The study aims to assess the viability of replacing serum samples with plasma samples in clinical chemistry and immunoassay tests, examining the implications on turnaround time (TAT) and sample quality during the transition process. Results demonstrate that while most tests showed no significant difference between serum and LIH tubes, some analytes exceeded total error (TE) values derived from total allowable error (TEa) limits. However, alternative allowable error limits were determined for certain tests, indicating that plasma tubes could be used instead of serum tubes for most tests, except for lactate dehydrogenase (LDH). Additionally, the use of plasma tubes improved sample quality, reduced aspiration errors, and significantly decreased TAT, thus suggesting that LIH tubes can effectively replace serum tubes in clinical laboratories, enhancing healthcare quality and reducing staff workload.