ESTABLISHING POPULATION-SPECIFIC CLINICAL REFERENCE INTERVALS IN NIGERIA: CHALLENGES AND A PROPOSED 3-PHASE ROADMAPOnuoha AC1, Onuoha-Ojeamiren G2, Iduda Ojeamiren,3 Ogbiti MI4, Samuel SO2.Affiliations1Department of Chemical Pathology, College of Basic Clinical Sciences, Ambrose Alli University, Ekpoma, Edo State, Nigeria. 2Department of Medical Microbiology, College of Basic Clinical Sciences, Ambrose Alli University. 3Biomedical Scientist Dartford and Gravesham NHS trust. kent. 4Department of Obstetrics and Gynecology, Ambrose Alli University Ekpoma, Edo State, Nigeria. Corresponding AuthorName: Dr. Onuoha Augunus ChidubemEmail: onuohachidubem1@aauekpoma.edu.ngDepartment: Chemical Pathology, AAU, Ekpoma, NigeriaTelephone: +2348051251828Orcid: https://orcid.org/0009-0005-6632-3149ABSTRACT:Background: Most laboratories in Nigeria still use reference intervals (RIs) copied from textbook manuals or equipment/reagent inserts, most of which were derived from Caucasian populations. This can lead to misclassification of results, unnecessary referrals, and poor clinical decisions. Despite these known limitations, Nigeria does not yet have a coordinated national effort to establish its own population-specific RIs. Objective: To identify the key challenges to establishing population-specific clinical RIs in Nigeria and to propose a practical 3-phase roadmap for their development, validation, and integration into the national health system.Methods: We searched PubMed, Scopus, African Journal Online (AJOL), and Google Scholar for Nigerian studies on RIs published from 2000 to 2025. We also reviewed national and international guidelines on RI establishment. Data on study populations, methods, reported intervals, and stated challenges were extracted. From these findings, we developed a 3-phase roadmap to guide the establishment of Nigerian RIs. Meta-analysis was not conducted because of differences in study methods. Results: The review identified major gaps including limited funding, lack of standardized methods, insufficient multi-center data, and weak policy integration. Most published studies were single-center and covered only a few analytes. No national compendium of RIs currently exists. Conclusion: Establishing population-specific RIs in Nigeria is feasible but requires a coordinated, phased approach. We proposed a 3-phase roadmap focused on standardization, multi-center data generation, and policy integration. Prioritizing Phase 1 is recommended to begin the process. Implementing this roadmap will improve diagnostic accuracy and patient care across Nigeria.Keywords: Reference intervals; Nigeria; Population-specific; Laboratory standardization; Clinical laboratory; Health policy; implementation roadmap.