Correct fever measurement

Synonyms in a broader sense

Cold, flu, cough, runny nose
med .: Hyperthermia
English: fever


Fever is a symptom of various diseases, and it is used to Increase in normal core body temperature of the body over 38 ° Celsius comes. It can occur with harmless illnesses, mostly cold infections, but also with dangerous illnesses. It should be noted, however, that the body temperature fluctuates during the day and is not always the same. Therefore, if the temperature is slightly elevated, it makes sense to measure the fever several times a day.

Measuring a fever is easy. Most of the time the excited patients already provide one pale, weakened and suffer Sight. The touch of the patient can be at high fever Have the diagnosis made without having the actual fever measured. If you want to make a quantitative fever diagnosis, you need a fever to measure it Clinical thermometer. On the basis of the read temperatures, one can now divide into subfebrile or febrile make. The cause has not yet been clarified. In most cases it will fever not be treated further, because the most common cause of fever are seasonal infections.

Depending on the level of the temperature, an antipyretic therapy will be initiated (see Lower fever).

Different models of clinical thermometers

The Clinical thermometer is essential for the precise determination of body temperature and is available in different models. Models with mercury have been since 2009 forbidden and should therefore no longer be used. thermometer of glass are for use not useful for children and babiesbecause they break easily.

When measuring with manual thermometers (Expansion thermometers) is the included Fluid expanded by body temperature. The column of liquid in the thermometer therefore rises and the temperature can then be read off on a scale. When taking measurements with these thermometers, the temperature must be measured at least 2 minutes to find out the current body temperature. The advantage of this type of thermometer is that it does not require batteries.

They are easier to use digital clinical thermometer. They measure the temperature quickly within 30 to 60 seconds and usually indicate the finished measurement with a beep. The measured temperature is then displayed on a digital display.

Furthermore there is also Infrared thermometerthat for the Measurement over the ear or forehead be used. They measure the infrared radiation emitted by the eardrum or forehead. For measurement at Babies over the mouth are too Pacifier thermometer available.

All clinical thermometers can be cleaned with warm soapy water.

Measure the temperature without a thermometer

Already the General condition of the patient can give an indication of whether there is a fever: it shows up paler, weaker, more ill-looking General condition. If you have a high fever, touching it may be enough to determine the fever. The Place the back of the hand on the forehead or in the neck can therefore be a reliable way of assessing whether or not there is a fever. However, an exact body temperature cannot be determined without a thermometer.

Different measurement methods

There are various methods of measuring fever, but their accuracy varies greatly. The target values ​​for normal body temperature are in a different range depending on the measurement method:

  • Under the armpit: 34.7 ° - 37.7 ° C

  • In the buttocks (rectal): 36.6 ° - 38.0 ° C

  • By mouth: 35.5 ° - 37.5 ° C

  • Forehead: 35.4 ° - 37.4 ° C

  • Ear: 35.6 ° - 37.8 ° C

After the rectal measurement, the fever measurement in the ear is the most accurate method.

Rectal fever measurement

This method uses the clinical thermometer Inserted about an inch deep into the anus and the body temperature measured through the anus. So that the thermometer can be inserted more easily, the tip can, for example, with vaseline be greased. It is the most accurate method and shows the actual core body temperature. This method should be preferred for children who are younger than 6 years. All other methods for measuring fever are too imprecise and difficult to carry out at this age.

Fever measurement in the ear

For this method of measuring a fever there is special ear thermometers (Infrared thermometers) that are inserted into the ear canal. However, for an accurate temperature measurement it is important to insert the thermometer very precisely into the ear. Therefore, it should be noted that with this measurement method the real body temperature is 0.3 ° above or below the measured value can. According to the rectal measurement method, measurement via the ear is the most precise method for determining body temperature.

Fever measurement in the mouth (orally)

This method is also very precise and can be used as an alternative to the rectal method in order to obtain an exact value. The clinical thermometer is used under the tongue placed. Approx 0.5 ° Celsius added become.

Fever measurement under the arms / in the armpit

The clinical thermometer will under the armpit placed and the upper arm placed on the body. This method is not very reliable and should therefore not be used. The measured temperature is one or even two degrees less than the actual body temperature. It should also be noted that false low fever values ​​are measured if fever-lowering medication has been taken beforehand. Then it may be that the temperature in the periphery, i.e. under the armpit, has already dropped, but is still high in the body or has even risen.

Fever measurement using a forehead thermometer

Forehead thermometers are brand new for measuring fever. Thereby the special thermometer placed on the forehead. However, there are also thermometers with a contact-free mode, in which the temperature can be measured from a distance of approx. 5 cm without having to hang up. The forehead thermometer then measures the radiated body heat, similar to the ear thermometer. Here too is that correct positioning of the thermometer is important to get a correct result. Therefore, the instructions for the respective thermometer should always be read beforehand. Nevertheless, this method can only measure the surface temperature and not the body core temperature.

Fever measurement in babies and toddlers

As described above, it should be used in babies and children up to 6 years the measurement method over the Po, i.e. rectally, are preferred. In order to be able to insert the thermometer easily, the baby should be placed on its back and both legs should be slightly bent. The two feet should then be held with one hand while the other hand can be used to insert the thermometer. The normal body temperature should between 36.8 ° and 37.5 ° Celsius lie. If the baby is very restless and a measurement using the method described above is not possible, the child can also be placed on its stomach on the lap. Then the baby can be held with one hand and the clinical thermometer carefully inserted into the bottom with the other.

Causes and Diagnosis

In the case of a trivial infection, the fever should go away within 4 days. In addition, the fever should stop or even increase, should definitely be one Consulted a doctor to find out the cause of the fever. After previous operations, the doctor should suppress the immune system Medication, Traveling abroad, dealing with sick animals and contact with patients with infectious diseases. If this is answered in the affirmative by the patient, appropriate therapy must be initiated immediately. When measuring a fever, of course, the generally valid physical examination of the patient with listening to the heart and the lung (Auscultation) etc. take place.

Also infection parameters like Leukocytes and CRPthat are increased with infection should be examined. If there is evidence of an increase in leukocytes, it is usually a bacterial inflammation; if there is evidence of a drop in leukocytes, it is usually a viral infection. For a more detailed diagnosis of the fever, a urine test or an examination of the sputum of the sick patient can be carried out. A so-called Blood culture can be created, which after a few days can provide information about the relevant pathogen. In most cases, however, the pathogen identification with this method is negative. A blood culture should be performed on 2 consecutive days (at least 2-3 samples a day) carry out. The examination of the so-called "big drop" can rule out malaria. However, it is important that the patient information is compatible with a malaria infection beforehand.

In the further course a Ultrasonic Provide information on whether organs are involved in the development of the fever through inflammation. Gynecological and urological examinations as well as X-ray examinations would represent the full picture of the diagnostic measures.

For some diseases it can be useful to have one Fever curve to create. For this purpose, the fever is measured at different times during the day and the values ​​are entered in a diagram. This results in a temperature curve that is best drawn up for several days. Some diseases, such as malaria, show one characteristic course of fever, The temperature curve can therefore be helpful in looking for the cause.

Should the high temperature should persist over a longer period of time, the Thyroid levels be tested in the blood because a Hyperthyroidism can lead to an increase in body temperature.

Further diagnostics when taking a fever should definitely be initiated if the fever is associated with Convulsions and Seizures occurs. The so-called febrile seizure occurs almost exclusively in young children and is an absolute one pediatric emergency that should be examined immediately in the hospital. Often it also happens with smaller children who are watching theirs first teeth get a rise in temperature and a fever, which need not cause further concern.

Also read: Causes of fever

Development of the fever

The fever is generated by certain centers in the brain (hypothalamus) that are responsible for the body's heat regulation. The setpoint of normal body temperature (between 36 ° and 38 ° Celsius) is increased. First, there is chills, where the body creates heat from the tremors in the muscles, which increases the body's temperature. Later, the familiar feeling of warmth and sweating occurs.

One speaks of fever as soon as the core body temperature is above 38.0 ° Celsius. This can be measured in different ways (e.g. with a thermometer under the armpit, in the mouth or in the ear), but the most accurate value is obtained by measuring in the buttocks (rectal measurement method). If the measured temperature with the selected method appears unusually low or incorrect, a rectal measurement should always be carried out in parallel. A value above 39.5 ° Celsius is called a high fever and it makes sense to ask a doctor for advice. A body temperature of 41 ° Celsius or more is life-threatening and should therefore be treated with antipyretic therapy.

Read more about the development and duration of fever on the following page: How long does a fever last?