Background: Hyperhomocysteinemia (HHCY) is an established cardiovascular risk factor, but its diagnostic threshold is primarily based on Caucasian reference values. Nutritional, genetic, and environmental factors vary across populations, potentially rendering these universal cut-offs inappropriate for specific regions like Northern Nigeria, where dietary B-vitamin deficiencies are prevalent.

Objective: To determine a locally derived cut-off value for hyperhomocysteinemia in an adult population in Gombe, North-Eastern Nigeria, and compare it with standard international values.

Methods: In this cross-sectional analytical study, plasma total homocysteine (tHcy) was measured in 90 heathy volunteers, using a competitive enzyme-linked immunosorbent assay (ELISA). Controls were recruited from patient relatives and hospital staff, excluding individuals with cardiovascular disease or on relevant medications. The local 90th and 95th percentile values of the tHcy distribution in the subjects were calculated to establish the upper reference limits. The derived value was applied to a cohort of 90 heart failure patients to assess the prevalence of HHCY.

Results: The mean plasma tHcy in the healthy control group was 10.24 ± 6.98 µmol/L. The 90th and 95th percentile values were 20.9 µmol/L and 25.1 µmol/L, respectively. Using the locally derived 90th percentile cut-off of 20.9 µmol/L, the prevalence of HHCY was 5.6. This cut-off is markedly higher than the commonly cited Caucasian threshold of 15 µmol/L.

Conclusion: This study establishes a higher local cut-off value for defining hyperhomocysteinemia in a Northern Nigerian population (90th percentile: 20.9 µmol/L). The application of Caucasian reference values would lead to significant over-diagnosis of HHCY in this setting. These findings underscore the critical need for population-specific reference ranges for homocysteine to ensure accurate clinical diagnosis, appropriate resource allocation, and valid epidemiological research in Sub-Saharan Africa.