From Big Medical Encyclopedia

SUBFEBRILE CONDITION (Latin the sub-prefix under, in weak degree + febris fever) — constant fervescence ranging from 37,1 ° to 38,0 °, noted is long, from two weeks to several months or years. For the characteristic of acute short-term hyper thermies in these limits use the concept «subfebrile fever». Distinguish low S. with temperature increase to 37,5 ° and high S. — St. 37,5 °.

In nek-ry cases of S. the long time can be the only symptom of a disease; it gave a reason for the use of this concept instead of the nosological diagnosis. Such approach contradicted the nosological principle of a formulation of the diagnosis of a disease (see. Diagnosis ), therefore it was subjected to fair criticism in 30 — the 40th. Most of modern clinical physicians understand as S. the nonspecific reactive condition of an organism arising at many diseases and connected with temporary reorganization on more high level of regulation of heat exchange. The numerous wedge, examples of the analysis of S. of not clear genesis indicate insufficient, unilateral inspection of the patient.

Interpretation of the mechanism of development fevers (see) allows to divide S. by its nature into two look: Page, caused by activation of effect of endogenous pyrogen (see. the Pyrogenic substances ) on the temperature center, and S. arising without participation of pyrogens (functional S.).

Diseases of the infectious, tumoral and immunoconflict nature happen the most frequent reason of S. of the first look.

From inf. diseases most often is S.'s reason hron. nonspecific focal infection (chronic cholecystitis, prostatitis, adnexitis, tonsillitis, tooth granuloma, hron. rhinitis at children, etc.). However it is not always followed by Page. Therefore only S.'s disappearance after sanitation of the center of an infection allows to establish connection between them. The page instead of febrile fever can be observed at purulent and septic processes in case of the insufficient or changed reaction of an organism on in-fekt or owing to small virulence of nonspecific pathogenic flora or its partial suppression by insufficient antibacterial therapy. In modern clinic the atypical, erased forms of sepsis with S. proceed both as a septicaemia, and as a septicopyemia. It is noted, by data A. F. Bilibin (1981), at 29% of patients sepsis (see). The infectious endocarditis (see) develops sometimes inertly and the long time by an indisposition and

S. without the expressed intoxication, with preservation of working capacity can be shown. At this disease of S. reflects first of all immunol. pathogenetic mechanisms. The page often accompanies small forms tuberculosis (see): bronchadenitis, primary complex, early tubercular intoxication, focal, infiltrative tuberculosis, etc. They often have the erased beginning and proceed under masks of different diseases. Temperature in evening (is more rare in morning) increases hours to 37,2 ° — 37,3 ° at several o'clock, then goes down to datum level below. Also the diseases caused by protozoa and helminths can be S.'s cause. In S.'s formation at inf. processes products pathogenic flora of endotoxin with weak pyrogenicity and weak activation of products of endogenous pyrogen leukocytic and macrophagic cells matter.

From the diseases interfaced to changes of imkhmunny reactions, S. are followed rheumatism (see), pseudorheumatism (see), collagenoses (see. Collagenic diseases), a sarcoidosis (see), hron. enteritis (see Enteritis), ulcer nonspecific colitis (see), a postinfarction syndrome (see), a medicinal allergy (see). At the same time strengthening of synthesis of endogenous pyrogen monocytic makrofa-galnymi cells in the course of increase in their phagocytal activity as a result of a sensitization of an organism matters. With synthesis of pyrogen other numerous factors of damage of fabrics can cause similar phagocytal activity. From them aseptic processes of a rassasyvaniye of the necrotic fabric causing so-called resorptive fever, napr at a recurrent myocardial infarction, hemorrhages in a perigastrium and fabric matter, etc.

At malignant tumors of S. can be one of the earliest displays of a disease, sometimes for 6 — 8 months advancing other its symptoms. At the same time in S.'s development formation of cell-bound immune complexes plays a role, but the earliest emergence it is connected with development by tumoral fabric of the protein having the pyrogenic properties. E.g., at lymphogranulomatosis (see), an adenocarcinoma of a kidney (see Kidneys, tumors) this protein is found in blood, urine, fabric of a tumor. In the absence of local displays of a malignant tumor diagnostic value has S.'s combination to so-called paraneoplastic manifestations (see. Paraneoplastic syndromes ). Besides, malignant lymphoma can be shown by plazmokletochny reaction and paraproteinemias; a gepatoma, a hypernephroma — a hyperglobulia etc. Carry hemolitic anemia, leukemoid and myeloproliferative reactions to early paraneoplastic manifestations of autoimmune genesis, etc. S. caused by generally autoimmune conflicts is characteristic of an aggravation hron. myeloleukemia and lymphoid leukosis, lymphoma and lymphosarcomas.

The page, arising without participation of pyrogens, is observed at the diseases and states breaking function thermal controls (see). Fervescence can be caused by reduction of a thermolysis, napr, at administration of atropine, or strengthening of heat production during the overheating. The page can be a consequence of strengthening of formation of energy and heat in an organism at a thyrotoxicosis, stressful reaction and at introduction of nek-ry drugs (Phenaminum, muscle relaxants); it is noted at a pheochromocytoma, patol. climax and other disturbances of endocrine functions.

Existence of the so-called thermoneurosis which is characterized by S.'s presence as manifestations of permanent disorder of heat exchange as a result of functional defeat of the temperature center meeting at vegetative dysfunction at children, teenagers and women of young age is allowed. Such S. is often dependent on intensity physical and cerebration, is quite often characterized by the big range of daily temperature variations (about 1 °) and its normalization during a night dream. Functional disturbance of thermal control can be hereditary caused; according to M. S. Veynberg, apprx. 2,5% of healthy people of the birth have body temperature higher than 37 °. Disturbances of thermal control can be display of organic pathology of a nervous system at the level of a trunk of a brain. At the same time in genesis of development of feverish reaction a certain value can have mechanical irritation hypothalamus (see). Injuries of the head, emotional an overstrain, endocrine shifts serve as the factors provoking disturbance of thermal control. It can be shown by S. after recovery from various diseases, including infectious.

Complexity in diagnosis of the functional reasons of S. consists that approximately a half of these patients has a focal infection, and S. in itself can be an indicator of activity having neoterminated-shegosya inflammatory process especially as the functional reasons of S. induce feverish reaction to pyrogen.

Studying biol. showed values of temperature reaction of gomoyotermny organisms that consensually with it along with increase in activity of a cellular host defense from an infection the sideropenia of redistribution character develops and production of steroid hormones increases (see) and Aldosteronum (see). At the same time in S.'s clinic it is described at the iron deficiency anemias and states accompanied with the increased content in blood of excess of steroid hormones and products of their metabolism. E.g., S. at premenstrual syndrome (see) explain with increase in content in blood of etiocholanolone, pregnane. Obviously, feverish reaction in these cases is not biologically purposeful, and is caused genetically.

Inspecting patients concerning S., it is necessary to exclude false sub-febrile temperature. At the same time it must be kept in mind the wrong indications of the thermometer which is not corresponding to a standard, an opportunity simulations (see), the artificial temperature increase by patients with a psychopathia and hysteria caused in various ways. In the latter case discrepancy of temperature and pulse attracts attention. At interpretation of results of the amidopirinovy test which is applied to differentiation of fever of an infectious and noninfectious origin it is necessary to consider that antipyretics (see) have hypothermal effect at the level of the temperature center, breaking influence on it of endogenous pyrogen. It explains decrease in body temperature even after single administration of antipyretics at all patol. the processes leading to strengthening of effect of endogenous pyrogen on the temperature center.

The village does not break the general condition of the patient and does not demand a symptomatic treatment. It is eliminated at treatment of the disease which was the reason of its development, impact on various links of system of thermal control. So, at a lymphogranulomatosis suppression of synthesis of endogenous pyrogen is the cornerstone of hypothermal effect of Prednisolonum. At the vegetative dysfunction which is followed by S., sedative therapy gives good effect. Unacceptably symptomatic appointment at S. of the glucocorticoids, salicylates derivative of pyrazyl ketone and antibiotics if the diagnosis is not found out. These drugs can eliminate nek-ry rather specific symptoms, in particular shade immunol. shifts and to delay diagnosis.

See also Body temperature , Thermometry .

Bibliography: Bilibin A. F., D in at-rechensky G. of Page and M and r to about in and E. A. Clinical laboratory features of sepsis, Rubbed. arkh., t. 53, No. 10, page 14, 1981; Vane A. M., Solovyova A. D. and Kolosova of O. A. Vegeto - vascular dystonia, M., 1981; Vorobyov A. I. and Brilliant of M. D. Gipertermiya in internal clinic, Rubbed. arkh., t. 53, No. 10, page 4, 1981; Hegglin R. Differential diagnosis of internal diseases, the lane with it., page 121, M., 1965; Atkins E. BodelP. Fever, New Engl. J. Med., v. 286, p. 27, 1972; Bern-heim H. A., Block L. H. a. Atkins E. Fever, pathogenesis, pathophysiology, and purpose, Ann. int. Med., v. 91, p. 261, 1979; Bod el P. Generalized perturbations in host physiology caused by localized tumors, Ann. N. Y. Acad. Sci., v. 230, p. 6, 1974; In about del P. Dillard M. Studies on steroid fever, J. clin. Invest., v. 47, p. 107, 1968; Collins K. J. a. Few J. D. Secretion and metabolism of cortisol and aldosterone during controlled hyperthermia, J. Physiol. (Lond.), v. 292, p. 1, 1979.

E. I. Sokolov, T. A. Polosova.