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Causes of fever
Last reviewed: 19.10.2021
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The most frequent cause of increased body temperature is the infectious process of various etiologies, but a non-infectious inflammatory process is also possible (for example, with myocardial infarction or with the so-called autoimmune inflammation). The pyrogenes formed during inflammation act on activated leukocytes that synthesize interleukin-1 (and also interleukin-6, tumor necrosis factor (TNF) and other biologically active substances), stimulating the formation of prostaglandin E2, under the influence of which the level of the "setting point" of the center of thermoregulation (and, correspondingly, body temperature). Sometimes the causes of fever for a long time may remain unclear ("fever syndrome of unclear genesis").
A rise in body temperature is accompanied by many malignant tumors, for example, bronchogenic cancer or a tumor of the kidney parenchyma, but especially often with lymphogranulomatosis, in which a prolonged, many-month high fever is often observed. Fever with malignant tumors is included in the concept of "paraneoplastic syndrome".
The increase in body temperature can be triggered by the intake of various medications, for example, some antibiotics, analgesics.
Influence on heat production has the endocrine system. The most striking example - the strengthening of thyroid function is often accompanied by subfebrile body temperature.
An increase in body temperature is possible with lesions of the intermediate brain of various etiologies (encephalitis, cerebral hemorrhage, etc.).
An increase in body temperature can also occur in so-called thermal diseases caused by a violation of the equilibrium between the processes of heat production and heat transfer while maintaining a normal level of the "fixing point" of the hypothalamus thermoregulatory center. In some cases, heat generation or exogenous heat input significantly exceeds the capabilities of the heat transfer mechanisms (at their maximum voltage), in others - heat transfer processes are lost during normal heat production. A combination of both causes is possible. The body temperature rises despite the efforts of the thermoregulatory center to keep it within normal limits.
In all cases, clarification of the cause of increase in body temperature is very important. Once again, it should be emphasized that not always a fever is contagious and, therefore, requires the appointment of an antimicrobial treatment.
Temperature curve
Temperature curve - a graph of changes in body temperature over time. To record the temperature curve, use a special temperature sheet where the abscissa represents the temperature of the body (in degrees Celsius), and the ordinate - the days with details of "morning" and "evening." On the graph, the body temperature is marked with dots, connecting which, get a temperature curve. The following types of temperature curves are distinguished.
- Constant fever (febris continua ). Fluctuations in body temperature during the day do not exceed 1 ° C, usually within 38-39 ° C. This type of fever is typical for acute infectious diseases (inflammation of the lungs, acute respiratory-viral infections (ARVI).
- Relaxing, or remittent, fever (febris remittens). Body temperature increases and different values with daily fluctuations of 1-2 ° C; is characteristic for purulent diseases.
- Intermittent, or intermittent, is a fever (febris intermittens). The body temperature suddenly rises to 39-40 ° C and after a while (hours) rapidly decreases to normal and even subnormal values. After 1-3 days such a rise in temperature is repeated, etc. This type of fever is characteristic of malaria.
- Recurrent fever (febris recurrent). Unlike intermittent fever, body temperature rises immediately to high values and persists at an elevated level for several days, then it temporarily falls to normal, followed by a new period of increase (from 2 to 5 seizures). Recurrent fever is typical for some spirochaitosis (recurrent typhus).
- Hectic, or debilitating fever (febris hectica). The fluctuation of body temperature during the day is 3-5 ° C. A similar type of temperature curve is especially characteristic for sepsis.
- Wavy fever (febris undulatts). The temperature of the body is increasing from day to day, reaching higher and higher values, and then gradually, with each passing day, it becomes lower and lower. Having reached subfebrile or normal knowledge, it again gives a fairly correct wave of ascent, etc. A distinctive feature of wave-like fever in comparison with recurrent fever is the gradual increase in body temperature and its gradual decline. Such a fever is observed in the most typical form with brucella.
- Wrong fever (febris irregularis). It is characterized by irregular increases in body temperature to different values. Most often observed with rheumatism, influenza, dysentery.
- Perverted fever (febris inversa). The morning temperature of the body is higher than the evening temperature. This type of temperature curve is sometimes observed with tuberculosis, prolonged sepsis.
[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]