Racial variation in fasting and random homocysteine levels

Homocysteine (Hcy) levels have been shown to be a predeterminant of thrombotic diseases. We measured the Hcy levels of 50 blacks and 50 whites equally divided by gender to determine if there is a significant racial difference in either fasting or random Hcy levels. Dietary, medication, smoking, alcohol, past medical, educational, and occupational histories were obtained, and the body mass index calculated. Total serum fasting and random Hcy levels, B₁₂, folate, BUN, creatinine, and lipid profiles were drawn from each participant. Analysis of the results showed that white males have the highest fasting Hcy levels, 10.5 μM/l, whereas random Hcy levels were not significantly different. Correlation between fasting and random Hcy levels was poor (R = 0.61). B₁₂ levels in black subjects were significantly higher, 490.8 pg/ml, compared to whites, 382.8 pg/ml, P = 0.001, but contributed little to total Hcy levels (R² = 0.08). Folic acid levels, all within normal range, were not significantly different between the two racial groups and also did not appear to greatly affect Hcy levels (R² = 0.06). Our study demonstrates that, despite the genetic diversity of these two racial groups in the U.S., white males in this age group have higher fasting Hcy levels than black males, and white males, but not black males, have higher fasting homocysteine levels than females. This discrepancy in Hcy levels may reflect methylenetetrahydrofolate reductase (MTHFR) enzyme polymorphisms, known to be higher in whites, rather than socioeconomic influences.