All diagnostic doctors sooner or later face a pathological condition of the patient - a fever of unknown origin. As for the doctor, these conditions require increased attention, and for the patient they are associated with constant anxiety and an increase in distrust of modern medicine. However, fevers with an unclear origin (ICD-10 code R50) have been known for a long time. About the pathology itself, the causes of its appearance and diagnostic methods, this article. And also about the diagnostic search algorithm for fever of unclear origin, which modern diagnosticians use.
Why the temperature rises
Thermoregulation of the human body is carried out at a reflex level and indicates the general condition of the body. An increase in temperature is a response of the body with a protective and adaptive mechanism.
The following levels of body temperature are characteristic of a person:
- Normal - from 36 to 37 ° C.
- Low-grade - from 37 to 37.9 ° C.
- Febrile - from 38 to 38.9 ° C.
- Pyretic - from 39 to 40.9 ° C.
- Hyperpyretic - from 41 ° C and above.
The mechanism of increasing body temperature is triggered by pyrogens - low molecular weight proteins that act on the hypothalamic neurons, which leads to an increase in heat production in the muscles. This leads to chills, and heat transfer is reduced due to the narrowing of the blood vessels of the skin.
Pyrogens are exogenous (bacterial, viral and non-bacterial in nature, for example, allergens) and endogenous. The latter is produced by the body itself, for example, hypothalamic neurons or the cells of various malignant and benign neoplasms themselves.
In addition, pyrogens in the form of interleukins produce cells of the immune response - macrophages, monocytes, neutrophils, eosinophils, T-lymphocytes. It is they that help our body cope with infections and provide inhibition of the vital activity of pathogenic agents in conditions of elevated body temperature.
general information
Fever of unclear origin is one of the most complicated pathologies, which is not so rare (up to 14% of cases in the practice of internal diseases). In general, this is the condition of the patient when:
- An increase in temperature of more than 38.3 ° C is observed, which is the main (often the only) symptom of the patient’s clinical condition.
- It lasts for more than 3 weeks.
- This fever is of unknown origin (no reasons found). Even after 1 week of diagnostic search using conventional and additional techniques.
In accordance with the international classification of diseases, the ICD-10 R50 fever of unknown origin (fever of unknown origin).
Background
From ancient times, fever was understood as a condition accompanied by an increase in body temperature above subfebrile. With the advent of thermometry, it has already become important for the doctor not only to ascertain the fever, but also to determine its causes.
But until the end of the 19th century, fever of unknown origin remained the cause of the death of many patients. The first studies of this disease were conducted at Peter Bent Brigham Hospital (USA, 1930).
Only in the mid 60-ies of the last century, this clinical condition was widely recognized when R. Petersdorf and P. Beeson published the results of studies of 100 patients for 2 years (only in 85 the cause of the fever was established). It was then introduced in the ICD-10 - a fever of unknown origin code R50.
But until 2003, there was no classification of this type of fever. It was this year that the Roth AR and Basello GM diagnosticians (USA) proposed a classification of fevers of unknown origin and an algorithm for the diagnostic search for the causes of its occurrence.
In the article we give only a general overview of the etiologically possible causes of the clinical picture of such a pathology.
Symptomatic picture
Symptoms of such a fever follow from its definition: the temperature is higher than subfebrile, which lasts more than 2 weeks (constant or episodic), and the usual diagnostic methods did not establish its cause during the first week.
Fever can be acute (up to 15 days), subacute (16-45 days), chronic (more than 45 days).
According to the temperature curve, a fever happens:
- Constant (temperature during the day fluctuates within 1 degree).
- Laxative (during the day, temperature fluctuations from 1 to 2 degrees).
- Intermittent (periods of normal and high temperature within 1-3 days).
- Hectic (daily or for several hours temperature drops of 3 degrees).
- Return (periods of elevated temperature are replaced by periods with normal body temperature).
- Wavy (gradual, from day to day, increase in temperature and its same decrease).
- Incorrect or atypical (temperature fluctuations without visible patterns).
- Perverse (in the morning the temperature is higher than in the evening).
Sometimes a fever is accompanied by pain in the heart, asphyxiation, sweating, chills. Most often, fever is the only symptom of the disease.
Unclear fever: diagnostic search algorithm
The developed algorithm for searching for the causes of pathology includes the following stages: examination and examination of the patient, diagnostic concept, formulation of the diagnosis and confirmation of the diagnosis.
At the first stage, the most important in establishing the causes of fever of unknown origin (ICD-10 R50) is a detailed history. It is necessary to study the characteristics of the pathology: the type of temperature curve, the presence of chills, sweating, additional symptoms and syndromes. At this stage, routine laboratory and instrumental examinations are prescribed.
If a diagnosis is not established at this stage, they proceed to the next stage of the algorithm for fever of unknown origin - a diagnostic search and the formulation of a preliminary diagnostic concept based on all available data. The task is to develop a rational plan for subsequent examinations using optimally informative methods as part of the diagnostic concept.
In the subsequent stages, all concomitant symptoms are identified, as well as the leading additional syndrome, which determines the likely range of pathologies and diseases. Then, the diagnosis and causes of the pathological condition of a fever of unknown origin are established, code R50 according to ICD-10.
It is difficult to establish the cause of these conditions, and the diagnostic doctor must have a sufficient level of knowledge in all areas of medicine, and also follow the algorithm of actions for fevers of unknown origin.
When to start treatment
Prescribing treatment to patients with fever of unclear origin (ICD-10 code R50) until the diagnostic search is fully deciphered is far from an unambiguous question. It should be considered exclusively individually for each patient.
Mostly, in a stable condition of a patient with a fever of unknown origin, the doctor’s recommendations come down to the use of anti-inflammatory non-steroid drugs. Prescribing antibiotic therapy and glucocorticosteroids is considered an empirical approach, which in this case is unacceptable. The use of this group of drugs can lead to generalization of infection and worsen the patient's condition.
Prescribing antibiotics without sufficient grounds can also lead to systemic pathologies of the connective tissue (blood, bones, cartilage).
The question of trial treatment can only be discussed if it is used as a diagnostic method. For example, the appointment of tuberculostatic drugs to exclude tuberculosis.
If there is a suspicion of thrombophlebitis or pulmonary embolism, it is advisable to administer drugs that help to reduce hematocrit (heparin).
What tests can prescribe
After analyzing the history and primary results of the examination, the doctor can prescribe the following studies:
- General urine analysis.
- General and biochemical analysis of blood.
- Blood coagulogram, analysis for hematocrit.
- Aspirin test.
- Verification of neural transmission and reflexes.
- Thermometry for 3 hours.
- Mantoux reaction.
- X-rays of light.
- Echocardiographic studies.
- Ultrasound examination of the abdominal cavity and genitourinary system.
- Magnetic resonance imaging and computed tomography of the brain.
- Consultations of narrow specialists - gynecologist, urologist, neurologist, otolaryngologist.
Additional research
Additional tests and studies may be needed.
- Analysis of nasopharyngeal swabs for infection.
- A blood test for intrauterine infections.
- Isolation of viral antibodies, determination of their titers (diagnosis of cytomegalovirus, toxoplasmosis, herpes).
- HIV antibody test.
- To exclude malaria, a microscopic examination of a thick blood smear is performed.
- Blood test for LE cells to exclude systemic lupus erythematosus disease.
- Bone marrow puncture
- Skeleton scintigraphy to detect metastases.
- Bone densitometry (bone density is determined to exclude malignant tumors).
- Endoscopy, biopsy, radiation diagnosis of the gastrointestinal tract.
- Collection of family history for the presence of genetic diseases and allergic reactions to various drugs.
The reasons for the clinical picture
According to statistics, the causes of fever syndrome of unknown origin in 50% of cases are various infectious and inflammatory processes, in 30% - various tumors, in 10% - systemic diseases (vasculitis, collagenosis) and in 10% - other pathologies. Moreover, in 10% of cases, the cause of the fever cannot be established during the life of the patient, and in 3% of cases the cause remains unclear even after the death of the patient.
Briefly, the causes of such conditions can be:
- Urogenital tract infections, streptococcal infections, pyelonephritis, abscesses, tuberculosis and so on.
- Inflammatory processes in the connective tissues - rheumatism, vasculitis.
- Tumors and neoplasms - lymphoma, cancer of the lungs and other organs, leukemia.
- Diseases of a hereditary nature.
- Metabolic pathology.
- Damage and pathology of the central nervous system.
- Pathology of the gastrointestinal tract.
In about 15% of cases, the true cause of the fever remains undecided.
Drug fever
If you have a fever of unknown origin, it is important to have complete information about the patient taking any medications. Quite often, an increase in body temperature is evidence of an increased sensitivity of the patient to drugs. In this case, the temperature may rise some time after taking the drug.
In case of discontinuation of the drug, if the fever did not stop within 1 week, its medicinal genesis is not confirmed.
The occurrence of a febrile state can lead to:
- Antimicrobial antibiotics (penicillin and tetracycline, cephalosporins, sulfonamides).
- Anti-inflammatory drugs (ibuprofen, aspirin).
- Preparations for the treatment of the gastrointestinal tract (cimetidine, phenolphthalein, metoclopramide).
- Cardiovascular preparations (heparin, quinidine, alpha-methyldopa, hydrochlorothiazide).
- Drugs that affect the central nervous system (phenobarbital, haloperidol, thioridazine).
- Cytotoxic drugs (bleomycin, asparaginase).
- Antihistamines and iodine preparations, levamisole and allopurinol.
Modern classification
Fever nosology of unknown origin, ICD-10 code R50 has undergone some changes in recent decades. Types of fever appeared in immunodeficiency states, mononucleosis, and borreliosis.
In the modern classification, four groups of fevers of unknown origin are distinguished:
- The classic type, which, along with previously known diseases ("ordinary diseases with an unusual course") includes chronic fatigue syndrome, Lyme disease.
- Fever on the background of neutropenia (violations of the blood formula in the direction of reducing the number of neutrophils).
- Nosocomial fever (bacterial origin).
- HIV-related conditions (microbacteriosis, cytomegalovirus, cryptococcosis, histoplasmosis).
Summarize
The range of pathologies that underlie fever of unknown origin is very wide and includes diseases of various groups. This type of fever is based on ordinary diseases, but with an atypical course. That is why the diagnostic search for this pathology includes additional clinical diagnostic procedures aimed at identifying leading additional syndromes. Based on them, a preliminary diagnosis is possible , then its verification and establishment of the true genesis of the pathological condition of the patient.