Serum estrogen levels tell you what is circulating. Essential Estrogens tells you what happens to estrogen afterwards — how it is broken down, which metabolites are formed, and whether they protect against or increase the risk of hormone-driven conditions.
2-OH metabolites are protective. 4-OH metabolites can form DNA adducts with carcinogenic potential. 16-OH metabolites are potently estrogenic. The ratio between these determines the risk profile — and the COMT enzyme, whose function is affected by genetic variants, governs critical steps of the breakdown pathway.
COMT rs4680 (Val/Met, Met/Met) impairs detoxification of catecholestrogens (4-OH) and potentially increases risk of hormone-driven cancers. Essential Estrogens confirms whether the genetic risk is actually expressed functionally — invisible in conventional serum estrogen tests.