C-Reactive Protein

Tiki_Torch · Oct 8, 2003

hi mofe'ny,

i've been away from nursing for 3 years (my old hospital didn't test crp routinely) and am now in a nicu in a new state. i've seen crps ordered on some babies but i'm so new here that i can't tell you how long after birth the tests are ordered, if they do serial tests, and the parameters for choosing the babies they want to test. hopefully i'll learn this soon. your post has prompted me to ask this question when i go to work tomorrow and i'll let you know what i find out.

in the meantime, i looked in my books here at home and some searching on the internet and here is some of what i've found:

in my a manual of laboratory diagnostic tests by francis fischbach i see: "during the course of an inflammatory process--whether due to infection or tissue destruction--an abnormal specific protein, crp, appears in the blood. this protein is virtually absent from the serum of healthy persons. crp appears rapidly in the blood in response to many injurious stimuli. almost any disease that brings about an inflammatory condition of any tissue will result in quantities of crp being present in the blood and body fluids (e.g., peritoneal fluid and synovial fluid). crp is thought to be synthesized mainly in the liver and is found in large amounts in inflammatory body fluids such as peritoneal, pleural, pericardial and synovial. it is considered to be a transport protein for certain polysaccharides. from recent studies, it appears that a major function of crp in health and disease involves its ability to interact with the complement system. the crp is an antigen-antibody reaction test that is a nonspecific method for evaluating the severity and course of inflammatory diseases and those conditions in which there is tissue necrosis, such as myocardial infarction, malignancies, and rheumatoid arthritis. the presence of c-reactive protein in the blood serum can be detected 18 to 24 hours after the onset of tissue damage. this is a useful test in following the progress of rheumatic fever under treatment and in the interpretation of the sedimentation rate. it is also valuable in monitoring the surgical wound healing process, especially in internal incisions, burn patients, and kidney transplant care. normal values: trace amounts"

in my workbook in practical neonatology by polin, yoder and burg, i find: "the acute phase reactant crp is perhaps the most widely studied adjunctive test. although some studies indicate that serial testing of crp may help support the diagnosis of infection, as well as assist in assessing the effectiveness of therapy, other studies suggest that crp levels are most useful in combination with other tests as part of a 'sepsis screen'. the concept of sepsis screens came about in an effort to improve the predictive accuracy of diagnosing neonatal sepsis before culture results are obtained. multiple parameters have been combined in this manner (most commonly a combination of neutrophil indices and acute phase reactants). unfortunately, the positive predictive value of most sepsis screens is less than 30%. the major value of sepsis screens appears to be in the identification of infants who have a low probability of infection (i.e., a high negative predictive value) and therefore may not require antibiotics or in whom antibiotics can be discontinued. nontheless, a few centers are currently routinely using such an approach."

in fetal and neonatal secrets by polin and spitzer, i found: "what is the relevance of c-reactive protein (crp) in the diagnosis of neonatal sepsis? serum crp is an acute phase reactant, which becomes elevated in the face of inflammation or infection, with a response time of 6-8 hours. the normal value in the neonate is 5.0 mg/dl) has a positive predictive value for sepsis of 10%. can a normal white blood cell (wbc) count, immature-to-total (i:t) neutrophil ratio, neutrophil count, or crp be used to rule out sepsis on admission? unfortunately not. neither these nor any other tests can be used to reliably rule out infection in the neonate. the usefulness of the tests improves markedly with serial measurements, because there have been many cases of sepsis described in which the wbc or crp became abnormal 12-24 hours after the onset of the disease. furthermore, these tests can be combined in a sepsis screen in which several parameters are used to improve the diagnostic accuracy. what parameters are useful in creating a sepsis screen strategy? a combination of diagnostic tests improves the predictive values over the use of a single test. in this strategy, negative serial sepsis screens substantially reduce the likelihood that the infant has sepsis."and following this answer is a nice table of a sepsis screen that can be used.

on the internet, related specifically to pregnancy i found:

"positive crp results also occur during the last half of pregnancy or with the use of oral contraceptives" http://www.nlm.nih.gov/medlineplus/ency/article/003356.htm

"normal levels for healthy individuals is http://www.haps.nsw.gov.au/edrsrch/edinfo/crp.html

"c-reactive protein levels are also affected by interleukin-6, steroids, estrogen, insulin resistance, and changes in fat mass. 'so the c-reactive protein change in pregnancy isn't just pathological; it may be physiological and related to hormones and metabolism.' naveed sattar, mbchb, mrcpath, phd" http://www.ctccomm.com/publishing/obgyn/obgynss1002thelink.htm

i learned a lot in researching this! i'm assuming that mom's crp can cross the placenta and be dectected in the baby's blood. it must be that she has elevated levels from normal increases in estrogen and fat as part of a normal pregnancy; that she can have extra crp from receiving steroids injected for stimulating fetal lung maturity, and the potential for inflammation and tissue injury during labor related activity... maybe these are some reasons why the crp level in the baby's blood right after delivery is not reliable. i know there are several lab tests that are of little value right after delivery because they actually reflect more of mom's lab values than the baby's... the crp seems to be one of those types fo tests...

thank you for posting your question because it stimulated me to learn more about it and when i ask about crp testing at work tomorrow i'll be able to speak intelligently about it too!

i hope someone else will have more to say about this subject too! by the way, i just adore the books by dr. polin!!!!!

:)

Tiki_Torch · Oct 8, 2003

I also meant to say I also went to the Las Vegas Neonatal Network's 3rd National Neonatal Nurses Convention and had an absolutely wonderful time!!!! I was able to attend 3 lectures given by Dr. Polin and he even autographed my 2 books he co-authored... and he autographed them on my birthday to boot!!! I took my books with me hoping he'd sign them and he turned out to be an incredibly warm and approachable man. I sure am glad I attended the convention and hope to never miss another one!!!

dawngloves, BSN, RN · Oct 8, 2003

We do CRPs on admit and 24 hours, sometimes 12 if the first is high. But the trauma of some births cause an elevated CRP I imagine.

When I did adults residents would get bent outta shape if a LOL that fell had a high CPK. DUH! She FELL! She damaged muscle!

NICUNURSE · Oct 8, 2003

I can't lead you to a specific article, but I know our attending said that an article he read stated that a CRP is actually more indicative of the previous 12-24 hours. So like Tiki said, a high CRP would mean that approx 12-24 hrs prior, the infectious process began. So I would think that a high CRP in a baby less than 25 hours would be inconclusive because you wouldn't be able to rule out some maternal factor causing the elevation. That being said, we still routiney check a CRP on all admits, many of whom are less than 12 hours old.