Introduction: We aimed to investigate the relationship between radiological extent and serum biochemical changes and body mass index (BMI) in patients with pulmonary tuberculosis (PTB) and pneumonia and to determine the usefulness of C-reactive protein (CRP) in clinical discriminative diagnosis.
Material and methods: One hundred fifteen patients with tuberculosis (group 1), 70 patients with pneumonia (group 2) and 30 healthy controls (group 3) were included in this case-control study.
Results: Total cholesterol (TC, p < 0.001 in group 1; p = 0.011 in group 2), high-density lipoprotein (HDL, p < 0.001), albumin (ALB, p < 0.001) and BMI (p < 0.001) values were significantly lower group 1 and group 2 than group 3. Erythrocyte sedimentation rate (ESR), leucocyte (LEU) and CRP were higher in group 2 than group 1 and group 3 (p < 0.001). As important point; triglyceride (TG) and BMI were significantly lower in group 1 than group 2 (p < 0.001). In group 1; BMI, HDL, TG, total protein (TP) and albumin were found to decrease, while CRP and ESR increased as the radiological stage increased (p < 0.05). But no significant difference was found in levels of TC and LDL (p > 0.05). In group 2; BMI, TC, HDL, LDL, TP and ALB were observed to decrease, while LEU, CRP and ESR increased as the radiological stage increased (p < 0.05). But no significant difference was found in levels of TG (p > 0.05). The best serum CRP cut-off value in differential diagnosis of tuberculosis and pneumonia was defined as 9.4.
Conclusions: The acute phase response occurring in tuberculosis and pneumonia determines the severity of the disease, leads to a decrease of serum levels of lipoproteins and BMI, and is correlated with the radiological extent. The CRP and ESR were found to be useful in differential diagnosis of tuberculosis and pneumonia.