Absence of effects of long-term growth hormone replacement therapy on insulin sensitivity in adults with growth hormone deficiency of childhood-onset (GHDA-CO)

Growth Hormone & IGF Research 13 (2003) 295–302 www.elsevier.com/locate/ghir

Absence of effects of long-term growth hormone replacement therapy on insulin sensitivity in adults with growth hormone deficiency of childhood-onset (GHDA-CO) Mirta Knoepfelmacher*, Raquel Soares Jallad, Bernardo Liberman Endocrine Unit, Hospital das Cl
ınicas from University of S~ ao Paulo Medical School, 05403-900 S~ ao Paulo, Brazil Received 7 February 2003; received in revised form 11 May 2003; accepted 13 May 2003

Abstract In order to assess long-term efficacy and safety of GH therapy in GHDA-CO, we studied 20 patients (8 female, 12 male; mean age 24.6
6.2 years) treated with GH for up to 24 months. The assessment (IGF-1, IGFBP3, lipid profile, body composition, glycated hemoglobin, oral glucose tolerance test, ISI-HOMA and ISI-composite derived from OGTT) was carried out before GH and every 3 months during the first year of treatment, and then every 6 months. We observed a significant increase of IGF-1, lean mass and HDL levels and a decrease in LDL levels. Fasting glucose presented a significant increase, within the normal range, after 6 months, returning to pre-treatment levels at 9 months with no further alteration. Fasting insulin, the areas under the glucose and insulin curves, ISI-HOMA and ISI-composite did not vary significantly. We conclude that long-term GH therapy improved body composition and lipid profile, without altering ISI in this cohort of patients with GHDA-CO. Ó 2003 Elsevier Science Ltd. All rights reserved. Keywords: Growth hormone-deficient adults of childhood-onset; Growth hormone replacement therapy; Carbohydrate metabolism; Insulin sensitivity; Lipid profile; Body composition

1. Introduction GH deficiency in adults has been associated with several cardiovascular risk factors including hyperlipidemia [1–3], altered body composition with increased abdominal adiposity [4,5] and increased insulin resistance [6,7]. Increased total body fat (BF) and reduced lean body mass (LBM) may impair insulin sensitivity and cause adverse metabolic effects as a consequence of hyperinsulinemia. Replacement therapy with recombinant GH tends to normalize body composition [8,9], reducing BF and increasing LBM. Nevertheless, the direct insulin antagonistic effects of GH have been demonstrated [10,11]. Therefore, some previous studies [12–14] on GH replacement therapy in adults with hypopituitarism have shown an increase in fasting plasma glucose, insulin, and C-peptide levels, indicating devel*

Corresponding author. Tel.: +55-11-3062-6654; fax: +55-11-30830626. E-mail address: [email protected] (M. Knoepfelmacher).

opment of insulin resistance during GH treatment. On the other hand, an euglycemic hyperinsulinemic clamp study in nine adults with GH deficiency showed a significant decrease in glucose disposal after six weeks of GH replacement followed by a significant increase after 6 months of treatment [15] suggesting that the acute insulin antagonistic action of GH may be counteracted by the long-term beneficial effects on body composition. However, the few long-term studies evaluating insulin sensitivity during GH replacement therapy in GHDA have shown conflicting results. Two groups reported decreased insulin sensitivity as measured by IVGTT over 18 months [16] and 30 months [17] of GH replacement. Nevertheless, the three longest open label studies involving a small group of GHDA patients showed no worsening in insulin sensitivity after 7–10 years of GH replacement [18–20]. With the objective of assessing the impact of longterm GH replacement therapy on insulin sensitivity, 20 GH-deficient adults of childhood onset (GHDA-CO) were submitted to OGTT before and during chronic GH

1096-6374/$ - see front matter Ó 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1096-6374(03)00040-6

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M. Knoepfelmacher et al. / Growth Hormone & IGF Research 13 (2003) 295–302

treatment. The insulin sensitivity index derived from the OGTT (ISI-composite) was calculated. The ISI-composite is a simple method that provides indices of hepatic and whole-body insulin sensitivity from data obtained from the OGTT and shows a high correlation to whole-body insulin sensitivity during euglycemic insulin clamp [21]. We also estimated the areas under the glucose and insulin curves during the OGTT, and the ISI-HOMA derived from homeostasis model assessment [22]. Body composition and lipid profile were also evaluated.

2. Subjects and methods 2.1. Patients Twenty patients (8 females and 12 males; mean age 24.6
6.2 years) with previously diagnosed growth hormone deficiency of childhood onset (GHDA-CO) were studied. Upon admittance into this study, all patients were submitted to two GH-stimulation tests (insulin tolerance test – ITT, and clonidine test) and all of them had GH deficiency confirmed by a GH peak <3 ng/ml and low levels of IGF-1 for sex and age (Table 1). Multiple pituitary deficiencies were present in all patients and all of them had been receiving adequate and stable replacement therapy for other pituitary deficiencies for at least 1 year before study entry. All patients were submitted to magnetic resonance imaging (MRI) of the pituitary region, upon entry into this study. Two

patients developed GHD as a consequence of the treatment for a central nervous system tumor, one pinealoma (patient 14, treated by radiotherapy 10 years before entering this protocol) and one astrocytoma of the optic nerve (patient 17, submitted to surgery via transsphenoidal route + radiotherapy, 8 years before entering this study). There was no evidence of tumor recurrence at MRI in these 2 patients; the other 18 patients presented pituitary hypoplasia and stalk transection with ectopic neurohypophysis. Four patients had never been treated (patients 5, 9, 18 and 20) and 16 patients had been treated with human pituitary derived or recombinant GH until final height was achieved. Time between the end of the previous GH therapy and admittance into this protocol in these patients was 1–7.6 years (3.7
2.0 years). None of the patients was a smoker and patients were asked not to change their lifestyles, including eating habits and physical activity. Patients were excluded if they suffered from diabetes mellitus or other chronic diseases. 2.2. Experimental protocol The study protocol was approved by the Ethical Committee of Hospital das Cl
ınicas, and patients gave written informed consent before starting the trial. Twenty patients were treated with GH (Norditropinâ , Novo Nordisk) for 12 months and 12 patients for 24 months. GH was administered daily, subcutaneously, at bedtime. The initial plan was to treat 20 patients for only 12 months. The first 9 patients started treatment

Table 1 Clinical and laboratorial data of 20 adult patients with GHDA-CO N

Sex (M/F)

Age (years)

BMI (kg/m2 )

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

F M F M F M M F M M M F F M M F M F M M

24 28 24 26 18 33 21 23 28 23 25 24 18 18 22 22 21 27 22 46

21.5 20.0 25.4 26.3 18.8 17.4 19.7 20.5 22.8 19.1 17.5 17.1 30.0 23.9 30.9 22.0 30.1 19.9 25.2 23.3

TSH, GN TSH, ACTH, TSH, ACTH, TSH, GN ADH TSH, ACTH, TSH, ACTH, GN TSH, ACTH, TSH, ACTH, TSH, ACTH, TSH, GN TSH TSH, ADH TSH TSH, ACTH, TSH, ACTH, TSH, ACTH, TSH, ACTH, TSH, ACTH,

GN GN

GN GN GN GN GN

GN GN GN GN GN

GH peak ITT (ng/ml)

GH peak clonidine (ng/ml)

IGF-1a (ng/ml)

IGFBP3a (mg/l)

<0.1 0.2 <0.1 <0.1 3 0.2 <0.1 0.2 <0.2 0.1 0.1 0.2 0.9 0.2 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

<0.1 <0.1 <0.1 <0.1 0.9 0.2 <0.1 <0.1 <0.1 0.1 0.2 0.2 0.1 0.2 0.1 <0.1 <0.1 <0.1 <0.1 <0.1

39.0 36.0 42.0 64.0 44.0 42.5 35.0 35.5 54.0 14.0 16.5 34.0 132.5 100.0 45.0 34.5 35.5 18 37.5 18

0.70 0.30 0.30 0.70 0.80 0.50 1.20 1.30 0.8 0.74 1.03 1.90 2.68 1.82 1.90 1.40 2.20 0.40 2.50 0.7

Abbreviations: BMI, body mass index; TSH, thyroid-stimulating hormone; GN, gonadotropins; ACTH, adrenocorticotropic hormone; ADH, antidiuretic hormone. a Mean of two basal values, ITT, insulin tolerance test.

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with 0.05 IU/kg/day and kept this dosage for 12 months, which was the initially proposed period for the length of the study. However, when 8 patients had already completed the protocol and stopped GH treatment, additional GH was made available for the study. The ninth patient, who was still on treatment, was asked to continue the study for an additional 12 months and had his dosage reduced to 0.025 IU/kg/day, during the latter period of the study. This was done to keep the same dosage of the 11 subsequent patients who started and were treated for 24 months with 0.025 IU/kg/day, following the more recent recommendations of low-dose GH treatment for adults. There was no drop out from the study. Patients were seen at baseline and monthly for the first 3 months of GH therapy, and then every 3 months during the first year, when they were submitted to a laboratorial and clinical evaluation. Afterwards, they were assessed every 6 months until the end of the study. Fasting glucose, IGF-1, and IGFBP-3 were assessed monthly at the first 3 months. From then on, these parameters were assessed concomitantly with glycated hemoglobin (HbA1c ), fasting plasma lipids and body composition at each visit throughout the 24 months of treatment. All patients were submitted to a 75-g oral glucose tolerance test (OGTT) at fasting state, between 8 and 9 a.m., performed basally and every 3 months during the first year of GH treatment, and then every 6 months during the following year. The patients were asked not to restrict carbohydrate ingestion and not to change habitual physical activity for at least one week prior to the test. Blood was collected at 30-min intervals for 2 h, for plasma glucose and insulin measurements. 2.3. Calculations The areas under the curve (AUC) for glucose and insulin responses during the OGTT were calculated using the trapezoidal rule. A composite measurement of whole-body insulin sensitivity, ISI-composite, that encompasses both hepatic and peripheral tissues [21] derived from OGTT was calculated according to the formula: 10 000 ISI-composite ¼ pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ; ðFPG  FPIÞðGm  Im Þ where FPG and FPI represent fasting plasma glucose (mg/dl) and insulin (lU/ml), respectively, and Gm and Im correspond to the mean value of plasma glucose and insulin during a 120-min OGTT, respectively. We also calculated the ISI-HOMA derived from the homeostasis model assessment [22] using the formula: 22:5 ; FPG  FPI where FPG is expressed in mmol/l and FPI in lU/ml. ISI-HOMA ¼

297

2.4. Laboratory methods GH was measured by IFMA (AutoDELFIAe, Wallacâ , Turku, Finland), IGF-1 was determined by RIA, after acid–ethanol extraction (Diagnostic Systems Laboratories – DSL, Webster, TX, USA), IGFBP-3 was assayed by IRMA (DSL) and insulin was determined by RIA (DSL), according to manufacturerÕs recommendations. The coefficient of variation (CV) of commercial serum control samples measured 2–4 times in each run in at least 10 different assays in our laboratory were 4.5% at 2.4 ng/ml, 3.8% at 7.8 ng/ml and 4.3% at 155 ng/ ml for GH (conversion factor 1 ng/ml ¼ 2.6 mU/l); 9.8% at 62.3 ng/ml and 12.6% at 181.4 ng/ml for IGF-1; 10.6% at 0.76 mg/l and 7.4% at 1.61 mg/ml for IGFBP-3 and 11.2% at 35.2 pmol/l, 9.5% at 116 pmol/l and 4.7% at 380 pmol/l for insulin. All determinations for insulin levels from each patient were run in the same assay. References for age and sex were determined by DSL for IGF-1 and IGFBP-3. Fasting total cholesterol, HDLcholesterol, tryglycerides, glucose and glycated hemoglobin levels were measured with standard procedures. LDL-cholesterol was calculated using Friedwald formula. Body composition was assessed by whole-body bioelectrical impedance analysis using a portable impedance analyzer (RJL Systems, Detroit, MI, USA). LBM and total BF were calculated from the measured impedance and reactance by a RJL Systems computer program. Adult bone age was confirmed in all patients. Pituitary–hypothalamic MRI were performed in all patients (Tesla 1.5, Sigma GE, Milwaukee, WI, USA) upon entering the study. The 2 patients with previously treated hypothalamic–pituitary tumors were also submitted to MRI after 1 year of GH treatment. 2.5. Statistical analysis Data are expressed as means
SD. The data obtained in basal state and during GH treatment were analyzed by ANOVA, after logarithmic transformation when necessary, on 20 patients up to 12 months and on 12 patients up to 24 months. The comparison among the different times was performed through the contrast analysis. The difference was considered significant when p was <0.05.

3. Results When we analyzed the laboratory and clinical data, including the incidence of adverse effects through all the study period, we did not find any statistical difference, comparing the groups treated with higher and lower GH dosages. Similarly, when we compared the data of all the

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20 patients during the first 12 months of treatment with the 12 separate patients that continued therapy up to 24 months of treatment, there was no difference in any parameter analyzed. Therefore, in Tables 2 and 3, the data from the 20 patients are shown altogether during the first 12 months of treatment. The results of IGF-1, IGFBP-3, body composition and lipid profile are shown in Table 2. Before treatment, IGF-1 concentrations were all below )2 SD for age and sex. All patients presented a significant increase, achieving normal IGF-1 concentrations for age and sex within 3 months of therapy (48
35 vs 163
98 ng/ml, p ¼ 0:0001, basal vs 3 months of treatment, respectively) with a further increase at 6 months (163
98 vs 211
113 ng/ml, p ¼ 0:038, 3 vs 6 months, respectively), which remained increased for the 24-month treatment period. Mean IGFBP-3 concentrations were also low for

age and sex before therapy and increased after 3 months (1.2
0.7 vs 2.4
1.2 mg/l, p ¼ 0:0001) remaining at those levels until the end of the study. There was no significant alteration in weight. Lean mass (kg) increased significantly at 6 months (39.4
9.6 vs 43.9
10.1 kg, p < 0:001) and lean mass percentile also increased significantly from 3 months on (71.2
6.1 vs 77.1
8.5%, p ¼ 0:0001) with no subsequent alterations until the end of the treatment. There was a significant decrease in fat mass after 3 months (16.3
6.6 vs 13.1
7.0 kg, p ¼ 0:0019) and in fat mass percentile (28.7
6.1 vs 23.0
8.6%, p ¼ 0:0002, basal vs 3 months, respectively), which remained decreased until the end of the study. We observed a significant decrease in the mean levels of LDL-cholesterol (3.2
0.8 vs 2.6
0.6 mmol/l, p ¼ 0:0023, basal vs 12 months, respectively) and a

Table 2 Effects of GH treatment on the mean values of IGF-1, IGFBP3, body composition and lipid profile Time of treatment (months) Basal IGF-1 (ng/ml) IGFBP3 (mg/l) Weight (kg) Fat mass (%) Lean mass (%) Triglycerides (mmol/l) Total cholesterol (mmol/l) HDL-cholesterol (mmol/l) LDL-cholesterol (mmol/l)

3

48
35 1.2
0.7a 55.8
15.0 28.7
6.1 71.2
6.1 1.16
0.58 4.9
0.85 1.17
0.39 3.2
0.8

6 a

163
97 2.4
1.2a 55.3
13.3 23.0
8.6a 77.1
8.5a 1.18
0.62 4.6
0.88 1.12
0.34 2.9
0.7

9 a

211
113 2.2
0.9a 57.6
15.6 22.6
8.7a 77.4
8.7a 1.15
0.62 4.6
0.90 1.24
0.37 2.9
0.7

12 a

171
100 2.4
1.0a 54.1
12.5 23.3
8.6a 76.8
8.9a 1.04
0.53 4.7
1.1 1.32
0.42b 2.9
0.8

18 a

24 a

246
91 2.6
1.3a 56.9
15.0 20.7
8.1a 79.3
8.1a 1.00
0.51 4.3
0.72 1.32
0.41b 2.6
0.6c

205
118 2.8
1.0a 56.2
153 23.0
7.7a 77.0
7.7a 0.88
0.7 4.5
0.56 1.30
0.27 2.8
0.5

202
91a 2.5
0.8a 57.3
17.3 24.8
7.1a 75.3
7.1a 0.99
0.44 4.7
0.67 1.34
0.30 3.0
0.6

a

vs basal, p < 0:001. vs basal, p < 0:005. c vs basal, p < 0:05. b

Table 3 Effects of GH treatment on the mean value parameters of the carbohydrate metabolism Time of treatment (months)

Fasting glucose (mmol/l) Fasting insulin (pmol/l) Glycated hemoglobin (%) 120 min glucose (mmol/l)c Glucose area under the curve (mmol/l min)c Insulin area under the curve (pmol/l min)c ISI-composite ISI-HOMA a

Basal

3

6

9

12

18

24

4.58
0.38

4.72
0.42

4.85
0.52a

4.57
0.43b

4.75
0.45

4.70
0.63

4.85
0.57

68.2
33.0

144.9
156.4

117.7
139.2

156.4
162.8

129.1
147.1

76.7
68.9

80.4
45.9

6.2
0.8

6.2
1.1

5.7
0.1

5.7
0.1

6.1
0.3

6.0
0.5

5.8
0.5

5.67
1.58

6.23
2.25

6.2
1.44

6.37
1.168

6.57
1.45

6.28
1.61

6.88
1.66

779
161

829
175

864
144

822
156

838
154

800
141

845
116

53 736
45 331

61 834
47 448

50 512
25 220

46 150
29 625

62 839
43 222

54 329
50 017

53 576
33 887

6.87
4.46 0.61
0.43

5.04
3.41 0.53
0.43

4.72
2.48 0.50
0.29

5.02
3.42 0.45
0.33

4.55
3.33 0.41
0.29

6.70
4.39 0.70
0.38

5.44
3.18 0.59
0.33

vs basal, p ¼ 0:0435. 6 month vs 9 month, p ¼ 0:0334. c On OGTT. b

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299

Fig. 1. Glucose and insulin mean levels at baseline and after 1 year and 2 years (n ¼ 12) of GH therapy.

significant increase in the mean levels of HDL-cholesterol compared to basal (1.17
0.39 vs 1.32
0.42 mmol/l, p ¼ 0:025, basal vs 9 months). There were no significant alterations on total cholesterol and triglyceride levels. The data on glucose and insulin parameters are shown in Table 3. Fasting glucose levels presented a significant increase, within the normal range, after 6 months (4.58
0.38 vs 4.85
0.52 mmol/l, p ¼ 0:04), returning to pre-treatment levels at 9 months, until the end of the study. We did not observe any significant alteration in the mean areas under the glucose curve (GAUC) during the OGTT performed at different times of treatment (Fig. 1). The mean 120-min glucose levels did not vary significantly during GH treatment. Nevertheless, when analyzing the glucose curves individually, we detected an intolerant test, at different occasions, in 9 patients (1,3, 6, 7, 8, 10, 13, 16 and 17). One patient (#6) had already presented intolerance at the time of enrollment, then presenting normal levels after 3 months of GH treatment, and intolerance again at 9 and 12 months, with a subsequent normalization. Two patients were obese before the beginning of treatment (#13 and #17) and 2 patients increased their total weight while increasing their lean body mass. No patient progressed to a biochemical or clinical picture of diabetes during the treatment. There was no variation in glycated hemoglobin throughout the study. There was no significant change in fasting insulin levels in the 20 patients treated for 12 months, nor in the 12 patients treated for 24 months. Insulin area under the

curve (IAUC) and the ratio IAUC/GAUC did not change during GH treatment. There was no significant variation either in the ISIHOMA or in the ISI-composite during the study. However, we observed a non-significant decrease of the ISI-composite (D ¼ 26%; 6.87
4.46 vs 5.04
3.41) at 3 months with a further reduction at 12 months (D ¼ 33%; 6.87
4.46 vs 4.55
3.33 basal vs 12 month), parallel to similar variations of the ISI-HOMA. Nevertheless, after 18 months of GH treatment, these indexes returned to the basal values.

4. Discussion In our study, we observed an increase of the mean fasting glucose levels in relation to the basal values after 6 months of GH therapy. However, this variation occurred within the normal range and decreased significantly to basal values at 9 months of therapy, remaining stable until the end of the study. We did not observe any significant variation in the concentration of fasting insulin throughout the study. Early short-term studies (less than 12 months) on GH replacement in adults with GHD have disclosed an increase of fasting glucose [8,13] and insulin [8] levels and others, an impairment of insulin sensitivity [4,13,15]. However, other authors did not observe variations in these parameters. The preliminary results of a multicentric register involving 602 patients (477 GHDA-AO and 125 GHDA-CO) of whom 217 were treated with GH for an average of 2.5 years, showed that there was no significant difference on fasting glucose and glycated hemoglobin between the

300

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treated group (n ¼ 217) and the untreated group (n ¼ 385) [23]. There was a significant increase of IGF-1 and fat mass reduction in the GH treated group. In our study, GAUC as well as IAUC and IAUC/ GAUC ratio were not significantly altered, suggesting that there was no significant alteration in beta cell function after glucose load throughout the study. Although we did not observed any significant variation on the mean 120-min glucose levels at OGTT, we detected an intolerant test in 9 patients, one of which (patient 6) had already demonstrated intolerance at the time of enrollment. The evolution of this patient seemed independent from the GH treatment and suggests a spontaneous oscillation of OGTT during the study. Moreover, among the 9 patients who presented altered OGTT, 6 (patients 3, 6, 7, 10, 16 and 17) had familial history of type 2 diabetes mellitus, with 3 of them presenting the involvement of a first-degree relative. The genetic predisposition may have caused the development of an abnormal test in these patients when they were exposed to GH therapy. Notwithstanding, there was no evolution to a clinical and/or biochemical picture of diabetes in these individuals during treatment, not even in patient 6 who presented intolerance at enrollment. The key limitation of the OGTT is its poor reproducibility [24–26], which could be responsible for the high incidence of patients with altered OGTT at different occasions during our study. Nevertheless, despite the occurrence of an increased percentage of OGTT-intolerant patients, at some time during the study, GH treatment improved abnormalities of body composition and lipid profile, reducing risk factors for cardiovascular disease. In the present study, ISI-composite derived from OGTT did not change significantly throughout 24 months of GH therapy, suggesting that long-term GH treatment was safe regarding the maintenance of carbohydrate metabolism. Few long-term studies evaluating carbohydrate metabolism and insulin secretion during GH replacement have been published. Glucose tolerance estimated by OGTT or by the technique of insulin clamp did not show alterations in relation to normal controls after 3–7 years of GH treatment [18,19,27,28]. Similarly, no alterations in fasting glucose and insulin levels were detected in 10 patients after 10 years of therapy [20]. Chipman et al. [29] treated 165 GHD patients for 18 months, with 98 of them of adult-onset (GHDA-AO) and 67 of childhood-onset GHD (GHDA-CO). These authors did not detect any significant alteration of fasting glycemia and insulin in relation to pre-treatment values, but a transitory elevation of fasting glucose and insulin was detected at 6 months of treatment, which was within the normal range, in comparison with the placebo group. Nevertheless, in other studies [16,30] the authors observed an increase on fasting insulin and IAUC up to 18 months of treatment.

On the other hand, Rosenfalck et al. [17] reported a significant increase of basal insulin, GAUC and IAUC up to 30 months into GH treatment. Studying 11 patients, the authors demonstrated a decrease in ISI evaluated at 12 and 30 months of GH treatment. In this study, the dose used was similar to the one used in our study, suggesting that the reported discrepancies regarding our findings cannot be attributed to the differences in posology. In the present study, the GH dose used was within the currently prescribed dose. The mean GH dose was 2.0
0.7 UI/day during the first year of the study and of 1.5
0.4 UI/day in the following year. The only side effect observed during this study was transient hand and/or foot edema in 7 patients (four with the higher dose) that resolved spontaneously in all patients, without the need of decreasing GH dose, suggesting a physiological adaptation to the initial expansion of the extra-cellular compartment, as reported previously [31]. Notwithstanding, the patientsÕ mean age in our study was 23 years, much younger than the patients included in RosenfalckÕs study. Age can be an important factor, since some authors have shown that insulin sensitivity decreases with age [32–35]. Similarly, some studies have observed a progressive decrease in beta cell function concomitantly with age [33,36–38]. These data suggest that elderly patients can be more susceptible to GH treatment and that the dose must be even lower than that used in younger patients. Moreover, the group of patients was heterogeneous regarding to the etiology of the GH deficiency, since 8 of 11 patients were GHDAAO as a consequence of a tumor of the pituitary region and only 3 were GHDA-CO. It has been shown that these patients present important differences regarding IGF-1 and lipid levels, body composition, physical performance and psychological profile [39]. All these variables can influence insulin sensitivity, and therefore, the inclusion of heterogeneous groups might lead to conflicting results. Our study group consisted of predominantly young, GHDA-CO patients only. The results of the present study demonstrate that long-term GH therapy improved body composition and lipid profile, reducing some cardiovascular risk factors, and did not appear to cause any significant effect on carbohydrate metabolism in this group of young adult patients with childhood-onset GH deficiency.

Acknowledgements This work was supported by a Grant from Fundacß~ ao de Amparo a Pesquisa do Estado de S~ao Paulo (FAPESP – 98/01481-0). We thank Novo Nordisk do Brasil for providing recombinant growth hormone (Norditropinâ 4U). We also thank the staff of Laborat
orio de Horm^ onios e Gen
etica Molecular LIM/42 do Hospital

M. Knoepfelmacher et al. / Growth Hormone & IGF Research 13 (2003) 295–302

das Cl
ınicas for the hormonal measurements, Prof. Dr. Berenice Mendonca and Dr. Marcelo Cidade Batista. We thank Prof. Dr Bernardo Leo Wajchenberg for the valuable discussions and suggestions.

References [1] T. Ros
en, S. Ed
en, G. Larson, L. Wilhelmsen, B.-A. Bengtsson, Cardiovascular risk factors in adult patients with growth hormone deficiency, Acta Endocrinol. (Copenh.) 129 (1993) 195–200. [2] R.C. Cuneo, F. Salomon, G.F. Watts, R. Hesp, P.H. S€ onksen, Growth hormone treatment improves serum lipids and lipoproteins in adults with growth hormone deficiency, Metabolism 42 (1993) 1519–1523. [3] K.A.S. Al-Shoumer, K.H. Cox, C.L. Hughs, W. Richmond, D.G. Johnston, Fasting and postprandial lipids abnormalities in hypopituitary women receiving conventional replacement therapy, J. Clin. Endocrinol. Metab. 82 (1997) 2653–2659. [4] J.U. Weaver, J.P. Monson, K. Noonan, et al., The effect of low dose recombinant human growth hormone replacement on regional fat distribution, insulin sensitivity, and cardiovascular risk factors in hypopituitary adults, J. Clin. Endocrinol. Metab. 80 (1995) 153–159. [5] Y.E.M. Snel, R.-J.M. Brummer, M.E. Doerga, et al., Adipose tissue assessed by magnetic resonance imaging in growth hormone-deficient adults: the effect of growth hormone replacement and a comparison with control subjects, Am. J. Clin. Nutr. 61 (1995) 1290–1294. [6] J.-O. Johansson, J. Fowelin, K. Landin, I. Lager, B.-A. Bengtsson, Growth hormone deficient adults are insulin resistant, Metabolism 44 (1995) 1126–1129. [7] F.L. Hew, M. Koschmann, et al., Insulin resistance in growth hormone-deficient adults: defects in glucose utilization and glycogen synthase activity, J. Clin. Endocrinol. Metab. 81 (1996) 555–564. [8] F. Salomon, R.C. Cuneo, R. Hesp, P.H. Sonksen, The effect of treatment with recombinant human growth hormone on body composition and metabolism in adults with growth hormone deficiency, N. Engl. J. Med. 321 (1989) 1797–1803. [9] J.O. J€ orgensen, S.A. Pedersen, L. Thuesen, J. J€ orgensen, T. Ingermann-Hasen, N.E. Skakkebaek, J.S. Christiansen, Beneficial effects of growth hormone treatment in GH-deficient adults, Lancet 1 (1989) 1221–1225. [10] P.R. Bratusch-Marrain, D. Smith, R.A. De Fronzo, The effect of growth hormone on glucose metabolism and insulin secretion in man, J. Clin. Endocrinol. Metab. 55 (1982) 973–982. [11] R.S. Sherwin, G.A. Scchulman, R.G. Hendler, Effect of growth hormone on oral glucose tolerance and circulating metabolic fuels in man, Diabetologia 24 (1983) 155–161. [12] A. Binnert, R.G. Swart, J.H.P. Wilson, N. Hoogerbrugge, H.A.P. Pots, J.C. Birkenhagen, S.W.J. Lamberts, The effect of growth hormone administration in growth hormone deficient adults on bone, protein, carbohydrate and lipid homeostasis, as well on body composition, Clin. Endocrinol. (Oxf.) 37 (1992) 79–87. [13] D.N. OÕNeal, A. Kalfas, M.J. Christopher, S.D. Sawyer, G. Ward, F.P. Alford, The effect of 3 months of recombinant growth hormone (GH) therapy on insulin and glucose-mediated glucose disposal and insulin secretion in GH-deficient adults: a minimal model analysis, J. Clin. Endocrinol. Metab. 79 (1994) 975–983. [14] T. Rosen, G. Johannsson, P. Hallgren, K. Caidahl, I. Bosaeues, B.A. Bengtsson, Beneficial effects of 12 months replacement therapy with recombinant growth hormone to growth hormone deficient adults, Endocrinol. Metab. 1 (1994) 55–66.

301

[15] J. Fowelin, S. Attvall, I. Lager, B.-A. Bengtsson, Effects of treatment with recombinant growth hormone on insulin sensitivity and glucose metabolism in adults with growth hormone deficiency, Metabolism 42 (1993) 1443–1447. [16] M. Riedl, B. Ludvik, G. Pacini, et al., The increased insulin sensitivity in growth-hormone-deficient adults is reduced by growth hormone replacement therapy, Eur. J. Clin. Invest. 30 (2000) 771–778. [17] Am. Rosenfalck, S. Maghsoudi, S. Fisfer, J.O.L. Jorgensen, J.S. Christiansen, J. Hilsted, A.A. Volund, S. Madsbad, The effect of 30 months of low-dose replacement therapy with recombinant growth hormone (rhGH) on insulin and C-peptide kinetics, insulin secretion, insulin sensitivity, glucose effectiveness, and body composition in GH-deficient adults, J. Clin. Endocrinol. Metab. 85 (2000) 4173–4181. [18] A. Chrisoulidou, S.A. Beshiah, O. Rutherford, T.J. Spinks, J. Mayet, P. Kyd, Anyaoku, A. Haida, AriffB, M. Murphy, E. Thomas, S. Robinson, R. Foale, D.G. Jonhston, Effect of 7 years of growth hormone replacement therapy in hypopituitary adults, J. Clin. Endocrinol. Metab. 85 (2000) 3762–3769. [19] J. Svensson, J. Fowelin, K. Landin, B.-A. Bengtsson, J.-O. Johansson, Effects of seven years of GH-replacement therapy on insulin sensitivity in GH-deficient adults, J. Clin. Endocrinol. Metab. 87 (2002) 2121–2127. [20] J. Gibney, J.D. Wallace, T. Spinks, L. Schnorr, A. Ranicar, R.C. Cuneo, S. Lockart, K.G. Burnand, F. Salomon, P.H. Sonksen, D. Russel-Jones, The effects of 10 years of recombinant human growth hormone (GH) in adult GH-deficient patients, J. Clin. Endocrinol. Metab. 84 (1999) 2596–2602. [21] M. Matsuda, R.A. DeFronzo, Insulin sensitivity indeces obtained from oral glucose tolerance test, Diabetes Care 22 (1999) 1462– 1470. [22] D.R. Matthews, J.P. Hosker, A.S. Rudenski, B.A. Naylor, D.R. Treacher, R.C. Turner, Homeostasis model assessment: insulin resistance and b-cell function from fasting plasma glucose and insulin concentration in man, Diabetologia 28 (1985) 412–419. [23] M. Knoepfelmacher on behalf of NordiReg Study Group, Growth hormone deficiency in adults: a comparison between treated and untreated patients, Abstract Book of 11th International Congress of Endocrinology (ICE 2000), Sydney, Australia, 2000, p.206. [24] G.W. MacDonald, G.F. Fisher, C. Burnham, Reproducibility of the glucose tolerance test, Diabetes 26 (1965) 473–480. [25] P.E. Harding, N.W. Oakley, V. Wynn, Reproducibility of glucose tolerance test data in normal and mildly diabetic subjects, Clin. Endocrinol. (Oxf.) 35 (1973) 387–395. [26] K.O. Chan, G.T. Lau, J.C. Yeung, E. Chow, G.T. Cockram, The reproducibility and usefulness of the oral glucose tolerance test in screening for diabetes and other cardiovascular risk factors, Ann. Clin. Biochem. 35 (1998) 62–67. [27] A.S. Al-Shoumer, R. Gray, V. Anyaoku, et al., Effects of four years treatment with biosynthetic human growth hormone on glucose homeostasis, insulin secretion and lipid metabolism in GH-deficient adults, J. Clin. Endocrinol. Metab. 48 (1998) 795–802. [28] B. B€ ulow, E.M. Erfurth, A low individualized dose in young patients with childhood onset GH deficiency normalized serum IGF-1 without significant deterioration in glucose tolerance, Clin. Endocrinol. (Oxf.) 50 (1) (1999) 45–55. [29] J.J. Chipman, A.F. Attanasio, M.A. Birbett, P.C. Bates, S. Webb, W.J. Lamberts, The safety profile of GH replacement therapy in adults, Clin. Endocrinol. 46 (1997) 473–481. [30] S.A. Beshiah, A. Henderson, R. Nithyanathan, E. Skinner, V. Anyaoku, W. Richmond, P. Sharp, D.G. Johnston, The effects of short and long term growth hormone replacement therapy in hypopituitary adults on lipid metabolism and carbohydrate tolerance, J. Clin. Endocrinol. Metab. 80 (1995) 356–363. [31] H.M. Whitehead, C. Boreham, E.M. Mc Ilrrath, B. Sheridan, L. Kennedy, A.B. Atkison, D.R. Hadden, Growth hormone

302

[32] [33]

[34]

[35]

M. Knoepfelmacher et al. / Growth Hormone & IGF Research 13 (2003) 295–302 treatment of adults with growth hormone deficiency: results of a 13-month placebo controlled cross-over study, Clin. Endocrinol. 37 (1992) 79–87. R.A. De Fronzo, Glucose intolerance and ageing: evidence for tissue insensitivity to insulin, Diabetes 28 (1979) 1095–1101. M. Chen, R.N. Bergman, G. Pacini, D.J. Porte, Pathogenesis of age-related intolerance in man: insulin resistance and decreased beta-cell function, J. Clin. Endocrinol. Metab. 60 (1985) 13–20. K. Yamanouchi, H. Nakajima, T. Shinozaki, K. Chikada, K. Kato, Y. Oshida, M. Higushi, Effects of daily physical activity on insulin action in the elderly, J. Appl. Physiol. 73 (1992) 2241–2245. D. Elahi, Dc Muller, M. Mc Aloon-Dike, J.D. Tobin, R. Anres, The effect of age on insulin response and glucose utilization during four hypoglicemic plateau, Exp. Geront. 28 (1993) 393–409.

[36] D.C. Muller, D. Elahi, J.D. Tobin, R. Andres, Insulin response during the oral glucose tolerance test: the role of age, sex, body fat and the of fat distribution, Aging 8 (1996) 13–21. [37] P. Iozzo, H. Beck-Nielsen, M. Laakso, U. Smith, H. Ykijearvinen, E. Ferranini, Independent basal insulin secretion in non diabetic humans, J. Clin. Endocrinol. Metab. 84 (1999) 863–868. [38] K.C. Chiu, N.P. Lee, P. Cohan, L.M. Chuang, Beta-cell function declines with age in glucose tolerant caucasians, Clin. Endocrinol. 53 (2000) 569–575. [39] A.F. Attanasio, S.W.J. Lamberts, A.M.C. Matranga, Adult growth hormone-deficient adults demonstrate heterogenicity between childhood onset and adult onset before and during human GH treatment, J. Clin. Endocrinol. Metab. 82 (1997) 82–88.