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2001; Elsevier BV; Volume: 76; Issue: 3 Linguagem: Inglês

10.1016/s0015-0282(01)01916-1

1556-5653

Hilton José Pereira Cardim, Ceci Mendes Carvalho Lopes, Daniel Giannella‐Neto, Ângela Maggio da Fonseca, José Aristodemo Pinotti,

Estrogen and related hormone effects

We agree that it is difficult to explain why our results were different from those presented by Heald et al. (1Heald A. Selby P.L. White A. Gibson J.M. Progestins abrogate estrogen-induced changes in the insulin-like growth factor axis.Am J Obstet Gynecol. 2000; 183: 593-600Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar) and Campagnoli et al. (2Campagnoli C. Biglia N. Altare F. Lanza M.G. Lesca L. Cantamessa C. et al.Differential effects of oral conjugated estrogens and transdermal estradiol on insulin-like growth factor 1, growth hormone and sex hormone binding globulin serum levels.Gynecol Endocrinol. 1993; 7: 251-258Crossref PubMed Scopus (113) Google Scholar). We also consider that it could be mostly related to methodological aspects. In fact, the major problem is that there is not any commercially available method with enough sensitivity that allows reliable measurement of free insulin-like growth factor I (IGF-I). To avoid misinterpretations of the results, we have routinely measured all IGFN insulin-like growth factor binding Protein (IGFBP) system components in ethylenediaminetetraacetic acid (EDTA) treated plasma. Although we believe that EDTA could block some proteolytic activity of plasma that could interfere with the assays, we really do not know whether it would be the source of such divergent results. Further studies would be necessary to investigate whether different routes of hormone replacement therapy can have different effects on plasma proteolytic activity.