Abnormal inhibin A and inhibin B secretion in obese women with and without insulin resistance.
OBJECTIVE
The present study aimed to establish inhibin A and B serum levels during the menstrual cycle of obese women, and its usefulness as an index of luteal-phase follicular development.


METHODS
Twenty-one obese patients (mean body mass index: 34.9+/-3.7 kg/m2; range: 30.0-45.0 kg/m2) were submitted to basal hormonal measurements and an oral glucose tolerance test after challenge with 75 g glucose. Progesterone and inhibin A and B levels were determined 5-7 days after the menstrual cycle and 7 days prior to expected menses.


RESULTS
As expected, an increase in inhibin A and a decrease in inhibin B were observed when first-phase samples were compared with samples obtained after 15-20 days. On the other hand, the percentage variation of both inhibin A and B was at least four times smaller than the values for normal women described previously by other authors employing the same enzyme-linked immunosorbent assays. A small number of obese women presented ovulatory cycles characterized by progesterone concentration higher than 5.8 ng/ml. The percentage elevation (>190%) of inhibin A in the second samples was in agreement with the progesterone levels, but it seemed to be more sensitive for the detection of follicle luteinization.


CONCLUSIONS
We conclude that obese women present less percentage variation of both inhibin A and B during the menstrual cycle, associated with a low frequency of ovulatory cycles. In obese women, the percentage increase of inhibin A can represent an additional marker to recognize follicle luteinization.
Auge
Antonio Pedro
AP
Department of Gynecology and Obstetrics, Endocrinology Gynecology Unit, Santa Casa de São Paulo - Faculty of Medical Sciences, São Paulo, Brazil. pedroauge@terra.com.br
Longui
Carlos Alberto
CA
Almeida Prado
Roberto A
RA
Rocha
Mylene Neves
MN
Neves
Mylene Rocha
MR
Hirota
Andrea
A
Busso
Newton Eduardo
NE
Monte
Osmar
O
Aldrighi
José Mendes
JM
D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D007265:Inhibins / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000097:blood; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D010060:Ovulation; D011374:Progesterone / Q000097:blood; D011446:Prospective Studies; D012738:Sex Hormone-Binding Globulin / Q000032:analysis
D007328:Insulin; D012738:Sex Hormone-Binding Globulin; C422362:inhibin A; C422364:inhibin B; D011374:Progesterone; D007265:Inhibins; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone