Why Do Doctors Take Your Temperature?
The body temperature of a human being is an indication of his physical condition, so that an abnormally high or low temperature is generally a sign that something is wrong. The normal temperature is usually given as 36.9°C. (98.4°F.), but as the body temperature varies throughout the day, anything between approximately 36.7°C. (or 98.1 °F.) and 37.2°C. (or 99.0°F.) may be taken as normal.
For instance, the temperature rises after a large meal, during hot weather and after violent exercise. Your temperature is at its lowest at night when you are asleep. Control of body temperature is exercised by a center in the brain which ensures that a balance exists between heat production and heat loss. This thermostat is found in a part of the brain called the hypothalamus. The hypothalamus knows what temperature your body should be (usually around 98.6°F/37°C) and will send messages to your body to keep it that way. Fever happens when the body’s internal “thermostat” raises the body temperature above its normal level.
Sometimes, though, the hypothalamus will “reset” the body to a higher temperature in response to an infection, illness, or some other cause. Why? Researchers believe turning up the heat is the body’s way of fighting the germs that cause infections and making the body a less comfortable place for them.
A raised temperature is often the sign of bacterial or virus infection. It may be due to heatstroke, to certain types of brain injury or disease or to shock. A very high temperature, or fever, may begin with a “rigor” (an attack of shivering and cold), in which the whole body may tremble uncontrollably and the teeth chatter. Although at this stage the skin feels cold and clammy, the temperature within the body is raised.
Soon the skin becomes hot and dry, pulse and breathing rate are speeded up and there is a feeling of exhaustion, aching muscles, headache, thirst and perhaps delirium and loss of the sense of time. Finally this stage is succeeded by profuse sweating and a gradual relief of the symptoms.
In the past, doctors advised treating a fever on the basis of temperature alone. But now they recommend considering both the temperature and a child’s overall condition.
Kids whose temperatures are lower than 102°F (38.9°C) often don’t need medicine unless they’re uncomfortable. There’s one important exception to this rule: If you have an infant 3 months or younger with a rectal temperature of 100.4°F (38°C) or higher, call your doctor or go to the emergency department immediately. Even a slight fever can be a sign of a potentially serious infection in very young infants.
If your child is between 3 months and 3 years old and has a fever of 102.2°F (39°C) or higher, call your doctor to see if he or she needs to see your child. For older kids, take behavior and activity level into account. Watching how your child behaves will give you a pretty good idea of whether a minor illness is the cause or if your child should be seen by a doctor.
The illness is probably not serious if your child:
- is still interested in playing
- is eating and drinking well
- is alert and smiling at you
- has a normal skin color
- looks well when his or her temperature comes down
And don’t worry too much about a child with a fever who doesn’t want to eat. This is very common with infections that cause fever. For kids who still drink and urinate (pee) normally, not eating as much as usual is OK.