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 Sustained fever. Persistent fever is mainly divided into infectious fever and non-infectious fever caused by pathogens. And the fever caused by infection is the most common. At the same time, this condition has a long fever and requires special attention to care.



There are many causes of fever, which can be roughly classified into infectious and non-infectious, and infectious fever is common. Infectious fever is caused by infection with bacteria, viruses, fungi, parasites, and the like. There are many reasons for non-infectious fever. It can be seen after major surgery, internal bleeding, large hematoma, extensive burns, tumors, rheumatism, hyperthyroidism and so on.


an examination

Related inspection

Lymphocyte ratio (LY%) monocyte ratio (MONO%) heterotypic neutrophil depolarization complete examination of heteromorphic neutrophils

First, medical history and physical examination

Detailed medical history (including epidemiological data) is very important. If the onset is urgent, the height and change of the fever period and body temperature are considered to be mostly chills, but about 2/3 of lymphoma and malignant histiocytoma also have chills, indicating that chills are not unique to infectious diseases. However, there are obvious chills that are common in serious bacterial infections (pneumococcus pneumonia, sepsis, acute pyelonephritis, acute cholecystitis, etc.), malaria transfusion or infusion reactions. Tuberculosis, typhoid rickettsial disease and viral infection are rare. Generally not seen in rheumatic fever. Fever is often accompanied by non-specific symptoms such as dizziness, dizziness, headache, and loss of appetite. There is no differential diagnosis. However, local symptoms of localization have important reference value. Such as fever with neurological symptoms, such as severe headache and vomiting. Consciousness disorder and convulsions, meningeal irritation signs, etc. suggest that the lesions in the central nervous system, should consider encephalitis, meningitis, elderly patients with serious infections, often have a change in consciousness, and body temperature is not necessarily high, it is worth noting to ask about epidemiological history The incidence area, season, age occupation, living habits, travel history and close contact history of the same patients, history of surgery, blood transfusion and history of traumatic history of blood products, history of contact between cattle and sheep, etc., all have important significance in diagnosis. Provides important diagnostic clues.

Second, analyze the heat type

Clinically, various infectious diseases have different heat types. During the course of disease progression, the heat type also changes. Therefore, understanding the heat type has certain reference significance for diagnosis, judgment of the disease, evaluation of efficacy and prognosis.

(1) According to the temperature (the armpit temperature), it is divided into low heat type (<38 °C), medium heat type (38-39), high heat type (39-40 °C), and ultra high heat type (>40 °C).

(2) Forming mechanism according to the shape of body temperature curve, such as heat retention, intermittent heat, bimodal heat consumption heat, wavy heat, irregular heat, etc., has not yet been fully elucidated. Most of them are considered to be related to the nature of the lesion. The factors that determine the nature of the lesion are the amount of velocity produced by endogenous pyrogens and the rate at which human blood is released, all of which affect the height and velocity of the up-regulation of the thermoregulatory point.

Third, the difference between infectious fever and non-infectious fever

(1) Infectious fever

Infectious fever has the following characteristics:

1. Onset of illness with or without chills.

2, systemic and localized symptoms and signs.

3. Blood: The white blood cell count is higher than 1.2x109/L or lower than 0.5109/L.

4, tetrazolium blue test (NBT): such as neutrophil reduction NBT more than 20%, suggesting bacterial infection, help with the identification of viral infection and non-infectious fever (normal value <10%) application of hormones It can be false negative afterwards.

5, C-reactive protein determination (CRP): positive suggestive of bacterial infections and rheumatic fever, negative mostly viral infection.

6, neutrophil alkaline phosphatase score increased: normal value is 0 ~ 37, the higher the higher the higher the more favorable for the diagnosis of bacterial infection, when the exclusion of pregnancy cancer, malignant lymphoma more meaningful. It can be raised or false positive after application of hormones.

(two) non-infectious fever

Non-infectious fever has the following characteristics:

1. The heat course is longer than 2 months, and the longer the heat stroke, the greater the possibility.

2, long-term fever is generally good, no obvious symptoms of poisoning.

3, anemia, painless multi-site lymphadenopathy, hepatosplenomegaly.

Fourth, laboratory and auxiliary inspection

It is necessary to selectively combine clinical performance analysis and judgment according to specific conditions. Such as blood routine, urine routine pathogen examination (direct smear, culture, specific antigen antibody detection molecular biological test, etc.) X-ray, B-mode ultrasound, CTMRI, ECT examination, tissue biopsy (lymph node liver, skin decidua), bone marrow Puncture, etc.

There is no diagnostic value for the diagnosis of most patients with fever. In view of clinical treatment problems, for patients with unknown causes of long-term fever, diagnostic treatment can be performed in addition to tumors. However, it is necessary to take a cautious attitude and choose drugs with specific specific effects and minimal side effects, such as nitrous acid to treat amebic liver disease and antimalarial drugs for malaria. Most of them are used for diagnostic treatments such as antibiotics, anti-protozoal anti-rheumatic drugs, etc. These drugs have side effects (such as drug fever, rash liver function damage, hematopoietic organ damage, etc.), such as improper application, but delay the disease. It should be noted that this method has its limitations, and the results of special effects treatment in terms of diagnosis are generally more negative than the diagnosis. If the suspected malaria patients are not treated with regular treatment with chlorsulfone, the possibility of malaria is considered to be small.


Differential diagnosis

1 primary liver cancer

More than 80% of domestic primary liver cancers have cirrhosis. The clinical features are insidious onset, and early lack of specific symptoms are usually advanced in the case of typical symptoms. A persistent fever or relaxation heat, or irregular low fever, a small number of people with high fever (such as inflammatory or diffuse liver cancer) can be mistaken for liver swelling or infectious diseases. Timely detection of alpha-fetoprotein (AFP), its sensitivity specificity is conducive to early diagnosis.

2 malignant lymphoma

Includes Hodgkin's disease and non-Hodgkin's lymphoma. More common in 20-40 years old, more common in men with clinical asymptomatic or progressive lymphadenopathy, night sweats, weight loss rash or skin itching. Anyone who has an unexplained lymph node enlargement is not effective for one month due to inflammation or tuberculosis; unexplained fever should consider the possible diagnosis of the disease mainly depends on pathology. Lymph node biopsy, bone marrow puncture liver penetration, B-ultrasound, CT and other examinations can be performed and differentiated from infectious mononucleosis, lymph node tuberculosis, chronic lymphadenitis metastasis, rheumatism and connective tissue disease.

3 malignant histiocytosis

The clinical manifestations of this disease are complex and fever is a common symptom. Some cases are like sepsis and typhoid. Tuberculosis, biliary tract infection, etc., but were not treated by clinical system examination and treatment, and were diagnosed in the late stage. The main points of identification with other acute infectious diseases are: 1 clinically infectious disease but no infection, no negative pathogens and serological tests; 2 progressive anemia, complete cytopenia; 3 hepatosplenomegaly and lymph nodes The degree of swelling was significant; 4 progressed with cachexia; 5 antibiotic treatment was ineffective.

4 acute leukemia

There may be fever, blood smear, bone marrow examination can be diagnosed, atypical leukemia only manifested as anemia and leukopenia of unknown cause, easy to be mistaken for acute aplastic anemia, abnormal changes in bone marrow smear can be diagnosed.

5 vascular-connective tissue disease: rheumatoid arthritis:

Typical cases are easier to diagnose juvenile rheumatoid arthritis (Still disease), may have chills, fever, transient rash, joint pain is not obvious, lymphadenopathy, hepatosplenomegaly, iridocyclitis, myocarditis, white blood cells Increased erythrocyte sedimentation rate but negative rheumatoid factor, anti-nuclear antibody and lupus cells were negative.

6 tuberculosis

For the common cause of low fever, tuberculosis is more common, and early asymptomatic signs are performed in time for chest X-ray examination. Secondly, extrapulmonary tuberculosis, such as liver and kidney, intestine, mesenteric lymph nodes, pelvic cavity, bone and joint tuberculosis, etc., in addition to local symptoms, often have symptoms of tuberculosis poisoning, ESR increased tuberculin test strong positive, anti-tuberculosis treatment has a definite effect, It is helpful to diagnose the symptoms of senile pulmonary tuberculosis, and its pulmonary complications are many. The tuberculin test is negative and easy to be diagnosed as chronic bronchitis or asthma.

7 chronic kidney and nephritis

Common causes of low fever for female patients. There can be no obvious symptoms, signs or even urine tests without abnormalities, with low heat as the only performance. Timely detection of urine Addi cell counts The first mid-stage urine culture and colony counts in the morning, such as leukocytosis >5/HP, positive bacterial culture, colony count >105 can determine the diagnosis.


It is a systemic disease in which human immunodeficiency virus (HlV) invades and destroys the body's immune system and damages multiple organs. It can spread through blood and body fluids. The clinical manifestations are complex, and its basic feature is that HlV causes the cellular immune damage of the human body to cause the body to be in a serious and progressive immunodeficiency state, and thus various opportunistic infections and malignant tumors manifest as long-term irregular fever, and more than one chronic diarrhea. In the month, the general antibiotic treatment is ineffective, and the cause is unknown. The lymph nodes are swollen, repeated bacterial fungi, protozoa and other infections. Combined with epidemiological data, anti-HlVP24 shaking antigen detection is performed in time.

9 cytomegalovirus infection

Sustained low fever, similar to infectious mononucleosis, viral hepatitis, based on anti-CMV IgM test diagnosis.

10 hyperthyroidism

Early low fever with palpitations, rapid pulse, excessive appetite, weight loss, thyroid gland, local murmur. Detection of T3T4, rT3, and the like. A 131I uptake test is needed for hyperthyroidism without exophthalmos to increase the levels of T3 and T4 in the blood caused by hormone spillover during thyroiditis.

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