Low-grade fever
Last reviewed: 23.04.2024
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What does subfebrile temperature mean? The Latin prefix sub has the meanings: "under, about" (remember words such as a submarine, offal or subtropics). A febris in Latin means "fever". So literally subfebrile temperature is defined as "near fever".
The human body temperature is a complex indicator of the thermal, that is, the thermal state of the body. The mechanism of our heat regulation is "automatically" adjusted to a normal value of + 36.6 ° C and allows its physiological changes within plus or minus 0.5-1 ° C. The overall temperature range is 36-39 ° C. When the thermometer's column rises to + 38-39 ° C, physicians talk about febrile temperature, and above + 39 ° C - about pyretic. And what is the subfebrile temperature?
The classical subfebrile body temperature is + 37-37.5 ° C, but experts point to a higher figure of 37.5-38 ° C. So it is quite justified low-grade temperature of 37 degrees and up to + 38 ° C by the majority of domestic doctors is recognized as "near fever", and their western colleagues consider that the temperature is 99.5-100.9 ° F or 37.5-38.3 ° C.
[Causes of low-grade fever
The causes of low-grade fever, as well as febrile and pyretic, are associated with changes in the limbic-hypothalamic-reticular system of the body. Simply put, the temperature is regulated in the hypothalamus, which works as a thermostat. Endogenous or exogenous pyrogens cause the release of prostaglandins (inflammatory mediators), and they act on the neurons responsible for thermoregulation, which are located in the hypothalamus. And the hypothalamus generates a systemic response, and as a result, the body is given a new level of temperature.
At what diseases does subfebrile temperature occur within a certain time? The list of such diseases is very extensive and includes:
- infectious diseases - influenza, SARS, tuberculosis, typhoid, brucellosis, malaria, ornithosis, mononucleosis, Epstein-Barr herpesvirus, cytomegalovirus, rotavirus gastroenteritis and gastroenterocolitis, tick-borne borreliosis (Lyme disease), HIV, urogenital infections, etc .;
- parasitic diseases (helminthic invasions, giardiasis, leishmaniasis, toxoplasmosis);
- Sluggish inflammatory processes with chronic rhinitis, sinusitis, sinusitis or tonsillitis; with inflammation of soft tissues (furuncles, abscesses); with focal pneumonia and lung abscess; with chronic cholecystitis, pancreatitis, cystitis, prostatitis, pyelonephritis, etc .;
- dysfunction of the thyroid gland (initial stages of hyperthyroidism, hypothyroidism, thyrotoxicosis);
- systemic immunological diseases - systemic lupus erythematosus, sarcoidosis, giant cell temporal arteritis (Horton's disease), rheumatoid arthritis, granulomatous enteritis (Crohn's disease), Wegener's granulomatosis, Bechterew's disease, Sjögren's syndrome;
- necrosis of tissues that can arise as a result of destruction of red blood cells (hemolysis) with cerebral hemorrhage, myocardial infarction, after surgical intervention, with compression syndrome, etc .;
- allergic reactions of various etiologies;
- metabolic disorders (gout, porphyria, etc.);
- thromboembolic processes (deep vein thrombosis, pulmonary embolism, etc.).
Symptoms of low-grade fever
Subfebrile body temperature accompanies a number of diseases, sometimes being, in fact, their only symptom, fixed at the initial stage of development. In addition to high temperature, this condition can not show any other signs, which is a potential health hazard.
So the key signs of subfebrile temperature are periodic or permanent (permanent), short-term or long-term increase in temperature indicators to + 37-38 ° C.
Subfebrile temperature as a symptom
Subfebrile temperature is a sign of one or another pathology. Subfebrile temperature and cough, low-grade fever and headache, as well as weakness and low-grade fever are typical symptoms not only of acute respiratory viral infection or influenza, but also of focal pneumonia and pulmonary tuberculosis. In particular, with focal or infiltrative tuberculosis, subfebrile temperature is observed in the evenings, which rises by 3-4 hours to + 37.3-37.5 ° C.
Often, low-grade fever after ARI is the result of incomplete recovery, weakened immunity or the effect of medications.
In most cases, the subfebrile temperature in bronchitis does not rise above + 37.7 ° C, approximately in the same range holds subfebrile temperature after pneumonia. Often doctors can not determine the exact cause of this phenomenon and call it postinfectional subfebrile condition.
The characteristic subfebrile temperature in tonsillitis is 37-37.5 ° C, and the subfebrile temperature after angina may remain at the same level for one to two weeks. Longer subfebrile condition should be alarming, as it is known that tonsillitis quickly becomes chronic decompensated, and streptococcal infection with frequent angina has a pathological effect by intoxication of the heart tissues, causing infective endocarditis, and affecting the kidneys, leading to glomerulonephritis.
The subfebrile temperature in cystitis, along with other symptoms of this disease, passes after appropriate drug therapy. However, when the subfebrile temperature rises to 37.5-37.8 ° C after the end of treatment, then there are good reasons to assume that the inflammation from the bladder went to the kidneys and threatens pyelonephritis.
The subfebrile temperature after removal of the tooth, as well as the subfebrile temperature after the operation performed on any tissues and organs, can have a separate list of causes, among which the organism's reaction to the damaging factor and infection (for example, infectious infection of blood -pemia) comes first. Their contribution is made by drugs taken both before and after the surgical intervention.
Subfebrile temperature in oncology is most often observed with myelo- and lymphocytic leukemia, lymphomas, lymphosarcoma and cancerous kidney damage. As oncologists note, a long subfebrile temperature - for half a year and even more - is one of the symptoms of the early stages of these diseases. Also for oncological patients after radiation and chemotherapy, neutropenic subfebrile condition is associated with the weakening of the immune system.
Nausea and subfebrile temperature of the gastroenterologist will suggest an intestinal dysbiosis. And here subfebrile temperature at night usually drops down to a physiologically normal level or slightly lower, although it can hold, for example, with latent herpesvirus infection, inflammation of the bile ducts or hepatitis C.
It should be borne in mind that the constant subfebrile temperature, which remains above the norm throughout the day and fluctuates during the day by more than one degree - a symptom of infective endocarditis. The long subfebrile temperature, which manifests itself every 24-48 hours is a typical manifestation of a malarial plasmodium.
The human immunodeficiency virus acts slowly, so that the subfebrile temperature for HIV, in the absence of other signs in the carriers of this infection, is an indicator of a total decrease in protective forces. The next stage can be the defeat of the body by any infection with the development of a variety of immune-mediated diseases.
Subfebrile temperature with IRR
Thermoregulation of the body - as the activity of all internal organs, secretory glands and blood vessels - is coordinated by the autonomic nervous system, which ensures the stability of the internal environment and the adaptive reactions of the body. Therefore, violations in her work can manifest as a subfebrile temperature with VSD, i.e., vegetative-vascular dystonia.
In addition to spontaneous daytime temperature rise to 37-37.3 ° C, there may be neurocirculatory disorders such as changes in blood pressure and heart rate, decreased muscle tone, and hyperhidrosis (increased sweating).
Depending on the cause of GVA, clinical vascular dystonia is distinguished in clinical medicine by genetic, infectious-allergic, traumatic and psychogenic.
Until recently, the rise in temperature under such conditions, that is, without an obvious cause, was defined as a subfebrile temperature of an unclear etiology. Now it is already known that there is a violation of the thermoregulation process due to the diencephalic syndrome - congenital or acquired dysfunction of the hypothalamus (our main "thermostat").
Congenital causes of this pathology include functional somatic disorders of the VSD type, and among the acquired ones there appear a disruption of the blood circulation in the area of the hypothalamus, craniocerebral trauma, encephalitis, intoxication, etc.
Anemia and low-grade fever
Anemia and subfebrile temperature are closely related to each other at the biochemical level. Iron deficiency anemia leads to a disruption in the production of hemoglobin and a decrease in its content in erythrocytes, which carry oxygen to the tapholes. And with a lack of oxygen in all cells of the body and, in the first place, the brain is disrupted metabolism. Therefore - in addition to all other signs of iron deficiency in the body - there is often a slight increase in body temperature. The most prone to iron deficiency anemia are children and adolescents during puberty. In addition to the subfebrile condition, they often have colds, and appetite and weight can decrease.
In addition, poor assimilation of iron is associated with a lack of vitamin B9 (folic acid) and vitamin B12 (cyanocobalamin), which regulate the synthesis of hemoglobin in the bone marrow. And this anemia is called pernicious.
Precision anemia and low-grade fever - if they do not pay attention - can lead to inflammation and atrophy of the gastrointestinal mucosa.
Low-grade fever in women
The subfebrile temperature before menstruation in women refers to the physiological periodic changes in thermoregulation (within 0.5 degrees) and is associated with increased intake of estrogen and estradiol and the products of their metabolism into the blood: hydroxyestrones, etiocholanolone, methoxy estradiol, etc.
The low-grade temperature during pregnancy (up to + 37.5 ° C) can be observed in the early stages, in the first 12 weeks - due to the increase in the level of progesterone produced by the yellow body and its influence on the hypothalamus. Later, the temperature values are normalized.
However, an insignificant but constant low-grade fever in pregnant women is quite possible when the so-called TORCH infections are manifested against the background of a natural decrease in the immunity of the so-called TORCH infections: toxoplasmosis, hepatitis B, varicella-zoster virus, rubella, cytomegalovirus and herpes simplex virus. Since all these infections can cause congenital fetal diseases, it is important to be vigilant at subfebrile temperature and take a blood test for TORCH infection.
And, at last, subfebrile temperature in women very often happens during menopause, and it is connected again with changes in their hormonal background.
Subfebrile temperature in a child
Detected in childhood, thermoregulation disorders in at least 2% of cases are congenital diencephalic syndrome, that is, problems with the hypothalamus, discussed above.
Subfebrile temperature in a child often accompanies infections of the upper respiratory tract, nasopharynx and ears. So, subfebrile temperature and cough can be with ARVI, chronic tonsillitis, bronchitis, pneumonia. The temperature is given by teething and grafting. To provoke a subfebrile condition physical activity, strong excitement, an overheat at wearing of heavy clothes, an anemia, etc. Can.
Subfebrile temperature in adolescents is related to the period of sexual development, but possible pathologies can not be ignored. In addition to those listed above (see Causes of subfebrile temperature), pediatricians pay special attention to pediatric and adolescent thermoneurosis, which is caused by diencephalic syndrome, malignant blood diseases, thyroid pathologies, and autoimmune diseases. For example, in children under the age of 16, Styl's disease or systemic juvenile idiopathic arthritis can develop, for which weakness and subfebrile temperature are characteristic.
It can also be a by-product of prolonged use of certain medications, for example, atropine, diuretic, anticonvulsant, antipsychotic and antibacterial. Thus, the subfebrile temperature for antibiotics is due to the fact that their use erases the symptoms of certain diseases, and then there is only one symptom - an increase in the thermometer readings.
What's bothering you?
Analyzes at subfebrile temperature
Doctors recognize the fact that setting the right diagnosis at subfebrile temperature is not an easy task. Therefore, it is necessary to pass all the tests at subfebrile temperature:
- general blood analysis;
- blood tests for RW, HIV, viral hepatitis B and C;
- blood test for TORCH infection;
- blood test for rheumatoid factor;
- a blood test for thyroid hormones;
- blood test for oncomarkers;
- general urine analysis;
- sputum culture for tuberculosis.
In addition to testing, x-ray or ultrasound can be used.
What tests are needed?
Who to contact?
Treatment of low-grade fever
How to bring down the low-febrile temperature? For your information, in this situation only an incompetent medical worker immediately - without examination - will prescribe a fever-reducing medication. And alone to drink tablets of aspirin, acetaminophen or ibuprofen, too, is not necessary, especially in those cases when subfebrile temperature is observed for 2 months or if the subfebrile temperature lasts more than a year, or even longer.
What should I do if I have low-grade fever? Seek medical help from intelligent doctors. If other symptoms are absent and there are no complaints of worsening of well-being, then treatment of subfebrile temperature is not required. Therapy of these conditions is extremely difficult, especially when doctors diagnose subfebrile temperature of unclear etiology.
A hundred years ago for the subfebrile condition used the old name - "general malaise", where it was recommended to eat better, walk more outdoors and not be nervous. And what do you think, it helped a lot ...
Today it is necessary to conduct etiologic treatment of subfebrile temperature, and how it will be depends on the pathogenesis of the disease.
If the subfebrile temperature appears frequently or is constant, if it causes you anxiety (especially when "nothing hurts anywhere"), consult a doctor.
If your subfebrile temperature lasts for a long time, the immunity is weakened or there are chronic diseases - consult a doctor without delay.