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.[ref]
Anatomy and Physiology 2e by J. Gordon Betts and others. §17.8, ovarian estrogens and their physiological functions
Estrogens also contribute to the growth of long bones, illustrating why their effects extend beyond reproductive tissues.[ref]
Estrogen in the NCI Dictionary of Cancer Terms. definition, sex characteristics and long-bone growth
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.[ref]
Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others. Abstract, sampling schedule and temporal association
This connects a specified member of the class to a measured time series; temporal association alone does not establish the direction of causation. New to topics? Read the docs here!