Are insulin-like growth factor and its binding proteins 1 and 3 clinically useful as markers of malnutrition, sarcopenia and inflammation in end-stage renal disease?

Role of specific nutritional biomarkers in predicting post-operative complications among patients undergoing elective abdominal surgery

PURPOSE

Nutritional biomarkers like serum prealbumin, transferrin, retinol-binding protein (RBP), C-reactive protein (CRP), leptin, and insulin-like growth factor 1 (IGF1) have the inherent ability to diagnose undernutrition objectively before it is clinically manifested. The primary objective of the study was to evaluate the diagnostic efficacy of the specific nutritional biomarkers in predicting post-operative complications.

METHODS

A prospective cohort study was conducted in the department of surgery and included all patients aged 18 years and above who underwent elective abdominal surgery. Demographic details and clinical and surgical details were documented from the case records. Nutritional biomarker assay was done at admission. The post-operative complications occurring until discharge were graded using the Clavien-Dindo classification. The diagnostic accuracy of the specific nutritional biomarkers in predicting post-operative complications was assessed.

RESULTS

A total of 320 patients were included in the study. Of these, 126 (39.38%) developed post-operative complications. Major complications accounted for 19.05% of the complications, while 80.95% were minor complications. Patients with blood prealbumin level less than 17.287 mg/dL had a higher incidence of complications (p < 0.001). Serum transferrin levels less than 168.04 mg/dL and IGF1 levels less than < 44.51 ng/ml showed increased incidence of complications (p < 0.001). The AUC was found to be the highest for serum IGF1 with 0.7782. Sensitivity was equally high for IGF1 and serum transferrin, with 76.98% for the former and 76.19% for the latter.

CONCLUSION

Specific nutritional biomarkers, like serum prealbumin and transferrin, were efficient in predicting postoperative complications of patients before undergoing elective abdominal surgeries even after adjusting for confounders. This can facilitate preoperative corrective measures to lower the overall postoperative complications.

The predictive value of temporal muscle thickness measured by ultrasonography for detecting moderate to severe malnutrition in chronic hemodialysis patients

INTRODUCTION AND AIM

To determine the predictive value of temporal muscle thickness (TMT) measured by ultrasonography in the diagnosing of moderate to severe malnutrition in chronic hemodialysis (CHD) patients.

MATERIALS AND METHODS

Adult patients (> 18 years) who had been on CHD for at least 3 months were included in this cross-sectional study. Patients with infection or inflammatory disease, malignancy, malabsorption syndrome, history of surgery within the last 3 months excluded. Demographic, anthropometric, laboratory parameters, and Malnutrition Inflammation Score (MIS) test results recorded.

RESULTS

A total of 60 chronic hemodialysis (CHD) patients (median age: 66 years, 46.7% female) and 30 healthy individuals (median age: 59.5 years, 55% female) were examined. While there were no significant difference between the dry weight (70 vs 71 kg) and body mass index (BMI) (25.8 vs 26 kg/m2) of the CHD patients and healthy control group, we found that triceps skinfold thickness (TST) (16 vs 19 mm) and left and right TMT (9.6 vs 10.7 and 9.8 vs 10.9 mm) values were significantly lower in the CHD patients (p < 0.001). CHD patients were divided into two groups according to their MIS values as mild (MIS < 6) and moderate/severe malnutrition (MIS ≥ 6). Patients with moderate/severe malnutrition were older, predominantly female and with longer HD vintage. Left (8.8 vs 11 mm) and right TMT (9.1 vs 11.2 mm) values were lower in moderate/severe malnutrition group. In the correlation analysis, a negative correlation was found between TMT and age and MIS, and a positive correlation determined with dry weight, BMI, TST and serum uric acid. In the ROC curve analysis, we found that the optimal cut-off value of left and right TMT for predicting moderate/severe malnutrition were 10.05 and 10.45 mm, respectively. Multivariate regression analysis showed that HD vintage, URR, and TMT values were independently associated with moderate/severe malnutrition.

CONCLUSION

TMT value measured by ultrasonography in CHD patients can be used as a reliable, easily accessible and non-invasive diagnostic method for predicting moderate/severe malnutrition.

Low Free Triiodothyronine as a More Sensitive Predictor of Survival Than Total Testosterone among Dialysis Men

BACKGROUND

Some endocrine disorders, previously considered benign, may be related to a poorer prognosis for patients with renal failure. Both low serum free triiodothyronine (fT3) and low total testosterone (TT) concentrations have been considered as predictors of death in dialysis patients, but the results of studies are inconsistent. In our study, we evaluated the relationships of the serum thyroid hormone levels and the total testosterone levels with survival in male dialysis patients.

METHODS

Forty-eight male dialysis patients, 31 on hemodialysis (HD) and 17 on peritoneal dialysis (PD), aged 61.4 ± 10.0, 59.2 ± 12.2 years, respectively, were included in the study. Serum thyroid hormones and total testosterone were measured.

RESULTS

During the 12-month follow-up, nine all-cause deaths were recorded. The concentrations of fT3 were significantly lower in those who died than in the survivors (p = 0.001). We did not observe any statistically considerable differences between the group of men who died and the rest of the participants in terms of the total serum testosterone concentration (p = 0.350). Total testosterone positively correlated with fT3 (r = 0.463, p = 0.009) in the HD group.

CONCLUSIONS

In the group of male dialysis patients, the serum concentration of fT3 had a better prognostic value in terms of survival than the total testosterone. A linear relationship between the fT3 levels and testosterone levels in men undergoing hemodialysis may confirm the hypothesis that some of the hormonal changes observed in chronic kidney disease (CKD) may have a common cause.

Exploring Metabolic Signature of Protein Energy Wasting in Hemodialysis Patients

End-stage renal disease patients undergoing maintenance hemodialysis (HD) are vulnerable to the protein energy wasting (PEW) syndrome. Identification and diagnosis of PEW relies on clinical processes of judgment dependent on fulfilling multiple criteria drawn from serum biochemistry, weight status, predictive muscle mass, dietary energy and protein intakes. Therefore, we sought to explore the biomarkers’ signature with plasma metabolites of PEW by using ¹H-nuclear magnetic resonance for an untargeted metabolomics approach in the HD population, to understand metabolic alteration of PEW. In this case-controlled study, a total of 53 patients undergoing chronic HD were identified having PEW based on established diagnostic criteria and were age- and sex-matched with non-PEW (n = 53) HD patients. Fasting predialysis plasma samples were analyzed. Partial least square discriminant analysis demonstrated a significant separation between groups for specific metabolic pattern alterations. Further quantitative analysis showed that the level of 3-hydroxybutyrate, acetate, arabinose, maltose, ribose, sucrose and tartrate were significantly increased whilst creatinine was significantly decreased (all p < 0.05) in PEW subjects. Pathway analysis indicated that PEW-related metabolites reflected perturbations in fatty acid mechanism and induction of glyoxylate and dicarboxylate pathway attributed to gluconeogenesis. These results provide preliminary data in understanding metabolic alteration of PEW and corresponding abnormal metabolites that could potentially serve as biomarkers of PEW.

Elevated levels of insulin-like growth factor-binding protein 1 predict outcome after acute myocardial infarction: A long-term follow-up of the glucose tolerance in patients with acute myocardial infarction (GAMI) cohort

OBJECTIVE

To investigate the long-term prognostic value of insulin-like growth factor-binding protein 1 in patients with acute myocardial infarction.

METHODS

Patients ( n = 180) with admission glucose < 11 mmol/L without previously known diabetes admitted for an acute myocardial infarction in 1998-2000 were followed for mortality and cardiovascular events (first of cardiovascular mortality/acute myocardial infarction/stroke/severe heart failure) until the end of 2011 (median 11.6 years). Fasting levels of insulin-like growth factor-binding protein 1 at day 2 were related to outcome in Cox proportional hazard regression analyses.

RESULTS

Median age was 64 years, 69% were male and median insulin-like growth factor-binding protein 1 was 20 µg/L. Total mortality was 34% ( n = 61) and 44% ( n = 80) experienced a cardiovascular event during a median follow-up time of 11.6 years. After age adjustment, insulin-like growth factor-binding protein 1 was associated with all-cause (1.40; 1.02-1.93, p = 0.039) and cancer mortality (2.09; 1.15-3.79, p = 0.015) but not with cardiovascular death ( p = 0.29) or cardiovascular events ( p = 0.57). After adjustments also for previous myocardial infarction, previous heart failure and body mass index, insulin-like growth factor-binding protein 1 was still associated with all-cause mortality (1.38; 1.01-1.89, p = 0.046).

CONCLUSION

In patients with acute myocardial infarction without previously known diabetes, high insulin-like growth factor-binding protein 1 was associated with long-term all-cause and cancer mortality but not with cardiovascular events.

High insulin-like growth factor-binding protein-1 (IGFBP-1) is associated with low relative muscle mass in older women

OBJECTIVE

Skeletal muscles serve several important roles in maintaining good health. Insulin-like growth factor-1 (IGF-1) is a promoter of protein synthesis in skeletal muscle. Its binding protein, Insulin-like growth factor-binding protein-1 (IGFBP-1) can be one determinant of IGF-1 activity. In the present study we investigate the association between serum IGFBP-1 and muscle mass.

DESIGN

Cross-sectional analysis of 4908 women, between 55 and 85years old, participating in the Swedish Mammography Cohort-Clinical.

METHODS

We defined low relative muscle mass (LRMM) as an appendicular lean mass divided by height squared of less than 5.45 (kg/m²), assessed by dual energy x-ray absorptiometry. IGFBP-1 was measured by radioimmunoassay. Logistic regression was used to calculate odds-ratios of LRMM across quartiles of IGFBP-1.

RESULTS

The odds of LRMM increased across quartiles of IGFBP-1. In the age-adjusted model the odds-ratio (OR) of LRMM was 3.41 (95% CI: 2.55-4.56), comparing the highest to the lowest quartile. This estimate was attenuated in multivariate models (OR: 1.84, 95% CI: 1.34-2.53), mainly due to inclusion of fat mass index.

CONCLUSION

Women with higher IGFBP-1 were more likely to have a low relative muscle mass. High IGFBP-1 may be a marker of a catabolic state.

Direct regulation of IGF-binding protein 1 promoter by interleukin-1β via an insulin- and FoxO-1-independent mechanism

The level of insulin-like growth factor-binding protein 1 (IGFBP1), a liver-produced serum protein that regulates insulin-like growth factor-I bioactivity, glucose homeostasis, and tissue regeneration, increases during inflammation. This manuscript describes a novel pathway for the regulation of hepatic IGFBP1 mRNA and protein levels by interleukin (IL)-1β. Experiments with the luciferase reporter system show that IL-1β stimulates transcriptional activity from the 1-kb promoter region of IGFBP1. Although IL-1β stimulation suppresses the insulin activation of protein kinase B, the major upstream regulator of IGFBP1 mRNA transcription, the induction of IGFBP1 by IL-1β did not require an intact insulin response element. Furthermore, neither overexpression nor silencing of FoxO-1 had any effect on the IL-1β-induced increase in IGFBP1 mRNA levels and promoter activity. However, inhibition of the ERK MAP kinases effectively prevented the IL-1β effects. Inhibition of neutral sphingomyelinase, a key player in the IL-1β signaling cascade that acts upstream of ERK, also suppressed the IL-1β effects, while increasing the ceramide, through the addition of C2-ceramide or via treatment with exogenous sphingomyelinase, was sufficient to induce IGFBP1 promoter-driven luciferase activity. Studies in primary rat hepatocytes where the levels of neutral sphingomyelinase were either elevated or suppressed using adenoviral constructs affirmed the key role of neutral sphingomyelinase and ceramide (exerted likely through ERK activation) in the IL-1β-induced IGFBP1 production. Finally, the IL-1β effects on IGFBP1 mRNA production and protein secretion could be abolished by the addition of insulin, either at very late time points or at very high doses.

A cohort study of insulin-like growth factor 1 and mortality in haemodialysis patients

Background

Protein-energy wasting (PEW) is highly prevalent in haemodialysis (HD) patients and associated with increased mortality and cardiovascular disease (CVD). Insulin-like growth factor 1 (IGF-1) correlates to markers of PEW and CVD. Disturbances in the growth hormone axis in end-stage renal disease (ESRD) could have an impact on survival through increased PEW and CVD.

Methods

A cohort of 265 incident HD patients (median age 68 years, 59% males) was followed for 3 years. Subjects were categorized according to IGF-1 levels at dialysis initiation. Outcome and comorbidity data were retrieved from national registers. The Kaplan–Meier diagram and Cox proportional hazards model were used for the analysis of survival.

Results

Patients with IGF-1 levels in the lowest tertile were characterized by female sex, low creatinine, hypoalbuminemia and high C-reactive protein (CRP) levels. IGF-1 levels within the lowest tertile were associated with increased mortality [hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.7–3.4]. This association persisted when corrected for demographic factors (age, sex) and comorbidities (diabetes mellitus, CVD, heart failure) in multivariable analysis. Including high-sensitivity C-reactive protein (hs-CRP) and serum creatinine in the model had a small effect on the magnitude of the hazard. When serum albumin was added to the model, the HR declined from 2.2 to 1.6, but remained significant (P = 0.02).

Conclusion

Low IGF-1 levels associate with increased mortality in HD, independent of biomarkers of inflammation (hs-CRP) and PEW (creatinine, albumin). Serum albumin modulates the relationship between IGF-1 levels and mortality, indicating shared pathophysiological pathways with IGF-1.

Sarcopenia in chronic kidney disease on conservative therapy: prevalence and association with mortality

BACKGROUND

In chronic kidney disease (CKD), multiple metabolic and nutritional abnormalities contribute to the impairment of skeletal muscle mass and function thus predisposing patients to the condition of sarcopenia. Herein, we investigated the prevalence and mortality predictive power of sarcopenia, defined by three different methods, in non-dialysis-dependent (NDD) CKD patients.

METHODS

We evaluated 287 NDD-CKD patients in stages 3-5 [59.9 ± 10.5 years; 62% men; 49% diabetics; glomerular filtration rate (GFR) 25.0 ± 15.8 mL/min/1.73 m(2)]. Sarcopenia was defined as reduced muscle function assessed by handgrip strength (HGS <30th percentile of a population-based reference adjusted for sex and age) plus diminished muscle mass assessed by three different methods: (i) midarm muscle circumference (MAMC) <90% of reference value (A), (ii) muscle wasting by subjective global assessment (B) and (iii) reduced skeletal muscle mass index (<10.76 kg/m² men; <6.76 kg/m² women) estimated by bioelectrical impedance analysis (BIA) (C). Patients were followed for up to 40 months for all-cause mortality, and there was no loss of follow-up.

RESULTS

The prevalence of sarcopenia was 9.8% (A), 9.4% (B) and 5.9% (C). The kappa agreement between the methods were 0.69 (A versus B), 0.49 (A versus C) and 0.46 (B versus C). During follow-up, 51 patients (18%) died, and the frequency of sarcopenia was significantly higher among non-survivors. In crude Cox analysis, sarcopenia diagnosed by the three methods was associated with a higher hazard for mortality; however, only sarcopenia diagnosed by method C remained as a predictor of mortality after multivariate adjustment.

CONCLUSIONS

The prevalence of sarcopenia in CKD patients on conservative therapy varies according to the method applied. Sarcopenia defined as reduced handgrip strength and low skeletal muscle mass index estimated by BIA was an independent predictor of mortality in these patients.

Evaluation of Nutritional Biochemical Parameters in Haemodialysis Patients over a Ten-year Period

AIM

Protein-energy malnutrition as well as systemic inflammation and metabolic disorders are common in patients with chronic kidney failure, who require renal replacement therapy (haemodialysis). Such malnutrition is a factor that significantly contributes to their morbidity and mortality. This study evaluated the nutritional status of haemodialysis patients by assessing biochemical and anthropometric parameters in order to determine whether these patients suffered disorders reflecting nutritional deterioration directly related to time on haemodialysis.

SUBJECTS AND METHOD

This research comprised 90 patients of both genders with chronic kidney failure, who regularly received haemodialysis at our unit over a period of ten years. The patients' blood was tested quarterly for plasma albumin, total cholesterol and total proteins, and tested monthly for transferrin. The patients' weight, height and body mass index (BMI) were monitored. Body mass index was calculated using the formula: weight (kg)/height (m2 ) and classified in one of the following categories defined in the World Health Organization (WHO) Global Database on Body Mass Index: (i) underweight [BMI < 18.50], (ii) normal [BMI 18.50 - 24.99], (iii) overweight [BMI 25 - 29.99], (iv) obese [BMI > 30].

RESULTS

In the ten-year period of the study, the patients experienced a substantial decline in their biochemical parameters. Nevertheless, their BMI did not show any significant changes despite the patients' state of malnutrition.

CONCLUSIONS

The prevalence of malnutrition in haemodialysis patients was evident. Nevertheless, the BMI of the subjects did not correspond to the biochemical parameters measured. Consequently, the results showed that the nutritional deterioration of these patients was mainly reflected in their biochemical parameters rather than in their anthropometric measurements.

Prevalence of sarcopenia in elderly maintenance hemodialysis patients: the impact of different diagnostic criteria

The prevalence of sarcopenia on elderly maintenance hemodialysis (MHD) has been scarcely investigated.

OBJECTIVES

To investigate the prevalence of decreased muscle mass and strength alone or combined (true sarcopenia) in elderly patients on MHD according to different methods and cutoff limits. Additionally, we evaluated the agreement between dual energy x-ray absorptiometry (DXA) and surrogate methods for the assessment of muscle mass.

DESIGN

Observational and cross-sectional study.

PARTICIPANTS

Non-institutionalized 102 elderly (age > 60 years) patients on MHD.

MEASUREMENTS

Sarcopenia was considered when the patient fit one criteria for low muscle mass assessed by DXA, bioelectrical impedance (BIA), sum of skinfold thicknesses (SKF), calf circumference and mid-arm muscle circumference (MAMC) and one for low muscle strength evaluated by handgrip dynamometer.

RESULTS

Decreased muscle strength was found in 85% of the patients. The prevalence of decreased muscle mass varied from 4 to 73.5% and of sarcopenia (decreased muscle mass and strength combined) from 4 to 63%, depending on the method and cutoff limit applied. A small percentage of patients (2 to 15%) were classified as sarcopenic by more than one diagnostic criteria. The agreement between DXA and the surrogate methods to assess muscle mass showed better kappa coefficients with BIA (r=0.36; P<0.01) and SKF (r=0.40; P<0.01).

CONCLUSION

A wide prevalence of sarcopenia is observed depending on the method and cutoff limit applied. This may limit extrapolate on to clinical practice. BIA and SKF were the surrogate methods to assess muscle mass with the best concordance with DXA in elderly MHD patients.

Impaired postprandial response of the insulin-like growth factor system in maintenance haemodialysis

OBJECTIVE

Patients on maintenance haemodialysis (HD) have reduced circulating free and bioactive insulin-like growth factor I (IGF-I) due to increased IGF-binding proteins (IGFBPs). This study investigated the postprandial response of the IGF system in HD patients compared with matched healthy subjects.

DESIGN AND PATIENTS

In a crossover study, twelve nondiabetic HD patients were assigned in a random order to three 10-h study days: (1) a non-HD day with one meal served at baseline (NHDM1), (2) an HD day with one meal served during HD (HDM1) and (3) an HD day with two meals served during and after HD, respectively (HDM2). Twelve healthy controls conducted session 1.

RESULTS

After the baseline meal, insulin concentrations changed similarly in HD patients and controls, whereas hyperglycaemia was more prolonged in HD patients (P < 0·001). Postprandial IGFBP-1 showed greater reductions from baseline in controls (-76% [-81; -70%], mean [95% confidence intervals], P < 0·001) than in patients on non-HD days (-45% [-57; -30%], P < 0·001). In the latter group, the response was even more attenuated during HD (-22% [-38; -1%] and -24% [-40; -4%], P ≤ 0·041). After the second meal on HDM2 days, IGFBP-1 further decreased (-50% [-61; -37%], P < 0·001), whereas IGFBP-1 returned to baseline levels on the other study days. Consistently, at the end of the study days, bioactive IGF-I was significantly above baseline only on HDM2 days (+22% [+5; +43%], P = 0·012).

CONCLUSIONS

HD patients were unable to suppress IGFBP-1 to the same extent as healthy controls, which may increase the risk of protein-energy wasting in maintenance HD. A second meal after HD, however, effectively suppressed IGFBP-1 and increased bioactive IGF-I.

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.

Association between the ratio of insulin-like growth factor-I to insulin-like growth factor binding protein-3 and inflammation in incident automated peritoneal dialysis patients

BACKGROUND

The insulin-like growth factor (IGF) system is known to be associated with inflammation in various populations. However, the association between the IGF system and inflammation has not previously been investigated in automated peritoneal dialysis (APD) patients. Therefore, the aim of this study was to investigate whether the IGF system correlates with inflammation in APD patients.

METHODS

We prospectively determined IGF-I activity, the ratio of serum IGF-I concentrations to those of IGF binding protein-3 (IGFBP-3), and inflammatory markers at initiation of APD and after 6 months of follow-up in 21 incident APD patients.

RESULTS

The mean age was 55.2 ± 13.1 years, and 11 patients (52.3%) were male. Continuous cyclic PD (CCPD) was performed in 11 patients, and nocturnal intermittent PD (NIPD) in 10 patients. The mean value of IGF-I/IGFBP-3 was 0.21 ± 0.13. At baseline, IGF-I/IGFBP-3 was negatively correlated with high-sensitivity C-reactive protein (hs-CRP) (r = -0.27, P = 0.032) and interleukin-6 (IL-6) (r = -0.19, P = 0.046) concentrations. After 6 months, IGF-I/IGFBP-3 (P = 0.048) had decreased significantly, while the hs-CRP (P = 0.036) increased significantly in the CCPD group. However, there were no significant changes in IGF-I/IGFBP-3 (P = 0.59) and hs-CRP (P = 0.14) during 6 months in the NIPD group. Furthermore, compared with the NIPD group, IGF-I/IGFBP-3 (P = 0.041) decreased greater, whereas hs-CRP (P = 0.048) concentrations increased greater in the CCPD group.

CONCLUSIONS

The IGF system was significantly associated with inflammatory markers in incident APD patients, and different APD modalities modulate the IGF system and inflammation.

Insulin-like growth factor-1 bioactivity plays a prosurvival role in older participants

The aim of this study was to address the intriguing issue of the role of the insulin-like growth factor (IGF)-1 system in longevity looking at the role of different components of IGF system. Vital status was ascertained in 1,197 men and women aged greater than or equal to 65 years from the InCHIANTI study. Hormonal levels were categorized into quartiles, and ratio of IGF-1 to IGF-binding protein (IGFBP)-1 was calculated. The relationship between hormones and mortality was tested by Cox proportional hazard models adjusted for age, sex, and confounders. During the 8-year follow-up period, 240 died and 957 survived. Lowest quartiles of IGF-1 and IGFBP-1 were considered as reference. Compared with the lowest quartiles, IGF-1 in upper quartiles was a negative predictor of mortality independent of age and sex (p = .01) but not independent of IGFBP-1 and other confounders. IGFBP-1 in second-third quartiles was negatively associated and that in the fourth quartiles was positively associated with risk of death. IGF-1/IGFBP-1 ratio in the lowest quartiles was a strong positive predictor of mortality, in age- and sex-adjusted model (p = .005), and independent of additional confounders (p = .037). High IGFBP-1 and low IGF-1/IGFBP-1 ratio are associated with all-cause mortality in older population.

Uremia attenuates growth hormone-stimulated insulin-like growth factor-1 expression, a process worsened by inflammation

Growth hormone (GH) resistance is common in uremia and together with resistance to insulin-like growth factor-1 (IGF-1) contributes to uremic growth retardation and muscle wasting. Previously, we found decreased GH-stimulated janus-kinase 2-signal transducers and activators of transcription 5 (STAT5) phosphorylation and nuclear translocation in uremia; however, it is unclear whether there are more distal defects. Therefore, we tested whether the binding of phosphorylated STAT5b to DNA is intact in uremia. Using uremic rats we found that in addition to impaired hepatic STAT5b phosphorylation, the binding of available phospho-STAT5b to DNA is decreased thus contributing to impaired IGF-1 gene expression. As sepsis-induced inflammation causes a loss of body protein and as Gram-negative infections are relatively common in uremia, we also characterized mechanisms in which acute inflammation might contribute to GH resistance in uremia. Endotoxin-induced inflammation markedly increased the resistance to GH-mediated STAT5b signaling, and further decreased STAT5b binding to DNA and IGF-1 gene expression. These perturbations appear to be related to increased cytokine expression. Thus, our findings indicate that hepatic resistance to GH-induced IGF-1 expression in uremia arises due to defects in STAT5b phosphorylation and its impaired binding to DNA, processes further aggravated by inflammation.

Marked reductions in bioactive insulin-like growth factor I (IGF-I) during hemodialysis

OBJECTIVE

Hemodialysis (HD) patients lose lean body mass, even when they are adequately dialysed. One reason may be a decreased activity of the IGF-system. However, data on changes in bioactive IGF-I during HD are sparse.

DESIGN

Ten stable, non-diabetic HD patients were studied with 30 min intervals during a scheduled HD, with blood sampling before (-15 and 0 min), during (4 h) and after (1 h) the session. Patients were fasted for at least 6 h before and during the study. Arterial and venous blood was sampled for determination of IGF-I bioactivity, free and total IGF-I and IGF-II, IGF binding protein-1 (IGFBP-1), IGFBP-1 complexed IGF-I and IGFBP-2.

RESULTS

Total IGF-I and -II decreased marginally (<12%) at the very end of the study (P<0.05). By contrast, at 3 h free and bioactive IGF-I had declined by approximately 35% and 50%, respectively, and levels remained suppressed for the rest of the study (P<0.05). Concomitantly, IGFBP-1 and IGFBP-1:IGF-I complex formation increased 5.0-fold and 2.6-fold, respectively (P<0.05). By contrast, IGFBP-2 did not increase as a result of HD. No major differences between arterial and venous concentrations were observed.

CONCLUSION

Despite marginal reductions in total IGF-I and -II, bioactive and free IGF-I declined markedly during and after HD. This is likely a consequence of the increase in IGFBP-1, sequestering free IGF-I, and reducing bioactive IGF-I. Based on the present data we hypothesize that the catabolism induced by HD is in part related to the observed reductions in bioactive IGF-I.

Identification of patients with eating disorders: clinical and biochemical signs of appetite loss in dialysis patients

Patients with chronic kidney disease (CKD) frequently experience loss of appetite (anorexia), which increases in severity during the disease progression. The optimal medical assessment of an anorectic patient depends on an appropriate knowledge of the associated signs and symptoms. Some of these signs are diagnostic of anorexia in CKD. The aim of the present review is to provide a general understanding of the consequences of anorexia in the CKD patient, while describing simple assessment methods of appetite loss easy to implement in the clinical setting. Early clinical and physical diagnostic signs associated with appetite loss, as well as the expected reflections in several blood biomarkers, are discussed. Finally, the potential role of sex hormones in modulating the severity of these symptoms is introduced as a platform toward the understanding of sex hormone action in regulating/treating uremic anorexia.

Hypoxia and leucine deprivation induce human insulin-like growth factor binding protein-1 hyperphosphorylation and increase its biological activity

Fetal growth restriction is often caused by uteroplacental insufficiency that leads to fetal hypoxia and nutrient deprivation. Elevated IGF binding protein (IGFBP)-1 expression associated with fetal growth restriction has been documented. In this study we tested the hypothesis that hypoxia and nutrient deprivation induce IGFBP-1 phosphorylation and increase its biological potency in inhibiting IGF actions. HepG2 cells were subjected to hypoxia and leucine deprivation to mimic the deprivation of metabolic substrates. The total IGFBP-1 levels measured by ELISA were approximately 2- to 2.5-fold higher in hypoxia and leucine deprivation-treated cells compared with the controls. Two-dimensional immunoblotting showed that whereas the nonphosphorylated isoform is the predominant IGFBP-1 in the controls, the highly phosphorylated isoforms were dominant in hypoxia and leucine deprivation-treated cells. Liquid chromatography-tandem mass spectrometry analysis revealed four serine phosphorylation sites: three known sites (pSer 101, pSer 119, and pSer 169); and a novel site (pSer 98). Liquid chromatography-mass spectrometry was used to estimate the changes of phosphorylation upon treatment. Biacore analysis indicated that the highly phosphorylated IGFBP-1 isoforms found in hypoxia and leucine deprivation-treated cells had greater affinity for IGF-I [dissociation constant 5.83E (times 10 to the power)--0 m and 6.40E-09 m] relative to the IGFBP-1 from the controls (dissociation constant approximately 1.54E-07 m). Furthermore, the highly phosphorylated IGFBP-1 had a stronger effect in inhibiting IGF-I-stimulated cell proliferation. These findings suggest that IGFBP-1 phosphorylation may be a novel mechanism of fetal adaptive response to hypoxia and nutrient restriction.

High insulinlike growth factor binding protein 1 level predicts incident congestive heart failure in the elderly

BACKGROUND

Low levels of insulinlike growth factor 1 (IGF-I) may influence the development of age-related cardiovascular diseases including congestive heart failure (CHF). Insulinlike growth factor binding protein 1 (IGFBP-1), which increases during catabolic states and inhibits anabolic IGF-I effects, is increased in patients with CHF and has been associated prospectively with increased mortality among older adults and survivors of myocardial infarction. We investigated the association between fasting plasma levels of IGF-I, IGFBP-1, IGFBP-3, and insulin and risk of incident CHF in the prospective Cardiovascular Health Study.

METHODS

From among 5,888 adults 65 years old and older in the Cardiovascular Health Study, we studied 566 incident CHF cases and 1,072 comparison subjects after exclusion of underweight individuals (body mass index <18.5 kg/m(2)) and insulin users. Hazard ratios (HRs) with 95% CIs for CHF were estimated after adjustment for age, race, sex, hypertension, systolic blood pressure, lipid levels, left ventricular hypertrophy, coronary disease, C-reactive protein, health status, diabetes, and body mass index.

RESULTS

High baseline IGFBP-1 level was a significant predictor of CHF, independent of established CHF risk factors and inflammation markers. The HR per SD of IGFBP-1 was 1.22 (95% CI 1.07-1.39, P < .01). Relative to the lowest IGFBP-1 tertile, the HR was 1.29 (95% CI 0.96-1.74, P = .09) for the second IGFBP-1 tertile and 1.47 (95% CI 1.06-2.04; P = .02) for the highest IGFBP-1 tertile (tertile cut points 19.5 and 35.8 ng/mL). Total IGF-I, IGFBP-3, or insulin levels had no association with CHF after adjustment for CHF risk factors.

CONCLUSIONS

High circulating IGFBP-1 level may be a CHF risk factor among older adults.

Adynamic bone in patients with chronic kidney disease

Adynamic bone in patients with chronic kidney disease (CKD) is a clinical concern because of its potential increased risk for fracture and cardiovascular disease (CVD). Prevalence rates for adynamic bone are reportedly increased, although the variance for its prevalence and incidence is large. Differences in its prevalence are largely attributed to classification and population differences, the latter of which constitutes divergent groups of elderly patients having diabetes and other comorbidities that are prone to low bone formation. Most patients have vitamin D deficiency and the active form, 1,25-dihydroxyvitamin D, invariably decreases to very low levels during CKD progression. Fortunately, therapy with vitamin D receptor activators (VDRAs) appears to be useful in preventing bone loss, in part, by its effect to stimulate bone formation and in decreasing CVD morbidity, and should be considered as essential therapy regardless of bone turnover status. Future studies will depend on assessing cardiovascular outcomes to determine whether the risk/reward profile for complications related to VDRA and CKD is tolerable.

Total insulinlike growth factor 1 and insulinlike growth factor binding protein levels, functional status, and mortality in older adults

OBJECTIVES

To assess the association between total insulinlike growth factor (IGF)-1, IGF binding protein-1 (IGFBP-1), and IGFBP-3 levels and functioning and mortality in older adults.

DESIGN

Cohort study.

SETTING/PARTICIPANTS

One thousand one hundred twenty-two individuals aged 65 and older without prior cardiovascular disease events participating in the Cardiovascular Health Study.

MEASUREMENTS

Baseline fasting plasma levels of IGF-1, IGFBP-1, and IGFBP-3 (defined as tertiles, T1-T3) were examined in relationship to handgrip strength, time to walk 15 feet, development of new difficulties with activities of daily living (ADLs), and mortality.

RESULTS

Higher IGFBP-1 predicted worse handgrip strength (P-trend(T1-T3)<.01) and slower walking speed (P-trend(T1-T3)=.03), lower IGF-1 had a borderline significant association with worse handgrip strength (P-trend(T1-T3)=.06), and better grip strength was observed in the middle IGFBP-3 tertile than in the low or high tertiles (P=.03). Adjusted for age, sex, and race, high IGFBP-1 predicted greater mortality (P-trend(T1-T3)<.001, hazard ratio (HR)(T3vsT1)=1.48, 95% confidence interval (CI)=1.15-1.90); this association was borderline significant after additional confounder adjustment (P-trend(T1-T3)=.05, HR(T3vsT1)=1.35, 95% CI=0.98-1.87). High IGFBP-1 was associated with greater risk of incident ADL difficulties after adjustment for age, sex, race, and other confounders (P-trend(T1-T3)=.04, HR(T3vsT1)=1.40, CI=1.01-1.94). Neither IGF-1 nor IGFBP-3 level predicted mortality or incident ADL difficulties.

CONCLUSION

In adults aged 65 and older, high IGFBP-1 levels were associated with greater risk of mortality and poorer functional ability, whereas IGF-1 and IGFBP-3 had little association with these outcomes.

A proposed nomenclature and diagnostic criteria for protein-energy wasting in acute and chronic kidney disease

The recent research findings concerning syndromes of muscle wasting, malnutrition, and inflammation in individuals with chronic kidney disease (CKD) or acute kidney injury (AKI) have led to a need for new terminology. To address this need, the International Society of Renal Nutrition and Metabolism (ISRNM) convened an expert panel to review and develop standard terminologies and definitions related to wasting, cachexia, malnutrition, and inflammation in CKD and AKI. The ISRNM expert panel recommends the term 'protein-energy wasting' for loss of body protein mass and fuel reserves. 'Kidney disease wasting' refers to the occurrence of protein-energy wasting in CKD or AKI regardless of the cause. Cachexia is a severe form of protein-energy wasting that occurs infrequently in kidney disease. Protein-energy wasting is diagnosed if three characteristics are present (low serum levels of albumin, transthyretin, or cholesterol), reduced body mass (low or reduced body or fat mass or weight loss with reduced intake of protein and energy), and reduced muscle mass (muscle wasting or sarcopenia, reduced mid-arm muscle circumference). The kidney disease wasting is divided into two main categories of CKD- and AKI-associated protein-energy wasting. Measures of chronic inflammation or other developing tests can be useful clues for the existence of protein-energy wasting but do not define protein-energy wasting. Clinical staging and potential treatment strategies for protein-energy wasting are to be developed in the future.

Clinical and biochemical implications of low thyroid hormone levels (total and free forms) in euthyroid patients with chronic kidney disease

OBJECTIVES

In this study, we explore the associations of decreased thyroid hormone levels with inflammation, wasting and survival in biochemically euthyroid patients with end-stage renal disease (ESRD).

DESIGN

After exclusion of 23 patients with thyroid-stimulating hormone (TSH) values outside the normal range (0.1-4.5 mIU L(-1)), 187 clinically and biochemically euthyroid incident ESRD stage 5 patients starting dialysis were followed for a median of 20 (range 1-60) months. Measurements of total and free forms of thyroid hormones, s-albumin, hs-CRP, interleukin (IL)-6, vascular adhesion molecule (VCAM)-1 and insulin-like growth factor 1 (IGF-1) were performed at baseline.

RESULTS

In this population, 17 out of 210 patients (8%) were defined as subclinically hypothyroid. Multivariate analysis, according to receiver operating characteristic (ROC) curves, showed that mortality was best predicted by total triiodothyronine (T3). When using the cut-off levels derived from ROC, low T3 levels were associated with increased inflammation (higher hs-CRP, IL-6 and VCAM-1) and lower concentration of both s-albumin and IGF-1. Finally, low T3 but not low free triiodothyronine was associated with worse all-cause (Likelihood ratio = 45.4; P < 0.0001) and cardiovascular mortality (Likelihood ratio = 47.8; P < 0.0001) after adjustment for confounding factors.

CONCLUSION

This study showed that low T3 levels are independent predictors of all-cause and also cardiovascular disease mortality in biochemically euthyroid patients, perhaps due to an intimate association with inflammation. Based on these results, the use of T3 levels in studies assessing the relationship between thyroid dysfunction and mortality risk is recommended.

Lifelong caloric restriction and interleukin-6 secretion from adipose tissue: effects on physical performance decline in aged rats

We investigated whether caloric restriction (CR) improves physical performance in a rodent model of aging, and whether this effect is accompanied with a decrease in visceral adipose tissue production of proinflammatory cytokines. Body composition, standardized physical performance measures, as well as in vitro visceral adipose tissue cytokine secretion and circulating levels of an inflammatory marker were cross-sectionally assessed in ad libitum (AL)-fed and lifelong CR Fischer 344 x Brown Norway male rats aged 18, 24, and 29 months. Fat to lean mass ratio increased and physical performance declined with age in the AL rats. Compared to AL rats, CR rats had lower fat mass, fat to lean ratio, adipose tissue secretion of interleukin-6, and circulating levels of C-reactive protein, and higher physical performance scores. Therefore, CR may be an effective intervention for improving functional status into advanced age and is perhaps mediated via a reduction in adipose tissue-generated proinflammatory cytokine production.

Comparison of nutritional and inflammatory markers in dialysis patients with reduced appetite

BACKGROUND

Anorexia is common in chronic kidney disease and worsens as the disease progresses. Sex hormones and inflammatory cytokines may be related to feeding behavior.

OBJECTIVE

We hypothesized that appetite would be related to inflammation and outcome in hemodialysis patients but that sex may account for differences in the symptoms associated with poor appetite.

DESIGN

A cross-sectional study was conducted in patients undergoing prevalent hemodialysis (n = 223; 127 M; x +/- SD age: 66 +/- 14 y). Anthropometric markers of body composition, handgrip strength, and nutritional and inflammatory status were measured, and 3 groups according to their self-reported appetite were established. Overall mortality was assessed after 19 mo (range: 2-29 mo) of follow-up.

RESULTS

Poor appetite was associated with a longer vintage time, increased inflammation (higher serum concentrations of interleukin 6 and C-reactive protein), and a worse nutritional status (lower serum concentrations of insulin-like growth factor I, albumin, urea, and creatinine). However, across worsening appetite scale, handgrip strength was incrementally lower in men but not in women (multivariate analysis of variance). In a multivariate logistic regression analysis (pseudo r(2) = 0.19), appetite loss was associated with sex [odds ratio (OR): 0.41; 95% CI: 0.24, 0.72], insulin-like growth factor I (3.58; 2.10, 6.32), and C-reactive protein > 10 mg/L (2.39; 1.34, 4.11). Finally, appetite loss was associated with worse clinical outcome even after adjustment for age, sex, inflammation, dialysis vintage, and comorbidity (likelihood ratio = 44.3; P < 0.0001).

CONCLUSIONS

These results show a close association among appetite, malnutrition, inflammation, and outcome in patients undergoing prevalent hemodialysis. Moreover, our data suggest that uremic men may be more susceptible than are women to inflammation-induced anorexia.