Which of the following lab test is assist in confirming the diagnosis of rheumatic fever in children?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2023

Child Health Nursing (Pediatrics)

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2023

Explanation

Rheumatic fever is an autoimmune inflammatory reaction that occurs as a delayed complication of a Group A Streptococcus (GAS) infection.
According to the revised Jones criteria, a definitive diagnosis of rheumatic fever requires supporting evidence of a recent GAS infection.
The Anti-streptolysin O (ASO) titer is a blood test that measures antibodies produced by the body in response to streptolysin O, a toxin released by GAS.
An elevated or rising ASO titer provides the necessary serological proof of a recent streptococcal infection, thus helping to confirm the diagnosis.

Option A: A WBC count can be elevated in rheumatic fever due to systemic inflammation, but this finding is non-specific. Many other infectious and inflammatory conditions can also cause an elevated WBC count.
Option B: The RBC count is not a primary diagnostic marker for rheumatic fever. While chronic inflammation can sometimes lead to anemia (a low RBC count), this is not a specific or required finding for diagnosis.
Option C: Measuring total immunoglobulin levels is too general and not helpful for diagnosis. The immune response in rheumatic fever involves the production of specific antibodies against streptococcal antigens.

Clinical Relevance

Nursing practice connection: Use the key finding related to Laboratory diagnosis of acute rheumatic fever to guide bedside assessment, documentation, and the next nursing action.
Early and accurate diagnosis of rheumatic fever is critical for initiating prompt antibiotic therapy (usually penicillin) to eradicate GAS and for starting anti-inflammatory treatment to manage symptoms.
The primary goal of treatment and secondary prophylaxis is to prevent the most severe long-term complication: rheumatic heart disease (RHD), which can cause permanent damage to heart valves.
Nurses play a key role in administering medications, monitoring for signs of carditis (e.g., new murmurs, tachycardia), managing joint pain, and educating the family on the importance of long-term antibiotic prophylaxis to prevent recurrence.

How to Approach the Question

Identify the key disease in the question: 'rheumatic fever'.
Recall the underlying cause of rheumatic fever: it is a post-infectious syndrome triggered by a Group A Streptococcus (GAS) infection.
Understand that a fundamental part of the diagnosis is proving that this preceding infection occurred.
Evaluate the options to see which test specifically looks for evidence of a past streptococcal infection.
Analyze the choices: WBC count indicates general inflammation, RBC count is irrelevant, and 'Immunoglobulin' is too broad. The ASO titer specifically measures antibodies against a streptococcal toxin.
Conclude that the ASO titer is the most specific and essential test among the options for confirming the necessary antecedent infection for a rheumatic fever diagnosis.

Concept Tested & Keywords

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E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 460-462

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1717-1719