Reference ranges of serum IGF-1 and IGFBP-3 levels in a general adult population: results of the Study of Health in Pomerania (SHIP)

Challenges of insulin-like growth factor-1 testing

Insulin-like growth factor 1 (IGF-1), primarily synthesized in the liver, was initially discovered due to its capacity to replicate the metabolic effects of insulin. Subsequently, it emerged as a key regulator of the actions of growth hormone (GH), managing critical processes like cell proliferation, differentiation, and apoptosis. Notably, IGF-1 displays a longer half-life compared to GH, making it less susceptible to factors that may affect GH concentrations. Consequently, the measurement of IGF-1 proves to be more specific and sensitive when diagnosing conditions such as acromegaly or GH deficiency. The recognition of the existence of IGFBPs and their potential to interfere with IGF-1 immunoassays urged the implementation of various techniques to moderate this issue and provide accurate IGF-1 results. Additionally, in response to the limitations associated with IGF-1 immunoassays and the occurrence of discordant IGF-1 results, modern mass spectrometric methods were developed to facilitate the quantification of IGF-1 levels. Taking advantage of their ability to minimize the interference caused by IGF-1 variants, mass spectrometric methods offer the capacity to deliver robust, reliable, and accurate IGF-1 results, relying on the precision of mass measurements. This also enables the potential detection of pathogenic mutations through protein sequence analysis. However, despite the analytical challenges, the discordance in IGF-1 reference intervals can be attributed to a multitude of factors, potentially leading to distinct interpretations of results. The establishment of reference intervals for each assay is a demanding task, and it requires nationwide multicenter collaboration among laboratorians, clinicians, and assay manufacturers to achieve this common goal in a cost-effective and resource-efficient manner. In this comprehensive review, we examine the challenges associated with the standardization of IGF-1 measurement methods, the minimization of pre-analytical factors, and the harmonization of reference intervals. Particular emphasis will be placed on the development of IGF-1 measurement techniques using "top-down" or "bottom-up" mass spectrometric methods.

Capillary blood as a complementary matrix for doping control purposes. Application to the definition of the individual longitudinal profile of IGF-1

We present a novel procedure to monitor the fluctuations of the levels of IGF-1 in capillary blood in the framework of doping control analysis. Being an endogenous hormone, direct methods are not applicable, so the most effective way to detect the intake of the exogenous hormone would be based on the longitudinal monitoring of the athlete. We have therefore followed the individual variability, in four subjects (two males and two females), of the levels of IGF-1 in capillary blood samples collected three times per day for five days, then once a week for at least two months. Analyses were performed by liquid chromatography coupled to tandem mass spectrometry following a bottom-up approach. The whole protocol, from the sample collection to the instrumental analysis, was validated according to the World Anti-Doping Agency's guidelines and ISO17025. The analytical protocol showed to be fit for purpose in terms of sensitivity (LOD 25 ng/mL and LOI 35 ng/mL), selectivity (no interferences were detected at the retention time of IGF-1 and the internal standard), and repeatability (CV<10%). The linearity was confirmed in the range of 50-1000 ng/mL (correlation coefficient R² >0.995, with a % relative bias of the experimental concentration of the different calibrators used for the estimation of the linearity lower than 20% for the lowest level and than 15% for the other levels). Stability studies were also performed, also to establish the optimal conditions for transport and storage: samples were stable at 4 °C for up to 72 h and at -20 °C and -80 °C for up to three months. Our preliminary results indicate that, in all subjects, the levels of IGF-1 did not present significant circadian fluctuations and remained stable during the entire period of the study (2-3 months, depending on the subject). The stability over time of IGF-1 levels in capillary blood indicates the possibility of detecting the intake of the non-endogenous hormone based on a longitudinal approach, as it is modeled in the framework of the endocrinological module of the athlete biological passport.

BMI and Contraceptives Affect New Age-, Sex-, and Puberty-adjusted IGF-I and IGFBP-3 Reference Ranges Across Life Span

CONTEXT

Various clinical factors influencing serum levels of insulin-like growth factor I (IGF-I) and its binding protein 3 (IGFBP-3) are not entirely consistently described.

OBJECTIVE

We asked whether body mass index (BMI), contraceptive drugs (CDs), and hormone replacement therapy (HRT) have potential effects on data for interpreting new age-, sex-, and puberty-adjusted reference ranges for IGF-I and IGFBP-3 serum levels.

DESIGN AND SETTING

Subjects were mainly participants from 2 population-based cohort studies: the LIFE Child study of children and adolescents and the LIFE Adult study.

PARTICIPANTS

We investigated 9400 serum samples from more than 7000 healthy and 1278 obese subjects between 3 months and 81 years old.

MAIN OUTCOME MEASURES

Associations between IGF-I or IGFBP-3, measured with a new electrochemiluminescence immunoassay, and the predictors BMI and CDs were estimated using hierarchical linear modeling.

RESULTS

During infancy, obese children had up to 1 SD score (SDS) higher mean predicted IGF-I values, converging with levels of normal-weight subjects up to 13 years old. Between 20 and 40 years of age, obesity was related to up to -0.5 lower IGF-I SDS values than the predicted values. Obesity had less impact on IGFBP-3. Estrogen- and progestin-based CDs, but not HRT, decreased IGF-I and increased IGFBP-3 (P < 0.01) in adolescents (β IGF-I = -0.45, β IGFBP-3  = 0.94) and adults (β IGF-I = -0.43, β IGFBP-3  = 1.12). Conversely, progestin-based CDs were significantly positive associated with IGF-I (β IGF-I  =0.82).

CONCLUSIONS

BMI and CDs must be considered when assessing and interpreting the clinical relevance of IGF-I and IGFBP-3 measurements.

Clinical presentation and management of acromegaly in elderly patients

BACKGROUND AND AIM

Acromegaly is a rare disease with a peak of incidence in early adulthood. However, enhanced awareness of this disease, combined with wide availability of magnetic resonance imaging (MRI), has increased the diagnosis of forms with mild presentation, especially in elderly patients. Moreover, due to increased life expectancy and proactive individualized treatment, patients with early-onset acromegaly are today aging. The aim of our study was to describe our cohort of elderly patients with acromegaly.

MATERIALS AND METHODS

This is a cross-sectional retrospective study of 96 outpatients. Clinical, endocrine, treatment, and follow-up data were collected using the electronic database of the University Hospital of Padova, Italy.

RESULTS

We diagnosed acromegaly in 13 patients, aged ≥65 years, presenting with relatively small adenomas and low IGF-1 secretion. Among them, 11 patients were initially treated with medical therapy and half normalized hormonal levels after 6 months without undergoing neurosurgery (TNS). Remission was achieved after TNS in three out of four patients (primary TNS in two); ten patients presented controlled acromegaly at the last visit. Acromegaly-related comorbidities (colon polyps, thyroid cancer, adrenal incidentaloma, hypertension, and bone disease) were more prevalent in patients who had an early diagnosis (31 patients, characterized by a longer follow-up of 24 years) than in those diagnosed aged ≥65 years (5 years of follow-up).

CONCLUSIONS

Elderly acromegalic patients are not uncommon. Primary medical therapy is a reasonable option and is effectively used, while the rate of surgical success is not reduced. A careful cost-benefit balance is suggested. Disease-specific comorbidities are more prevalent in acromegalic patients with a longer follow-up rather than in those diagnosed aged ≥65 years.

Female Specific Association of Low Insulin-Like Growth Factor 1 (IGF1) Levels with Increased Risk of Premature Mortality in Renal Transplant Recipients

Associations between insulin-like growth factor 1 (IGF1) and mortality have been reported to be female specific in mice and in human nonagenarians. Intervention in the growth hormone (GH)-IGF1 axis may particularly benefit patients with high risk of losing muscle mass, including renal transplant recipients (RTR). We investigated whether a potential association of circulating IGF1 with all-cause mortality in stable RTR could be female specific and mediated by variation in muscle mass. To this end, plasma IGF1 levels were measured in 277 female and 343 male RTR by mass spectrometry, and their association with mortality was assessed by Cox regression. During a median follow-up time of 5.4 years, 56 female and 77 male RTR died. In females, IGF1 was inversely associated with risk (hazard ratio (HR) per 1-unit increment in log2-transformed (doubling of) IGF1 levels, 95% confidence interval (CI)) of mortality (0.40, 0.24-0.65; p < 0.001), independent of age and the estimated Glomerular filtration rate (eGFR). In equivalent analyses, no significant association was observed for males (0.85, 0.56-1.29; p = 0.44), for which it should be noted that in males, age was negatively and strongly associated with IGF1 levels. The association for females remained materially unchanged upon adjustment for potential confounders and was furthermore found to be mediated for 39% by 24 h urinary creatinine excretion. In conclusion, low IGF1 levels associate with an increased risk of all-cause mortality in female RTR, which may link to conditions of low muscle mass that are known to be associated with poor outcomes in transplantation patients. For males, the strongly negative association of age with IGF1 levels may explain why low IGF1 levels were not found to be associated with an increased risk of all-cause mortality.

Laboratory investigations in the diagnosis and follow-up of GH-related disorders

In addition to auxiological, clinical and metabolic features measurements of growth hormone (GH) and insulin-like growth factor I (IGF-I) complement our tools in diagnosis and follow-up of GH-related disorders. While comparably robust during the pre-analytical phase, measurement and interpretation of concentrations of both hormones can be challenging due to analytical issues and biological confounders. Assay methods differ in terms of antibody specificity, interference from binding proteins, reference preparations and sensitivity. GH assays have different specificity towards different GH-isoforms (e.g. 20 kDa GH, placental GH) and interference from the GH antagonist Pegvisomant. The efficacy to prevent binding protein interference is most important in IGF-I assays. Methodological differences between assays require that reference intervals and diagnostic cut-offs are assay-specific. Among biological variables, pubertal development and age are most relevant for IGF-I, making detailed reference intervals mandatory for interpretation. GH has pulsatile secretion and short half-life. Its concentration is modified by acute factors such as stress, exercise and sleep, but also by intake of oral estrogens and anthropometric factors (e.g. BMI). Other GH dependent biomarkers such as free IGF-I, IGF binding protein 3 (IGFBP 3) and acid labile subunit (ALS) have been proposed. Their concentrations largely mirror the information obtained through measurement of IGF-I, but their measurement can be helpful in particular situations. In this review, we describe the evolution of analytical methods to measure biomarkers of GH action, the impact of the methodological changes on laboratory results and the need to include biological variables in their interpretation. Arch Endocrinol Metab. 2019;63(6):618-29.

Evaluation of Indian Prediction Models for Lung Function Parameters: A Statistical Approach

BACKGROUND

Interpretation of lung function test parameters is usually based on comparisons of data with reference (predicted) values based on healthy subjects. Predicted values are obtained from studies of "normal" or "healthy" subjects with similar anthropometric and ethnic characteristics. Regression models are generally used to obtain the reference values from measurements observed in a representative sample of healthy subjects.

OBJECTIVES

The study aims to carry out a statistical evaluation of the Indian prediction models of lung function parameters and critically evaluate the reference values for the same in an Indian context.

METHODS

The screening and inclusion of the articles for the study was done using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Evaluation of the prediction models has been done with respect to modeling approach, regression diagnostics and methodology protocol. The suitability of the models has also been evaluated using a checklist comprising of 8 criteria developed using the American Thoracic Society (ATS) guidelines.

RESULTS

Using the PRISMA guidelines 32 articles with a total sample size of 25,289 subjects were included in the final synthesis. Multiple linear regression models were used in 27 articles, with one additionally using weighted least squares technique and 4 using step-wise regression method. Regression diagnostics as per the ATS guidelines were performed and reported by 22 articles. The prediction models were traditionally developed using ordinary least squares method (OLS) without examining the homoskedasticity of residuals. The quality assessment using the checklist developed revealed that only 5 articles satisfied more than 7 out of 8 criteria, and a further 8 articles satisfied less than 3 criteria of suitability of prediction models.

CONCLUSIONS

Indian prediction models for lung function models are traditionally based on linear regression models, however with more advancement in computational power for sophisticated statistical techniques, more robust prediction models are required in the Indian context.

Enhancing engineered vascular networks in vitro and in vivo: The effects of IGF1 on vascular development and durability

OBJECTIVES

Creation of functional, durable vasculature remains an important goal within the field of regenerative medicine. Engineered biological vasculature has the potential to restore or improve human tissue function. We hypothesized that the pleotropic effects of insulin-like growth factor 1 (IGF1) would enhance the engineering of capillary-like vasculature.

MATERIALS AND METHODS

The impact of IGF1 upon vasculogenesis was examined in in vitro cultures for a period of up to 40 days and as subcutaneous implants within immunodeficient mice. Co-cultures of human umbilical vein endothelial cells and human bone marrow-derived mesenchymal stem cells in collagen-fibronectin hydrogels were supplemented with either recombinant IGF1 protein or genetically engineered cells to provide sustained IGF1. Morphometric analysis was performed on the vascular networks that formed in four concentrations of IGF1.

RESULTS

IGF1 supplementation significantly enhanced de novo vasculogenesis both in vitro and in vivo. Effects were long-term as they lasted the duration of the study period, and included network density, vessel length, and diameter. Bifurcation density was not affected. However, the highest concentrations of IGF1 tested were either ineffective or even deleterious. Sustained IGF1 delivery was required in vivo as the inclusion of recombinant IGF1 protein had minimal impact.

CONCLUSION

IGF1 supplementation can be used to produce neovasculature with significantly enhanced network density and durability. Its use is a promising methodology for engineering de novo vasculature to support regeneration of functional tissue.

Reference ranges for serum insulin-like growth factor I (IGF-I) in healthy Chinese adults

Purpose

To determine serum insulin-like growth factor 1 (IGF-I) levels in healthy Chinese adults, establish reference ranges for serum IGF-I levels and observe the effects of age, sex, body mass index (BMI) and geographical region on serum IGF-I levels.

Methods

In total, 2791 healthy adults (1339 males and 1452 females) from the north (Beijing) and south (Guizhou Province) of China were recruited following a questionnaire survey, physical examination and laboratory examination. Both sexes were divided into 13 groups according to age (18, 19, 20–24, 25–29, 30–34, 35–39, 40–44, 45–49, 50–54, 55–59, 60–64, 65–69 and ≥70 years). The serum IGF-I levels were measured by performing a chemiluminescent assay (Immulite 2000®), and the LMS (Lambda-Mu-Sigma) method was applied to construct smooth centile curves of age-specific IGF-I levels.

Results

Serum IGF-I levels in the adults gradually decreased with increasing age from 18 to 70 years in both the male and female participants. Although the decrease in the level of IGF-1 was more pronounced in females than in males, no significant difference was observed between the sexes, except in the 60- to 64-year-old age group (P = 0.0329). The multiple linear regression model showed that there was an inverse relationship between the serum IGF-I level and BMI (P<0.001), and the serum IGF-I level in the Guizhou population was higher than that in the Beijing population (P<0.05).

Conclusion

The normal reference ranges for age- and sex-specific serum IGF-I levels were established for the first time in a large sample of Chinese adults. The serum IGF-I levels were significantly influenced by age, BMI and geographical region.

Statistical methods used in the calculation of geriatric reference intervals: a systematic review

Geriatric reference intervals (RIs) are not commonly available and are rarely used. It is difficult to select a reference population from a cohort with a high degree of morbidity. Also important are the statistical approaches used to determine health-associated reference values. It is the aim of this study to examine the statistical methods used in the calculation of geriatric RIs.

A search was conducted on EMBASE and Medline for articles between January 1989 and January 2014. Studies were selected if they: 1) were English primary articles; 2) performed a clinical chemistry test on a blood fraction; 3) had a population sub-group consisting of individuals ≥65 years of age; and 4) calculated a RI for the subgroup ≥65 years of age.

There were 64 articles identified, of which 78.1% described the RI calculation method used. RI calculation was performed by non-parametric (21.9%), parametric (42.2%), robust (3.1%), or other (17.2%) methods. Outlier detection (SD, Grubb’s test, Tukey’s fence, Dixon) was infrequently used and although most studies performed partitioning, only 57.8% tested the statistical significance of the partitions. Few studies (17.2%) reported confidence intervals for the RI estimates. Overall, only 14.1% of studies provided RI estimates which followed the CLSI guideline EP28-A3c.

Statistical methods for RI calculation and partitioning varied considerably between studies and many failed to provide adequate descriptions of these methods. Challenges in analyses arose from insufficient sample sizes and heterogeneity in the elderly population. Geriatric RIs, although present in the literature, may not be properly calculated and should be carefully considered before applying them for clinical care.

Insulin-like Growth Factor 1 and Adiponectin and Associations with Muscle Deficits, Disease Characteristics, and Treatments in Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with low muscle mass and density. The objective of our study was to evaluate associations between 2 serum biomarkers [insulin-like growth factor 1 (IGF-1) and adiponectin] and skeletal muscle in RA.

METHODS

Whole-body dual energy X-ray absorptiometry measures of the appendicular lean mass index (ALMI; kg/m(2)) and total fat mass index (kg/m(2)), as well as the peripheral quantitative computed tomography measures of the lower leg muscle and fat cross-sectional area (CSA; cm(2)) and muscle density (an index of fat infiltration) were obtained from 50 participants with RA, ages 18-70 years. Multivariable linear regression analyses evaluated associations between body composition and levels of adiponectin and IGF-1, adjusted for age, sex, and adiposity.

RESULTS

Greater age was associated with higher adiponectin (p = 0.06) and lower IGF-1 (p = 0.004). Eight subjects had IGF-1 levels below the reference range for their age and sex. These subjects had significantly lower ALMI and muscle CSA in multivariable models. Lower IGF-1 levels were associated with greater clinical disease activity and severity, as well as low ALMI, muscle CSA, and muscle density (defined as 1 SD below normative mean). After adjusting for age and sex, greater adiponectin levels were associated with lower BMI (p = 0.02) as well as lower ALMI, and lower muscle CSA, independent of adiposity (p < 0.05). Only greater Health Assessment Questionnaire scores were significantly associated with lower adiponectin levels.

CONCLUSION

Low IGF-1 and greater adiponectin levels are associated with lower muscle mass in RA. Lower IGF-1 levels were seen in subjects with greater disease activity and severity.

Reference values of IGF1, IGFBP3 and IGF1/IGFBP3 ratio in adult population in the Czech Republic

BACKGROUND

IGF1 is responsible for regulation of growth, metabolism and differentiation of human cells. IGFBP3 is the most abundant of the carrier proteins for IGF1 in the blood. IGF1/IGFBP3 molar ratio is an indicator of IGF1 bioavailability. We decided to create a file of reference ranges of IGF1, IGFBP3 and IGF1/IGFBPP3 ratio for the adult Czech population across the age spectrum.

METHODS

We selected a group of 1022 subjects, 467 males and 555 females (ages 20-98 years), from several regions in the Czech Republic. The group consisted of blood donors and patients undergoing regular preventive examinations. Serum levels of IGF1 and IGFBP3 were measured using the following radioimmunoassay kits: IRMA IGF1 (Immunotech, Marseille, France) and IRMA IGFBP3 (Immunotech, Prague, Czech Republic). The IGF1/IGFBP3 ratio was also calculated. The following groups of patients were excluded: patients with diabetes, high blood glucose, high insulin levels, post-surgery patients, polymorbid patients, and subjects with oncological diseases. Subjects were divided into seven age-groups. Changes in the levels of observed analytes in each decade across the age spectrum were evaluated. All statistical analyses were performed by SAS 9.3 (Statistical Analysis Software release 9.3; SAS Institute Inc., Cary, NC, USA).

RESULTS

All three parameters IGF1, IGFBP3 and IGF1/IGFBP3 decreased in parallel with decrease in age: p<0.0001, r=-0.64, -0.35 and -0.54, respectively. The dynamics of the decline was different between males and females. Linear regression models with age as independent variable fitted by gender are displayed in Fig. 1. Non-parametric reference interval curves (medians and 2.5th-97.5th percentiles) for IGF1, IGFBP3 and IGF1/IGFBP3 ratio as function of age by gender are displayed in Fig. 2(a,b,c). All medians and 2.5th-97.5th percentiles were plotted by cubic spline. For males, linear regression models were as follows: IGF1=291.34619-2.41211 × age, IGFBP3=2931.62778-6.11659 × age, IGF1/IGFBP3=0.02897-0.00021213 × age. For females, we plotted the following: IGF1=241.67406-1.98466 × age, IGFBP3=3688.60561-16.39560 × age, IGF1/IGFBP3=0.02029-0.00013233 × age. IGF1 was statistically significantly higher in males with p<0.0001 (Wilcoxon test) but decreased faster (p=0.0121). IGFBP3 was statistically significantly higher in females with p=0.0004 (Wilcoxon test) but decreased faster (p<0.0001). IGF1/IGFBP3 was statistically significantly higher in males with p<0.0001 (Wilcoxon test) but decreased faster (p<0.0001).

CONCLUSION

Authors recommend using of a linear regression model based reference ranges for IGF1, IGFBP3 and IGF1/IGFBP3 ratio and using different reference ranges for genders.

Insulin-like growth factor- I and factors affecting it in thalassemia major

Despite improvement of blood transfusion regimens and iron chelation therapy growth and maturational delay, cardiomyopathy, endocrinopathies and osteoporosis still occur in good number of thalassemic patients. Decreased IGF-1 secretion occurs in the majority of the thalassemic patients particularly those with growth and pubertal delay. Many factors contribute to this decreased synthesis of IGF-I including disturbed growth hormone (GH) - insulin-like growth factor - I (IGF-I) axis. The possible factors contributing to low IGF-I synthesis in thalassemia and the possible interaction between low IGF-I secretion and the occurrence of these complications is discussed in this mini-review. Improvement of IGF-I secretion in thalassemic patients should be intended to improve linear growth and bone mineral accretion in thalassemic patients. This can be attained through adequate correction of anemia and proper chelation, nutritional supplementation (increasing caloric intake), correction of vitamin D and zinc deficiencies, induction of puberty and correction of hypogonadism at the proper time and treating GH deficiency. This review paper provides a summary of the current state of knowledge regarding IGF-I and factors affecting it in patients with thalassaemia major (TM). Search on PubMed and reference lists of articles with the term 'IGF-I, GH, growth, thalassemia, thyroxine, anemia, vitamin D, and zinc' was carried out. A hundred and forty-eight articles were found and used in the write up and the data analyzed was included in this report.

Management and interpretation of heterogeneous observational data: using insulin-like growth factor-I data from the NordiNet® International Outcome Study

OBJECTIVE

The NordiNet® International Outcome Study (IOS), a large-scale, non-interventional, multi-centre, real-world study of Norditropin® treatment, registers insulin-like growth factor-I (IGF-I) values, as measured by different assays. This paper considers the potential biases introduced by using a single IGF-I reference data set in analysing NordiNet® IOS data.

DESIGN

To evaluate possible biases from different IGF-I assays used across NordiNet® IOS, a mixed-effect linear model was fitted to IGF-I data (analyses on log-transformed data). Pre-growth hormone treatment (pre-GHT) IGF-I values were assumed to depend on diagnosis, sex and age. During GHT, a treatment-effect dependent on these factors was added. Differences between assays were assumed multiplicative on the original scale. Individual measurements were scaled to a common level (Nichols Advantage) giving adjusted IGF-I standard deviation score (SDS) values.

RESULTS

In total, 49 495 IGF-I measurements were available from 9481 paediatric patients. Mixed-effect linear modelling showed a systematic difference between IGF-I levels measured by different assays. Differences were minimised when assessing change in IGF-I SDS from the start of GHT to 1-year follow-up. This applied to values adjusted for actual-assay used and for unadjusted delta IGF-I SDS values. Largest differences between unadjusted change in IGF-I SDS values were: for growth hormone deficiency 0.1 (girls) and 0.3 (boys); for small-for-gestational age 0.1; and for Turner syndrome 0.2. Similar magnitude differences were seen for data with unknown assay.

CONCLUSIONS

Analysis and modelling suggest the current approach to IGF-I data collection and analyses in the NordiNet® IOS is sound: in a large cohort without assay-used information, potential bias is minimised by analysing changes in IGF-I SDS.

Increased miR-223 expression in T cells from patients with rheumatoid arthritis leads to decreased insulin-like growth factor-1-mediated interleukin-10 production

We hypothesized that the aberrant expression of microRNAs (miRNAs) in rheumatoid arthritis (RA) T cells was involved in the pathogenesis of RA. The expression profile of 270 human miRNAs in T cells from the first five RA patients and five controls were analysed by real-time polymerase chain reaction. Twelve miRNAs exhibited potentially aberrant expression in RA T cells compared to normal T cells. After validation with another 22 RA patients and 19 controls, miR-223 and miR-34b were over-expressed in RA T cells. The expression levels of miR-223 were correlated positively with the titre of rheumatoid factor (RF) in RA patients. Transfection of Jurkat cells with miR-223 mimic suppressed insulin-like growth factor-1 receptor (IGF-1R) and transfection with miR-34b mimic suppressed cAMP response element binding protein (CREB) protein expression by Western blotting. The protein expression of IGF-1R but not CREB was decreased in RA T cells. The addition of recombinant IGF-1-stimulated interleukin (IL)-10 production by activated normal T cells, but not RA T cells. The transfection of miR-223 mimic impaired IGF-1-mediated IL-10 production in activated normal T cells. The expression levels of SCD5, targeted by miR-34b, were decreased in RA T cells after microarray analysis. In conclusion, both miR-223 and miR-34b were over-expressed in RA T cells, but only the miR-223 expression levels were correlated positively with RF titre in RA patients. Functionally, the increased miR-223 expression could impair the IGF-1-mediated IL-10 production in activated RA T cells in vivo, which might contribute to the imbalance between proinflammatory and anti-inflammatory cytokines.

Effects of the anti-receptor activator of nuclear factor kappa B ligand denusomab on beta thalassemia major-induced osteoporosis

INTRODUCTION

Osteoporosis represents the second most common cause of endocrinopathy in patients with beta thalassemia major (BTM). Some drugs proved effective to reduce vertebral and non-vertebral fracture risk. Denosumab is a fully human monoclonal antibody to the receptor activator of nuclear factor kappa B ligand (RANKL), a member of the tumor necrosis factor receptor superfamily essential for osteoclastogenesis. The efficacy and safety of denosumab in BTM-induced osteoporosis has not been tested.

OBJECTIVE

To evaluate the efficacy and safety of anti-RANKL on the biochemical and radiological parameters of bone mineralization in patients with BTM-induced osteoporosis.

DESIGN

The study population was selected using the random sampling method from the patient's database of our thalassemia clinic. Transfusion-dependent BTM patients above 18 years with no history of treatment with bisphosphonates were randomly selected. Bone mineral density (BMD) of the lumbar spine (LS) and right femoral neck (FN) were measured by dual energy X-ray absorption (DEXA) scan using a calibrated method. Independent factors likely to be associated with low bone mass were determined and included in the analysis to ascertain possible associations.

PATIENTS AND METHODS

We studied 30 patients with BTM-induced osteoporosis as per World Health Organization criteria (T Score of less than - 1.0 being defined as osteopenic and a T Score of less than - 2.5 being referred as osteoporotic). 19 males and 11 females aged between 18 and 32 years, with full pubertal development (Tanner's stage 5) at the time of the study. Their mean serum ferritin concentration was 3557 ng ± 1488 ng/ml. Every patient underwent DEXA scan as a baseline and after 12 months of denosumab therapy. Biochemical evaluation including serum concentrations of creatinine, Na, K, calcium, phosphorus, parathormone, bone specific alkaline phosphatase and type 1 collagen carboxy telopetide (ICCT) using enzyme-linked immunosorbent assay (Nordic Bioscience Diagnostics A/S) was done at baseline, after a month and then every 3 months for 12 months after starting denosumab. 60 mg of denosumab was administered subcutaneously twice yearly for a year. The mean BMD T Scores at baseline were -2.7 at the LS and -2.1 at the FN.

RESULTS

Denosumab therapy for a year was associated with a significant increase in BMD of 9.2% (95% confidence interval [CI], 8.2-10.1) at the LS and 6.0% (95% CI, 5.2-6.7) at the FN. Denosumab treatment decreased serum ICCT levels by 56% at 1 month and normalized them in all patients at 1 year. Significant correlations were found between BMD T Score before and 1 year after denosumab in LS (r = 0.752, P < 0.001) and FN (r = 0.758 P < 0.001), respectively. The most common side effects were pain in the back and extremities (12%) and nausea (10%). Asymptomatic hypocalcaemia occurred in two patients.

CONCLUSION

Denosumab therapy for a year significantly increased BMD density at LS and FN of patients with BTM and was associated with a rapid and sustained reduction in ICCT levels. Further studies are required to confirm long-term effects of this therapy.

Identification of pregnancy-associated plasma protein A as a migration-promoting gene in malignant pleural mesothelioma cells: a potential therapeutic target

Despite recent advances in treatment, malignant pleural mesothelioma (MPM) remains a deadly disease. Targeted therapy generated broad interests and is highly expected for the treatment of MPM, yet promising preclinical results have not been translated into substantial clinical benefits for the patients. In this study, we tried to identify the genes which play functional roles in cell migration as well as to test whether they can be used as novel targets for molecular targeted therapy for MPM in preclinical model. In our study, pregnancy-associated plasma protein A (PAPPA) was identified as a gene whose expression level is correlated with MPM cell migration by correlation analysis combining MPM cell migration ability and their gene expression profiles. Highly migratory cells were selected from MPM cell lines, MSTO-211H, NCI-H290 and EHMES-1 in vitro and up-regulation of PAPPA in these cells were confirmed. In vitro, PAPPA was demonstrated to stimulate the MPM cell migration via cleavage of insulin-like growth factor-binding protein-4 and subsequent release of IGF-1. Gene silencing of PAPPA in MPM cells led to reduced migration, invasion and proliferation. Furthermore, PAPPA shRNA transfected NCI-H290 when orthotopically inoculated into pleural cavity of severe combined immunodeficiency recipient mice, failed to develop tumors and produce bloody pleural effusion as control shRNA transfected cells did. Our study suggests that PAPPA plays a functional role in promoting MPM cell migration and it might serve as a potential therapeutic target for the treatment of MPM.

Insulin-like-growth-factor-binding-protein-3 (IGFBP-3) contrasts melanoma progression in vitro and in vivo

Insulin-like-factor-binding-protein 3 (IGFBP-3) is known to modulate the activity of insulin-like growth factors (IGFs) besides having a number of IGF-independent effects on cell growth and survival. IGFBP-3 has been reported to decrease significantly in the blood serum of patients affected by certain cancers. In the present work, we have evaluated the levels of IGFBP-3 in the blood serum and tissues of patients affected by cutaneous melanoma, showing that loss of IGFBP-3 from both is strongly correlated with disease progression and reduced survival. In vitro treatment with IGFBP-3 of human and murine metastatic melanoma cell lines specifically inhibited the cells' migratory and invasive behaviour, inducing up-regulation of melanocytic differentiation markers such as tyrosinase activity and melanin content. A molecular analysis of the cellular pathways transducing the effect of IGFBP-3 implicated the Akt-GSK3β axis. Moreover, administration of IGFBP-3 in vivo to SCID mice inoculated with human metastatic melanoma cells strongly reduced or completely inhibited tumor growth. In summary, IGFBP-3 appears to exert a specific inhibitory effect on melanoma growth and dissemination, suggesting that it may qualify as a useful therapeutic agent in melanomas and perhaps other cancers, at the least as a valid adjuvant therapy during treatment with conventional anti-tumoral drugs.

Age- and sex-specific reference intervals across life span for insulin-like growth factor binding protein 3 (IGFBP-3) and the IGF-I to IGFBP-3 ratio measured by new automated chemiluminescence assays

CONTEXT

Measurement of IGF-binding protein-3 (IGFBP-3) can aid the diagnosis of GH-related diseases. Furthermore, epidemiological studies suggest that IGFBP-3 and the molar IGF-I to IGFBP-3 ratio are associated with clinical end points like cancer or cardiovascular disease. However, their clinical use is limited by the lack of validated reference intervals.

OBJECTIVE

The objective of the study was the establishment of age- and sex-specific reference intervals for IGFBP-3 and the molar IGF-I to IGFBP-3 ratio by newly developed automated immunoassays.

SETTING

This was a multicenter study with samples from 11 cohorts from the United States, Canada, and Europe.

PARTICIPANTS

A total of 14 970 healthy subjects covering all ages from birth to senescence participated in the study.

MAIN OUTCOME MEASURES

Concentrations of IGFBP-3 and the IGF-I to IGFBP-3 ratio as determined by the IDS iSYS IGF-I and IGFBP-3 assays were measured.

RESULTS

Both the concentration of IGFBP-3 and the IGF-I to IGFBP-3 ratio are mainly determined by age. IGFBP-3 concentrations increase until the age of 22 years, with a plateau being visible between 15 and 25 years. Determined by the high peripubertal peak in IGF-I, the peak in the IGF-I to IGFBP-3 ratio occurs already around the age of 15 years, with a slightly earlier and higher peak in females. Beyond the age of 60 years, IGFBP-3 concentrations remain higher in females, whereas IGF-I as well as the IGF-I to IGFBP-3 ratio remains significantly higher in males.

CONCLUSIONS

We present an extensive set of assay-specific age- and sex-adjusted normative data for concentrations of IGFBP-3 and the molar IGF-I to IGFBP-3 ratio and demonstrate distinct sex specific differences across the life span.

Long-term changes in serum IGF-1 levels after successful surgical treatment of growth hormone-secreting pituitary adenoma

BACKGROUND

Successful treatment of acromegaly is known to normalize serum insulin-like growth factor 1 (IGF-1) levels within days after surgery. However, our clinical observations indicate that many cases of acromegaly show delayed normalization of serum IGF-1 levels after complete tumor resection.

OBJECTIVE

To study long-term changes of the serum IGF-1 levels in acromegalic patients for whom surgical treatment was thought to be successful.

METHODS

A retrospective observational study was performed with 46 acromegalic patients with no residual tumor on sellar magnetic resonance imaging, and a nadir growth hormone of less than 0.4 μg/L on a postoperative oral glucose tolerance test.

RESULTS

In all patients, serum IGF-1 levels returned to the normal reference values for age and sex during the observational period (12-132 months). The mean duration from the time of surgery until IGF-1 normalization was 10 months (range, 3 days-57 months). Twenty-seven patients (59%) reached normal IGF-1 ranges within 3 months of surgery, whereas 19 patients (41%) experienced delayed (>3 months) IGF-1 normalization. Eleven patients (24%) recovered normal IGF-1 levels 12 to 57 months after surgery. The possibility of delayed IGF-1 cure was increased 8.8-fold with an immediate postoperative IGF-1 level increase of 100 μg/L.

CONCLUSION

Satisfactory remission of acromegaly by IGF-1 criteria was delayed in a large proportion of acromegalic patients, especially those with high postoperative IGF-1 levels. Hence, additional treatment can be delayed in clinically stable acromegalic patients who show no evidence of residual tumors on postoperative magnetic resonance imaging and a normal growth hormone suppressive response to a glucose load.

Obesity and colorectal adenomatous polyps: a cross-sectional study in Korean adults

OBJECTIVE

This study aimed to examine the association between obesity and the risk of colorectal adenomatous polyps.

DESIGN AND METHODS

The design of this study is a cross-sectional study. A total of 1,574 participants (818 males and 756 females), who had undergone colonoscopy for health examinations at the National Cancer Center hospital in South Korea from February to September 2009, were included in the analysis.

RESULTS

The prevalence of colorectal adenomatous polyps was 39.5% in males and 22.6% in females. In multiple logistic regression analysis, obesity (odds ratio [OR] = 1.69, 95% CI = 1.16-2.48) and abdominal obesity (OR = 1.59, 95% CI = 1.13-2.23) were significantly associated with an increased risk of colorectal adenomatous polyps in males, but not in females. In the subgroup analyses by age, obesity (OR = 2.27, 95% CI = 1.32-3.89), and abdominal obesity (OR = 1.76, 95% CI = 1.12-2.76) significantly increased a risk of colorectal adenomatous polyps in males aged <50 years, but not in males aged ≥50 years. However, interaction terms were not significant between obesity and gender (P = 0.397) and between obesity and age (P = 0.531) in the overall analyses.

CONCLUSION

Our findings should be explored in further research.

Decreased IGF-1 levels potentiate association of inflammation with all-cause and cardiovascular mortality in prevalent hemodialysis patients

OBJECTIVE

Insulin-like growth factor-1 (IGF-1) and inflammation have both been linked to high cardiovascular risk and mortality in the general population, as well as in hemodialysis (HD) patients. We hypothesized that the association of low IGF-1 with chronic inflammation may increase the mortality risk in HD patients.

DESIGN

We investigated the interactions between inflammatory biomarkers (IL-6 and TNF-α) and IGF-1 as predictors of death over a 4 years of follow-up (median--47 months, interquartile range--17.5-75 months) in 96 prevalent HD patients (35% women, mean age of 64.9 ± 11.6 years).

RESULTS

A significant interaction effect of low IGF-1 (defined as a level less than median) and high IL-6 (defined as a level higher than median) on all-cause and cardiovascular mortality was found: crude Cox hazard ratios (HR) for the product termed IGF-1 × IL-6 were 4.27, with a 95% confidence interval (CI): 2.10 to 8.68 (P<0.001) and 7.49, with a 95% CI: 2.40-24.1 (P=0.001), respectively. Across the four IGF-1-IL-6 categories, the group with low IGF-1 and high IL-6 exhibited the worse outcome in both all-cause and cardiovascular mortality (multivariable adjusted hazard ratios were 4.92, 95% CI 1.86 to 13.03, and 14.34, 95% CI 1.49 to 137.8, respectively). The main clinical characteristics of patients in the low-IGF-1-high IL-6 group didn't differ from other IGF-1-IL-6 categorized groups besides gender that consequently was inserted in all multivariable models together with the other potential confounders.

CONCLUSIONS

An increase in mortality risk was observed in HD patients with low IGF-1 and high IL-6 levels, especially cardiovascular causes.

The association between insulin-like growth factor I and bone turnover markers in the general adult population

OBJECTIVES

Growth hormone (GH) and its main mediator, insulin-like growth factor I (IGF-I), play a fundamental role in human metabolism. Previous epidemiological studies investigating the association of IGF-I and bone turnover markers (BTMs) yielded conflicting results and were limited by study design or sample size. Therefore, we aimed to investigate the associations between serum levels of IGF-I or the IGF-I/IGF binging protein 3 (IGFBP-3) ratio and levels of BTMs including procollagen type 1 N-terminal propeptide (PINP), C-terminal telopeptides of type 1 collagen (CTX), and bone-specific alkaline phosphatase (BAP).

METHODS

Data from 1463 men and 1481 women who participated in the first follow-up of the Study of Health in Pomerania were used. IGF-I and IGFBP-3 levels were measured using chemiluminescent immunometric assays on an Immulite 2500 analyzer. BTM levels were measured on the IDS-iSYS Multi-Discipline Automated Analyser. Analyses of variance (ANOVA) and quantile regression models were calculated.

RESULTS

In men <55 years and premenopausal women ANOVA and quantile regression analyses revealed positive associations between IGF-I or even stronger the IGF-I/IGFBP-3 ratio and PINP [per unit increase in IGF-I/IGFBP-3 ratio in men: beta (95%-CI) 2.33 ng/ml (0.91; 3.75), p < 0.01; women: 3.63 ng/ml (2.31; 4.95), p < 0.01] or CTX [men: 20.8 ng/l (3.5; 38.0), p = 0.02; women: 12.0 ng/l (-1.2; 25.2), p = 0.07]. Furthermore in postmenopausal women, IGF-I and the IGF-I/IGFBP-3 ratio were inversely related with CTX levels, whereas an inverse U-shaped relation between IGF-I/IGFBP-3 ratio and PINP was found. Regarding BAP, we observed borderline significant associations with IGF-I or the IGF-I/IGFBP-3 ratio in older subjects only.

CONCLUSION

IGF-I levels and particularly free IGF-I, estimated by the IGF-I/IGFBP-3 ratio, are positively related with PINP as a bone formation marker and CTX as a bone resorption marker in healthy adult men younger than 55 years and premenopausal women. In older subjects the found positive as well as negative relations with BTMs have to be further investigated.

Acromegaly: a single centre's experience of stereotactic radiosurgery and radiotherapy for growth hormone secreting pituitary tumours with the linear accelerator

Primary treatment for growth-hormone secreting pituitary adenomas usually involves surgery, with treatment options for recurrent and persistent disease including repeat surgery, medication and radiation therapy. The majority of previously published series for radiation therapy in acromegaly in the past 20 years have been based on Gamma-Knife (Elekta, Stockholm, Sweden) surgery. To our knowledge, we present the largest series of linear accelerator-based treatment for this disease, with a review of 121 patients treated at our institution; since 1990, 86 patients underwent stereotactic radiosurgery (SRS), 10 patients underwent fractionated stereotactic radiotherapy (FSRT), and for the purposes of comparison we also reviewed 25 patients who underwent conventional radiotherapy prior to 1990. Tumour volume control in all three groups was excellent and consistent with previously reported literature - only three of 86 (4%) patients undergoing SRS had a documented increase in tumour size, and none of the patients undergoing FSRT had a documented increase in size following a median follow-up of 5.5 and 5.1 years for SRS and FSRT, respectively. Target growth hormone levels of <2.5 ng/mL were met by 12 of 86 (14%) of the SRS group, and by two of 10 (20%) in the FSRT group. Target insulin-like growth factor-1 levels of age and sex matched controls were achieved in 16 of 86 patients (18.6%) post-SRS and five of 10 patients (50%) post-FSRT. New hormonal deficits requiring replacement therapy were identified in 17 of 86 (19.8%) patients post-SRS which is consistent with previously published radiosurgical series. Identified non-hormonal morbidity was low (<5%).

Effect of occupational exposure to aflatoxins on some liver tumor markers in textile workers

BACKGROUND

In a study of textile workers, the effects of occupational exposure to cotton dust-with possible exposure to aflatoxin-on levels of some liver tumor biomarkers were explored.

METHODS

The study included 58 textile workers and 64 controls. Skin prick tests, urinary Aflatoxin M1 (AFM1) and the tumor biomarkers (alpha-fetoprotein (AFP), alpha-L-fucosidase (AFU), insulin-like growth factors (IGF-1) were measured.

RESULTS

Positive reactants to Aspergillus niger, Aspergillus flavus, and cotton dust were significantly higher in pre-spinning (14.3%, 28.6%, and 28.6%, respectively) and spinning workers (25.0%, 33.3%, and 25.0%, respectively) compared to controls (4.7%, 7.8%, and 3.1%, respectively). Urinary AFM1 was significantly higher in the pre-spinning, spinning, and weaving groups compared to controls (554.2 ± 346.2 pg/ml, 459.1 ± 781.6 pg/ml, 296.5 ± 336.5 pg/ml and 68.5 ± 136.8 pg/ml, respectively). We found a highly significant increase in levels of serum AFU in textile workers, compared to the control group.

CONCLUSION

Exposure to fungi had a significant effect on AFM1 measurements and tumor biomarkers, especially in allergic textile workers (with the exception of the arginase biomarker), though results were generally within normal limits.

Static lung volumes and airway resistance reference values in healthy adults

BACKGROUND AND OBJECTIVE

The assessment of static lung volumes and airway resistance is a frequently performed diagnostic procedure and considered as an important tool in medical surveillance to detect pulmonary diseases. The objectives of the study are to establish reference equations for body plethysmographic parameters in a representative adult population across a wide age range and to compare the normative values from this sample with previous ones.

METHODS

Body plethysmography was applied in 1809 participants (885 males) of a cross-sectional, population-based survey (Study of Health in Pomerania). Individuals with cardiopulmonary disorders and/or a pack-year smoking history >10 years and participants with a body mass index >30 kg/m(2) were excluded. In total, 686 healthy individuals (275 males) aged 25-85 years were assessed.

RESULTS

Prediction equations for both genders were established by quantile regression analysis taking into account the influence of age, height and weight.

CONCLUSIONS

The study provides a novel set of prediction equations for static lung volumes and airway resistance obtained using body plethysmography. Compared with our findings, existing equations underestimated some normal values. The results emphasize the need for up-to-date reference equations.

A survey of correlation between insulin-like growth factor-I (igf-I) levels and severity of liver cirrhosis

BACKGROUND

Insulin-like growth factor is a polypeptide with endocrine, autocrine and paracrine effects which its structure is similar to the insulin molecule. While various tissues secrete IGF-1, 90% of the circulating IGF-1 is secreted by liver. Cirrhosis of liver is a condition accompanied by decreased level of IGF-1, in which the level of IGF-1 may be further decreased thorough the progression of the disease.

OBJECTIVES

The aim of the present study was to demonstrate the relation between the IGF-1 levels and severity of liver disease according to Child- Pugh and Model for end stage liver diseases (MELD) Scores.

PATIENTS AND METHOD

This was a descriptive-analytic cross sectional study performed on patients with cirrhosis admitted to gastroenterology clinic of Imam Khomeini Hospital in Tehran, Iran during the years 2007-2008. The diagnosis was based on liver biopsy. Initially for all patients, laboratory investigations including IGF-1, CBC, liver Enzymes, Alkaline phosphates, serum Albumin, Creatinine, direct and total Bilirubin were conducted. Also ultrasound and endoscopy were performed for evaluation of ascites and varices.

RESULTS

100 patients with cirrhosis with a male to Female ratio of 63:37 and a mean age of 44.4 ± 15 years were enrolled in the study. Median IGF-1 was 92.95 ± 91.51 ng/mL. 14 patients (14%) had IGF-1 within normal limits while 86 patients (86%) had abnormal IGF-1 levels. In all patients the correlation coefficient between IGF-1 and MELD was -0.317 (P = 0.001) and 0.478 between IGF-1 and Child- Pugh (P < 0.001).

CONCLUSIONS

Our findings showed that IGF-1 can be used as an index for evaluating the severity of cirrhosis; also it can be used for determining the severity of the disease, when liver biopsy is not possible.

Multiple protein biomarker assessment for recombinant bovine somatotropin (rbST) abuse in cattle

Biomarker profiling, as a rapid screening approach for detection of hormone abuse, requires well selected candidate biomarkers and a thorough in vivo biomarker evaluation as previously done for detection of growth hormone doping in athletes. The bovine equivalent of growth hormone, called recombinant bovine somatotropin (rbST) is (il)legally administered to enhance milk production in dairy cows. In this study, first a generic sample pre-treatment and 4-plex flow cytometric immunoassay (FCIA) were developed for simultaneous measurement of four candidate biomarkers selected from literature: insulin-like growth factor 1 (IGF-1), its binding protein 2 (IGFBP2), osteocalcin and endogenously produced antibodies against rbST. Next, bovine serum samples from two extensive controlled rbST animal treatment studies were used for in vivo validation and biomarker evaluation. Finally, advanced statistic tools were tested for the assessment of biomarker combination quality aiming to correctly identify rbST-treated animals. The statistical prediction tool k-nearest neighbours using a combination of the biomarkers osteocalcin and endogenously produced antibodies against rbST proved to be very reliable and correctly predicted 95% of the treated samples starting from the second rbST injection until the end of the treatment period and even thereafter. With the same biomarker combination, only 12% of untreated animals appeared false-positive. This reliability meets the requirements of Commission Decision 2002/657/EC for screening methods in veterinary control. From the results of this multidisciplinary study, it is concluded that the osteocalcin - anti-rbST-antibodies combination represent fit-for-purpose biomarkers for screening of rbST abuse in dairy cattle and can be reliably measured in both the developed 4-plex FCIA as well as in a cost-effective 2-plex microsphere-based binding assay. This screening method can be incorporated in routine veterinary monitoring programmes: in the European Union for detection of rbST abuse and in the control of rbST-free dairy farms in the United States of America and other countries.

Association between serum insulin-like growth factor I or IGF-binding protein 3 and estimated glomerular filtration rate: results of a population-based sample

BACKGROUND

Insulin-like growth factor I (IGF-I), which is mostly carried in blood by IGF-binding protein 3 (IGFBP-3), was associated to the glomerular filtration rate and chronic kidney disease in a multiethnic study among US adults. The aim of the present study was to investigate whether serum IGF-I or IGFBP-3 are associated with estimated glomerular filtration rate (eGFR) in a population-based study of Caucasian adults.

METHODS

Data from 4028 subjects (2048 women) aged 20 to 81 years from the Study of Health in Pomerania (SHIP) were analyzed. Total serum IGF-I and IGFBP-3 concentrations were determined by chemiluminescence immunoassays and categorized into sex- and age-specific quartiles.

RESULTS

After adjusting for age, waist circumference and type 2 diabetes mellitus, analysis of variance (ANOVA) revealed inverse associations between serum IGF-I concentrations and eGFR in men as well as between serum IGFBP-3 concentrations and eGFR in men and women. Logistic regression analyses confirmed these findings and showed that high IGF-I or IGFBP-3 concentrations were associated with an increased risk of decreased eGFR (<60 mL/min/1.73 m2) in men or women. These relations became stronger when lower eGFR cut-offs were used for the analyses.

CONCLUSION

Our data revealed associations of increased serum IGF-I concentrations and decreased eGFR in men but not in women and an association of increased serum IGFBP-3 concentrations and decreased eGFR in both sexes.

Assessment of glucocorticoid therapy with salivary cortisol in secondary adrenal insufficiency

CONTEXT

Appropriate glucocorticoid replacement therapy in adrenal insufficiency (AI) is crucial, given the risks of chronic under- or overtreatment, particularly in patients on multiple medications. Salivary sampling allows for non-invasive, stress-free cortisol measurement.

OBJECTIVE

To determine whether salivary cortisol measurement is helpful in assessing the adequacy of glucocorticoid therapy with cortisone acetate (CA) in patients with secondary AI.

DESIGN

A prospective cohort study at the Endocrinology Unit of Padua University Hospital.

METHODS

Six samples of salivary cortisol were collected from 28 patients with secondary AI on CA treatment and from 36 healthy volunteers at fixed times of the day, and used to calculate salivary cortisol levels at each time point and the area under the curve (AUC) across the different sampling times.

RESULTS

Salivary cortisol levels were lower in patients than in controls in the morning but no differences were found in the afternoon or at night before resting. Salivary cortisol levels were higher in patients immediately following CA administration. Ten patients showed an AUC above the 97.5th percentile of controls, without clinical signs of hypercortisolism, and salivary cortisol levels 90 min after each dose of CA predict the AUC. All patients had severe GH deficiency and there were no differences in salivary cortisol levels or AUC between patients treated or not with GH.

CONCLUSIONS

Two salivary cortisol determinations, able to predict the daily AUC, may allow for assessing the adequacy of glucocorticoid replacement therapy in secondary AI and for identifying cases of over- or undertreatment.

Association between the insulin-like growth factor axis in serum and periodontitis in the Study of Health in Pomerania: an exploratory study

AIM

To evaluate the association of Insulin-like Growth Factor (IGF) I-related variables with periodontitis in the population-based Study of Health in Pomerania (SHIP).

MATERIAL AND METHODS

From the cross-sectional SHIP, 2293 subjects with clinical attachment loss (CAL) data and 2398 subjects with tooth count data aged 20-59 years were analysed. Serum IGF-I and IGF-binding protein (BP)-3 levels were determined by chemiluminescence immunoassays. Linear and logistic regressions with fractional polynomials were used to study associations between IGF-related variables and mean CAL or high tooth loss. For non-linear relations between IGFBP-3 and mean CAL, graphical presentations of fractional polynomials were used to deduce knots for linear splines.

RESULTS

In fully adjusted models, for serum IGFBP-3 values ≤1200 ng/ml, mean CAL increased significantly for decreasing serum IGFBP-3 levels [B = -0.027 (95% CI, -0.049; -0.005), p = 0.02]. The odds for high tooth loss decreased significantly for high serum IGFBP-3 values [OR = 0.97 (0.95; 0.99), p = 0.02]. Serum IGF-I levels and the IGF-I/IGFBP-3 ratio were not related to mean CAL or tooth loss after full adjustment.

CONCLUSIONS

Low serum IGFBP-3 levels might be associated with higher levels of periodontal disease. Neither serum IGF-I nor IGF-I/IGFBP-3 ratios were associated with periodontitis.

Serum insulin-like growth factor-I (IGF-I) reference ranges for chemiluminescence assay in childhood and adolescence. Data from a population of in- and out-patients

BACKGROUND

Insulin-like growth factor I (IGF-I) measurement is widely used for the diagnosis of disorders of GH secretion and sensitivity, and for monitoring of both GH and IGF-I replacement therapies. However, the lack of appropriate reference values obtained from large and representative samples undermines its practical utility.

OBJECTIVE

To establish IGF-I reference values for a commonly used enzyme-labeled chemiluminescent immunometric assay in a large population of children aged 0 to 18 years.

DESIGN

Cross-sectional analysis of serum IGF-I levels from samples collected in the two major Italian Children's Hospitals.

SUBJECTS AND METHODS

IGF-I was measured using a solid-phase, enzyme-labeled chemiluminescent immunometric assay in 24403 children (50.6% girls) aged 0 to 18 years. Quantile regression coupled to multivariable fractional polynomials was used to produce age- and sex-specific reference values.

MAIN OUTCOME MEASURE

Age- and sex-specific IGF-I reference values.

RESULTS AND CONCLUSION

Reference values for immunometric assay of IGF-I were produced in a large sample of children and adolescents. Prediction equations were provided to automatize their calculations.

Normal and pathologic concentrations of uremic toxins

An updated review of the existing knowledge regarding uremic toxins facilitates the design of experimental studies. We performed a literature search and found 621 articles about uremic toxicity published after a 2003 review of this topic. Eighty-seven records provided serum or blood measurements of one or more solutes in patients with CKD. These records described 32 previously known uremic toxins and 56 newly reported solutes. The articles most frequently reported concentrations of β2-microglobulin, indoxyl sulfate, homocysteine, uric acid, and parathyroid hormone. We found most solutes (59%) in only one report. Compared with previous results, more recent articles reported higher uremic concentrations of many solutes, including carboxymethyllysine, cystatin C, and parathyroid hormone. However, five solutes had uremic concentrations less than 10% of the originally reported values. Furthermore, the uremic concentrations of four solutes did not exceed their respective normal concentrations, although they had been previously described as uremic retention solutes. In summary, this review extends the classification of uremic retention solutes and their normal and uremic concentrations, and it should aid the design of experiments to study the biologic effects of these solutes in CKD.

Serum IGF-I in middle age covaries with reproductive life-history traits in British men and women

OBJECTIVES

The growth hormone/insulin-like growth factor-I (GH/IGF-I) axis may be an important component of individual life-history variation. This study examined whether IGF-I levels covary with reproductive life-history traits in a long-term British cohort study (the National Child Development Study).

METHODS

Using data on up to 5,252 individuals (2,431 men and 2,821 women) born in March 1958, relationships of serum IGF-I at age 45 with pubertal age, time to pregnancy (TTP), age at first reproduction (AFR), and lifetime reproductive success (LRS) were analyzed using general linear models.

RESULTS

IGF-I showed modest non-linear associations with pubertal age, being low in women who first menstruated, and men whose voice broke, in the oldest respective age categories. In women, but not men, IGF-I was negatively related to TTP. IGF-I was positively associated with AFR in both sexes and tended to be negatively related to LRS in women only. Some, but not all, relationships were attenuated after controlling for multiple potential confounders.

CONCLUSION

These results are consistent with the hypothesis that the GH/IGF-I axis partially underlies individual variance in reproductive outcomes, through either direct endocrine effects on reproductive function or behavior, indirect effects on other traits, or a combination of the above. Several limitations of this study include the late age at which blood samples were collected and the difficulty of disentangling social and biological factors contributing to the traits studied. Am. J. Hum. Biol., 2012. © 2012 Wiley Periodicals, Inc.

Standardized centile curves and reference intervals of serum insulin-like growth factor-I (IGF-I) levels in a normal Japanese population using the LMS method

Measurements of insulin-like growth factor-I (IGF-I) are useful not only for diagnosis and management of patients with growth hormone (GH)-related disorders but also for assessing nutritional status. We reported population-based references of serum IGF-I in 1996. However, they did not properly reflect data in the transition period from puberty to maturity. The aim of the present study was to re-establish a set of normative data for IGF-I for the Japanese population. The study included 1,685 healthy Japanese subjects (845 males, 840 females) from 0 to 83 years old. Subjects suffering from diseases that could affect IGF-I levels were excluded. Obese or extremely thin adult subjects were also excluded. IGF-I concentrations were determined by commercially available immunoradiometric assays. The reference intervals were calculated using the LMS method. Median IGF-I levels reached 310 ng/mL in males at the age of 14 years and 349 ng/mL in females at the age of 13 years, falling to 124 ng/mL and 103 ng/mL, respectively, by the age of 70 years. The mean pretreatment IGF-1 SD scores in patients with severe GH deficiency (GHD) obtained from the database of the Foundation for Growth Science and from clinical studies for adult GHD were -2.1±1.6 and -4.9±2.5, respectively. The present study established age- and gender-specific normative IGF-I data for the Japanese population and showed the utility of these references for screening patients with severe GHD.

Engineered insulin-like growth factor-1 for improved smooth muscle regeneration

Insulin-like growth factor-1 (IGF-1) has been shown to induce potent mitogenic responses in various cell types, yet its sustained local delivery is still an underdeveloped domain in the clinic. We report here an engineered IGF-1 that facilitates extended local delivery to a site through its immobilization capacity within fibrin. Through recombinant fusion with a substrate sequence tag derived from α(2)-plasmin inhibitor (α(2)PI(1-8)), the resulting variant, α(2)PI(1-8)-IGF-1, was covalently incorporated into fibrin matrices during normal thrombin/factor XIIIa-mediated polymerization. Bioactivity of the variant was confirmed to be equivalent to wild type (WT) IGF-1 via IGF-1 receptor phosphorylation and cell proliferation studies in urinary tract-derived cells in 2-D. Assessment of functional retention within 3-D fibrin matrices demonstrated that incorporation of α(2)PI(1-8)-IGF-1 induced a 1.3- and 1.5-fold more robust proliferative response in smooth muscle cells (SMCs) than WT IGF-1 and negative control matrices, respectively, when release was not contained. Sustained α(2)PI(1-8)-IGF-1 availability at bladder lesion sites in vivo evoked a considerable increase in SMC proliferation and a favorable host tissue response after 28 days in rats. We conclude that the sustained local IGF-1 availability from fibrin provided by our variant protein enhances smooth muscle regeneration better than the WT form of the protein.

Epidemiologic survey: reference ranges of serum insulin-like growth factor 1 levels in Caucasian adult population with immunoradiometric assay

Gender, age adjusted, population based reference ranges are necessary to use insulin-like growth factor 1 (IGF-1) as a diagnostic marker or for therapeutic monitoring in growth hormone (GH) related diseases. The aim of the present study was to describe the serum IGF-1 distribution and to calculate age and gender specific reference values for Caucasian adult population. A representative sample of 1002 male and 1039 female, totally 2041 participants aged above 18 years old was examined. The subjects suffering from diabetes mellitus, renal diseases, liver diseases, cancer, or diseases of pituitary gland were excluded by medical history, physical examination, and laboratory tests. The subjects were not using any drug that could affect IGF-1 levels. Body mass index (BMI)>30 or<18 kg/m2 were excluded. Serum IGF-1 concentrations were determined by immunoradiometric assay (IRMA). Serum IGF-1 concentrations were declined with age in both males and females after the age of 18. Males had significantly higher serum IGF-1 levels than females in the age groups 18-24, 50-69 (P<0.05), but not in others (P>0.05). The present study established age and gender specific reference ranges for serum IGF-1 levels calculated for Caucasian adult population with IRMA that could be used in medical practice.

IGF-I increases the expression of fibronectin by Nox4-dependent Akt phosphorylation in renal tubular epithelial cells

Extracellular matrix accumulation contributes to the progression of chronic kidney disease. Many growth factors including insulin-like growth factor-I (IGF-I) enhance matrix protein accumulation. Proximal tubular epithelial cells (PTCs) synthesize matrix proteins. NADPH oxidases are major sources of reactive oxygen species (ROS), important signaling molecules that mediate biological responses in a variety of cells and tissue. We investigated the mechanism by which IGF-I regulates fibronectin accumulation in PTCs and the role of a potential redox-dependent signaling pathway. IGF-I induces an increase in NADPH-dependent superoxide generation, enhances the release of hydrogen peroxide, and increases the expression of NADPH oxidase 4 (Nox4) in PTCs. IGF-I also stimulates phosphorylation of Akt, and inhibition of Akt or its upstream activator phosphatidylinositol 3-kinase attenuates IGF-I-induced fibronectin accumulation. Expression of dominant negative Akt also inhibits IGF-I-induced expression of fibronectin, indicating a role for this kinase in fibronectin accumulation. Expression of dominant negative adenovirus Nox4 inhibits IGF-I-induced NADPH oxidase activity, Akt phosphorylation, and fibronectin protein expression. Moreover, transfection of small interfering RNA targeting Nox4 decreases Nox4 protein expression and blocks IGF-I-induced Akt phosphorylation and the increase in fibronectin, placing Nox4 and ROS upstream of Akt signaling pathway. To confirm the role of Nox4, PTCs were infected with adenovirus construct expressing wild-type Nox4. Ad-Nox4, but not control Ad-green fluorescent protein, upregulated Nox4 expression and increased NADPH oxidase activity as well as fibronectin expression. Taken together, these results provide the first evidence for a role of Nox4 in IGF-I-induced Akt phosphorylation and fibronectin expression in tubular epithelial cells.

Cognitive response to estradiol in postmenopausal women is modified by high cortisol

Estradiol has potent favorable effects on brain function and behavior in animals while in human trials, the results are inconsistent. A number of potential mediating variables influencing response to estradiol have been proposed to account for this variability, 1 of which includes stress. We conducted a placebo-controlled study to examine joint and independent effects of estradiol and elevated levels of the stress hormone cortisol on cognition and biomarkers of aging and neurodegenerative disease. Thirty-nine healthy postmenopausal women (56-84 years) received 0.10 mg/dL of transdermal 17β-estradiol (E2) or placebo for 8 weeks. During the last 4 days of the trial, subjects also received 90 mg/day (30 mg 3×/day) of oral hydrocortisone (CORT) to induce stress-level elevations in cortisol, or a matched placebo. The 4 groups thus included placebo (placebo patch/placebo pill), CORT-alone (placebo patch/hydrocortisone), E2-alone (estradiol patch/placebo pill), and E2+CORT (estradiol patch/hydrocortisone). Eight weeks of E2 increased plasma estradiol by 167%, and 4 days of CORT increased plasma cortisol by 119%. Overall, E2 had favorable effects on verbal memory (p = 0.03), working memory (p = 0.02), and selective attention (p = 0.04), and the magnitude of these effects was attenuated for E2+CORT. E2-alone and E2+CORT had opposing effects on plasma levels of the amyloid-β (Aβ) biomarker (Aβ40/42 ratio, p < 0.05), with the more favorable response observed for E2-alone. CORT-induced increases in insulin-like growth factor-1 were blunted by E2 coadministration. Our findings indicate that cognitive and physiological responses to estradiol are adversely affected by elevated stress hormone levels of cortisol in healthy postmenopausal women.

Serum insulin-like growth factor I and its binding protein 3 in their relation to intima-media thickness: results of the study of health in Pomerania (SHIP)

OBJECTIVE

Previous studies detected associations between lower insulin-like growth factor I (IGF-I) levels and increased risk of congestive heart failure or ischaemic heart disease. The aim of the present study was to assess the association of IGF-I and its binding protein 3 (IGFBP-3) with the carotid intima-media thickness (IMT) as marker of asymptomatic cardiovascular disease.

DESIGN AND POPULATION

From the population-based Study of Health in Pomerania (SHIP), a total of 2286 participants aged 45 years or older with readable ultrasound of the carotid arteries were available for the present analyses.

METHODS AND MEASUREMENTS

Serum IGF-I and IGFBP-3 levels were categorized into three groups (low, moderate, high) according to the sex-specific 10th and 90th percentile. Analyses of variance (anova) and logistic regression analyses adjusted for age, waist circumference, diabetes, hypertension and creatinine clearance were performed.

RESULTS

After adjusting for confounding factors, IGF-I and the IGF-I/IGFBP-3 ratio were positively related to IMT in anova. Logistic regression analyses confirmed these findings and showed that high IGF-I levels, a high IGF-I/IGFBP-3 ratio and low IGFBP-3 levels were associated to higher odds of increased IMT.

CONCLUSION

In conclusion, high IGF-I or high IGF-I/IGFBP-3 ratio values and low IGFBP-3 levels are associated with increased IMT. Therefore, systemic levels of the IGF axis or alterations in the balance of its components are associated with subclinical atherosclerotic disease.

Adrenal lesions in acromegaly: do metabolic aspects and aryl hydrocarbon receptor interacting protein gene have a role? Evaluation at baseline and after long-term follow-up

BACKGROUND

Adrenal lesions are discovered in acromegaly more frequently than in general population, without relationship with primary disease. Some patients, carriers of aryl hydrocarbon receptor interacting protein (AIP) gene mutations, developed an adrenal neoplasm.

AIM

To evaluate the role of metabolic and genetic aspects and the follow-up of adrenal nodules in acromegaly.

MATERIAL AND METHODS

We studied 69 acromegalic patients (30 male and 39 female, 56 ± 15 yr) who had been referred to the Endocrinology Unit of Padua. In all patients we determined body mass index (BMI) and waist-to-hip ratio (WHR); we performed an oral glucose tolerance test (OGTT) whenever possible. If adrenal computed tomography revealed a lesion, the patient underwent an endocrine and genetic study.

RESULTS

Adrenal lesions were identified in 14 patients and were not related to gender, duration of disease, GH or IGF-I concentrations, basal and after-OGTT glucose and insulin levels, log(HOMA-IR) and Quantitative Insulin Sensitivity Check Index (QUICKI) values, whereas BMI and WHR were higher in patients with adrenal lesions. Baseline endocrine and radiological study revealed benign lesions; during mean 4-yr follow-up none of the patients showed hormone excess, even though some lesions increased in size. We did not find any mutation in AIP gene, except heterozygous silent alteration (T48T).

CONCLUSIONS

The frequency of non-functioning adrenal lesions in acromegaly is not associated with the considered aspects, except BMI and WHR. The prolonged follow-up showed that these lesions have a tendency to increase in size independently of the control of acromegaly, so a morphological follow- up is recommended.

Association of IGF-I and IGFBP-3 with health care costs and hospitalization: results from a prospective observational study

OBJECTIVE

Previous cohort studies found robust associations of serum insulin-like growth factor I (IGF-I) and its main binding protein IGFBP-3 with increased morbidity or mortality. This study investigates the relationships between IGF-I and IGFBP-3 with health care costs and hospitalization in a general population and whether adding IGF-I or IGFBP-3 to a model of established health care predictors improves prediction.

METHODS

Data from a population-based cohort study of 3139 men and women in Germany, aged 20 to 80 years at baseline were used (median follow-up time: 5.0 years). Self-reported physician visits, length of hospital stay were used to estimate annual costs. IGF-I and IGFBP-3 were categorized at the 10th and 90th percentile, to indicate 'low', 'intermediate', and 'high' concentrations, respectively.

RESULTS

Total annual health care costs, with the major component of inpatient costs, and risk of hospitalization at baseline and follow-up were higher in subjects with low compared to intermediate IGF-I or IGFBP-3, after multivariable-adjustment. Subjects with low in contrast to intermediate IGF-I exhibited 30.6% higher annual total costs 5 years after baseline examination, corresponding to a difference in adjusted costs of EUR436.61.

CONCLUSIONS

Low IGF-I and IGFBP-3 independently predict future health care costs and hospitalization. IGF-I or IGFBP-3 might be useful to identify subjects with excess health care use. The predictive performance of cross-sectional and longitudinal models of total and inpatient costs were slightly improved by adding IGF-I or IGFBP-3 but the cost-effectiveness of inclusion into prediction models needs to be examined.

Association of circulating IGF-I and IGFBP-3 concentrations and exercise capacity in healthy volunteers: results of the Study of Health in Pomerania

BACKGROUND

Insulin-like growth factor I (IGF-I) and its binding protein 3 (IGFBP-3) are central mediators of endocrine effects of growth hormone and there is increasing evidence for an association with muscle strength and exercise capacity. The aim of the present study was to clarify the possible association of circulating IGF-I and IGFBP-3 concentrations and exercise capacity in a general adult population.

MATERIALS AND METHODS

From the Study of Health in Pomerania (SHIP) 1332 subjects aged 25 to 85 years participated in a standardised symptom limited cardiopulmonary exercise test on a bicycle. Exercise capacity was characterized by oxygen uptake at anaerobic threshold (VO₂@AT), peak exercise (peakVO₂), oxygen pulse and maximum power output at peak exertion. Multivariable linear regression analyses adjusted for age, sex, body mass index, physical activity and smoking were performed.

RESULTS

At peak exercise performance, in women IGF-I showed significant associations to peakVO₂ and maximum power output, IGF-I/IGFBP-3 ratio was associated with maximum power output. In men, this association was not consistently reproducible. Neither IGF-I nor IGFBP-3 did reveal any association to VO₂@AT in both genders.

CONCLUSION

Serum IGF-I concentrations are associated with peak exercise capacity in healthy women, but not in men over a wide range in ages, body sizes and activity scores.

IGF-I, IGF-II, IGFBP2, IGFBP3 and acid-labile subunit (ALS) in colorectal cancer patients before surgery and during one year follow up in relation to age

PURPOSE

To investigate the changes of IGF system in colon cancer patients in relation to age, the serum IGF-I, IGF-II, IGFBP2, IGFBP3 and ALS were measured by immunochemistry before surgery, as well as one and six months after surgery.

MATERIAL AND METHODS

One hundred and twenty six patients were included into the study: group I (<50 yrs, N=21); group II (50 to <55 yrs, N=16) ; group III (55 to <65 yrs, N=34); group IV (65 to <75 yrs, N=42) and group V (> or =75 yrs, N=13).

RESULTS

Before surgery: only the mean value of IGF-I concentration in group I was significantly higher as compared to group V (p<0.01). One month after surgery: 1) a decrease in the mean values of IGF-I, IGF-II, IGFBP3 and ALS levels was observed, but only for IGF-II (groups II-V), IGFBP3 (groups II-V) and ALS (groups III-V) the changes were significant; 2) the mean value of ALS level in group I was higher as compared to group III-V (p<0.05 to 0.02); 3) higher mean values of IGF-I/alb, IGFBP3/alb and ALS/alb were noted for group I as compared to group V (p<0.01 to 0.001); 4) the mean levels of IGFBP2 were significantly lower in group I as compared to groups II, III, IV and V (p<0.001 in all cases).

CONCLUSIONS

In colon cancer patients IGF-I, IGFBP3 and ALS decrease with age, but the relation between them exists regardless the patient's age and time of observation. Lower IGFBP2 level together with higher IGF-I might contribute to more aggressive course of disease in colon cancer patients below 50 years of age.

Full-length huntingtin levels modulate body weight by influencing insulin-like growth factor 1 expression

Levels of full-length huntingtin (FL htt) influence organ and body weight, independent of polyglutamine length. The growth hormone-insulin like growth factor-1 (GH-IGF-1) axis is well established as a regulator of organ growth and body weight. In this study, we investigate the involvement of the IGF-1 pathway in mediating the effect of htt on body weight. IGF-1 expression was examined in transgenic mouse lines expressing different levels of FL wild-type (WT) htt (YAC18 mice), FL mutant htt (YAC128 and BACHD mice) and truncated mutant htt (shortstop mice). We demonstrate that htt influences body weight by modulating the IGF-1 pathway. Plasma IGF-1 levels correlate with body weight and htt levels in the transgenic YAC mice expressing human htt. The effect of htt on IGF-1 expression is independent of CAG size. No effect on body weight is observed in transgenic YAC mice expressing a truncated N-terminal htt fragment (shortstop), indicating that FL htt is required for the modulation of IGF-1 expression. Treatment with 17beta-estradiol (17beta-ED) lowers the levels of circulating IGF-1 in mammals. Treatment of YAC128 with 17beta-ED, but not placebo, reduces plasma IGF-1 levels and decreases the body weight of YAC128 animals to WT levels. Furthermore, given the ubiquitous expression of IGF-1 within the central nervous system, we also examined the impact of FL htt levels on IGF-1 expression in different regions of the brain, including the striatum, cerebellum of YAC18, YAC128 and littermate WT mice. We demonstrate that the levels of FL htt influence IGF-1 expression in striatal tissues. Our data identify a novel function for FL htt in influencing IGF-1 expression.

Growth hormone deficiency in patients with chronic heart failure and beneficial effects of its correction

CONTEXT

A reduced activity of the GH/IGF-I axis in chronic heart failure (CHF) has been described by several independent groups and is associated with poor clinical status and outcome.

OBJECTIVE

The aim of the current study was to investigate the prevalence of GH deficiency in a patient population with CHF and evaluate the cardiovascular effects of GH replacement therapy.

DESIGN AND SETTING

The randomized, single-blind, controlled trial was conducted at the Federico II University.

PARTICIPANTS

One hundred fifty-eight patients with CHF, New York Heart Association class II-IV, underwent a GH stimulation test. Sixty-three patients satisfied the criteria for GH deficiency, and 56 of them were enrolled in the trial.

INTERVENTION

The treated group (n = 28) received GH at a replacement dose of 0.012 mg/kg every second day (approximately 2.5 IU).

MAIN OUTCOMES MEASURES

Changes in physical performance and various cardiovascular indexes were measured.

RESULTS

GH replacement therapy improved quality of life score (from 46 +/- 5 to 38 +/- 4; P < 0.01), increased peak oxygen uptake and exercise duration (from 12.9 +/- .9 to 14.5 +/- 1 ml/kg x min and from 520 +/- 36 to 586 +/- 43 sec, respectively; P < 0.01), and flow-mediated vasodilation (from 8.8 +/- 1.3 to 12.7 +/- 1.2%; P < 0.01). GH increased left ventricular ejection fraction (from 34 +/- 2 to 36 +/- 2%; P < 0.01) and reduced circulating N-terminal pro-brain natriuretic peptide levels (from 3201 +/- 900 to 2177 +/- 720 pg/ml; P = 0.006). No significant changes from baseline were observed in controls.

CONCLUSIONS

As many as 40% of patients with CHF are GH deficient. GH replacement therapy in these patients improves exercise capacity, vascular reactivity, left ventricular function, and indices of quality of life.