Growth Hormone Bioactivity in Girls with Turner's Syndrome: Correlation with Insulin-like Growth Factor I1

Foster, Carol M.; Borondy, Maria; Markovs, Mara E.; Hopwood, Nancy J.; Kletter, Gad B.; Beitins, Inese Z.

doi:10.1203/00006450-199402000-00019

Cited by 15 publications

(3 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In another report, after arginine and insulin stimulation, the responses of GH measured by RIA were 8-fold greater than those measured by bioassay, suggesting that the GH isoforms released by pharmacologic stimuli are not highly bioactive (15). Moreover, also in Turner syndrome, GH bioactivity has been described to be lower than that expected for immunoreactivity (16). To our knowledge, this is the first report of a dissociation between GH bioactivity and immunoreactivity measured in overnight samples and in physiologic conditions.…”

Section: Discussionmentioning

confidence: 99%

Growth Hormone Immunoreactivity Does Not Reflect Bioactivity

et al. 2000

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Growth Hormone Immunoreactivity Does Not Reflect Bioactivity

et al. 2000

View full text Add to dashboard Cite

“…However, results are equivocal; the spontaneous and stimulated GH secretion has been found to be diminished by some (35,39), whereas others have found a normal GH secretion (38,42,50). Also, the bioactivity of the circulating GH has been reported to be reduced (16), and different GH isoforms have been found to prevail by some (7) but not by others (30). The normal pubertal increase in GH secretion is absent in Turner girls but can be restored partially by replacement of sex hormones (41,51).…”

mentioning

confidence: 97%

Reduced free IGF-I and increased IGFBP-3 proteolysis in Turner syndrome: modulation by female sex steroids

Gravholt

Frystyk

Flyvbjerg

et al. 2001

American Journal of Physiology-Endocrinology and Metabolism

View full text Add to dashboard Cite

The bioactivity of the growth hormone-insulin-like growth factor (IGF) system is reduced in Turner syndrome and may explain the reduction seen in final height. We compared levels of free and total IGF-I, immunoreactive and Western ligand blot IGF-binding protein (IGFBP)-3, and IGFBP-3 proteolysis in women with Turner syndrome (n = 23) before (T(B)) and during 6 mo treatment with 17beta-estradiol and norethisterone. An age-matched group of controls (n = 24) was included. Total IGF-I and immunoreactive levels of IGFBP-3 were comparable in T(B) and controls, whereas free IGF-I (P = 0.02) in T(B) was less than in controls. Western ligand blotting (WLB)-IGFBP-3 was significantly lower in T(B) than in controls (P = 0.0005). Accordingly, IGFBP-3 proteolysis was greater in Turner syndrome (P = 0.001). Female sex steroid treatment increased WLB-IGFBP-3 (P = 0.0005), whereas immunoreactive IGFBP-3 and IGFBP-3 proteolysis were normalized (P = 0.004). Free IGF-I remained unchanged (P = 0.8), with a tendency toward a decrease in total IGF-I (P = 0.1). In conclusion, despite normal total IGF-I and immunoreactive IGFBP-3, free serum IGF-I is less and IGFBP-3 proteolysis is greater in Turner syndrome than in controls. During sex steroid treatment, IGFBP-3 proteolysis normalized, without any change in free IGF-I.

show abstract

“…Sex hormone replacement in Turner's syndrome is associated with normalizing effects on the GH-IGF axis, body composition, physical fitness, and hepatic function. The bioactivity of GH produced has been suggested to be lower than that in controls (8), and different isoforms have been found to prevail (9). Finally, the route of administration of 17␤-estradiol is of minor importance in Turner's syndrome.…”

mentioning

confidence: 99%

Body Composition and Physical Fitness Are Major Determinants of the Growth Hormone-Insulin-Like Growth Factor Axis Aberrations in Adult Turner’s Syndrome, with Important Modulations by Treatment with 17β-Estradiol1

Gravholt¹,

Naeraa

Fisker³

et al. 1997

The Journal of Clinical Endocrinology &Amp; Metabolism

View full text Add to dashboard Cite

The objectives of this study were to 1) study the GH-insulin-like growth factor (IGF) axis in adult untreated Turner's syndrome compared to that in age-matched controls; 2) examine the effects of sex hormone substitution on this axis, 3) study the effects of route of administration of 17 beta-estradiol on the measured variables, and 4) examine the effects of sex steroids on hepatic function in Turner patients. Twenty-seven patients with Turner's syndrome were evaluated before and during sex hormone replacement, and an age-matched control group (n = 24) was evaluated once. Main outcome variables were GH and other measures of the GH-IGF axis, body composition, maximal oxygen uptake, sex hormone-binding globulin, and hepatic enzymes and proteins. The integrated 24-h GH concentration (IC-GH; micrograms per L/24 h) was reduced in women with Turner's syndrome (T) compared to controls [C; mean +/- SD, 18.3 +/- 12.0 (T) vs. 37.2 +/- 29.7 (C); P = 0.007]. However, multiple regression revealed that fat-free mass (FFM) and maximal oxygen uptake were significant explanatory variables (joint r = 0.77; P < 0.0005), accounting for 60% of the variance in the 24-h IC-GH. This association was also present in controls. After adjustment for these two variables, any difference in GH concentration between Turner patients and controls disappeared. Serum IGF-I and IGF-II were identical in Turner patients and controls despite the difference in 24-h IC-GH. The level of GH-binding protein (GHBP; nanomoles per L) was higher in Turner women [1.87 +/- 0.72 (T) vs. 1.22 +/- 0.33 (C); P = 0.0005]; after adjustment for FFM, the difference in GHBP levels disappeared between Turner patients and controls. During sex hormone treatment a significant increase was seen in the 24-h IC-GH (P = 0.02), FFM (percentage of weight; P < 0.0005) and maximal oxygen uptake (milliliters of O2 per kg/min; P = 0.02). Serum IGF-I was unchanged, whereas serum IGF-II (micrograms per L) decreased significantly [Turner, basal (TB), vs. Turner, treatment (TT), 860 +/- 135 vs. 823 +/- 150; P = 0.04]. Alanine aminotransferase (units per L), gamma-glutamyl transferase (units per L), and alkaline phosphatase (units per L) were significantly elevated during the basal study period, and all decreased during treatment [alanine amino-transferase, 55 +/- 55 (TB) vs. 30 +/- 20 (TT; P = 0.006); gamma-glutamyl transferase, 92 +/- 98 (TB) vs. 43 +/- 65 (TT; P = 0.003); alkaline phosphatase, 211 +/- 113 (TB) vs. 175 +/- 54 (TT); P = 0.06]. The route of administration of 17 beta-estradiol did not affect its actions. In conclusion, we found the GH-IGF axis in Turner's syndrome to be normal, with body composition and physical fitness exerting the same modifying effects on this axis as seen in the normal population. Sex hormone replacement in Turner's syndrome is associated with normalizing effects on the GH-IGF axis, body composition, physical fitness, and hepatic function. The lowering of hepatic enzymes is a surprising and hitherto undiscovered action of sex steroids. Finally, the route ...

show abstract

Growth Hormone Bioactivity in Girls with Turner's Syndrome: Correlation with Insulin-like Growth Factor I1

Cited by 15 publications

References 14 publications

Growth Hormone Immunoreactivity Does Not Reflect Bioactivity

Growth Hormone Immunoreactivity Does Not Reflect Bioactivity

Reduced free IGF-I and increased IGFBP-3 proteolysis in Turner syndrome: modulation by female sex steroids

Body Composition and Physical Fitness Are Major Determinants of the Growth Hormone-Insulin-Like Growth Factor Axis Aberrations in Adult Turner’s Syndrome, with Important Modulations by Treatment with 17β-Estradiol1

Contact Info

Product

Resources

About