Why does body temperature decrease as we age and how does this affect our health?

Contrary to what happens with children, fever should not be considered the main symptom in the elderly, according to geriatricians consulted by BBC News Brazil.

In this group, diseases such as prostration, difficulty with balance, mental confusion and frequent falls may be the first symptoms of the disease.

Paying attention to these and other signs, along with periodic temperature measurement, are ways to detect various problems early and start treatment if necessary.

But what is the reason for this temperature change?

Two articles published by Santa Casa de São Paulo in 2010 addressed this topic.

Analyzing hundreds of records, the researchers concluded that the average temperature was a a healthy young adult is 37°C, and this normal range varies between 36.3°C and 37.5°C.

in in the elderly, the average is 36.1ºCwith a variation of 0.21ºC up or down.

Studies also show that there is “Temperature drop of 0.15°C for every decade of life”.

But what is hidden behind this natural cooling of the body? The researchers explain that there are three main reasons for this.

The first refers to changes own aging: metabolism slows down, muscle mass is smaller, blood vessels narrow, the nervous system loses part of its ability to retain heat…

“We have a kind of thermostat in the hypothalamus, one of the regions of the brain. And it controls the temperature of our body,” explains geriatrician Marcelo Altona from Hospital Israelita Albert Einstein in São Paulo.

“During the aging process, this natural thermostat can change,” he adds.

Marco Túlio Cintra, vice president of the Brazilian Geriatrics and Gerontology Society, points out that the hypothalamus often continues to function properly during aging.

In these cases, the change in temperature involves a simple loss of heat to the environment.

– Elderly people have a harder time retaining heat in the body, due to the changes that occur in the skin and fat cells – explains the doctor.

Second, this group is most often affected diseases that affect temperature regulationsuch as diabetes, neurological disorders, malnutrition and sarcopenia (progressive loss of muscle mass).

In addition, the use of certain medications and immobility associated with movement problems also affect this process.

Third, very difficulty in measuring temperature in this age group it can lead to underestimated results (when the number on the thermometer is lower than the actual temperature).

This is because the parts of the body where the mercury thermometer is placed change over the years.

In the armpit, excess sweat, skin folds and fat can be a problem. The same thing happens in the ear if wax builds up in the ear canal.

In the mouth, the lack of some teeth, problems with the secretion of saliva or difficulty in keeping the thermometer stable are factors that complicate the situation.

In the anus, the last alternative on the list, the obstacle is the inconvenience of inserting the thermometer there.

One option is state-of-the-art digital devices, which measure on the forehead, but are more expensive and you have to be careful to change the battery when needed.

Difficulty in taking temperature correctly – or lack of knowledge about what is the normal range for temperature in an elderly person – can be health threat.

This is because an elderly person may have pneumonia or another serious illness and, because they do not have a high fever, do not need to undergo a medical examination.

this confusion delay the diagnosis of the disease which, if detected in time, would have a less invasive and more effective treatment, such as pneumonia and urinary tract infections.

“Unlike what happens in children, in the elderly, fever is not among the main symptoms of infection. They often have a normal temperature or even hypothermia,” warns Cintra.

“The caregiver and the elderly themselves must watch for other signs, such as prostration, changes in balance, mental confusion, frequent falls… In many cases of urinary tract infections in people over 60, the only sign is an increase in accidents and falls,” he says.

If the average temperature of an elderly person is 35.5ºC or 36ºC, and hers is 36.9ºC or 37ºC, this is already a sign that she needs to be monitored more closely, says Altona.

“In very weak or very old people, small changes in vital signs, such as temperature, blood pressure and heart rate, already require greater care,” says the specialist.

A guideline that might be useful to some is keep a continuous record from the temperature.

If the thermometer is used every 15 days or once a month, it is possible to know what the average healthy temperature is and notice when the body is warmer than normal.

That is: if a person always has 36ºC, and on a certain day appears with 37.2ºC, this can be a sign of alarm depending on the case, although it is not considered a fever in other age groups.

But Cintra believes that this monitoring must be very well managed and strictly follow the guidelines of health professionals and thermometer manufacturers.

“Constantly elevated temperature can be an unnecessary source of stress,” he says. “This habit is useful in some cases, but not for everyone.”

If recommended, these regular temperature measurements should always be carried out at same place on the body and preferably with the same device.

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