What kind of inductions is seen in a person with no known risk factor of tuberculosis?

PGIMER NO - 2020

Medical & Surgical Nursing

Easy

Appeared in: PGIMER NO - 2020

Explanation

The question asks for the positive cutoff for a Tuberculin Skin Test (TST or Mantoux test) in a person with no known risk factors for tuberculosis.
For individuals in this low-risk category, an induration (not 'induction') of 15 millimeters or more is considered a positive result.
This higher threshold is used to increase the specificity of the test and reduce the number of false-positive results in populations where TB prevalence is low.

Option A: An induration of 5 mm or more is considered positive only for the highest-risk groups, not for individuals with no risk factors.
Option C: An induration of 10 mm or more is the cutoff for individuals with moderate risk, not for those with no known risk factors.
Option D: This option is incorrect because a specific cutoff value does exist for this scenario.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of Tuberculin Skin Test (Mantoux Test) results based on risk stratification as background academic context rather than a clinical decision trigger.
Accurate interpretation of the TST is a fundamental nursing skill for screening and identifying individuals who may have latent TB infection (LTBI) or active TB disease.
A nurse must perform a thorough risk assessment before reading a TST result, as the interpretation is entirely dependent on the patient's individual risk factors.
A positive TST result does not distinguish between active TB disease and latent infection. It indicates that further evaluation, such as a chest X-ray and sputum analysis, is required to determine the patient's status and need for treatment.

How to Approach the Question

First, identify the core subject of the question, which is the interpretation of a tuberculosis screening test.
Recognize the term 'inductions' as a likely typo for 'induration', the key measurement in the Mantoux test.
Isolate the most critical information in the stem: 'a person with no known risk factor'. This is the determining factor for interpretation.
Recall the three-tiered system for TST interpretation based on risk (5 mm, 10 mm, 15 mm).
Match the patient's characteristic ('no known risk factor') to the correct induration size cutoff, which is the highest threshold (15 mm) for the lowest risk group.
Select the option that corresponds to this value.

Concept Tested & Keywords

Concept Tested: Interpretation of Tuberculin Skin Test (Mantoux Test) results based on risk stratification.
Stem keywords: tuberculosis, no known risk factor, inductions, induration
Lead-in keywords: What kind
Clinical cues: The phrase 'no known risk factor' is the most critical piece of information, as it places the individual in the low-risk category for TST interpretation.

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 25-27

E6 Medicine Harrison 22e Part 1 p. 1442-1444