Leptin concentrations in stimulated cycles

Abstract

differences in progesterone concentrations, rather the dichotomy appears to be a genetic device by mother nature'. Since Bernstein offers no explanation of how this device works, I suggest it has a hormonal basis -as, apparently, has a very large range of other mammalian sex ratio variation (James, 1996). References Foote, R.H. (1977) Leptin concentrations in stimulated cyclesDear Sir, We read the paper by with interest. The authors demonstrate rising leptin concentrations in cycles stimulated with follicle stimulating hormone (FSH) up to cycle day 6. Significantly higher leptin concentrations were found in the midcycle phase, compared with unstimulated cycles. These data confirm two previous reports by and our own group (Strowitzki et al., 1997), both presented at the 13th annual meeting of ESHRE 1997. Bützow et al. examined 45 patients of a routine in-vitro fertilization (IVF) programme in down-regulated cycles. They described a significant rise of endogenous leptin concentrations during ovarian stimulation (10.7 Ϯ 1.1 to 16.0 Ϯ 1.3 ng/ml). After 16 days the leptin concentrations returned back to normal. There was a significant correlation between oestradiol and leptin concentrations. Our own group reported similar results. In seven IVF patients in down-regulated cycles, stimulated with FSH, we found a significant leptin rise from day 3 to day 9. Meanwhile we have confirmed our findings in a larger series of 20 patients (Strowitzki et al., 1998).Since the authors have cited two presentations by and of the same abstract book they should have been aware of these reports. In order to ensure a thorough scientific discussion we feel that presentations dealing with exactly the same issue should not be simply neglected. Instead of claiming '...is the first in which changes in leptin concentrations...' a more careful research of literature would have been desirable to allow a better understanding of the behaviour and possible impact of leptin serum concentrations in two stimulated cycles. Dear Sir, We thank Dr Strowitzki for his interest in our study . The two studies by and Strowitzki et al. (1997) that Dr Strowitzki mentions have been published only as abstracts and not as full papers. We did not neglect these two studies, simply we were not aware of them. The two abstracts by and that are cited in our paper were not included in the initial manuscript submitted to the journal. They were only added after suggestions were made by one of the Referees. Nevertheless, between our study and the two studies mentioned by Dr Strowitzki, there are great differences. In these studies Strowitzki et al., 1997), the authors are presenting only two values of leptin during the follicular phase of gonadotrophin stimulated cycles, while in our study daily changes in leptin values are presented. Therefore, when we claim that 'the present study is the first in which changes in leptin concentrations were investigated during the follicular phase...' is absolutely true, because we mean 'during the whole follicular phase' and not ...