Estimation of Salivary LDH Level in Oral Lichen Planus and OSCC- A Biochemical Study

Abstract

Introduction: LDH is a cytoplasmic enzyme that appears extracellularly during cell necrosis and tissue damage. Increased LDH levels in saliva have been associated with oral diseases, including oral lichen planus (OLP) and oral squamous cell carcinoma (OSCC). Normally, LDH converts pyruvate into lactic acid to generate ATP under anaerobic conditions. In OSCC, cells preferentially convert glucose into lactic acid even under aerobic conditions, leading to upregulated LDH expression. Increased LDH levels are also observed in premalignant conditions such as OLP, a common chronic inflammatory mucocutaneous condition with a malignant transformation rate of 0–3.5%. Hypoxia and oxidative stress lead to increased glycolysis to meet cellular energy demands, resulting in increased LDH release. Thus, salivary LDH may serve as a non-invasive diagnostic indicator for assessing cellular damage and disease activity in OLP and OSCC. Aim and Objectives: To estimate and compare salivary LDH levels in patients with oral lichen planus, oral squamous cell carcinoma, and healthy individuals. Materials and Methods: The study included 45 subjects divided into three groups: 15 healthy controls, 15 patients with oral lichen planus, and 15 patients with oral squamous cell carcinoma. Unstimulated whole-saliva samples (2 mL) were collected under standardised conditions. The samples were centrifuged, and salivary LDH levels were estimated using a biochemical enzymatic assay. Statistical analysis was performed using ANOVA and Kruskal–Wallis tests. Results: Mean salivary LDH levels were significantly higher in patients with OLP (135.80 ± 50.43 U/L) and OSCC (304.46 ± 142.92 U/L) than in healthy controls (48.59 ± 24.97 U/L). The highest LDH levels were observed in patients with OSCC. Statistical analysis using ANOVA and Kruskal–Wallis tests showed a highly significant difference among the groups (p < 0.001). Conclusion: Salivary LDH levels are significantly elevated in OLP and OSCC compared with those in healthy individuals. Estimation of salivary LDH may serve as a simple, non-invasive, and cost-effective adjunctive biochemical marker for the early detection and monitoring of oral potentially malignant disorders and oral cancer.