place to be treated for lupus? ›The general recommendation is to find a physician who is affiliated with a medical school—a university hospital, for example. They are generally regarded as very good places to go for the diagnosis and treatment of lupus.
What are the top 5 signs of lupus? ›- Fatigue.
- Fever.
- Joint pain, stiffness and swelling.
- Butterfly-shaped rash on the face that covers the cheeks and bridge of the nose or rashes elsewhere on the body.
- Skin lesions that appear or worsen with sun exposure.
The most important blood screening test is ANA. If ANA is negative, you don't have lupus. However, if ANA is positive, you might have lupus and will need more specific tests. These blood tests include antibodies to anti-dsDNA and anti-Sm, which are specific to the diagnosis of lupus.
Is lupus hard to diagnose? ›
Lupus is a disease that is known for being difficult to diagnose because the symptoms are different from person to person, they mimic the symptoms of many other diseases, and they can come and go. It can sometimes take several years to receive an official diagnosis.
What are the 11 criteria for lupus diagnosis? ›- Butterfly (malar) rash on cheeks.
- Rash on face, arms, neck, torso (discoid rash)
- Skin rashes that result from exposure to sunlight or ultraviolet light (photosensitivity)
- Mouth or nasal sores (ulcers), usually painless.
- Joint swelling, stiffness, pain involving two or more joints (arthritis)
Foods High in Cholesterol and Saturated Fats
Heart attack risk is 50 times higher in people with lupus, so patients with lupus should be extra vigilant against foods with known links to heart disease, such as red meat, fried foods, and dairy.
Joint and muscle pain is often the first sign of lupus. This pain tends to occur on both sides of the body at the same time, particularly in the joints of the wrists, hands, fingers, and knees. The joints may look inflamed and feel warm to the touch.
What can trigger lupus? ›An infection, a cold or a viral illness. An injury, particularly traumatic injury. Emotional stress, such as a divorce, illness, death in the family, or other life complications. Anything that causes stress to the body, such as surgery, physical harm, pregnancy, or giving birth.
What is included in a lupus panel? ›A LUPUS blood test includes: Antinuclear Antibodies (ANA) Direct, Complete Blood Count with Differential and Platelets (CBC), Urinalysis Complete, Rheumatoid Arthritis (RA) Factor, Sedimentation Rate (ESR), C-Reactive Protein (CRP) High Sensitivity Cardiac Risk, Comprehensive Metabolic Panel - 14 tests, Prothrombin ...
Who is the best doctor to treat lupus? ›Rheumatologist. This specialist is an expert on joints and muscle, and some autoimmune diseases. They're typically your go-to doctor for lupus.
Do I have lupus checklist? ›Common signs and symptoms of lupus
Extreme fatigue (feeling tired all the time) Pain or swelling in the joints. Swelling in the hands, feet, or around the eyes. Headaches.
Conclusions: The prevalence of chronic low back pain in individuals with systemic lupus erythematosus was 26%. The maximal voluntary isometric contraction of the back muscles was 63% predicted by five variables of interest, however, only the handgrip strength was a statistically significant predictive variable.
Can you have lupus for years without knowing? ›Lupus symptoms can also be unclear, can come and go, and can change. On average, it takes nearly six years for people with lupus to be diagnosed, from the time they first notice their lupus symptoms.
What labs are abnormal in lupus? ›
Low C3 and C4 levels (below 60 for C3 and below 15 for C4 in the usual American measure), occur in active lupus, especially when the kidneys are affected or there is immune breakdown of blood cells (autoimmune hemolytic anemia, AIHA).
What is the first line of treatment for lupus? ›Hydroxychloroquine is first-line treatment unless contraindicated and is useful in almost all manifestations of lupus. Other treatments are titrated against type and severity of organ involvement. Monoclonal antibodies have a limited role in the management of lupus.
What is lupus pain like? ›Lupus can also cause inflammation in the joints, which doctors call “inflammatory arthritis.” It can make your joints hurt and feel stiff, tender, warm, and swollen. Lupus arthritis most often affects joints that are farther from the middle of your body, like your fingers, wrists, elbows, knees, ankles, and toes.