Effect of growth hormone administration frequency on 24-hour growth hormone profiles and levels of other growth related parameters in girls with Turner's syndrome. Dutch Working Group on Growth Hormone

Randomized GH trial with two different dosages in combination with a GnRH analogue in short small for gestational age children: effects on metabolic profile and serum GH, IGF1, and IGFBP3 levels

BACKGROUND

GnRH analogue (GnRHa) combined with GH treatment has been proposed to increase adult height. Effect on metabolic profile and GH, IGF1, and IGFBP3 levels in short small for gestational age (SGA) children is unknown.

OBJECTIVE

To assess fat mass and lean body mass SDS, percentage trunk fat, blood pressure (BP), insulin sensitivity (Si), beta-cell function (disposition index, DI), lipid profile, and GH, IGF1, and IGFBP3 levels during 2 years of combined treatment.

SUBJECTS

Forty-one pubertal short SGA children with a mean (+/-S.D.) age of 12.1 (+/-1.0) years.

DESIGN

Children received 3.75 mg of leuprolide acetate depot subcutaneously every 4 weeks, and they were randomly assigned to receive 1 mg (group A) or 2 mg (group B) of GH/m(2) per day.

RESULTS

Percentage trunk fat increased in both groups, but to a lower extent in group B. Lean body mass SDS increased only in group B. Changes in BP, Si, DI, and lipids were similar in both groups. Si significantly decreased, but DI remained unchanged. Lipids remained normal. GH and IGF1 levels were significantly higher in group B.

CONCLUSION

Our study is the first to report that 2 years of combined treatment with a GnRHa and either 1 or 2 mg GH/m(2) per day does not adversely affect body composition and metabolic profile of short SGA children who come under medical attention at the onset of puberty. There was a dose-dependent effect on fat mass SDS(height), percentage trunk fat, lean body mass SDS(height), and GH and IGF1 levels in favor of treatment with GnRHa and the higher GH dose of 2 mg/m(2) per day.

High serum levels of growth hormone (GH) and insulin-like growth factor-I (IGF-I) during high-dose GH treatment in short children born small for gestational age

CONTEXT

Epidemiological studies have indicated that high serum levels of GH and IGF-I are associated with long-term risks.

OBJECTIVE

The objective of the study was to evaluate the changes in serum levels of GH during overnight profiles, IGF-I, and IGF binding protein 3 (IGFBP-3) in short small for gestational age (SGA) children during GH treatment with two doses.

PATIENTS

Thirty-six prepubertal short SGA children were the subjects of this study.

INTERVENTION

Subjects received 1 (group A) or 2 (group B) mg GH/m(2).d.

MAIN OUTCOME MEASURES

At baseline and after 6 months of GH treatment, overnight GH profiles were performed, and serum IGF-I and IGFBP-3 levels were measured.

RESULTS

After 6 months, group B had significantly higher GH levels during the profile (mean, maximum, and area under the curve above zero line) than group A (P < 0.009). In group B, maximum GH levels increased from 43.9-161 mU/liter (P < 0.0002), and in group A, from 57.2-104 mU/liter (P = 0.002). During the profile (i.e. 12 h per day), children of group B had mean GH levels of 64.4 vs. 34.8 mU/liter in group A (P = 0.001). The IGF-I and IGF-I to IGFBP-3 ratio sd scores increased significantly in both groups, but were higher in group B than A [1.5 vs. 0.2 (P = 0.002) and 1.4 vs. 0.3 (P = 0.007), respectively]. In group B, 74% of the children had IGF-I levels in the highest quintile during GH treatment compared with 19% in group A.

CONCLUSION

Our study shows that high-dose GH treatment in short SGA children results in high serum GH and IGF-I levels in most children. We recommend monitoring IGF-I levels during GH therapy to ensure that these remain within the normal range.

Physiology and pathophysiology of growth hormone-binding protein: methodological and clinical aspects

Circulating GH is partly bound to a high-affinity binding protein (GHBP), which in humans is derived from cleavage of the extracellular domain of the GH receptor. The precise biological function GHBP is unknown, although a regulation of GH bioactivity appears plausible. GHBP levels are determined by GH secretory status, body composition, age, and sex hormones, but the cause-effect relationships remain unclarified. In addition to the possible in vivo significance of GHBP, the interaction between GH and GHBP has methodological implications for both GH and GHBP assays. The present review concentrates on methodological aspects of GHBP measurements, GHBP levels in certain clinical conditions with a special emphasis on disturbances in the GH-IGF axis, and discusses the possible relationship between plasma GHBP and GH receptor status in peripheral tissues.

Final height in girls with turner syndrome after long-term growth hormone treatment in three dosages and low dose estrogens

Although GH treatment for short stature in Turner syndrome is an accepted treatment in many countries, which GH dosage to use and which age to start puberty induction are issues of debate. This study shows final height (FH) in 60 girls with Turner syndrome treated in a randomized dose-response trial, combining GH treatment with low dose estrogens at a relatively young age. Girls were randomly assigned to group A (4 IU/m(2).d; approximately 0.045 mg/kg/d), group B (first year, 4 IU/m(2).d; thereafter 6 IU/m(2).d), or group C (first year, 4 IU/m(2).d; second year, 6 IU/m(2).d; thereafter, 8 IU/m(2).d). After a minimum of 4 yr of GH treatment, at a mean age of 12.7 +/- 0.7 yr, low dose micronized 17beta-estradiol was given orally. After a mean duration of GH treatment of 8.6 +/- 1.9 yr, FH was reached at a mean age of 15.8 +/- 0.9 yr. FH, expressed in centimeters or SD score, was 157.6 +/- 6.5 or -1.6 +/- 1.0 in group A, 162.9 +/- 6.1 or -0.7 +/- 1.0 in group B, and 163.6 +/- 6.0 or -0.6 +/- 1.0 in group C. The difference in FH in centimeters, corrected for height SD score and age at start of treatment, was significant between groups A and B [regression coefficient, 4.1; 95% confidence interval (CI), 1.4, 6.9; P < 0.01], and groups A and C (coefficient, 5.0; 95% CI, 2.3, 7.7; P < 0.001), but not between groups B and C (coefficient, 0.9; 95% CI, -1.8, 3.6). Fifty of the 60 girls (83%) had reached a normal FH (FH SD score, more than -2). After starting estrogen treatment, the decrease in height velocity (HV) changed significantly to a stable HV, without affecting bone maturation (change in bone age/change in chronological age). The following variables contributed significantly to predicting FH SD score: GH dose, height SD score (ref. normal girls), chronological age at start of treatment, and HV in the first year of GH treatment. GH treatment was well tolerated. In conclusion, GH treatment leads to a normalization of FH in most girls, even when puberty is induced at a normal pubertal age. The optimal GH dosage depends on height and age at the start of treatment and first year HV.

Carbohydrate metabolism during growth hormone treatment and after discontinuation of growth hormone treatment in girls with Turner syndrome treated with once or twice daily growth hormone injections

OBJECTIVE

To assess possible side-effects of treatment with supraphysiological GH dosages on carbohydrate (CH) metabolism in girls with Turner syndrome (TS) during GH treatment until adult height is reached as well as after discontinuation of GH treatment.

DESIGN

In a prospective, randomized injection frequency-response study, the effect of GH treatment in combination with low dose ethinyl oestradiol on CH metabolism was evaluated, comparing twice daily (BID) with once daily (OD) injections of a total GH dose of 6 U/m2/day until adult height was reached.

PATIENTS

Nineteen untreated girls with TS, mean (SD) pretreatment age 13.3 (1.7) (range 11.0-17.6) year.

MEASUREMENTS

Glucose and insulin concentrations during oral glucose tolerance tests (OGTT) were measured before and during GH treatment, as well as at 6 months after discontinuation of GH treatment.

RESULTS

GH treatment was discontinued after a mean of 43 (range 27-57) months. In one of the 19 girls, a different girl at each time point before, during and after discontinuation of GH treatment, the glucose response to OGTT after 120 minutes was above 7.8 mmol/l but below 11.1 mmol/l, indicating impaired glucose tolerance. None of the girls developed diabetes mellitus. Fasting glucose levels did not significantly change during, or after discontinuation of GH treatment. The 3 h area under the curve for time-concentration adjusted for fasting levels during the OGTT for glucose showed a significant decrease during GH treatment. In contrast to the glucose levels, GH treatment induced considerably higher insulin levels compared to pretreatment values. After discontinuation of GH insulin levels decreased to values comparable with pretreatment levels. None of these observed changes were different between the GH injection frequency groups. The changes in CH variables during and after discontinuation of GH were not related to changes in body mass index.

CONCLUSIONS

GH treatment with 6 U/m2/day in combination with low dose ethinyl oestradiol in girls with Turner syndrome aged > or =11 years did not negatively influence glucose levels, but induced higher levels of insulin indicating relative insulin resistance. These changes in insulin levels were independent of the frequency of the GH injections (once vs. twice daily). After discontinuation of GH treatment, insulin values decreased to baseline levels.

A longitudinal study on bone mineral density until adulthood in girls with Turner's syndrome participating in a growth hormone injection frequency-response trial

OBJECTIVE

The aim of this study was to assess the volumetric bone mineral density (BMD) in girls with Turner's syndrome (TS) before and during growth hormone (GH) treatment in combination with low dose oestrogens as well as three years after discontinuation of GH treatment.

DESIGN

In a prospective, randomized injection frequency-response study, the effect of GH treatment in combination with low dose ethinyl oestradiol (starting with 0.05 microgram/kg/day), on BMD was evaluated, comparing twice daily (BID) with once daily (OD) injections of a total GH dose of 6 IU/m2/day until adult height was reached. After discontinuation of GH treatment, the dosage of oestrogens was further increased to adult supplementation levels.

PATIENTS

Nineteen untreated girls with TS, mean (SD) baseline pretreatment age 13.3 (1.7) (range 11.0-17.6) year.

MEASUREMENTS

Before and during GH treatment, measurements of volumetric BMD were performed using phalangeal radiographic absorptiometry. In addition, the BMD measurements were repeated three years after discontinuation of GH treatment. BMD results were adjusted for bone age and sex, and expressed as SD-scores (SDS) using reference values of healthy Dutch girls.

RESULTS

At baseline, most individual BMD values of cortical bone as well as those of trabecular bone were within the normal range of healthy girls. However, the mean BMD SDS of the trabecular bone was significantly lower than zero. During treatment, the BMD SDS showed a significant increment to values equal or higher than zero after mean (SD) GH treatment period of 36.6 (7.5) months. The increase in BMD of the cortical bone was significantly higher in the OD group than in the BID group. The BMD SDS in the last year of GH treatment was not significant different between the two injection frequency groups. Three years after discontinuation of GH treatment, the BMD values had increased further similar as in healthy girls, resulting in BMD values all within normal range or even higher.

CONCLUSIONS

Most untreated girls with Turner syndrome, age >/= 11 years, have a normal volumetric BMD of the cortical, as well as of the trabecular bone compared to healthy girls. During GH treatment with 6 IU/m2/day in combination with low dose oestrogens, the BMD SDS increases significantly. After discontinuation of GH treatment and the use of oestrogens in an adult dosage, the BMD was as high as in young healthy women.

Carbohydrate and lipid metabolism during various growth hormone dosing regimens in girls with Turner syndrome. Dutch Working Group on Growth Hormone

To analyze the effects of supraphysiological dosages of growth hormone (GH) on carbohydrate (CH) and lipid metabolism, we investigated 87 girls with Turner syndrome (TS) in two studies: (1) a 4-year GH dose-response (DR) study comparing three groups with stepwise GH dosage increases up to 8 IU/m2/d in girls aged 2 to 11 years, and (2) a 2-year GH administration frequency-response (FR) study in girls aged 11 to 17 years, comparing once-daily (OD) and twice-daily (BID) injections of a total GH dose of 6 IU/m2/d in combination with low-dose ethinyl estradiol (50 ng/kg/d orally). At baseline, impaired glucose tolerance (IGT) was present in 6% of the girls, and at the end of the studies, in 5%. In the DR study, the area under the curve for time-concentration (AUCab) for glucose after an oral glucose tolerance test (OGTT) showed no change over time and no significant difference between any of the study groups. However, in all three DR groups, the AUCab for insulin, fasting glucose, the insulinogenic index, hemoglobin A1c (HbA1c), and urinary C-peptide (uCp) were all significantly higher after 4 years compared with pretreatment (P<.05). In the FR study, group differences were not observed. Compared with healthy Dutch control subjects, the median baseline levels in relatively young girls in the DR study were similar for total cholesterol (TC) and lower for high-density lipoprotein (HDL) cholesterol. In contrast, the median TC levels of relatively older girls in the FR study were higher and HDL levels were similar. With increasing GH dosage in the DR study, median TC and low-density lipoprotein (LDL) levels decreased, whereas median HDL levels increased. The changes after 4 years were significant, including a decrease in the atherogenic index. GH treatment at the supraphysiological dosages used in this study did not increase the frequency of IGT or clinical diabetes. However, we observed an increased insulinogenic index indicative of insulin resistance. Therefore, long-term follow-up study is warranted in these otherwise healthy subjects. OD injection regimens changed the lipid profile toward a more cardioprotective direction with a significant reduction of the TC/HDL cholesterol ratio.

Final height in girls with Turner's syndrome treated with once or twice daily growth hormone injections. Dutch Advisory Group on Growth Hormone

OBJECTIVES

To study final height in girls with Turner's syndrome treated with once or twice daily injections of growth hormone (GH) in combination with low dose ethinyl oestradiol.

DESIGN

Until final height was reached, the effect of fractionated subcutaneous injections given twice daily was compared with once daily injections of a total GH dose of 6 IU/m2/day. Twice daily injections were given as one third in the morning and two thirds at bedtime. All girls concurrently received low dose oestradiol (0.05 microgram ethinyl oestradiol/kg/day, increased to 0.10 microgram/kg/day after 2.25 years).

PATIENTS

Nineteen girls with Turner's syndrome aged > or = 11 years (mean (SD) 13.6 (1.7) years).

MEASUREMENTS

To determine final height gain, we assessed the difference between the attained final height and the final height predictions at the start of treatment. These final height predictions were calculated using the Bayley-Pinneau (BP) prediction method, the modified projected adult height (mPAH), the modified index of potential height (mIPHRUS), and the Turner's specific prediction method (PTSRUS).

RESULTS

The gain in final height (mean (SD)) was not significantly different between the once daily and the twice daily regimens (7.6 (2.3) v 5.1 (3.2) cm). All girls exceeded their adult height prediction (range, 1.6-12.3 cm). Thirteen of the 19 girls had a final height gain > 5.0 cm. Mean (SD) attained final height was 155.5 (5.4) cm. A "younger bone age" at baseline and a higher increase in height standard deviation score for chronological age (Dutch-Swedish-Danish references) in the first year of GH treatment predicted a higher final height gain after GH treatment.

CONCLUSIONS

Division of the total daily GH dose (6 IU/m2/day) into two thirds in the evening and one third in the morning is not advantageous over the once daily GH regimen with respect to final height gain. Treatment with a GH dose of 6 IU/m2/day in combination with low dose oestrogens can result in a significant increase in adult height in girls with Turner's syndrome, even if they start GH treatment at a relatively late age.

Growth and hormone characteristics of pubertal development in the hamadryas baboon

The semi-longitudinal collection of growth measurements in male and female hamadryas baboons has enabled documentation of the timing of puberty and the development of sexually dimorphic growth patterns in body weight, crown-rump length (CRL), limb lengths, and muscle mass. In addition, another sexually dimorphic characteristic appears to be the presence of a pubertal growth spurt in body weight, and possibly CRL, in male but not female baboons. Serum testosterone levels rose during male development; however, there was a progressive decrease in dehydroepiandrosterone sulfate levels indicating the absence of adrenarche. Insulin-like growth factor-I (IGF-I) and its major binding protein, IGFBP-3, both rose during pubertal development; however, a simultaneous rise in the IGF-I:IGFBP-3 molar ratio suggests other factors may enhance the bioactivity of IGF-I during puberty. A distinct rise in serum osteocalcin levels was also associated with puberty in male baboons. These growth and hormonal changes during puberty in the hamadryas baboon indicate that this species provides a close primate model for human puberty.

Plasma levels of insulin-like growth factor binding protein-3 in acute trauma patients

Insulin-like growth factors (IGFs) are a family of polypeptides that regulate cell growth. Their action and bioavailability are modified by binding proteins such as IGF binding protein-3 (IGFBP-3). Plasma IGFBP-3 level was found to be growth hormone (GH)-dependent, which makes detection of IGFBP-3 useful in the evaluation of GH secretion. In the early catabolic flow phase of severe injury, when plasma levels of GH and IGF-1 are low versus uninjured levels, the role of IGFBP-3 has not been investigated. We have measured basal levels of these polypeptide hormones in 16 adult (13 men and three women aged 47 +/- 7 years) severely injured (Injury Severity Score, 32 +/- 2), hypermetabolic resting energy expenditure [REE] to basal energy expenditure [BEE] ratio, 1.30 +/- 0.05), ventilator-dependent, multiple-trauma patients within 48 to 60 hours of injury when the patients were receiving maintenance fluids without calories or nitrogen. These basal values were compared with those of 16 age-matched postabsorptive normals. In the catabolic flow phase of injury, plasma levels of GH, IGF-1, and IGFBP-3 were significantly reduced by 50%, 46%, and 45%, respectively. There was a significant linear inverse relationship between IGFBP-3 and age and also a positive correlation between IGFBP-3 and IGF-1 in both control and injured subjects. The ratio of IGFBP-3 to IGF-1 was not changed in trauma victims. Measurement of plasma IGFBP-3 levels has potential as a marker for monitoring GH therapeutic efficacy.

Metabolic effects of growth hormone administered subcutaneously once or twice daily to growth hormone deficient adults

OBJECTIVE

The aim of this study was to compare the metabolic effects of GH administered subcutaneously either once or twice daily. The actions of GH might depend upon a pulsatile pattern of serum GH. Pulsatile and continuous intravenous delivery of GH, however, induce similar short-term metabolic effects in GH deficient patients. An improved growth response is obtained in GH deficient children when a fixed weekly GH dose is administered by daily subcutaneous injections instead of twice or thrice-weekly intramuscular injections. A more pulsatile pattern and serum GH levels above zero might be achieved by further increasing the injection frequency. Increased daytime GH levels might, however, adversely affect the circadian patterns of metabolic indices, which have been demonstrated to be more successfully reproduced by evening compared with morning GH administration.

DESIGN AND MEASUREMENTS

In a cross-over study, 8 GH deficient patients (age 16-43 years) were treated with 3 IU/m2/24 h of human GH. The dose was injected in the evening for 4 weeks and for another 4 weeks two-thirds was injected in the evening and one-third in the morning. At the end of each period the patients were admitted to the hospital for 37 hours. Steady-state profiles of GH, IGF-I, IGF binding proteins 1 and 3, insulin, glucose, lipid intermediates and metabolites were obtained following administration of 3 IU/m2 of GH (at 1900 h (one injection) and at 1900 and 0800 h (two injections)).

RESULTS

Similar mean integrated levels of serum GH (mU/l) were obtained (7.46 +/- 0.84 (one injection) vs 6.46 +/- 0.62 (two injections) (P = 0.15)). Mean levels +/- SEM of serum IGF-I (micrograms/l) were significantly increased (P < 0.01) following two daily GH injections (330.3 +/- 48.1 (one injection) vs 399.1 +/- 53.0 (two injections)). Serum IGFBP-3 levels were not significantly different on the two occasions, while levels of the GH independent IGFBP-1 (micrograms/l) were slightly but significantly lower following twice-daily GH injections (1.61 +/- 0.42 vs 1.13 +/- 0.56, respectively (P < 0.04)). The pattern of IGFBP-1 was opposite to that of insulin. Similar levels of insulin and glucose were obtained with both GH regimens, while levels of non-esterified fatty acids were significantly higher following once-daily GH injection (P < 0.001).

CONCLUSIONS

Twice-daily GH injections, apart from producing a more physiological serum GH profile, were superior to one injection in increasing serum IGF-I and decreasing IGFBP-1 levels. Both of these changes tend to amplify the effects of the administered GH. Twice-daily injections, however, resulted in lower night-time levels of lipid intermediates.