= Estrogen
<Estrogens> are a class of <steroid hormones> that includes <estradiol>, <estrone> and <estriol>. They participate in several physiological processes, including development of reproductive tissues and regulation of the <menstrual cycle>. The class name identifies a family of signals, rather than one uniquely specified chemical.<Anatomy and Physiology 2e by J. Gordon Betts and others>[§17.8, ovarian estrogens and their physiological functions]{ref}
<Estrogens> also contribute to the growth of long <bones>, illustrating why their effects extend beyond reproductive tissues.<Estrogen in the NCI Dictionary of Cancer Terms>[definition, sex characteristics and long-bone growth]{ref} An experimental measurement consequently needs to identify both the substance being measured and the response of interest. An <estradiol> assay does not automatically measure every <estrogen> or summarize all of their biological effects.
For example, a 1983 study sampled five women at two-hour intervals over five days around midcycle. Peak <estradiol> levels were temporally associated with the onset of <luteinizing hormone> and <follicle-stimulating hormone> surges.<Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others>[Abstract, sampling schedule and temporal association]{ref} This connects a specified member of the class to a measured <time series>; temporal association alone does not establish the direction of causation.
Back to article page
