Body temperature measurement is a common practice for assessing health, particularly in identifying fever. Taking an axillary, or armpit, temperature is a widely used method, especially for infants and young children, due to its non-invasive nature and ease of access. This method involves placing a thermometer in the armpit and holding the arm close to the body to obtain a reading.
The Axillary Temperature Adjustment: Fact or Fiction?
The question of whether to add a degree to an axillary temperature reading is common, as armpit temperatures are generally lower than internal core body temperatures. Historically, some medical institutions advised adding 0.5 to 1 degree Fahrenheit (0.3 to 0.6 degrees Celsius) to an axillary reading. This practice was common because older thermometers were less precise, and the armpit provides a surface temperature rather than a true core temperature.
Modern digital thermometers provide accurate readings for the specific site without manual adjustment. Many current medical guidelines provide specific fever thresholds for axillary readings that do not require additional degrees. Axillary temperature measurement is often a convenient screening tool. If a fever is suspected, healthcare providers often recommend confirming the temperature with a more accurate method, such as rectal or oral measurement, depending on age and comfort.
Understanding Axillary Temperature Readings
Axillary temperature is considered a surface temperature, reflecting the skin and surrounding tissues rather than internal organs. This makes axillary readings naturally lower than core body temperatures, which are typically measured rectally. Factors such as external air temperature, clothing, and how tightly the arm is held against the body can influence an axillary reading.
Axillary readings are typically 0.5 to 1 degree Fahrenheit (0.3 to 0.6 degrees Celsius) lower than oral temperatures. When compared to rectal temperatures, considered the most accurate representation of core body temperature, axillary readings may be up to 2 degrees Fahrenheit (1.1 degrees Celsius) lower. This difference highlights why an unadjusted axillary temperature should be interpreted with awareness of its inherent variability and its nature as a screening tool.
Best Practices for Measuring Axillary Temperature
To obtain the most accurate axillary temperature reading, proper technique is important. Ensure the armpit is dry, as moisture can affect the reading. The tip of a digital thermometer should be placed directly into the center of the armpit, ensuring good contact with the skin and no clothing interference.
Once the thermometer is in place, the arm should be held down firmly against the body. This helps secure the thermometer and create a closed space for an accurate reading. The thermometer should remain in place until it beeps, signaling completion, or for about 4 to 5 minutes, depending on the device and age. While convenient for initial screening, especially in children, more precise temperature assessment may require other methods if a fever is suspected.