Generality
Laboratory tests are generally characterized by a moderate anemia, a leukopenia (decrease in white blood cells) and thrombocytopenia (decreased platelets). All this due to the presence of reactive antibodies against these three blood cell lines. The other antibodies that can be found in the circulation, and that are typical of the disease, are:
- Anti-nucleus antibodies or ANA : they are turned against the cell nucleus; their presence, although very indicative of Systemic Lupus Erythematosus, is however not absolutely specific as this finding may also be present in other diseases (rheumatoid arthritis, scleroderma, Sjögren's syndrome, chronic hepatitis, leukemia, lymphoma, other neoplasms, diseases pulmonary such as chronic bronchitis or tuberculosis, Hashimoto's thyroiditis, pernicious anemia, ulcerative colitis, chronic glomerulonephritis, lepromatous leprosy, myasthenia gravis, recurrent thrombophlebitis, infectious mononucleosis, use of some drugs, aging).
- Anti-DNA antibodies : turned against cell DNA;
- A antistone antibodies : histones are integral component proteins of the cell nucleus. In the LES these autoantibodies are accompanied by anti-DNA, instead, in drug lupus, they can appear in isolation.
- Anti-Sm antibodies (an acid protein): characteristic of Systemic Lupus Erythematosus ;
- Anti-RNP (nuclear ribonucleoprotein) antibodies : present in low quantity in the LES;
- Anti-SSA and anti-SSB antibodies : present in 50% of patients with Sjögren's syndrome (another autoimmune disease). Sometimes they can be found in SLE, especially if associated with this syndrome.
Diagnosis
The diagnosis is usually based on the presence of a set of symptoms and characteristic signs accompanied by the presence of auto-antibodies in the blood. Sometimes, however, it can be difficult because the LES is a very polymorphous disease, that is, which gives extremely varied and numerous clinical pictures. For this reason, the American Association of Rheumatologists (ARA) has proposed a set of criteria; the diagnosis of Systemic Lupus Erythematosus would be safe in the presence of four or more criteria, even if not simultaneously:
1. Butterfly rash (also called malar), ie erythema on the face;
2. Discoid lupus, that is, with lesions localized only to the skin;
3. Photosensitivity;
4. Oral ulcers (observed by a doctor);
5. Arthritis of 2 or more peripheral joints;
6. Pleurisy or pericarditis;
7. Renal involvement;
8. Neurological involvement (convulsions or psychosis);
9. Haematological involvement (anemia, leukopenia, thrombocytopenia);
10. Immunological disorders;
11. Positive antinuclear antibodies (in the absence of the use of drugs that can positivize this phenomenon).
