Fever is defined as temperature greater than?

Appeared in: AIIMS Bhuvneshwar NO- 2018

Explanation

Fever (pyrexia) is clinically defined as a core body temperature at or above 38°C (100.4°F).
This elevation is a regulated response where the hypothalamic set-point is increased, often due to pyrogens like bacteria and viruses.
The image provided shows a thermometer reading of 38.8°C, which is a clear example of a febrile temperature.
Unlike hyperthermia, where heat regulation fails, fever is a controlled increase in the body's core temperature as a defense mechanism.

Option A: A temperature of 36°C is within the low-normal range for an adult and is not considered a fever.
Option C: A temperature of 37°C (98.6°F) is widely accepted as the average normal body temperature, not the threshold for fever.
Option D: A temperature of 35°C (95°F) or below defines hypothermia, a condition of dangerously low body temperature, which is the opposite of fever.

Visual 1: Chart - A visual chart illustrating the different ranges of body temperature from hypothermia to hyperpyrexia, with clear labels for normal, fever, and emergency levels. This helps in quick recall of the specific temperature thresholds.
Visual 2: Diagram - An infographic showing the mechanism of fever, illustrating how pyrogens cause the hypothalamus to raise the body's temperature set-point, leading to physiological responses like shivering and vasoconstriction.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition of fever and classification of body temperature ranges as background academic context rather than a clinical decision trigger.
Accurate identification of fever is a fundamental nursing skill crucial for early detection of infections and inflammatory conditions.
It is important to differentiate fever (a regulated rise in set-point) from hyperthermia (uncontrolled overheating), as hyperthermia does not respond to antipyretic medications and requires immediate physical cooling.
What if? If an elderly patient presents with confusion and lethargy but has a temperature of only 37.6°C, a nurse should still suspect an infection. Elderly individuals often have a lower baseline temperature and can have a serious infection without a high fever (a blunted febrile response).

How to Approach the Question

This is a factual recall question that tests your knowledge of a standard clinical definition.
First, identify the key term in the question, which is 'Fever'.
Recall the specific numerical threshold that defines fever in Celsius.
Compare this recalled value to the options provided.
Eliminate options that represent normal temperature (36°C, 37°C) and hypothermia (35°C) to confirm the correct answer.

Concept Tested & Keywords

Concept Tested: Definition of fever and classification of body temperature ranges.
Stem keywords: Fever, temperature, defined as
Lead-in keywords: greater than
Negative lead-in flag: false

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