What is low-grade fever: causes, diagnosis
Subfeverility is a condition in which there is an increase in body temperature up to 38 °C over a long period of time. Chronic subfebrile temperature is called an unexplained increase in body temperature for more than two weeks. In this state, a person can either feel unchanged or feel unwell. Often low-grade fever is the patient's only complaint. Prolonged low-grade fever and weakness can be the first symptoms of a serious illness.
Possible causes of low-grade fever
In humans, normal body temperature (TT) is maintained by special mechanisms of thermoregulation. Physiological fluctuations of TT during the day are called daily rhythms: the difference between morning and evening body temperature reaches 0.5-1.0 °C. What is a low-grade fever? This is an elevated temperature that persists for a long period of time. Isolated cases of TT rise above 37.1 °С are not considered subfebrile. Low subfebrility (up to 37.1 °С) and high (up to 38.0 °С) are distinguished.
Possible causes of low-grade fever in adults:
- bacterial infections that cause diseases of the upper respiratory tract, pneumonia, typhoid and others;
- viral infections: flu, ARVI, hepatitis, HIV/AIDS;
- infections of the urinary tract: cystitis, urethritis;
- allergy - for example, hay fever;
- reaction to drug therapy. Some medications can cause a fever known as drug fever. When the drug is stopped, hyperthermia disappears;
- inflammatory diseases of the pelvic organs;
- hyperthyroidism;
- appendicitis;
- tuberculosis. Constant subfebrility is observed in difficult-to-diagnose forms of tuberculosis;
- hormonal changes. Subfebrile temperature in women can be observed in the second half of the menstrual cycle, during PMS, pregnancy and menopause;
- inflammatory diseases of the gastrointestinal tract;
- lymphoma and other types of malignant neoplasms;
- intense physical activity;
- eating;
- emotional tension and stress;
- effect of external heat (for example, when staying in a sauna, a hot workshop).
The child has had a low-grade fever for a week: possible reasons
Subfeverility is a frequently diagnosed condition in babies, as well as the first symptom of many diseases.
The main causes of low-grade fever in children:
- acute respiratory diseases;
- infectious lesions of the gastrointestinal tract. In this case, an increase in temperature is often accompanied by vomiting and diarrhea;
- cutting teeth;
- children's infectious diseases: chicken pox, measles, mumps, rubella and others;
- some vaccinations. Usually, the temperature reaction to the vaccine lasts 1-3 days;
- otitis;
- cystitis;
- active games;
- prolonged crying.
If the child has a low-grade fever for a week, it is necessary to consult a doctor. Differential diagnosis of febrile conditions is considered quite difficult even for experienced specialists. Subfebrile fever can be accompanied by other symptoms, this will make it easier for the doctor to make a diagnosis. The range of diseases that occur with low fever includes pathologies that belong to the competence of a pediatrician, otolaryngologist, infectious disease specialist, surgeon, phthisiologist, cardiologist, oncologist and other specialists. Sometimes a full examination may be necessary to identify the cause of a prolonged fever. Read more about the examination program on our website https://dobrobut.com.
What tests will help to find out the cause of chronic low fever
To find out the reasons for a prolonged increase in temperature, you may need:
- general analysis of urine;
- clinical and biochemical blood tests;
- stool analysis for worm eggs;
- video laryngoscopy;
- otoscopy;
- tuberculin samples;
- hormone analysis;
- ECG;
- Ultrasound.
If there is a regular increase in body temperature in the evening, the doctor will refer to fluorography or X-ray of the lungs.
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