Isoniazid-Related Hepatotoxicity in Clinical Practice: Incidence and Predictors

The objective of this observational study is to determine how frequently isoniazid (INH) causes liver injury (hepatotoxicity) in adults treated for tuberculosis (TB) or latent tuberculosis infection (LTBI) and to understand which factors increase this risk. The study also aims to describe how hepatotoxicity is managed in real-world clinical practice and whether treatments such as corticosteroids can improve liver function tests. The main questions this study aims to answer are: * How frequently does INH-induced hepatotoxicity occur in adults treated for TB or LTBI? * What demographic, clinical, microbiological, or lifestyle factors increase the risk of developing hepatotoxicity? * How do different management strategies, including treatment modification or the use of corticosteroids, affect liver recovery and completion of TB/LTBI therapy? This study does not involve experimental treatments. Researchers will analyze information already collected during routine clinical care, both retrospectively (from 2020 to 2025) and prospectively (2026-2028). There is no comparison group, but participants may have different clinical profiles or treatments, which will be compared to understand risk factors and outcomes. Participants will: * Receive standard treatment for tuberculosis or LTBI, including isoniazid, as prescribed by their treating physicians. * Undergo routine assessments, such as blood tests, microbiology, imaging, and clinic visits, as part of their regular care. * Their clinical data will be recorded in the study database to analyze liver function trends, treatment changes, and outcomes. The study will contribute to improving understanding of INH-induced hepatotoxicity and supporting safer and more effective treatment strategies for tuberculosis and LTBI.