Associations of Acute Phase Reactants with Disease Activity and Radiological Involvement in Pulmonary Tuberculosis

Background: Smear microscopy is widely used in diagnosing tuberculosis (TB), but its sensitivity may be limited in cases with low bacillary load or extrapulmonary involvement.This has led to growing interest in laboratory biomarkers that reflect disease activity.The immune response to Mycobacterium tuberculosis stimulates the release of inflammatory cytokines, triggering an acute-phase reaction.This study aimed to evaluate the associations of acute-phase reactants-including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and mean platelet volume (MPV)-with bacillary load, radiological involvement, and hospital stay in pulmonary TB patients. Materials and Methods:This retrospective study included 137 patients diagnosed with pulmonary TB.They were grouped as smearpositive or smear-negative, and culture-positive.Data on demographics, laboratory results (CRP, ESR, MPV), chest radiography, bacillary load, culture results, and length of hospital stay were analyzed.Radiological involvement was categorized as minimal, moderate, or extensive Results:The cohort was 69% male with a median age of 42 years.Smear positivity was found in 71% and culture positivity in 74% of cases.Radiological assessments showed minimal (47%), moderate (41%), and extensive (12%) involvement.CRP levels were significantly higher in smear-positive patients (p<0.001) and increased with more extensive radiological involvement (p=0.02).These patients also had longer hospital stays (p=0.001).No significant associations were found between MPV or ESR and bacillary load or radiological extent (p>0.05). Conclusion:CRP is a sensitive marker of inflammatory activity in pulmonary TB, correlating with both bacillary burden and radiological spread.It may be useful for evaluating disease severity and treatment response.MPV and ESR, however, appear to have limited clinical relevance in this context.