Measurement of the C1 esterase inhibitor (the first component of the complement) is used to diagnose hereditary angioedema and to monitor levels of the inhibitor during treatment.
The most common form (85% of cases) of hereditary angioedema is due to an absolute decrease in the amount of C1 esterase inhibitor. A less common form (15% of cases) is due to the functional abnormality of the inhibitor where levels may be normal. Both abnormalities need to be tested because of the potentially life-threatening nature of the disease.
In addition to the decreased serum esterase C1 inhibitor in patients with hereditary angioedema, there is still a unique quinine polypeptide at elevated concentration during the edema crisis. Patients with episodes of hereditary angioedema also have a low total complement and C4 and C2 components of the complement. Hereditary angioedema is transmitted in an autosomal dominant manner. Heterozygotes also have reduced levels of the C1 esterase inhibitor. During acute attacks of the disease, complement components of C4 and C2 may be significantly reduced, but C1 and C3 components are normal. The factors that promote the onset of angioedema attacks are often unknown.
Angioedema can also occur as an acquired disease. The acquired form includes non-hereditary C1 esterase deficiency and may be caused by medications, allergies, idiopathic forms, angioedema associated with autoimmune disease especially with systemic lupus erythematosus and hypereosinophilia, angioedema occasionally associated with malignancy, and angioedema caused by natural stimuli.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.