Disagreement in normative IGF-I levels may lead to different clinical interpretations and GH dose adjustments in GH deficiency.

INTRODUCTION AND BACKGROUND: Normative data for the iSYS IGF-I assay have been published both in the VARIETE cohort and by Bidlingmaier et al. OBJECTIVE: To investigate whether normative data of the VARIETE cohort lead to differences in Z-scores for total IGF-I and clinical interpretation compared to normative data of Bidlingmaier et al. DESIGN: We used total IGF-I values previously measured by the IDS-iSYS assay in 102 GH-deficient subjects before starting GH treatment and after 12 months of GH treatment. Z-scores were calculated for all samples by using the normative data of the VARIETE cohort and by the normative data reported by Bidlingmaier et al. RESULT: Before GH treatment, Z-scores calculated by using the normative data of the VARIETE cohort were significantly lower than those calculated by the normative data of Bidlingmaier et al: -2.40 (-4.52 to +1.31) (mean [range]) vs. -1.41 (-3.14 to +1.76); P < .001). After 12 months of GH treatment, again the Z-scores based on the normative data of the VARIETE cohort were significantly lower than those based on the normative data of Bidlingmaier et al: -0.65 (-4.32 to +2.79) vs 0.21 (-3.00 to +3.28); P < .001). CONCLUSION: IGF-I Z-scores in 102 GH-deficient subjects differed significantly when normative data from two different sources were used. In daily clinical practice, this would most likely have led to different clinical interpretations and GH dose adjustments.

Efficacy and safety of bariatric surgery for craniopharyngioma-related hypothalamic obesity: a matched case-control study with 2 years of follow-up.

BACKGROUND: Hypothalamic obesity is a devastating consequence of craniopharyngioma. Bariatric surgery could be a promising therapeutic option. However, its efficacy and safety in patients with craniopharyngioma-related hypothalamic obesity remain largely unknown. OBJECTIVES: We investigated the efficacy of bariatric surgery for inducing weight loss in patients with craniopharyngioma-related hypothalamic obesity. In addition, we studied the safety of bariatric surgery regarding its effects on hormone replacement therapy for pituitary insufficiency. METHODS: In this retrospective matched case-control study, we compared weight loss after bariatric surgery (that is, Roux-en-Y gastric bypass and sleeve gastrectomy) between eight patients with craniopharyngioma-related hypothalamic obesity and 75 controls with 'common' obesity during 2 years of follow-up. We validated our results at 1 year of follow-up in a meta-analysis. In addition, we studied alterations in hormone replacement therapy after bariatric surgery in patients with craniopharyngioma. RESULTS: Mean weight loss after bariatric surgery was 19% vs 25% (difference -6%, 95% confidence of interval (CI) -14.1 to 4.6; P=0.091) at 2 years of follow-up in patients with craniopharyngioma-related hypothalamic obesity compared with control subjects with 'common' obesity. Mean weight loss was 25% vs 29% (difference -4%, 95% CI -11.6 to 8.1; P=0.419) after Roux-en-Y gastric bypass and 10% vs 20% (difference -10%, 95% CI -14.1 to -6.2; P=0.003) after sleeve gastrectomy at 2 years of follow-up in patients with craniopharyngioma-related hypothalamic obesity vs control subjects with 'common' obesity. Our meta-analysis demonstrated significant weight loss 1 year after Roux-en-Y gastric bypass, but not after sleeve gastrectomy. Seven patients with craniopharyngioma suffered from pituitary insufficiency; three of them required minor adjustments in hormone replacement therapy after bariatric surgery. CONCLUSIONS: Weight loss after Roux-en-Y gastric bypass, but not sleeve gastrectomy, was comparable between patients with craniopharyngioma-related hypothalamic obesity and control subjects with 'common' obesity at 2 years of follow-up. Bariatric surgery seems safe regarding its effects on hormone replacement therapy.

Methylation of IGF2 regulatory regions to diagnose adrenocortical carcinomas.

Adrenocortical carcinoma (ACC) is a rare malignancy with a poor prognosis. Discrimination of ACCs from adrenocortical adenomas (ACAs) is challenging on both imaging and histopathological grounds. High IGF2 expression is associated with malignancy, but shows large variability. In this study, we investigate whether specific methylation patterns of IGF2 regulatory regions could serve as a valuable biomarker in distinguishing ACCs from ACAs. Pyrosequencing was used to analyse methylation percentages in DMR0, DMR2, imprinting control region (ICR) (consisting of CTCF3 and CTCF6) and the H19 promoter. Expression of IGF2 and H19 mRNA was assessed by real-time quantitative PCR. Analyses were performed in 24 ACCs, 14 ACAs and 11 normal adrenals. Using receiver operating characteristic (ROC) analysis, we evaluated which regions showed the best predictive value for diagnosis of ACC and determined the diagnostic accuracy of these regions. In ACCs, the DMR0, CTCF3, CTCF6 and the H19 promoter were positively correlated with IGF2 mRNA expression (P<0.05). Methylation in the most discriminating regions distinguished ACCs from ACAs with a sensitivity of 96%, specificity of 100% and an area under the curve (AUC) of 0.997±0.005. Our findings were validated in an independent cohort of 9 ACCs and 13 ACAs, resulting in a sensitivity of 89% and a specificity of 92%. Thus, methylation patterns of IGF2 regulatory regions can discriminate ACCs from ACAs with high diagnostic accuracy. This proposed test may become the first objective diagnostic tool to assess malignancy in adrenal tumours and facilitate the choice of therapeutic strategies in this group of patients.

What is the efficacy of switching to weekly pegvisomant in acromegaly patients well controlled on combination therapy?

CONTEXT: Although combination therapy of acromegaly with long-acting somatostatin analogs (LA-SSAs) and pegvisomant (PEGV) normalizes insulin-like growth factor-1 (IGF1) levels in the majority of patients, it requires long-term adherence. Switching from combination therapy to monotherapy with weekly PEGV could improve patients' comfort, but the efficacy is unknown. OBJECTIVE: To assess the efficacy of switching to PEGV monotherapy in patients well controlled on combination therapy of LA-SSAs and PEGV. DESIGN: Single-center, open-label observational pilot study. LA-SSA therapy was discontinued at baseline and all patients were switched to PEGV monotherapy for 12 months. If IGF1 levels exceeded 1.0 times upper limit of normal (ULN), PEGV dose was increased by 20 mg weekly. SUBJECTS AND METHODS: The study included 15 subjects (eight males), with a median age of 58 years (range 35-80) on combination therapy of high-dose LA-SSAs and weekly PEGV for >6 months, and IGF1 levels within the normal range. Treatment efficacy was assessed by measuring serum IGF1 levels. RESULTS: After 12 months of weekly PEGV monotherapy, serum IGF1 levels of 73% of the subjects remained controlled. In one patient, LA-SSA had to be restarted due to recurrence of headache. IGF1 levels increased from a baseline level of 0.62 × ULN (range 0.30-0.84) to 0.83 × ULN (0.30-1.75) after 12 months, while the median weekly PEGV dose increased from 60 (30-80) mg to 80 (50-120) mg. CONCLUSION: Our results suggest that switching from combination therapy of LA-SSAs and PEGV to PEGV monotherapy can be a viable treatment option for acromegaly patients without compromising efficacy.

The introduction of the IDS-iSYS total IGF-1 assay may have far-reaching consequences for diagnosis and treatment of GH deficiency.

CONTEXT: IGF-1 measurements are used for screening and monitoring GH deficiency (GHD) and acromegaly. OBJECTIVE: Our objective was to study whether the introduction of the IDS-iSYS IGF-1 assay would lead to different clinical interpretations in GHD and acromegaly. DESIGN: In 106 GHD subjects and in 15 acromegalic subjects visiting our university hospital, total IGF-1 levels were measured before and during therapy by using the Immulite (IM) assay and IDS-iSYS (ID) assay. Z-scores were calculated by using assay-specific age-specific normative range values. All treatment decisions were based upon results obtained by the IM assay. RESULTS: In GHD subjects, absolute IGF-1 concentrations differed significantly between both IGF-1 assays before treatment (P < .001) but not during GH treatment (P = .32), and mean Z-scores for IGF-1 differed significantly before starting (IM, -2.23, vs ID, -1.43; P < .001) and during GH treatment (IM, -0.60, vs ID, +0.21; P < .001). In acromegalic subjects, absolute IGF-1 concentrations did not differ between both IGF-1 assays before treatment (P = .18) but were significantly different during treatment (P = 0.009), and mean Z-scores for IGF-1 were not different before starting (IM, 10.93, vs ID, 10.78; P = .41) or during treatment (IM, 3.60, vs ID, 3.18; P = .23). CONCLUSIONS: In GHD subjects, mean IGF-1 Z-scores significantly differed when measured by the IM assay compared with the ID assay irrespective of treatment. In contrast, in acromegaly, mean IGF-1 Z-scores did not differ significantly between both assays. Our study suggests that replacement of the IM assay by the ID assay may have far-reaching consequences for the clinical diagnosis and treatment of GHD.

Long-term efficacy and safety of pegvisomant in combination with long-acting somatostatin analogs in acromegaly.

BACKGROUND: Treatment for acromegaly patients with long-acting somatotropin release-inhibiting factor (LA-SRIF) often does not result in complete normalization of IGF-1. Addition of pegvisomant (PEGV), a GH receptor antagonist, could improve this; however, the literature has not described long-term follow-up. OBJECTIVE: To assess long-term efficacy and safety of this combined treatment in the largest current single-center cohort of patients, from 2004-2013. DESIGN: Acromegaly patients were treated for at least 6 months with a high-dose LA-SRIF. To patients with persistently elevated IGF-1 levels (>1.2 × upper limit of normal) or poor quality of life, PEGV was added as one weekly injection. RESULTS: The patients (n = 141) were treated with PEGV and LA-SRIFs for a median period of 4.9 years (range, 0.5-9.2). Efficacy, defined as the lowest measured IGF-1 level during treatment, was 97.0%. The median PEGV dose to achieve this efficacy was 80 mg weekly (interquartile range, 60-120 mg). Combination treatment-related adverse events were recorded in 26 subjects (18.4%). Pituitary tumor size increase was observed in one patient. Injection-site reactions were observed in four subjects. In 19 patients (13.5%), transiently elevated liver transaminases of more than three times the upper limit of normal were observed, of which 83% occurred within the first year of combination treatment. Eight patients died, at a mean age of 71 years; none of them were considered treatment-related. CONCLUSIONS: The combination treatment with LA-SRIFs and PEGV was effective in 97% of the patients, it appears to be a safe medical treatment and it reduces the required dose of PEGV.

In active acromegaly, IGF1 bioactivity is related to soluble Klotho levels and quality of life.

The value of measuring IGF1 bioactivity in active acromegaly is unknown. Soluble Klotho (S-Klotho) level is elevated in active acromegaly and it has been suggested that S-Klotho can inhibit activation of the IGF1 receptor (IGF1R). A cross-sectional study was carried out in 15 patients with active acromegaly based on clinical presentation, unsuppressed GH during an oral glucose tolerance test, and elevated total IGF1 levels (>+2 s.d.). Total IGF1 was measured by immunoassay, IGF1 bioactivity by the IGF1R kinase receptor activation assay and S-Klotho by an ELISA. Quality of Life (QoL) was assessed by Acromegaly QoL (AcroQoL) Questionnaire and Short-Form-36 Health Survey Questionnaire (SF-36). Out of 15 patients, nine had IGF1 bioactivity values within the reference range. S-Klotho was higher in active acromegaly compared with controls. Age-adjusted S-Klotho was significantly related to IGF1 bioactivity (r=0.75, P=0.002) and to total IGF1 (r=0.62, P=0.02). IGF1 bioactivity and total IGF1 were inversely related to the physical component summary of the SF-36 (r=-0.78, P=0.002 vs r=-0.60, P=0.03). Moreover, IGF1 bioactivity, but not total IGF1, was significantly inversely related to the physical dimension of the AcroQoL Questionnaire (r=-0.60, P=0.02 vs r=-0.37, P=0.19). In contrast to total IGF1, IGF1 bioactivity was within the reference range in a considerable number of subjects with active acromegaly. Elevated S-Klotho levels may have reduced IGF1 bioactivity. Moreover, IGF1 bioactivity was more strongly related to physical measures of QoL than total IGF1, suggesting that IGF1 bioactivity may better reflect physical limitations perceived in active acromegaly.

The IGSF1 deficiency syndrome: characteristics of male and female patients.

CONTEXT: Ig superfamily member 1 (IGSF1) deficiency was recently discovered as a novel X-linked cause of central hypothyroidism (CeH) and macro-orchidism. However, clinical and biochemical data regarding growth, puberty, and metabolic outcome, as well as features of female carriers, are scarce. OBJECTIVE: Our objective was to investigate clinical and biochemical characteristics associated with IGSF1 deficiency in both sexes. METHODS: All patients (n = 42, 24 males) from 10 families examined in the university clinics of Leiden, Amsterdam, Cambridge, and Milan were included in this case series. Detailed clinical data were collected with an identical protocol, and biochemical measurements were performed in a central laboratory. RESULTS: Male patients (age 0-87 years, 17 index cases and 7 from family studies) showed CeH (100%), hypoprolactinemia (n = 16, 67%), and transient partial GH deficiency (n = 3, 13%). Pubertal testosterone production was delayed, as were the growth spurt and pubic hair development. However, testicular growth started at a normal age and attained macro-orchid size in all evaluable adults. Body mass index, percent fat, and waist circumference tended to be elevated. The metabolic syndrome was present in 4 of 5 patients over 55 years of age. Heterozygous female carriers (age 32-80 years) showed CeH in 6 of 18 cases (33%), hypoprolactinemia in 2 (11%), and GH deficiency in none. As in men, body mass index, percent fat, and waist circumference were relatively high, and the metabolic syndrome was present in 3 cases. CONCLUSION: In male patients, the X-linked IGSF1 deficiency syndrome is characterized by CeH, hypoprolactinemia, delayed puberty, macro-orchidism, and increased body weight. A subset of female carriers also exhibits CeH.

Chromogranin A, Ki-67 index and IGF-related genes in patients with neuroendocrine tumors.

Chromogranin A (CgA) and the Ki-67 proliferation index are considered as important biochemical and pathological markers for clinical behaviour of gastroenteropancreatic neuroendocrine tumors (GEP NETs), respectively. The IGF system has been suggested as an important regulator of GEP NET proliferation and differentiation. A possible relationship between serum CgA (sCgA), Ki-67 proliferation index, and expression of IGF-related genes in patients with GEP NETs has not been demonstrated yet. This study investigates the relationship between sCgA, the Ki-67 proliferation index, and the expression of IGF-related genes in GEP NET tissues and their relation with 5-year survival. Tumor and blood samples from 22 GEP NET patients were studied. TUMORAL MRNA EXPRESSION OF IGF-RELATED GENES (IGFS: IGF1, IGF2; IGF receptors: IGF1R, IGF2R; insulin receptors: subtype A (IR-A) and B (IR-B); IGF-binding proteins (IGFBPs): IGFBP1, IGFBP2, IGFBP3, and IGFBP6) was measured using quantitative RT-PCR. Ki-67 proliferation index was determined using immunohistochemistry. sCgA was measured with ELISA. Five-year survival in patients with nonelevated sCgA (n=11) was 91 vs 46% in patients with elevated sCgA (n=11) (P=0.006). IR-A mRNA expression was significantly higher in tumors obtained from patients with elevated sCgA than in those from patients with nonelevated sCgA (6.42±2.08 vs 2.60±0.40; P=0.04). This data suggests that sCgA correlates well with 5-year survival of GEP NET patients, and that IR-A mRNA expression correlates well with tumor mass in GEP NET patients.

Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases IGF-I bioactivity similarly.

AIMS/HYPOTHESIS: The aim of this study was to compare IGF-I bioactivity 36 weeks after the addition of insulin glargine (A21Gly,B31Arg,B32Arg human insulin) or NPH insulin to metformin therapy in type 2 diabetic patients who had poor glucose control under metformin monotherapy. METHODS: In the Lantus plus Metformin (LANMET) study, 110 poorly controlled insulin-naive type 2 diabetic patients were randomised to receive metformin with either insulin glargine (G+MET) or NPH insulin (NPH+MET). In the present study, IGF-I bioactivity was measured, retrospectively, in 104 out of the 110 initially included LANMET participants before and after 36 weeks of insulin therapy. IGF-I bioactivity was measured using an IGF-I kinase receptor activation assay. RESULTS: After 36 weeks of insulin therapy, insulin doses were comparable between the G+MET (68 ± 5.7 U/day) and NPH+MET (71 ± 6.2 U/day) groups (p = 0.68). Before insulin therapy, circulating IGF-I bioactivity was similar between the G+MET (134 ± 9 pmol/l) and NPH+MET (135 ± 10 pmol/l) groups (p = 0.83). After 36 weeks, IGF-I bioactivity had decreased significantly (p = 0.001) and did not differ between the G+MET (116 ± 9 pmol/l) and NPH+MET (117 ± 10 pmol/l) groups (p = 0.91). At baseline and after insulin therapy, total IGF-I concentrations were comparable in both groups (baseline: G+MET 13.3 ± 1.0 vs NPH+MET 13.3 ± 1.0 nmol/l, p = 0.97; and 36 weeks: 13.4 ± 1.0 vs 13.1 ± 0.9 nmol/l, p = 0.71). Total IGF-I concentration did not change during insulin therapy (13.3 ± 0.7 vs 13.3 ± 0.7 nmol/l, baseline vs 36 weeks, p = 0.86). CONCLUSIONS/INTERPRETATION: Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases serum IGF-I bioactivity in a similar manner.

Insulin-like growth factor I: pros and cons of a bioassay.

BACKGROUND: Insulin-like growth factor I (IGF-I) immunoassays are primarily used to estimate IGF-I status. Recently an IGF-I-specific kinase receptor activation assay (KIRA) was developed as an alternative method for measuring IGF-I bioactivity. When compared with IGF-I immunoassays, the IGF-I KIRA has the theoretical advantage of measuring the net effects of IGF-binding proteins on IGF-I receptor activation. The IGF-I KIRA is sensitive and specific and has, for a bioassay, a very low intra- and inter-assay coefficient of variation (<7 and <15%, respectively). Several studies have shown that the IGF-I KIRA is more sensitive than IGF-I immunoassays for detecting differences in clinical state. In addition, the IGF-I KIRA seems superior to IGF-I immunoassays for monitoring acute effects of therapeutic interventions. CONCLUSIONS: It is not known if IGF-I KIRA is superior to IGF-I immunoassays for evaluating the efficacy of growth hormone (GH) treatment for GH deficiency and of GH receptor antagonist treatment for acromegaly. However, IGF-I KIRA undoubtedly will provide new insights into the factors that regulate IGF-I bioactivity in the circulation in both healthy and diseased states.

IGF-I bioactivity better reflects growth hormone deficiency than total IGF-I.

CONTEXT: GH is considered the main regulator of circulating IGF-I. Total (extractable) IGF-I is therefore routinely used for diagnosis of GH deficiency (GHD) and for monitoring treatment. Methods currently used for measurement of circulating total IGF-I may be hampered by interferences of IGF-binding proteins. Recently a kinase receptor activation assay was developed to determine IGF-I bioactivity in human serum. The principle of this assay is based on quantification of IGF-I receptor activation after stimulation with serum in vitro. OBJECTIVE: The objective of the study was to investigate the diagnostic potential of IGF-I bioactivity in adults with GHD. DESIGN: This was a single-center observational study. STUDY PARTICIPANTS: Ninety-four GH-untreated patients diagnosed with GHD by GH-provocative tests were included. MAIN OUTCOME MEASURES: IGF-I bioactivity (determined by the IGF-I kinase receptor activation assay) and total IGF-I (determined by immunoassay) were measured in fasting blood samples. RESULTS: IGF-I bioactivity was more frequently below the normal range (<-2 sd) in untreated GH-deficient patients than total IGF-I levels (81.9 vs. 61.7%, respectively), especially in patients older than 40 years of age. IGF-I bioactivity decreased with the duration of GHD, whereas total IGF-I did not. With a decreasing number of additional pituitary deficits, total IGF-I levels more frequently remained within the normal range, whereas the percentage below the normal range was high for IGF-I bioactivity, independent of additional deficits. CONCLUSION: Determination of IGF-I bioactivity may offer advantages in the evaluation of adult GHD compared with total IGF-I as bioactivity better reflects GHD as defined by GH stimulation tests, especially in subjects older than 40 years of age.

Insulin glargine is more potent in activating the human IGF-I receptor than human insulin and insulin detemir.

OBJECTIVE: To investigate whether human insulin (HI) and insulin analogues differ in their ability to activate the human IGF-I receptor (IGF-IR), the human insulin receptor A (IR-A) and the human insulin receptor B (IR-B) in vitro. METHODS: HI, short-acting insulin analogues (insulin aspart; insulin lispro) and long-acting insulin analogues (insulin glargine; insulin detemir) were compared by using kinase receptor activation (KIRA) bioassays specific for IGF-IR, IR-A or IR-B, respectively. These assays quantify ligand activity by measuring receptor auto-phosphorylation upon ligand binding. HI and insulin analogues were tested in a range from 0.1 to 100 nM. RESULTS: Short-acting analogues: Overall, short-acting insulin analogues did not differ substantially from HI, nor from each other. Insulin lispro was slightly more potent than HI and insulin aspart in activating the IGF-IR, only reaching statistical significance at 100 nM (p<0.01). Long-acting analogues: At <10 nM insulin glargine was as potent as HI in activating the IRs and IGF-IR. At 10-100 nM insulin glargine was significantly more potent than HI in activating the IR-B (p<0.05) and IGF-IR (p<0.001). Insulin glargine was more potent than insulin detemir in activating all three receptors (p<0.001). Insulin detemir was less potent than HI in activating the IRs at 1-10 nM (p<0.01) and IGF-IR at >1 nM (p<0.05). CONCLUSIONS: Insulin glargine was more potent in activating the IGF-IR than HI and insulin detemir. Since KIRA bioassays do not mimic the exact in vivo situation, further research is needed to find out whether our data have implications for clinical use of insulin glargine.

Bioactive rather than total IGF-I is involved in acute responses to nutritional interventions in CAPD patients.

BACKGROUND: Inadequate food intake plays an important role in the development of malnutrition in continuous ambulatory peritoneal dialysis (CAPD) patients. Aim of the study. The aim of the study was to investigate in CAPD patients whether circulating insulin-like growth factor-I (IGF-I) bioactivity may offer a more sensitive index to acute nutritional interventions than total IGF-I. METHODS: An open-label, randomized, crossover study of 2 days-with a 1-week interval-was performed in 12 CAPD patients in the fed state to compare a mixture of amino acids (Nutrineal 1.1%) plus glucose (AA plus G) (Physioneal 1.36% to 3.86%) dialysate versus G only as control dialysate. Fed-state conditions were created by identical liquid hourly meals. IGF-I bioactivity was measured by the kinase receptor activation assay (IGF-I KIRA); total IGF-I was measured by immunoassay. RESULTS: In the fed state, both after AA plus G as well as after G dialysis IGF-I bioactivity increased compared to baseline, while no changes in circulating total IGF-I levels were observed in both treatment arms. However, the increase in IGF-I bioactivity was only significant after AA plus G dialysis (P = 0.02). CONCLUSIONS: Our results provide evidence that in CAPD patients changes in circulating IGF-I bioactivity are associated with nutrient intake and that IGF-I bioactivity rather than total IGF-I is involved in acute responses to nutritional interventions in CAPD patients.

Combined treatment for acromegaly with long-acting somatostatin analogs and pegvisomant: long-term safety for up to 4.5 years (median 2.2 years) of follow-up in 86 patients.

BACKGROUND: We previously reported on the efficacy, safety, and quality of life (QoL) of long-acting somatostatin analogs (SSA) and (twice) weekly pegvisomant (PEG-V) in acromegaly and improvement after the addition of PEG-V to long-acting SSA. OBJECTIVE: To assess the long-term safety in a larger group of acromegalic patients over a larger period of time: 29.2 (1.2-57.4) months (mean (range)). DESIGN: Pegvisomant was added to SSA monotherapy in 86 subjects (37 females), to normalize serum IGF1 concentrations (n=63) or to increase the QoL. The median dosage was 60.0 (20-200) mg weekly. RESULTS: After a mean treatment period of 29.2 months, 23 patients showed dose-independent PEG-V related transient liver enzyme elevations (TLEE). TLEE occurred only once during the continuation of combination therapy, but discontinuation and re-challenge induced a second episode of TLEE. Ten of these patients with TLEE also suffered from diabetes mellitus (DM). In our present series, DM had a 2.28 odds ratio (CI 1.16-9.22; p=0.03) higher risk for developing TLEE. During the combined therapy, a clinical significant decrease in tumor size by more than 20% was observed in 14 patients. Two of these patients were previously treated by pituitary surgery, 1 with additional radiotherapy and all other patients received primary medical treatment. CONCLUSION: Long-term combined treatment with SSA and twice weekly PEG-V up to more than 4 years seems to be safe. Patients with both acromegaly and DM have a 2.28 higher risk of developing TLEE. Clinical significant tumor shrinkage was observed in 14 patients during combined treatment.

Advantages and disadvantages of GH/IGF-I combination treatment.

Growth hormone (GH) is the primary regulator of insulin-like growth factor-I (IGF-I) production in a wide variety of tissues. There is much overlap in the endocrine, metabolic and anabolic effects of GH and IGF-I but both hormones have divergent effects on glucose metabolism, insulin sensitivity and differentiation of prechondrocytes. Theoretically combined administration of GH and IGF-I may be more effective than GH alone or IGF-I alone. Arguments in favor for this are: 1] Clearance of IGF-I may be markedly altered by the co-administration of GH and this will provide sustained actions of IGF-I. 2] Higher serum IGF-I levels are achieved with a combination treatment of GH and IGF-I than with GH treatment alone or IGF-I alone. In addition, combination therapy may have additive or synergistic effects. 3] The combination GH and IGF-I counteracts disadvantageous effects on glucose metabolism of either GH alone or IGF-I alone. 4] GH may exert direct actions on tissues independently from IGF-I. 5] Combination of GH and IGF-I may be more effective in improving tissue IGF-I levels. The combination therapy of GH and IGF-I might be beneficial in growth retardation, in certain specific subgroups of critically ill or catabolic patients and in the treatment of GH-deficient subjects with the metabolic syndrome and/or manifest diabetes. It is at present unknown whether an optimal balance between safety and efficacy can be achieved with the combination therapy of GH and IGF-I, since this combination has been evaluated in only a small number of patient populations and in studies of a relatively short duration. In addition, a disadvantage may be the financial costs of combination therapy of GH and IGF-I. In conclusion, there are many reasons for believing that administration of the combination therapy of GH and IGF-I could have advantages above GH alone or IGF-I alone. However, determination of whether co-administration of GH and IGF-I indeed is superior to either agent alone awaits further study.

Quality of life in acromegalic patients during long-term somatostatin analog treatment with and without pegvisomant.

OBJECTIVE: The objective of the study was to assess whether weekly administration of 40 mg pegvisomant (PEG-V) improves quality of life (QoL) and metabolic parameters in acromegalic patients with normal age-adjusted IGF-I concentrations during long-acting somatostatin analog (SSA) treatment. DESIGN: This was a prospective, investigator-initiated, double blind, placebo-controlled, crossover study. Twenty acromegalic subjects received either PEG-V or placebo for two consecutive treatment periods of 16 wk, separated by a washout period of 4 wk. Efficacy was assessed as change between baseline and end of each treatment period. QoL was assessed by the Acromegaly Quality of Life Questionnaire (AcroQoL) and the Patient-Assessed Acromegaly Symptom Questionnaire (PASQ). RESULTS: The AcroQoL (P = 0.008) and AcroQoL physical (P = 0.002) improved significantly after PEG-V was added. The addition of PEG-V also significantly improved the PASQ (P = 0.038) and the single PASQ questions, perspiration (P = 0.024), soft tissue swelling (P = 0.036), and overall health status (P = 0.035). No significant change in Z-score of IGF-I (P = 0.34) was observed during addition of PEG-V. Transient liver enzyme elevations were observed in five subjects (25%). CONCLUSION: Improvement in quality of life was observed without significant change in IGF-I after the addition of 40 mg pegvisomant weekly to monthly SSA therapy in acromegalic patients who had normalized IGF-I on SSA monotherapy. These data question the current recommendations in how to assess disease activity in acromegaly. Moreover, the findings question the validity of the current approach of medical treatment in which pegvisomant is used only when SSA therapy has failed to normalize IGF-I.

Low circulating insulin-like growth factor I bioactivity in elderly men is associated with increased mortality.

CONTEXT: Low IGF-I signaling activity prolongs lifespan in certain animal models, but the precise role of IGF-I in human survival remains controversial. The IGF-I kinase receptor activation assay is a novel method for measuring IGF-I bioactivity in human serum. We speculated that determination of circulating IGF-I bioactivity is more informative than levels of immunoreactive IGF-I. OBJECTIVE: Our objective was to study IGF-I bioactivity in relation to human survival. DESIGN, SETTING, AND STUDY PARTICIPANTS: We conducted a prospective observational study at a clinical research center at a university hospital of 376 healthy elderly men (aged 73-94 yr). MAIN OUTCOME MEASURES: IGF-I bioactivity was determined by the IGF-I kinase receptor activation assay. Total and free IGF-I were determined by IGF-I immunoassays. Mortality was registered during follow-up (mean 82 months). RESULTS: During the follow-up period of 8.6 yr, 170 men (45%) died. Survival of subjects in the highest quartile of IGF-I bioactivity was significantly better than in the lowest quartile, both in the total study group [hazard ratio (HR) = 1.8; 95% confidence interval (95% CI) = 1.2-2.8; P = 0.01] as well as in subgroups having a medical history of cardiovascular disease (HR = 2.4; 95% CI = 1.3-4.3; P = 0.003) or a high inflammatory risk profile (HR = 2.3; 95% CI = 1.2-4.5; P = 0.01). Significant relationships were not observed for total or free IGF-I. CONCLUSION: Our study suggests that a relatively high circulating IGF-I bioactivity in elderly men is associated with extended survival and with reduced cardiovascular risk.