Introduction to Serology
Serology tests are used for the detection of antibodies in the blood in order to diagnose an active or previous infection, or to determine disease of the immune system such as autoimmune disorder. There are various types of serologic tests, each to diagnose a different disease; some include Anti-Streptolysin-O, Rheumatic factor, Syphilis and CRP.
Antibodies enable identification of past or present infection
Antibodies are formed by the body in response to infection against foreign proteins called antigens. Antigens enter the body via the mouth, nasal passages or through broken skin. Upon doing so the body’s immune system defends the body by producing antibodies, particles that attach to the antigens to deactivate them. Serology tests identify the type of antibodies and antigens present in the blood and determine the type of infection the patient may have or may have had in the past. Serology tests can also determine immunity to a certain organism.
Serology tests include:
Anti-Streptolysin O used to determine recent streptococcal infection caused by the streptococcus bacteria. Infections can be mild or severe, varying from throat infections, cellulitis, sinusitis, impetigo and middle ear infections to life-threatening infections of the blood or organs such as pneumonia, meningitis and sepsis. In addition this test also helps identify the presence of post streptococcal complications including rheumatic fever which causes inflammation of the joints or heart, and glomerulonephritis which refers to damage of the glomeruli (tiny filters in the kidneys). The latter are rare and are caused by the body’s immune system attacking healthy body tissue in response to streptococcus bacteria.
CRP used to detect inflammation, infection and tissue injury of the liver. CRP (C-reactive protein) is a protein produced by the liver in response to inflammation, infection and tissue injury; it is released into the blood within a few hours and therefore the CRP test enables quick detection of trauma or infection. It can be used together with consideration of signs and symptoms to diagnose the condition causing the infection or inflammation, in addition to being useful in monitoring the treatment of people with chronic inflammatory conditions.
Rheumatoid factor used to help diagnose rheumatoid arthritis and distinguish it from other forms of arthritis or conditions causing similar symptoms. Rheumatoid factors are antibodies produced by the body’s immune system that can attack healthy tissue in the body. Symptoms of rheumatoid arthritis include pain, stiffness in the joints (particularly in the morning), and, swelling, warmth and redness.
Syphilis (RPR and TPHA) used to screen for the Treponema pallidum bacteria which causes syphilis, a chronic, contagious and often congenital venereal disease. The 2 types of tests we use include Rapid Plasma Reagin (RPR) and T. pallidum particle agglutination assay (TPHA).
RPR is a non-treponemal antibody test which detects antibodies not specifically directed against the Treponema pallidum bacteria; these are produced by the body in response to several conditions including syphilis and are therefore non-specific. Such tests are highly sensitive, however, and the RPR test can also be used to monitor the treatment of syphilis.
TPHA test is a treponemal l antibody test used to detect antibodies specifically directed against the Treponema pallidum bacteria; these are highly-specific for the detection of syphilis.
Treponemal (syphilis specific) antibodies remain in the blood for life, whereas non-treponemal (non-syphilis specific) antibodies typically clear the blood after approx. 3 years following successful treatment; therefore following a positive treponemal test result, a non-treponemal antibody test may be used to determine between an active syphilis infection/reinfection, or a past infection which has been successfully treated.
Rapid tests include:
Randox Pregnancy test used for early confirmation of pregnancy by identifying Human Chorionic Gonadotrophin (hCG) in urine; hCG is a hormone released by the cells of a developing placenta shortly after conception. Levels of hCG are detectable in urine in the first week after conception, therefore making it an excellent marker for early confirmation of pregnancy.
Randox pregnancy test is highly sensitive, able to detect hCG concentrations as low as 25mlU/ml, and produces results in 3 minutes. In addition a variety of methods and kit sizes provide choice and enhances suitability.