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Diagnosis of systemic lupus erythematosus
Last reviewed: 03.07.2025

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Laboratory diagnostics of systemic lupus erythematosus
Clinical blood test. The active period of systemic lupus erythematosus is characterized by an increase in ESR, the development of leukopenia with lymphopenia, and hemolytic anemia with a positive Coombs reaction is found less often. Hypochromic anemia may be a consequence of a chronic inflammatory process and intoxication, hidden bleeding, etc.
Thrombocytopenia (usually moderate) is usually diagnosed in patients with secondary APS. In some cases, autoimmune thrombocytopenia develops, caused by the appearance of antibodies to platelets.
General urine analysis. Proteinuria, hematuria, leukocyturia, cylindruria of varying degrees of severity are detected, correlating with the type and activity of lupus nephritis.
Biochemical blood test. Changes in biochemical parameters are non-specific, their study is carried out to assess the functions of various organs and systems. An increase in the level of C-reactive protein is not typical for systemic lupus erythematosus, it is usually noted when a secondary infection occurs.
Immunological diagnostics of systemic lupus erythematosus
ANF (antinuclear antibodies) is a heterogeneous group of antibodies that react with various components of the nucleus. The sensitivity of this test is very significant (95% of patients with systemic lupus erythematosus), but the specificity is low (it is often determined in patients with other rheumatic and non-rheumatic diseases).
Antibodies to double-stranded DNA are registered in 20-70% of patients with systemic lupus erythematosus. They are highly specific for systemic lupus erythematosus, their level usually correlates with the activity of the disease, especially in the presence of lupus nephritis.
Anti-histone antibodies are more characteristic of drug-induced lupus-like syndrome; in systemic lupus erythematosus they are associated with the development of arthritis.
Antibodies to Sm antigen are highly specific for systemic lupus erythematosus, but they are detected in only 20-30% of patients.
Low titers of AT to small nuclear ribonucleoproteins recorded in systemic lupus erythematosus are usually associated with Raynaud's syndrome and leukopenia; their high titers are found in patients with mixed connective tissue disease.
Antibodies to SS-A/Ro-antigen, SS-B/La-antigen are less characteristic of systemic lupus erythematosus, associated with lymphopenia, thrombocytopenia, photodermatitis and pulmonary fibrosis. They are detected in 60-80% of patients with Sjögren's syndrome, these antigens are also characteristic of subacute cutaneous and drug-induced lupus.
Anti-cardiolipin antibodies (ACL), antibodies to S2 - glycoprotein 1, lupus anticoagulant are detected in an average of 60% of children with systemic lupus erythematosus. These are markers of secondary APS.
Rheumatoid factor (IgM class autoantibodies that react with the Fc fragment of IgG) is often observed in children with systemic lupus erythematosus who have severe articular syndrome.
LE cells are polymorphonuclear neutrophils (less often eosinophils or basophils) with a phagocytized cell nucleus or individual fragments of it, formed in the presence of antibodies to the DNA-histone complex. These cells are found on average in 70% of children with systemic lupus erythematosus.
A decrease in the total hemolytic activity of complement (CH50) and its components (C3, C4) usually correlates with the activity of lupus nephritis and in some cases may be a consequence of a genetically determined deficiency.
Instrumental methods of diagnostics of lupus erythematosus
Musculoskeletal system: X-ray of bones and joints, ultrasound of joints and soft tissues, MRI (if indicated), densitometry.
Respiratory system: chest X-ray (at least once a year), chest CT (if indicated), echocardiography (to detect pulmonary hypertension).
Cardiovascular system: ECG, echocardiography, Holter ECG monitoring (if indicated).
Gastrointestinal tract: ultrasound of abdominal organs, esophagogastroduodenoscopy, CT and MRI (if indicated).
Nervous system: if indicated - electroencephalography, CT, MRI.
The classification criteria of the American Rheumatology Association are most widely used to establish the diagnosis of systemic lupus erythematosus.
American Rheumatology Association criteria for the diagnosis of systemic lupus erythematosus (1997)
Criteria |
Definition |
Rashes in the zygomatic region |
Fixed erythema, flat or raised, on the zygomatic arches with a tendency to extend to the nasolabial folds |
Discoid rash |
Erythematous raised plaques with keratotic lesions and follicular plugs; older lesions may have atrophic scars |
Photosensitization |
Skin rashes as a result of an unusual reaction to sun exposure, based on medical history or observations |
Oral ulcers |
Ulcers in the mouth or nasopharyngeal area, usually painless, observed by a doctor |
Arthritis |
Nonerosive arthritis of 2 or more peripheral joints characterized by pain, swelling, or effusion |
Serositis |
A) Pleurisy (history of pleural pain, pleural friction rub on auscultation, pleural effusion); B) pericarditis (pericardial friction rub, pericardial effusion, ECG signs) |
Kidney damage |
A) Persistent proteinuria >0.5 g/day; B) cylindruria (erythrocyte, hemoglobin, granular, mixed cylinders) |
Neurological disorders |
Seizures or psychosis not related to medications or metabolic disturbances due to uremia, ketoacidosis, electrolyte imbalance |
Hematological disorders |
A) Hemolytic anemia with reticulocytosis; B) leukopenia (<4x10 9 /l) with 2 or more determinations; B) lymphopenia (<1.5x10 9 /l) in 2 or more studies; D) thrombocytopenia (<100x10 9 /l) not associated with drug intake |
Immune disorders |
A) Antibodies to native DNA in elevated titers; B) the presence of antibodies to Sm antigen; B) the presence of AFA: Elevated titer of lupus anticoagulant (IgM or IgG); detection of lupus anticoagulant by standard method; false-positive Wasserman reaction for at least 6 months in the absence of syphilis, confirmed by the immobilization reaction of pale treponema or in the absorption test of fluorescent antitreponemal antibodies |
ANF (antinuclear antibodies) |
Increased ANF titer in an immunofluorescence test or other similar test, not associated with taking drugs that can cause drug-induced lupus |
If the patient has 4 or more signs in any combination, the diagnosis is considered reliable; if there are 3 signs, the diagnosis is considered probable.
The sensitivity of these criteria is 78-96%, and the specificity is 89-96%.
Stages of activity of systemic lupus erythematosus
The activity of systemic lupus erythematosus is determined based on the severity of the patient's condition, taking into account the totality and degree of severity of the existing clinical and laboratory signs of the disease.
There are 3 degrees of activity of systemic lupus erythematosus:
At high activity (grade III), high fever, pronounced changes in the internal organs (nephritis with nephrotic syndrome, endomyocarditis, pericarditis with effusion and/or exudative pleurisy), severe damage to the central nervous system, skin (dermatitis), musculoskeletal system (acute polyarthritis and/or polymyositis) and others are observed, accompanied by pronounced changes in laboratory parameters, including a significant increase in ESR (more than 45 mm/h) and immunological parameters (increased titers of ANF and antibodies to DNA, a significant decrease in the total hemolytic activity of complement and its components C3, C4).
Lupus crisis is diagnosed in patients in critical conditions, characterized by the development of functional insufficiency of any organ against the background of excessively high activity of the pathological process.
At moderate activity (grade II)fever is usually subfebrile, signs of damage to various organs are expressed moderately. Patients may have polyarthralgia or polyarthritis, dermatitis, moderate reaction from the serous membranes, nephritis without nephrotic syndrome and renal dysfunction, myocarditis, etc. ESR is increased within 25-45 mm/h, an increase in titers of ANF, antibodies to DNA, circulating immune complexes is noted.
At low activity (I degree)The general condition of patients is usually not disturbed, laboratory parameters are slightly changed, signs of damage to internal organs are determined only by complex instrumental examination. Clinically, mild signs of skin and joint syndromes are noted.
Assessing the degree of activity of the pathological process is of crucial importance for determining the patient’s treatment tactics at each stage of the disease.
The state of remission is determined in the absence of clinical and laboratory signs of process activity in the patient.
For a more accurate assessment of the patient's condition during dynamic observation, various scoring indices are used.
[ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ], [ 13 ]
Assessment of the activity of systemic lupus erythematosus according to the ECLAM (European Consensus Lupus Activity Measurement) scale
1. General symptoms (any of the following x 0.5 points)
Fever |
Morning temperature above 37.5 C, not associated with infection |
Fatigue |
Subjective feeling of increased fatigue |
2. Symptoms of joint damage (any of the following x 0.5 points)
Arthritis |
Nonerosive arthritis involving 2 or more peripheral joints (wrist, distal or proximal interphalangeal joints, metacarpophalangeal joints) |
Arthralgia |
Localized pain without objective symptoms of inflammation of 2 or more peripheral joints) |
For. Symptoms of active skin and mucous membrane lesions
Erythematous rash in the malar region |
Fixed erythema, flat or raised, in the malar region with a tendency to spread to the nasolabial region |
Generalized rash |
A maculopapular rash that is not associated with medication. It can be anywhere on the body, regardless of sun exposure. |
Discoid rash |
Erythematous or depigmented raised plaque with adherent keratic scale or follicular plug |
Cutaneous vasculitis |
Including digital ulcers, purpura, urticaria, bullous eruptions |
Oral ulcers |
Ulcers in the mouth or nasopharynx, usually painless, that can be detected by a doctor |
3b. Development of symptoms of skin and mucous membrane damage (x 1 point if the above-mentioned signs appear again; +1 point if an increase in the severity of signs is noted after the last observation) | |
4. Myositis (x 2 points if confirmed by elevated CPK levels and/or EMG or histological examination) | |
5. Pericarditis (x 1 point if confirmed by ECG or EchoCG or by listening to pericardial friction rub during auscultation) | |
6. Signs of intestinal lesions (any of the following x 2 points) | |
Intestinal vasculitis | Obvious signs of acute intestinal vasculitis |
Aseptic peritonitis |
Abdominal effusion in the absence of infection |
7. Symptoms of pulmonary disorders (any of the following x 1 point) |
|
Pleurisy |
Adhesive or exudative, confirmed by auscultation or radiography) |
Pneumonitis |
Single or multiple opacities on radiographs that reflect disease activity and are not associated with infection |
Progressive dyspnea |
- |
8. Symptoms of psychoneurological disorders (any of the following x 2 points) |
|
Headache/migraine |
Recent onset, persistent or recalcitrant, difficult to treat with analgesics and easily treated with corticosteroids |
Epilepsy |
Minor or major seizures and choreokinetic syndrome that do not develop due to adverse drug effects or metabolic disorders |
Stroke |
- |
Encephalopathy |
Decreased memory, orientation, perception, and numeracy |
Psychoses |
If the drugs do not work |
9a. Symptoms of kidney damage (any of the following x 0.5 points) |
|
Proteinuria |
Daily proteinuria >0.5 g/day |
Urine sediment |
Erythrocyturia, cylindruria |
Hematuria |
Macroscopic or microscopic |
Increased creatinine levels or decreased creatinine clearance |
" |
9b. Development of kidney damage symptoms (x 2 points if any of the above signs of kidney damage are noted again or are observed to worsen compared to the last observation) |
|
10. Signs of hematological disorders (any of the following x 1 point) |
|
Non-hemolytic anemia |
Coombs-negative hypochromic or normochromic anemia without reticulocytosis) |
Hemolytic anemia |
Coombs-positive hemolytic anemia with reticulocytosis |
Leukopenia |
<3500 or lymphopenia <1500/µl |
Thrombocytopenia |
<100,000vmkl |
11. ESR |
<25 mm/h in the absence of other causes |
12. Hypocomplementemia (any of the following x 1 point) |
|
SZ |
Radial diffusion or nephelometry |
CH50 |
Standard hemolytic method |
12b. Developing hypocomplementemia (x 1 point with a significant decrease in the complement level (C4) compared to the last observation |
[ 14 ], [ 15 ], [ 16 ], [ 17 ], [ 18 ], [ 19 ], [ 20 ]
Final score
If myositis, symptoms of psychoneurological disorders and kidney damage are the only ones recorded among points 1-10, add 2 points. If the calculation does not result in a whole number, it should be rounded down if the value is less than 6 and up if the value is more than 6. If the final score is more than 10, it should be rounded up to 10.
Assessment of systemic lupus erythematosus activity using the SLEDAI-2K scale
Points |
SLEDAI-account |
Symptoms |
Definition |
8 |
- |
Epileptic seizure |
Recent onset. Metabolic, infectious and drug causes should be excluded. |
8 |
Psychosis |
Impaired ability to perform normal activities due to marked changes in perception of reality, including hallucinations, restless thinking, markedly reduced associative abilities, exhaustion of thought processes, marked illogicality of thinking, bizarre disorganized or catatonic behavior. Should be distinguished from similar conditions caused by uremia or drugs |
|
8 |
Organic brain syndromes |
Impaired mental functioning with disturbance of orientation, memory or other intellectual abilities with acute onset and variable clinical symptoms, including clouding of consciousness with decreased ability to concentrate and inability to maintain attention to surroundings, plus at least two of the following: impaired perception, incoherent speech, insomnia or daytime sleepiness, decreased or increased psychomotor activity. Metabolic, infectious and drug effects should be excluded |
|
8 |
Visual impairment |
Retinal changes (including cellular bodies, hemorrhages, serous exudates, or hemorrhages in the choroid) or optic neuritis. Should be distinguished from disorders caused by hypertension, infection, drug effects |
|
8 |
- |
Cranial nerve dysfunction |
New onset sensory or motor neuropathy of the cranial nerves |
8 |
- |
Headache |
Severe persistent headache that does not respond to narcotic analgesics |
8 |
- |
Cerebral circulatory disorder |
A newly occurring cerebrovascular accident. Should be distinguished from disorders that arise as a result of atherosclerosis. |
8 |
Vasculitis |
Ulcers, gangrene, painful nodules on the fingers, periungual infarctions, hemorrhages, or biopsy or angiogram findings suggestive of vasculitis |
|
4 |
- |
Arthritis |
>2 painful joints with signs of inflammation (swelling or effusion) |
4 |
~ |
Myositis |
Proximal muscle pain/weakness associated with elevated CPK/aldolase levels, or EMG or biopsy findings consistent with myositis |
4 |
- |
Cylindruria |
Granular or red blood cell casts |
4 |
Hematuria |
>5 erythrocytes in the field of view. Hematuria caused by urolithiasis, infections and other causes should be excluded. |
|
4 |
- |
Proteinuria |
>0.5 g/day |
4 |
- |
Leukocyturia |
>5 leukocytes in the field of view. The possibility of infectious causes of leukocyturia should be excluded. |
2 |
- |
Skin rashes |
Inflammatory rashes |
2 |
- |
Alopecia |
Increased focal or diffuse hair loss |
2 |
- |
Ulcers of the mucous membrane |
Ulceration of the mucous membrane of the mouth and nose |
2 |
- |
Pleurisy |
Chest pain with pleural friction rub or pleural effusion or pleural effusion |
2 |
- |
Pericarditis |
Pericardial pain with one of the following: pericardial friction rub, electrocardiographic or echographic confirmation |
2 |
- |
Low complement |
A drop in the level of CH50, C3 or C4 below the lower limit of the norm (according to the testing laboratory) |
2 |
- |
Elevated anti-DNA levels |
>25% Farr binding or above the testing laboratory's reference range |
1 |
- |
Fever |
>38 C, infectious causes should be excluded |
1 |
- |
Thrombocytopenia |
< 100x10 7 l, the factor of drug exposure should be excluded |
1 |
- |
Leukopenia |
<3x10 9 /l, drug exposure should be excluded |
[ 21 ], [ 22 ], [ 23 ], [ 24 ], [ 25 ], [ 26 ], [ 27 ], [ 28 ]
Total SLEDAI score
The SLEDAI score column is entered with points if the symptom is present at the time of examination or occurred during the 10 days preceding the examination. SLEDAI-1K, unlike the SLEDAT scale, allows for persistent activity associated with the presence of skin rashes, ulcers of the mucous membranes, alopecia, and proteinuria. The SLEDAI scale takes into account only relapse or primary occurrence of such signs as skin rash, alopecia, ulcers of the mucous membranes, and proteinuria, while the SLEDAI-2K scale takes into account any variant of these signs (newly emerged, relapse, persistent activity).
Differential diagnosis of lupus erythematosus
In most children (>80%), a polysyndromic clinical picture with signs of damage to various organs and systems usually develops within a few weeks (less often months) from the onset of the first symptoms. If a patient has a lupus "butterfly", the diagnosis is usually established early from the onset of the disease. Difficulties in diagnosing systemic lupus erythematosus arise in the absence of characteristic erythematous rashes in the child. Differential diagnostics in such cases must be carried out with diseases that have a polysyndromic clinical picture:
- rheumatic systemic forms of juvenile rheumatoid arthritis, juvenile dermatomyositis, acute rheumatic fever, Henoch-Schonlein disease, primary antiphospholipid syndrome, polyarteritis nodosa, microscopic polyarteritis, etc.;
- hematological diseases: hemolytic anemia, ITP;
- lymphoproliferative diseases: lymphogranulomatosis, lymphoma;
- infectious diseases: borreliosis (Lyme disease), hepatitis B and C with extrahepatic manifestations, tuberculosis, syphilis, yersiniosis, HIV infection, etc.;
- inflammatory bowel diseases: nonspecific ulcerative colitis with systemic manifestations, Crohn's disease;
- kidney diseases: glomerulonephritis, etc.;
- infective endocarditis;
- drug-induced lupus and paraneoplastic lupus-like syndrome.