The increasing order of potency of estrogens is (least potent to most potent) ?
**Core Concept**
Estrogen potency is determined by the strength of estrogen receptors binding and the subsequent activation of downstream signaling pathways. Estrogen potency is typically measured by their ability to stimulate uterine growth, which is a reflection of their binding affinity to estrogen receptors.
**Why the Correct Answer is Right**
The correct answer is Estrone (E1), followed by Estradiol (E2), and then Estriol (E3). This order is based on their binding affinity to estrogen receptors, particularly ERα and ERβ. Estradiol has the highest binding affinity, followed by Estrone and then Estriol. Estradiol's higher potency is due to its ability to activate both estrogen receptors, whereas Estrone and Estriol have preferential binding to ERβ.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely incorrect because it does not follow the established order of estrogen potency.
* **Option B:** This option is incorrect because it places Estriol as the most potent estrogen, which contradicts the established order.
* **Option C:** This option is incorrect because it does not accurately reflect the order of estrogen potency.
**Clinical Pearl / High-Yield Fact**
The relative potencies of estrogens can be remembered using the mnemonic "Estradiol Eats Everything Else": Estradiol (E2) has the highest binding affinity to estrogen receptors, making it the most potent estrogen.
**Correct Answer:** C. Estrone, Estradiol, Estriol.