This study determined reference ranges for s-adenosylmethionine (SAM), s-adenosylhomocysteine (SAH), and their ratio in healthy male and female Caucasians, showing gender differences in these levels. It also investigated determinants influencing these levels, finding that the MTHFR 677C>T polymorphism affects SAM and SAH, while B-vitamin levels do not. Increased SAH and decreased SAM/SAH ratios are noted in patients with a history of pre-eclampsia, suggesting implications for vitamin interventions aimed at reducing cardiovascular risk.