Terry Gimpel

Serum leptin concentration in women: effect of age, obesity, and estrogen administration

OBJECTIVE To compare serum leptin levels in normally cycling reproductive females (20-35 years old) with those in age-matched males, in women who were receiving oral contraceptives, and in older (postmenopausal) women (50-65 years old) who were or who were not receiving hormone replacement therapy. DESIGN Case-control study. SETTING Obstetrics and Gynecology Clinic, Texas Tech University Health Sciences Center-Amarillo, or the Exercise Physiology Laboratory at Southeastern Louisiana University. PATIENT(S) Normally cycling women between the ages of 20-35 years and age-matched controls who were receiving oral contraceptives. Postmenopausal women between the ages of 50-65 years who were or who were not receiving hormone replacement therapy. MAIN OUTCOME MEASURE(S) Serum leptin concentration. RESULT(S) In all groups, serum leptin concentrations were correlated significantly with body mass index. Leptin levels were significantly higher in young women than young men (P <.001), but no other statistically significant differences were found for the other three comparisons. CONCLUSION(S) Serum leptin concentrations expressed as a measure of adiposity (body mass index) are greater in young normally cycling females (20-35 years old) than in age-matched males. There is no difference in levels of serum leptin between young and postmenopausal (50-65 years old) women. Estrogen administration, either in young women who are receiving estrogen-progestin oral contraceptives or in postmenopausal women who are receiving hormone replacement therapy, does not effect serum leptin concentrations.

Variability of serum estrogens among postmenopausal women treated with the same transdermal estrogen therapy and the effect on androgens and sex hormone binding globulin

OBJECTIVE To examine the variability of serum estrogens in response to transdermal estrogen replacement therapy (ET), and to determine the effects on androgens and sex hormone binding globulin (SHBG). DESIGN Randomized, double-blind, placebo-controlled study. SETTING Womens hospital. PATIENT(S) Two groups of postmenopausal women: [1] 21 women not on ET enrolled and 17 completed the study; [2] 19 women on continuous transdermal ET enrolled and 13 completed the study. INTERVENTION(S) Women not on ET were administered a placebo patch or a newly initiated estrogen patch, then crossed over to the alternate treatment. Serum samples were obtained at baseline and the subsequent 3 days from the placebo and new-patch groups and from a separate group of women receiving continuous estrogen patch treatment. MAIN OUTCOME MEASURE(S) Estradiol (E(2)), estrone, estrone sulfate, T, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), androstenedione, free androgen index, and SHBG. RESULT(S) There was considerable intrapatient and interpatient variability in the estrogen response to identical treatment doses, with E(2) values differing between women as much as 138 pg/mL and E(2) increases above baseline differing as much as 90 pg/mL. Continuous treatment increased SHBG and decreased androstenedione levels; however, levels of T, DHEA, DHEAS, and free androgen index did not change. CONCLUSION(S) There is great variability of estrogen in response to transdermal ET, but minimal effect on circulating androgens.

Effects of high-intensity exercise on leptin and testosterone concentrations in well-trained males.

Objective: A number of investigations have examined the effect of exercise on leptin concentrations, because leptin is associated with obesity, satiety, and reproductive function. High-intensity exercise is known to increase testosterone, an inhibitor of leptin. The objective of the study was to determine whether the leptin responses to a progressive, intermittent exercise protocol were related to serum testosterone concentrations. Most previous studies have examined leptin responses to low or moderately high exercise intensities. A second objective was to determine whether leptin responses were different than previous experiments using intermittent moderate and high-intensity exercise.Methods: Well-trained runners completed strenuous intermittent exercise consisting of treadmill running at 60, 75, 90, and 100% VO2max and a subsequent resting control trial was also conducted.Results: There were significant increases in mean serum levels of leptin and testosterone with both quickly returning to baseline during recovery, but no relationship between the two hormones was found. After examining individual data for both hormones, it was discovered that subjects could be classified as leptin responders or nonresponders, whereas testosterone increased in all subjects. Responders had elevated serum leptin levels at baseline and exhibited increases after high-intensity exercise, whereas nonresponders did not show changes in leptin during exercise.Conclusions: Data suggest testosterone levels do not acutely affect leptin responses to exercise or 1-h of recovery. Moreover, varied leptin responses to intense exercise in comparable well-trained runners was observed and was associated with baseline leptin concentrations.

Comparison of three methods for 17α-Hydroxyprogesterone

We compared the performance of three 17α‐hydroxyprogesterone kits: the double antibody method, the coated tube method (ACTIVE™), both from Diagnostic Systems Laboratories, Inc. (DSL) and the coated tube method (COAT‐A‐COUNT®) from Diagnostic Products Corporation (DPC). The assay performance of the two DSL kits was very similar in terms of sensitivity, intra‐ and inter‐assay precision, linearity of dilution, recovery, and specificity. We also analyzed 190 samples for 17α‐hydroxyprogesterone values using the above three kits. Twenty‐three subjects were from prepubertal population (ages 1 month–13 years), thirty subjects were normal adult males (ages 20–53 years) and the remaining subjects were females in different phase of menstrual cycle (n = 40), on oral contraceptives (n = 20), post‐menopausal (n = 17), or pregnant women in their first, second, or third trimester (n = 60). In addition to these 60 pregnancy samples, we analyzed serial samples from 3 pregnancies. 17α‐OHP levels paralleled the progesterone levels in all three kits. Although there was reasonable correlation between the DPC and the two DSL kits, the 17α‐OHP values were found to be significantly higher with DPC kit during the 2nd and 3rd trimester of pregnancy indicating probable interference in the DPC assay by some structurally related steroids present during pregnancy. The DSL assays may be particularly well suited for measuring 17α‐OHP levels during pregnancy. J. Clin. Lab. Anal. 11:179–185, 1997.