Why body temperature is below 36, 35.5: what does it mean, what to do?

Humans are homeothermic, i.e. warm-blooded, and have a constant temperature, which can fluctuate between +36.5°C and +37°C during the day. But any temperature above or below this range is abnormal. And if the body temperature is below normal, it means that not all body systems are functioning properly.

Body temperature is an indicator of the amount of heat produced by the body during the process of basic metabolism. And the process of its regulation occurs at the reflex level - in the hypothalamus, which belongs to the sections of the diencephalon. The hypothalamus also controls the work of our entire endocrine and autonomic nervous system, and it is in it, in addition to the centers regulating body temperature, that the "control levers" for the feeling of hunger and thirst, the sleep-wake cycle, as well as many other important physiological and psychosomatic processes are located.

Fatally low body temperature

A potentially fatal condition in which a person's body temperature drops below +35°C is medically defined as hypothermia.

It can be moderate – with a body temperature of 32.2-35°C, and severe – with readings of 30.5-32.2°C. A fatal or critically low body temperature is less than 30°C, and this is a deep degree of hypothermia.

The effect of temperature drop on the body – when the body temperature is low 35, 34.5, 34°C – is manifested by impaired coordination of movements. Also, the first signs include pale skin (with cyanosis of the lips, ears, fingers and toes) and strong tremors, which occur due to heat loss: to replenish it, the brain triggers physiological reactions, and involuntary muscle contractions in the form of tremors help to obtain heat by accelerating metabolism.

If the cold stress is too great, between 32.2 and 30°C, shivering stops, and then symptoms such as disorientation, decreased vision, incoherence, muscle rigidity, numbness, decreased heart rate and breathing appear. However, a short-term acceleration of the heart rate (as ventricular tachycardia) is possible, but when the body temperature is fatally low at 28°C and below, ventricular fibrillation begins. The body quickly becomes dehydrated, the liver and kidneys stop functioning, and clinical death occurs.

Statistics show that it is possible to survive hypothermia, but mortality from severe and profound hypothermia remains high and is estimated at 38-75%.

All this is primary hypothermia, in which the body's thermoregulation mechanisms work normally (i.e. the person is healthy), but the body is subject to severe hypothermia. And then we will talk about secondary hypothermia, when the body temperature is below 35-36°C. It is most often called a thermoregulation disorder, which has many causes.

Causes of low body temperature

A body temperature below +36°C is possible in practically healthy people, for example, with chronic fatigue syndrome or a lack of vitamins, primarily ascorbic acid.

If you have a low body temperature in the morning, this is the result of its physiological decrease - from two o'clock in the morning until six o'clock in the morning (to about 36.3°C). With great physical exertion and overfatigue during the day, you may have a low body temperature in the evening. From a medical point of view, a low basal body temperature at night - while the muscles are relaxed and heat production is slow - is associated with the absence of thermoregulatory reactions (between two and four o'clock).

However, attention should be paid to possible metabolic problems: a decrease in temperature at night can be the result of elevated blood glucose levels in people with diabetes. In this case, the absorption of glucose in the body is insufficient for energy production, which slows down the metabolic rate and disrupts temperature homeostasis.

Low body temperature after an illness, especially an infectious and inflammatory one, is associated with a general weakening of the body. It can also be caused by the use of certain medications: antipyretics (antipyretic drugs); drugs that block alpha- and beta-adrenergic receptors (used in cardiovascular pathologies); psychotropic, sedative, local anesthetics.

In surgery, low body temperature after surgery (within 24 hours from the onset of general anesthesia and the start of surgery) is considered to be the result of: suppression of hypothalamic function by inhalation or intravenous anesthesia drugs; temporary disruption of blood flow, as well as increased heat loss, which simply cannot be compensated for by the patient's body during surgery.

In most cases, a low body temperature during pregnancy may indicate anemia, which is a result of iron deficiency and a lack of red blood cells that carry oxygen. Pregnant women are at increased risk of developing anemia, which is accompanied by a feeling of fatigue, dizziness, and headaches. Therefore, if the expectant mother has headaches and a low body temperature, the hemoglobin level in the blood should be checked.

Obstetricians claim that if a low body temperature in the early stages of pregnancy (during the first 6-8 weeks) lasts longer than 10-14 days, then this is a risk factor for its spontaneous termination (miscarriage).

In women in labor, low body temperature after childbirth may be a manifestation of postpartum sepsis, especially when vomiting begins and breathing becomes difficult. In addition, low temperature readings after childbirth with significant blood loss are characteristic of Sheehan's syndrome (other names for this pathology: ischemic necrosis of the pituitary gland, diencephalic-pituitary cachexia, postpartum hypopituitarism, Simmonds' disease).

As is known, the basal body temperature of women changes during the menstrual cycle, and low body temperature during menstruation is observed after their end - with another decrease in the level of estradiol and estrogen (if pregnancy has not occurred).

Women experience a dramatic change in their hormonal system during menopause, and low body temperature during menopause is caused by a sharp reduction in estrogen synthesis. The thermoregulatory system responds to this with a slight decrease in temperature and nighttime hyperhidrosis (increased sweating).

By the way, low body temperature in men over 50 is often associated with a decrease in testosterone levels, and in men of any age – with alcohol intoxication.

Parents should know that a child's low body temperature can also be a symptom of diabetes or anemia. But it is possible that this is the child's body's reaction to the treatment of a runny nose by instilling Naphthyzin, Nazol or Otrivin (and other vasoconstrictors) into the nose.

In the first two months after birth, a low body temperature in a baby (especially a premature baby) is a hypothermic reaction of the period during which the baby's thermoregulation system adapts. However, pediatricians remind that a decrease in temperature can occur with insufficient nutrition, if the mother does not have enough breast milk. In addition, low body temperature and diarrhea in a baby are a consequence of congenital lactase deficiency (inability to digest milk sugar).

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Low body temperature as a sign of illness

In medicine, the causes of low body temperature are associated with various diseases, since temperature indicators are included in the list of their symptoms. And the first signs of a decrease in temperature are manifested by general malaise, weakness, chilliness and increased drowsiness.

Low body temperature during a cold, which is most often caused by rhinoviruses, is a consequence of weakened immunity, insufficient production of endogenous interferon and a decrease in overall metabolism. Therefore, colds are often accompanied by chills at a low body temperature.

For the same reason, low body temperature is not uncommon in bronchitis (chronic or obstructive), as well as low body temperature and cough with phlegm in pneumonia. And most patients with pneumonia do not know that low body temperature and weakness are also symptoms of this disease. The body also aches, nausea, and vomiting may occur.

Low body temperature in tuberculosis is noted by phthisiatricians very rarely: in cases of extrapulmonary localization of the disease, accompanied by vegetative disorders.

Weakness, headache, dizziness and low body temperature, as well as nausea and increased sweating are included in the list of symptoms of vegetative-vascular dystonia, which is characterized by instability of blood pressure.

Many patients with Parkinson's disease have low basal body temperature and low blood pressure (orthostatic hypotension); the pathogenesis of this disorder is associated with degenerative processes in the cells of the hypothalamus.

There are frequent cases when patients have a constantly low body temperature. In this condition, first of all, there is a suspicion of a dysfunction of the hypothalamus itself, which occurs due to genetic pathologies, brain or spinal cord injuries, stroke, inflammation and cerebral edema. It is necessary to take into account such risk factors for the development of hypothalamic syndrome as ionizing radiation, tumors and brain surgery, as well as general exhaustion of the body - cachexia (often caused by nervous anorexia or "starvation" diets).

Severe hypothalamic syndrome is characterized by high blood pressure at low body temperature, increased heart rate, rush of blood to the head, low body temperature and sweating.

In case of problems with the thyroid gland, in particular, its inflammation (thyroiditis), patients experience: low body temperature and weakness, increased fatigue and daytime sleepiness, headaches and low body temperature. In this case, the pathogenesis lies in the decrease in the level of the hormone thyroxine, which enters the blood in limited quantities. The brain is especially sensitive to this hormone, and its deficiency affects thermoregulation.

Cardiovascular problems, diabetes and hypothyroidism can trigger metabolic syndrome, among the non-specific signs of which doctors note low body temperature and sweating, dizziness and low body temperature.

The symptoms of adrenal cortex insufficiency - Addison's disease - include low body temperature and nausea with vomiting, hypotension, a drop in blood glucose levels, etc. The pathogenesis of thermoregulation disorders in this disease is associated with a decrease in cortisol production, resulting in hypoglycemia, and a lack of sugar in the blood, as noted above, slows down metabolism.

Low body temperature in hepatitis can be explained by the fact that when the liver is damaged by hepatitis viruses, the hepatocytes that provide chemical thermoregulation fail.

Oncologists note low body temperature in cancer. And this phenomenon is especially common in malignant proliferation of leukocytes and their precursors in the blood and bone marrow of patients with lymphocytic and myeloblastic leukemia and myelogenous leukemia, as well as Hodgkin's lymphoma.

Consequences and complications

Why is low body temperature dangerous? The body needs energy to stay warm, and low body temperature does not allow this energy to be produced.

A body temperature below normal is dangerous because it disrupts the conditions for maintaining the body's homeostasis and the normal functioning of not only many of its systems, but also each cell, due to the slowdown of chemical reactions and physiological processes.

The action of enzymes, hormones, neurotransmitters and other biochemical factors that ensure the functioning of internal organs, the central and autonomic nervous systems changes.

In this condition, which is accompanied by increased acidity of the body's biological fluids, both adults and children are more susceptible to any infections - due to the lack of an adequate immune response. While the response to therapy and the effect of drugs, even the most effective, is reduced.

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Diagnosis of diseases that cause a decrease in temperature

To determine the causes of thermoregulation disorders, diagnostics are carried out, including:

Blood tests (general, biochemical, glucose levels, antibodies, sex and thyroid-stimulating hormones, ACTH, cortisol, hepatitis viruses, etc.) and urine tests.

Instrumental diagnostics are used, including: electrocardiography, encephalography, chest X-ray or fluorography, ultrasound examination of the thyroid gland, adrenal cortex, liver. CT of the spinal cord or MRI of the brain may be required.

Given the wide range of diseases and conditions in which temperature readings may be below the physiological norm, differential diagnostics and the involvement of doctors of various specializations are necessary – from endocrinologists to neurologists.

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What to do if a person has a low body temperature?

Everyone knows that there are many antipyretic drugs - to reduce elevated temperature. But are there any drugs that can raise it?

There are drugs that can cause a rise in temperature after taking them (antihypertensive adrenergic agonists, sulfonamides, histamine type I receptor blockers, etc.), but their direct purpose is not to increase temperature indicators: the pyrogenic effect that they have on the body is their side effect...

So what should you take at low body temperature? And how to raise low body temperature? Undoubtedly, vitamins play an important role in increasing the body's defenses, but they are not able to influence thermoregulation. Various immunomodulatory agents are not able to do this either.

Low body temperature is one of those symptoms that can only be treated by therapeutically treating the diseases that cause it. Doctors prescribe medications and apply methods for each specific case: antibiotics are needed for infectious pneumonia, hypoglycemic drugs and diet therapy are needed for diabetes, and radiation therapy and cytostatics are needed for oncology.

Read more about treatment methods for some of them:

• Treatment of obstructive bronchitis
• What to do if you have pneumonia?
• Treatment of vegetative-vascular dystonia
• Treatment of diabetes mellitus
• Treatment of autoimmune thyroiditis
• Hepatitis B - Treatment
• How is acute myeloid leukemia treated?

Physiotherapy treatment

Physiotherapy (in the form of various hardware procedures), therapeutic massage and physical education are aimed at improving the condition of patients, depending on the specific diagnosis.

See - Physiotherapy for vegetative-vascular dystonia

Traditional medicine - Treatment of thyroid diseases with traditional medicine

Herbal Treatment – Herbs that Boost Immunity, and – Herbs that Boost Hemoglobin

Prevention

It is almost impossible to prevent a decrease in temperature during a particular disease. This applies to a decrease in hormone production, genetic pathologies of the hypothalamus, the development of brain tumors, and leukemia. Doctors traditionally advise strengthening the immune system, eating normally, and leading a healthy lifestyle. Physical exercise and movement are also important for activating metabolism, since most of the thermal energy is produced by our muscles.

And for more information on how to prevent anemia, see the article – How to Prevent Iron Deficiency Anemia

Forecast

There can also be no single forecast regarding how low body temperature will affect health.

However, it should be borne in mind that normal temperature is important for the body, and its internal mechanisms can overcome most unfavorable factors.

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