Recurrent fever

Introduction The fever is higher than normal. The normal body temperature fluctuates within a narrow range. For example, the mouth temperature fluctuates between 36.0 and 37 °C, the lowest is from 0 to 4 in the morning, and the highest is from 5 to 7 in the afternoon. The difference is about plus or minus 1 °C. The oral temperature is above 37.3 ° C, the temperature in the rectum is above 37.6 ° C, and the temperature of the armpit is above 37.2, which is called fever.

Cause

There are many diseases that cause fever, and they can be divided into two categories depending on the cause of the disease.

(1) Infectious diseases

It ranks first in fever, including common infectious diseases caused by various pathogens, systemic or focal infections. Infectious fever caused by bacteria is the most common, followed by viruses.

(2) Non-infectious diseases

1, blood diseases and malignant tumors such as leukemia, malignant histiocytosis, malignant lymphoma, colon cancer, primary hepatocellular carcinoma.

2, allergic diseases such as drug fever, rheumatic fever.

3. Connective tissue diseases such as systemic lupus erythematosus (SIE) dermatomyositis, nodular polyarteritis, mixed connective tissue disease (MCTD), and the like.

4, other

Such as hyperthyroidism, thyroid crisis. Severe water loss or bleeding, heat radiation, heat stroke, fracture, extensive burns, cerebral hemorrhage, visceral vascular infarction, tissue necrosis.

mechanism

Recent studies have shown that fever is caused by exogenous pyrogens, and its mechanism is mainly due to the up-regulation of the body temperature regulation point of the body temperature regulation center. An external pyrogen is an activator (including various pathogens, endotoxins, antigen-antibody complexes, lymphokines, steroid products, and some inflammatory substances) that produces endogenous pyrogen cells in the body. Different pathways activate endogenous and pyrogenic cells to produce and release endogenous pyrogens (interleukin 1, interleukin 2, tumor necrosis factor and interferon, etc.). The mechanism of its fever has not been fully elucidated. It is currently believed that it may be through certain biologically active substances such as prostaglandin E (PGE), monoamine (demethylephrine, serotonin), cyclic adenosine monophosphate (cAMP), calcium/sodium ratio change, endorphin As an intermediary, it acts on the body temperature regulation center and moves the body temperature adjustment point up. The body temperature is readjusted, and the regulating impulse is emitted. The sympathetic nerve causes the skin to contract and the heat dissipation is reduced.

On the other hand, the action of the motor nerve causes periodic contraction of the skeletal muscle to cause chills, which increases the heat production. The skin temperature drops due to skin vasoconstriction, stimulating the cold receptors to send impulses to the lower part of the thalamus, and also participate in the occurrence of chills. Therefore, the result of the adjustment is that the heat production is greater than the heat dissipation, so that the body temperature rises and rises to a new level that is compatible with the body temperature setting point. This is the basic mechanism of elevated body temperature during infectious fever. In recent years, some scholars believe that in the visual crypt of the third ventricle wall, there is a special part of the hypothalamic endplate vascular device, and the endogenous pyrogen acts on the macrophage and is released. The medium acts here to cause fever.

Non-infectious fever such as aseptic tissue injury (myocardial infarction, pulmonary embolism, postoperative fever, chest or abdominal hemorrhage, etc.) allergic reaction, blood group incompatibility, drug fever, drug-induced hemolytic anemia, connective tissue disease, etc. The mechanism of the increase in body temperature is mainly that the antigen-antibody complex has a special activation effect on the production of pyrogenogenic cells, so that endogenous pyrogens are produced and released. Malignant tumors cause fever, some patients have infections, and nearly half of them are caused by simple tumors. Most scholars believe that the inflammatory lesions damaged by malignant tumors and the immune response of fibroids themselves. Common malignant histiocytosis, lymphoma (especially Hodgkin's disease), prostate cancer, kidney cancer, colon cancer, pancreatic cancer, liver cancer, lung cancer, multiple myeloma and the like. Due to fever caused by abnormal heat production, heat production is greater than heat, thyroid crisis, status epilepticus and pheochromocytoma. Atropine poisoning, large amount of water loss, blood loss, etc. due to reduced heat dissipation. The brain has extensive chronic degenerative diseases or cerebral hemorrhage, epidemic encephalitis and other damage to the hypothalamus, which may have super high fever. Sympathetic nerves are inhibited, the skin is dry and sweat-free, and heat dissipation is reduced.

an examination

First, comprehensive and careful physical examination

The examination should be detailed and comprehensive, combined with medical history and symptoms, and then in-depth examination.

Oral in many fever patients, pathological changes are common. Such as tonsillitis can be seen tonsils redness or purulent secretion, herpetic pharyngitis can be seen in the pharynx and other areas of herpes and ulcers, measles in the early buccal mucosa with Coriolis spots, diphtheria visible pharyngeal and tonsil with white pseudomembrane.

Pay attention to the distribution and morphology of the rash. Allococcal sepsis, streptococcal infections are common with scarlet fever-like rashes, blood diseases, epidemic cerebrospinal meningitis, epidemic hemorrhagic fever and other skin may have bleeding points, rheumatic fever can be seen in ring erythema, viral infection, connective tissue disease, sepsis Bacterial endocarditis, histiocytosis X, mucocutaneous lymph node syndrome and many drugs can cause rash, but their morphology and appearance are different.

People with good mental state during high fever are often mildly infected. Such as lethargy, apathetic, unconscious, with meningeal irritation, suggesting intracranial infection. In the early stage of infant intracranial infection, meningeal irritation is often not obvious, but the performance is apathy, lethargy, irritability, nervous or full of sputum, etc., must be alert to intracranial infection.

Hepatosplenomegaly is common in leukemia, connective tissue disease, inflammation of the hepatobiliary system, typhoid fever, sepsis, malaria, and tumors. Lymph node enlargement can be seen in blood diseases, infectious mononucleosis, mycoplasma infection, lymph node syndrome of the skin and mucous membranes. Local lymphadenopathy, tenderness, should pay attention to find adjacent areas with or without inflammatory lesions.

Second, laboratory inspection

First check the general, according to the general screening results, and then decide to further check the project, try to avoid the purposeless "casting" type inspection.

Common tests for blood, urine, and feces are preferred items for screening. The total number of white blood cells and neutrophils are increased, and more are considered bacterial infections; those with reduced weight are more viral or bacilli infections. If you suspect sepsis, intestinal and urinary tract infections, you need to send blood, feces, and urine separately. In addition to routine examinations, various puncture fluids are sometimes sent for culture or smear examination. For example, meningococcal smear and cerebrospinal fluid smear in patients with epidemic cerebrospinal meningitis can find meningococcal bacteria, blood smears for malaria can find malaria parasites, and diphtheria pseudomembrane smears to check diphtheria bacilli.

If necessary, check the fatda reaction, the external Fischer reaction, the heterophilic agglutination test, the condensation set test, etc., to help the differential diagnosis. Rheumatoid fever or rheumatoid disease was examined for anti-streptolysin O or rheumatoid factor, respectively. Patients with suspected viral infections may have early rapid diagnostic tests for immunological aspects. Patients with repeated infections caused by immunodeficiency disease can be used for serum immunoglobulin and cellular immunity and complement determination. Blood diseases should be checked for bone marrow. Suspected tuberculosis requires a tuberculin test. Patients with suspected biliary tract infections are often examined and cultured for duodenal drainage, and often have meaningful results. In short, the relevant examinations can be carried out according to the condition of the disease, but it is necessary to pay attention to the analysis of the results of the examination, to eliminate false positives or false negatives caused by errors and pollutions such as sampling or operation.

Third, X-ray and other inspections

Chest X-rays help diagnose lung and chest diseases. Others, such as malignant tumors, can be selected for CT, nuclear magnetic resonance, angiography, radioisotope, B-mode ultrasound, and living tissue according to the site, which is also necessary.

Differential diagnosis

1. Non-infectious fever: caused by various infectious diseases, aseptic substances or various inflammatory effects on the body temperature regulation center, body temperature center dysfunction or excessive heat production caused by various causes, heat dissipation is reduced, resulting in body temperature rise High above the normal range.

2, unexplained fever: the concept of generalized unexplained fever refers to all unexplained fever. However, in the clinic, the narrow concept of fever is also adopted, that is, fever of unknown cause. The fever lasted for more than 3 weeks, the body temperature was above 38.5 °C, and the diagnosis was not confirmed by detailed medical history, physical examination and routine laboratory tests.

3, central fever: refers to the fever caused by central nervous system disorders caused by abnormal body temperature regulation. The fever caused by systemic or local inflammation should be strictly excluded before diagnosis, and other causes of fever should be excluded. Most cases of intracranial disease with fever are critical cases, most of which are caused by intracranial inflammation, intrapulmonary infection, and urinary tract infection. For the unexplained increase in moderate body temperature, the source of infection or the cause of infection cannot be found at one time, and it cannot be easily considered as central fever. The cause of systemic or local infection should be repeatedly searched for, and attention should be paid to the cause of drug fever and other fevers.

4. Persistent fever: When the mouth temperature is higher than 37.3 °C or the anus temperature is higher than 37.6 °C, the change in one day exceeds 1.2 °C, which is called fever. According to the level of fever, it can be divided into the following clinical classifications: low heat 37.4 ° C ~ 38 ° C moderate heat 38.1 ° C ~ 39 ° C high heat 39.1 ° C ~ 41 ° C ultra high heat 41 ° C or more, lasting more than 4 weeks, for continuous fever .

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.