CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
coronary attack. CRP appears to assist in the binding of complement to damaged
cells, foreign organisms, and cells that have invaded the body. This binding
enhances phagocytosis or eating by macrophages of opsonin-mediated organisms
or cells (those coated with antibodies). The term phagocyte literally means “big
eater” and refers to a type of protective cell that develops from a white cell called
a monocyte. Phagocytes express a receptor on their cell surfaces for CRP. CRP is
also believed to play an important role in innate immunity, as an early defense system
against infections. When inflammatory processes are present, CRP levels in a
patient may rise to 50,000 times the normal concentration. CRP rises above normal
limits usually within 6 hours and peaks at 48 hours following a heart attack or a traumatic
injury or infection.
Several procedures for testing for CRP are available from various manufacturers.
Testing for CRP is often used in conjunction with other procedures to narrow
the possibilities of certain ailments during a diagnosis. Although the procedure was
developed in the 1930s, it was seldom used for several decades due to its lack of
specificity. However, it has enjoyed increased stature in recent years, as the presence
of CRP in the serum or plasma often indicates inflammation of the arteries
(arteritis), which may indicate an impending heart attack.
Performing a CRP procedure requires care, including the following precautions:
• All reagents and specimens should be at room temperature before use.
• Avoid contaminating reagents with each other or with test specimens.
• The latex reagent should be gently mixed but not vigorously shaken before use.
Dispense contents of the dropper and refill as needed for multiple tests.
• Both positive control and negative controls should be run concurrently with each
specimen or batch of specimens. Do not dilute the controls before testing.
• Small amounts of detergent or residue from previous specimens may adversely
affect the results, so use only a thoroughly cleaned glass slide. Use only deionized
or distilled water to clean the slide and avoid the use of detergents.
• The results must be read at 2 minutes as erroneously false positive results may
occur when the time limit is exceeded.
Equipment and Supplies
1. Gloves, disposable paper towels, and disinfectant or other cleaning solution
2. Report form provided by your instructor
3. Kit for measuring CRP, containing latex reagent, positive and negative controls,
and a specialized glass slide that makes it easier to see the results (These slides
often provide a black background for reading a fine white precipitate.)
4. Test tubes with rack appropriate for the test tube size (size of the test tubes is not
important)
5. Deionized water or normal saline for diluting samples to obtain a semi- quantitative
result, if required by the test methodology
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