Research Center for Endocrinology and Metabolism, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden
Address correspondence to: Professor John-Olov Jansson, M.D., Ph.D., Research Center for Endocrinology and Metabolism, Gröna Stråket 8, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden. E-mail: JOJ{at}medic.gu.se.
To the editor:
In hypopituitary adult humans with GH deficiency, men have a more beneficial response to treatment with GH in terms of serum IGF-I concentration, body composition, and bone mineral density compared with women receiving a similar GH dose (1, 2). There are several possible explanations for this gender difference. Oral estrogen treatment has been shown to decrease the serum IGF-I response to GH in hypopituitary women (2) and, consequently, could be one explanation for the lesser treatment response in women. Moreover, total daily secretion of endogenous GH is higher in women than in men (3). However, it is not fully clear whether women can achieve a similar treatment response as men, even if they receive a higher dose of GH. Furthermore, there is a risk of increased fluid-related side effects in women if the dose of GH is increased.
The study by Jessup et al. (4) in the October 2003 issue of JCEM, which also is in line with previous studies (5), could add one further explanation to the gender difference in the response to treatment. Men produce most of their GH during nighttime, whereas women produce GH throughout the 24-h day (see Fig. 1 in Ref. 4). At present, the standard GH treatment is one daily sc GH injection given at bedtime. This regimen has been shown to increase mainly nighttime GH levels for about 12 h (6). Therefore, this serum GH pattern seems to be more similar to that observed in healthy men than to that in healthy women. We hypothesize that the present standard treatment with GH results in a serum pattern that is less beneficial in women, because it does not mimic their endogenous GH secretory pattern. Rodents have similar gender differences in the GH secretion pattern as humans, and it has been shown that gender-adapted GH treatment patterns result in appropriate physiological replacement effects (7). Further studies are needed to investigate whether the present GH replacement, including administration mode, is optimal in GH-deficient women.
Footnotes
A response to this letter was invited, but the authors of the original article (Jessup et al.) chose not to provide one.
Received December 24, 2003.
References
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