Correlation of TB LAM Ag (Tuberculosis Lipoarabinomannan Antigen) Results from Urine with Adenosine Deaminase Levels from Pleural Fluid Patients with Pulmonary TB Accompanied by Pleural Effusion

Abstract

Background: One of the newest testing methods for active TB uses TB LAM Antigen, in which lipoarabinomannan (LAM) as the examined substance serves as the main component of the cell wall of M. tuberculosis (MTB) and the degradation product of MTB by macrophages in the human body. Patients with active TB with or without HIV infection may experience a decreased antibody response, which causes LAM not to bind to antibodies so that it can pass through the normal glomerular basement membrane and can be detected in the urine. Lateral flow urine lipoarabinomannan assay (LF-LAM) can detect this material with urine samples from active TB patients. Another TB screening method uses the measurement of adenosine deaminase (ADA) activity. ADA has a very important function for the proliferation and differentiation of lymphoid cells, especially T cells, and assists in the maturation of monocytes into macrophages. Objective: This study aims to qualitatively prove the correlation between the pleural fluid ADA levels of pulmonary TB patients with pleural effusion using the LF-LAM test results and examine the potential of TB LAM Ag, which correlates with increased pleural fluid ADA levels, as a diagnostic tool for diagnosing pulmonary TB. Method: It is an observational analytic study with a crosssectional design. Materials for this study included temporary urine from active TB patients at Dr. Soetomo Regional Public Hospital collected in May-August 2022. The descriptive analysis was conducted using SPSS 25.0. The data were tested for normal distribution and with the homogeneity test of Shapiro-Wilk's data. The statistical analysis was performed using the Mann-Whitney test, while the kappa suitability test was carried out to determine the correlation and level of concordance between the ADA cut-off value of pleural fluid and the TB LAM Ag test results. Results: This study involved 50 subjects consisting of 22 (44%) subjects with ADA test results between 40-100 IU/L compared to 28 subjects (56%) with ADA test results below 40 IU/L. There were 14 (28%) subjects with positive TB LAM Ag test results, consisting of 10 (45%) active TB subjects with a high ADA test cut-off of 40-100 IU/L and 4 (14%) active TB subjects with a low ADA test cut-off below 40 IU/L, with a p-value = 0.012. Conclusions: There is a correlation between TB Lipoarabinomannan antigen test results of TB patients with pleural effusion. TB LAM Ag can be detected positive on ADA test results of < 40 IU/L and more positive in active TB patients with high ADA test results of > 40-100 IU/L. Therefore, the TB LAM Ag test is more sensitive than the ADA test. The cut-off value of the ADA test reached 76.4 U/L, and a positive TB LAM was found. Key words: TB Lipoarabinomannan (LAM) Antigen, Adenosine deaminase (ADA) test, Active TB with pleural effusion.