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RHEUMATIC FEVER[ LABORATORY MANIFESTATIONS
]SITI MARIAM BINTI MOHD HAMZAH
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Minor criteria:Clinical & Laboratory features ELEVATED ACUTE PHASE REACTANTS:
ERYTHROCYTE SEDIMENTATION RATE
C-REACTIVE PROTEIN PROLONGED P-R INTERVAL
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ESSENTIAL CRITERIA this refers to supporting evidence of antecedent streptococcal
infection, NOT for diagnosing ARF
• Positive throat culture for streptococci
• Streptococcal serum antibody tests
• Presence of residua of scarlet fever
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ACUTE PHASE IN RHEUMATIC FEVER Acute phase develop in a small proportion of individuals several
weeks after a streptococcal infection of the throat. ACUTE PHASE RESPONSE is a major pathophysiological
phenomenon which accompanies inflammation resulting from tissue damage. (etiopathogenesis)
ACUTE PHASE REACTANTS get altered both in acute and chronic inflammation.
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Streptococcal proteins display molecular mimicry recognized by the immune system; bacterial M-proteins & human cardiac antigens
T-cells that are responsive to streptococcal M-protein infiltrate the valve through valvular endothelium, activated by the binding antistreptococcal carbohydrates with release of TNF and IL
INFL
AMM
ATIO N
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1.LABORATORY
FEATURES
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ELEVATED ERYTHROCYTE SEDIMENTATION RATE (ESR)
• Normal value• 10 mm/hour in men• 20 mm/hour in women
• In rheumatic fever,• At least 60 mm/hour in low-
risk populations• At least 30 mm/hour in high-
risk populations
• Rise in ESR suggests inflammatory processes. In many cases, the level of
ESR may reflect the severity of the
inflammatory process.
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ELEVATED C-REACTIVE PROTEIN (CRP)
• CRP is a beta-globulin present in serum, capable of reacting with the outer coat of pneumococci.
• Normally it is absent from human plasma. When inflammatory processes occur, the liver produces an identical protein which can be detected by a slide test using readymade reagents.
• CRP level in rheumatic fever, is at least 3.0 mg/dl
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PROLONGED P-R INTERVAL• P-R interval is a measure of the atrioventricular
(AV) conduction. Prolonged PR interval indicates AV block.
• Normal PR interval is 0.12 to 0.20 sec, slightly shorter in children with upper limit being 0.18 sec.
• In case of rheumatic fever, it is due to the inflammation of the myocardium that caused delay in the AV conduction, thus prolonged PR interval.
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2.ESSENTIAL CRITERIA
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POSITIVE THROAT CULTURE FOR STREPTOCOCCI
The gold standard for detecting Streptococcus pyogenes remains a throat swab cultured on blood agar.
If possible, throat swabs should be examined for all patients with clinically suspected streptococcal upper respiratory tract infection.
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STREPTOCOCCAL SERUM ANTIBODY TESTSThe most commonly performed and commercially
available tests are the antistreptolysin-O test, and the antideoxyribonuclease-B test.
At least one anti-streptococcal antibody titre should be elevated for a diagnosis of acute RF.
Although a single elevated antibody titre may be useful for documenting a previous streptococcal infection, it is recommended that an additional test be performed 3–4 weeks after the onset of RF. Rising titer of antibody is a stronger evidence for a recent streptococcal infection.
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http://www.who.int/cardiovascular_diseases/resources/en/cvd_trs923.pdf
A serum antibody is judged to be elevated if the titre exceeds the upper limit of the normal titre range
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PRESENCE OF RESIDUA OF SCARLET FEVER
The desquamation of skin of palms and soles indicates that the patient has had scarlet fever within the previous 2 weeks. Scarlet fever is rare in India.
an infectious bacterial disease affecting especially children, and causing fever
and a scarlet rash. It is caused by streptococci.
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