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E2: E1 Ratio

Meaning

The E2:E1 Ratio represents the quantitative relationship between the two primary circulating estrogens: Estradiol (E2) and Estrone (E1). Estradiol is recognized as the most potent estrogen, while Estrone is a weaker estrogen often predominant after menopause. Clinically, this ratio is a significant indicator of estrogenic dominance and metabolic balance, particularly relevant in hormone replacement therapy and risk assessment. A low ratio often signifies a metabolic shift toward the less potent, but sometimes less desirable, estrogen form.