This session provides an overview of key laboratory investigations used in the diagnosis and management of rheumatic diseases, including inflammatory markers, autoantibodies, and organ function tests. Emphasis will be placed on understanding test indications, interpreting results in clinical context, and recognizing their role in differentiating between autoimmune, inflammatory, and degenerative conditions. Clinical implications such as monitoring disease activity (e.g., CRP in RA, anti-dsDNA in SLE), predicting prognosis (e.g., anti-CCP in RA), and identifying organ involvement (e.g., complement levels and urinalysis in lupus nephritis) will be highlighted to aid clinical decision-making in both undergraduate and postgraduate practice.