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Joined 2026-09-21 Message
Incoming links: Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others
Estradiol 2026-11-05
Estradiol is an estrogen steroid hormone involved in reproductive development and regulation. It is one of the estrogens produced by the ovary and participates in the interacting hormonal signals of the menstrual cycle.[ref][ref]
Anatomy and Physiology 2e by J. Gordon Betts and others. §17.8, ovarian estrogens and reproductive functions
A concentration measured once cannot show the shape or ordering of a changing hormonal signal. In 1983, J. D. Hoff and collaborators sampled five women at two-hour intervals for five days around midcycle. The onset of the luteinizing hormone and follicle-stimulating hormone surges was temporally associated with peak estradiol levels.[ref]
Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others. Abstract, sampling schedule and timing relative to the estradiol peak
Plotting these measurements as time series distinguishes an increase, a peak and a subsequent decline. The observations support a temporal relationship in the measured cohort; their timing alone does not isolate every causal link in the feedback system. This makes sampling interval and the chosen time reference part of an interpretable hormone measurement.
Estrogen 2026-11-05
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. J. D. Hoff 2026-11-05
J. D. Hoff is an author of the 1983 study Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others, which examined how hormones from the ovary and pituitary gland change around ovulation. Its contribution was a time-resolved comparison: samples from five participants were taken at two-hour intervals over five days, allowing changes in estradiol, progesterone, luteinizing hormone and follicle-stimulating hormone to be aligned around the onset of the luteinizing hormone surge.[ref]
Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others. abstract, study design and timing reference
That alignment exposed relationships which a single measurement could miss: the surge began abruptly near peak estradiol, while the rise in progesterone had already begun. The experiment supplied a temporal picture of the hypothalamic–pituitary–ovarian axis; temporal association by itself does not prove which change caused another. The cited paper identifies Hoff by initials, which are retained here.
Luteinizing hormone 2026-11-05
Luteinizing hormone (LH) is a glycoprotein gonadotropin released by gonadotrophs in the anterior pituitary under control of gonadotropin-releasing hormone. It participates in ovulation and formation of the corpus luteum, and promotes testosterone production in the testis. The hormone's output is regulated within interacting pituitary and gonadal feedback pathways.[ref]
Anatomy and Physiology 2e by J. Gordon Betts and others. Section 17.3: Luteinizing Hormone and the pituitary hormone summary
The shape of a LH surge can be investigated by measuring several signals through time. In 1983, J. D. Hoff and colleagues studied five women with hormone measurements every two hours for five consecutive days around midcycle. They compared estradiol, progesterone and gonadotropin trajectories, finding an abrupt onset of the LH and follicle-stimulating hormone surges in temporal association with the estradiol peak.[ref]
Hormonal dynamics at midcycle: a reevaluation by J. D. Hoff and others. Abstract: sampling schedule, surge onset and the associated ovarian hormone changes
The report included a doubling of LH within a two-hour interval at surge onset. Such a change illustrates why sampling frequency matters: coarse measurements can blur an abrupt transition or shift the apparent ordering of events. The study describes a measured cohort pattern; it does not turn one isolated hormone measurement into a complete account of the cycle.
The relation to GnRH can also be probed by paired portal and peripheral blood plasma measurements. The hypophyseal portal system makes those two locations physiologically different: one carries the hypothalamic input, while the other records the pituitary's released output.