of cancer patients with fever and neutropenia develop culture proven bacterial infections. Fever
can also be caused by viral infections or may be by other non-infectious causes. Because
of significant morbidity and mortality in this group, there is aggressive use of antibiotics.
Chemotherapy or transfusions do not affect CRP. Pronounced elevations of CRP do not occur
in malignancies without other concomitant stimuli for synthesis such as intercurrent infection.
If CRP concentration is less than 4 mg/dL for 48 hours after the onset of fever, infection is
unlikely, whereas levels above 10 mg/dL should be treated by antibodies even in absence of
bacteriological confirmation. If after treatement levels do not fall below then it must be assumed
that response has not occured and therapy must be maintained and changed
It is often difficult to diagnose abdominal infection in
pregnant women, since CRP is at normal levels in pregnant
women, increased CRP concentration indicates infection
Bacterial sepsis is one of the most common diagnostic
challenges in neonatal medicine. A definitive diagnosis
based on culture of blood, CSF or urine is usually reached
only after a delay of a day or two, yet rapid progression of
untreated infection may greatly increase morbidity and
mortality. Initiation of antibiotic therapy may result in
treatment of as many as 30 uninfected infants for every
single infant who is determined to have been infected.
Attempts to develop a screening test that can identify
infected infants, sparing others from invasive diagnostic
procedures, intravenous antibiotic therapy, mother infant
separation and heightened parental anxiety has led to the
observation that CRP levels during these intervals may be
useful for early identification of infants for whom antibiotic
therapy can be safely discontinued. In addition to better
management of disease or disorders, CRP has been known
to aid in the differential diagnosis of many illnesses.
The degree of elevation of CRP reflects the mass or
activity of the inflamed tissue, which may be secondary
to the underlying disease as in myocardial infarction and
malignancy, or a primary component as in rheumatoid
In many cases, the changes in palsma CRP levels
precede changes in clinical symptoms. In every situation
sequential measurements provide more information than
To summarize, quantitative CRP measurement would
¾ Screening or organic diseases
¾ Assessment of disease activity and monitoring of
¾ Recognition of intercurrent infections
¾ Prognosis of conditions such as myocardial infarction.
DETERMINATION OF C-REACTIVE PROTEIN
(Courtesy: Tulip Group of Companies)
C-reactive protein (CRP) is an acute phase protein
synthesized in the liver. Its rate of synthesis increases
within hours of acute injury or the inflammation and
may reach as high as 20 times the normal levels. A rapid
fall of CRP indicates recovery. The degree of elevation of
CRP level directly reflects the mass or activity of inflamed
tissue. And its ability to fall to normal levels on resolution
of the condition renders quantified CRP values to be a
are, clinically difficult to assess. Apart from indicating
inflammatory disorders, CRP levels help in differential
diagnosis, in the management of neonatal septicemia and
meningitis where standard microbiological investigations
are difficult. CRP levels rise invariably after major surgery,
but fall to normal within 7–10 days. Absence of this fall
is indicative of septic or inflammatory postoperative
complications. Serum CRP concentration provides useful
information in patients with myocardial infarction there
being an excellent correlation between peak levels of CRP
ULTRASENSITIVE DETERMINATION OF
(Courtesy: Tulip Group of Companies)
C-reactive protein (CRP), the classical acute phase protein
is an extremely valuable marker for underlying systemic
centile of distribution in such subjects is approximately
0.03 mg/dL. The baseline values for CRP in a healthy
individual remain stable over a long period of time. The
baseline serum concentration of CRP predicts the risk of
future myocardial infarction and stroke independent of
other risk factors, in apparently healthy subjects.
Increased values of CRP below 0.5 mg/dL previously
considered to be within the reference interval are strongly
associated with increased risk of atherothrombotic
events. Several prospective studies suggest that in
apparently healthy individuals, as the concentration
of CRP increases from greater than 0.055 to 0.211 mg/
dL, the probability for developing AMI increases
significantly from a factor of 1 to 2.9. Apparently, healthy
individuals in the highest quartile (the upper 25%) of
the above-mentioned range have 2 to 3 times higher
risk of developing subsequent atherosclerotic diseases
compared to those in the lowest quartile. Simultaneous
ultrasensitive measurements of CRP and total HDL
cholesterol predict future vascular risk better than lipid
Such low levels of CRP in apparently healthy adults can
be determined by ultrasensitive immunoassays such as
Role of CRP in Differential Diagnosis
Clinical condition Significantly Elevated CRP Normal CRP/mildly elevated CRP
Rheumatic diseases In established RA disease—levels relate to
severity. Values upto 5 mg/dL are associated
with mild inflammation and values around
10 mg/dL indicate more severe disease
Crohn’s disease Ulcerative colitis, normal CRP or mild elevation
Pediatric fever Children ill for more than 12 hours with CRP
> 4 mg/dL generally indicates bacterial infection
CRP level < 4 mg/dL may be bacterial or viral
Genital infections Chlamydial infections when extended into
the pelvic organs with acute or chronic pelvic
Uncomplicated gonococcal or chlamydial
Pulmonary infection Above 10 mg/dL provide a strong indication
of bacterial infection such as pneumonia or
Typically viral pneumonia does not result in
Causes related with chest pain Elevated in pulmonary embolism, pleurisy, or
Not elevated in angina without infarction or
DETERMINATION OF ANTISTREPTOLYSIN ‘O’
(Courtesy: Tulip Group of Companies)
The group A, β-hemolytic streptococci produce various
exotoxins such as streptolysin O, steptolysin S that can
act as antigens. The affected individuals produce specific
antibodies against streptolysin ‘O’ that has clinical
significance namely, Antistreptolysin ‘O’. Antistreptolysin
‘O’ can be detected 1–3 weeks after infection, attaining
a maximum level at around 3–6 weeks. Determination
of these antibodies is very useful for the diagnosis of
streptococcal infections and their relative effects such as
rheumatic fever and acute glomerulonephritis.
DETERMINATION OF MICROALBUMINURIA
(Courtesy: Tulip Group of Companies)
Urinary albumin excretion between 30 and 300 mg/
day (microalbuminuria), far below the levels found in
clinical proteinuria (> 300 mg/day) is a strong predictor
of development of diabetic nephropathy and vascular
complications. diabetic nephropathy leads to progressive
loss of renal function or end-stage renal disease (ESRD)
and may necessitate need for dialysis or transplantation
in most cases. The progression of microalbuminuria is
closely associated with progressive hypertension and loss
and timely intervention of drugs early in the course
of disease can arrest the progression of diabetic renal
disease. Quantitative values of albumin are useful for
differentiating microalbuminuria from clinical proteinuria
and the effective monitoring of intervention strategies.
Annual screening of microalbuminuria is recommended by the ‘WHO’ and ‘International Diabetes
Foundation’ in all patients with IDDM over the age of 12
years and who have had diabetes for five years or more.
Microalbuminuria is also a significant risk marker of
cardiovascular diseases. Its presence can be regarded as
an index of increased cardiovascular vulnerability and a
signal for correction of known risk factors.
Information regarding the concentration of albumin
in urine for the detection of microalbuminuria can be
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