Tuberculose: parâmetros de severidade, aspectos imunológicos e laboratoriais

Abstract

Inflammatory cytokines induced by phagocytosis of Mycobacterium tuberculosis promote a systemic response by inducing hepatic synthesis, by raising serum levels of acute phase proteins, such as C-reactive protein (CRP), and by decreasing others, such as albumin (ALB). In addition, phagocytosis stimulates the production of nitric oxide (NO) by macrophages, potential microbicidal agent. The study of biomarkers can be useful to identify good markers of diagnosis and follow-up of antituberculosis treatment, especially in cases of smear microscopy and/or negative culture, contributing to the closure of the presumptive diagnosis of tuberculosis (TB), in association with the clinical-radiological history. Some studies have already shown the role of PCR and ALB as markers, but few have evaluated the potential of the PCR/ALB ratio and the studies associated with NO are controversial. Besides that, the evaluation of tuberculosis severity through the evaluation of clinic, bacteriological and image exam with routine laboratory results could collaborate to improve diagnosis and monitoring suspected cases. The objective of this study was to evaluate the acute phase and oxidative stress markers of tuberculosis patients during antituberculosis treatment and its association with clinical, laboratory and radiological parameters, as if, the severity of tuberculosis through the evaluation of clinic, bacteriological and image exam and its correlation with routine laboratory results before antituberculosis treatment. We evaluated the levels of CRP, ALB, PCR/ALB ratio and NO in patients with tuberculosis (n=37) at different times of antituberculosis treatment: T1 (1 and 2 months, n = 16), T2 (4 months, n = 11) and T3 (5 and 6 months, n = 10) and NO in controls (n = 21). The risk of complications of inflammatory stress was associated with different levels of CRP/ALB. The clinical, laboratory and radiological data of the patients was obtained through the analysis of medical records. This work demonstrated that the levels of CRP and the PCR/ALB ratio were higher in T1 than in T2. The PCR/ALB ratio demonstrated a higher risk of complications of inflammatory stress in T1, with a reduction in T2. PCR and PCR/ALB ratio levels decreased from T1 to T2 in patients with positive (1+) smear microscopy and with the presence of fever and other symptoms. The levels of NO between controls and patients were not significant. The evaluation of severity demonstrated a prevalence of acid-fast-bacilli (AFB) (43,48%), fever associated with other symptoms (56,52%) and infiltrative tuberculosis on image (60,87%). Analises of tuberculosis severity demonstrated positive correlation only between micobacteria excretion and image diagnosis (rho=0,47; p=0,023), and no correlation between micobactria excretion and and clinic and between clinic and image diagnosis. The results showed that 9/21 patients presented hyponatremia, 6/13 presented hypomagnesaemia and 1/13 hypercalcaemia. When we associated these variables with the tuberculosis severity parameters, we verified that there was no difference in any of the stratifications evaluated. In this way, we conclude that PCR and PCR/ALB ratio can be used as diagnostic markers and antituberculosis treatment followup and the association of the PCR/ALB ratio associated risk of complications of inflammatory stress to follow the treatment efficacy. Similarly, the evaluation of different severity characteristics of tuberculosis, although reflecting the patient's degree of impairment, is not always correlated, nor does it influence changes in electrolytes, which can be associated with the general state of the patient, and may contribute to the clinical conduct.