Insulin-Like Growth Factor 1 in the Cardiovascular System

Normal or improved cardiovascular risk factors in IGF-I-deficient adults with growth hormone receptor deficiency

BACKGROUND

Human subjects with generalized growth hormone (GH) insensitivity due to GH receptor deficiency (GHRD)/Laron syndrome display a very low incidence of insulin resistance, diabetes, and cancer, as well as delayed age-related cognitive decline. However, the risk of cardiovascular disease (CVD) in these subjects is poorly understood. Here, we have assessed cardiovascular function, damage, and risk factors in GHRD subjects and their relatives.

METHODS

We measured markers of CVD in two phases: one in a cohort of 30 individuals (GHRD = 16, control relatives = 14) brought to USC (in Los Angeles, CA) and one in a cohort including additional individuals examined in Ecuador (where the subjects live) for a total of 44 individuals (GHRD = 21, control relatives = 23). Data were collected on GHRD and control groups living in similar geographical locations and sharing comparable environmental and socio-economic circumstances.

RESULTS

Compared to controls, GHRD subjects displayed lower serum glucose, insulin, blood pressure, smaller cardiac dimensions, similar pulse wave velocity, lower carotid artery intima-media thickness, lower creatinine, and a non-significant but major reduction in the portion of subjects with carotid atherosclerotic plaques (7% GHRDs vs. 36%, Controls p = 0.1333) despite elevated low-density lipoprotein cholesterol levels.

CONCLUSION

The current study indicates that individuals with GHRD have normal or improved levels of cardiovascular disease risk factors as compared to their relatives.

FUNDING

This study was funded in part by NIH/NIA grant P01 AG034906 to V.D.L.

Identifying Key Biomarkers in Pediatric Pulmonary Hypertension: An Investigative Approach

This study assesses the utility of early biomarkers-5-hydroxyindoleacetic acid (5-HIAA) and insulin-like growth factor 1 (IGF-1)-for diagnosing and monitoring pulmonary hypertension (PH) in children with congenital heart defects (CHD). Due to the risks associated with invasive diagnostics, such as right heart catheterization, non-invasive biomarkers provide a safer alternative for early PH detection. This cohort-based study utilized blood and urine samples to measure 5-HIAA and IGF-1 levels via enzyme immunoassays. Our findings revealed significant changes in 5-HIAA concentrations across various biological matrices, supporting its potential as a diagnostic tool. Specifically, altered levels in urine and plasma reflect its role in serotonin metabolism and vascular remodeling in PH. IGF-1 levels were notably reduced in plasma, suggesting its involvement in PH pathophysiology. ROC analysis confirmed the diagnostic efficacy of these biomarkers, particularly 5-HIAA's high specificity and sensitivity. In conclusion, 5-HIAA and IGF-1 levels correlate well with PH, underscoring their diagnostic value for early PH detection in children with CHD.

Platelet rich fibrin and simvastatin-loaded pectin-based 3D printed-electrospun bilayer scaffold for skin tissue regeneration

Designing multifunctional wound dressings is a prerequisite to prevent infection and stimulate healing. In this study, a bilayer scaffold (BS) with a top layer (TL) comprising 3D printed pectin/polyacrylic acid/platelet rich fibrin hydrogel (Pec/PAA/PRF) and a bottom nanofibrous layer (NL) containing Pec/PAA/simvastatin (SIM) was produced. The biodegradable and biocompatible polymers Pec and PAA were cross-linked to form hydrogels via Ca2+ activation through galacturonate linkage and chelation, respectively. PRF as an autologous growth factor (GF) source and SIM together augmented angiogenesis and neovascularization. Because of 3D printing, the BS possessed a uniform distribution of PRF in TL and an average fiber diameter of 96.71 ± 18.14 nm was obtained in NL. The Young's modulus of BS was recorded as 6.02 ± 0.31 MPa and its elongation at break was measured as 30.16 ± 2.70 %. The wound dressing gradually released growth factors over 7 days of investigation. Furthermore, the BS significantly outperformed other groups in increasing cell viability and in vivo wound closure rate (95.80 ± 3.47 % after 14 days). Wounds covered with BS healed faster with more collagen deposition and re-epithelialization. The results demonstrate that the BS can be a potential remedy for skin tissue regeneration.

The effect of SGLT2i on the GH/IGF1 axis in newly diagnosed male T2D patients - a prospective, randomized case-control study

PURPOSE

To investigate the effect of SGLT2i on the GH/IGF1 axis in male patients with newly diagnosed type 2 diabetes (T2D).

METHODS

Sixty male patients with newly diagnosed T2D were recruited, and randomly assigned to Metformin+SGLT2i group or Metformin group after baseline assessment. All patients received standard lifestyle interventions, and blood indices were obtained before and after 12 weeks of treatment.

RESULTS

After 12 weeks of treatment with Metformin+SGLT2i, there were noteworthy improvements in patients' FPG (Fasting plasma glucose), HBA1c, HOMA-IR, HOMA-β, TyG (Triglyceride-glucose) index and UACR (P < 0.05). Both IGF1 (P = 0.01) and the IGF1/IGFBP3 ratio (P < 0.01) considerably increased, while GH and IGFBP3 did not show significant changes. When comparing Metformin+SGLT2i group to Metformin group, SGLT2i significantly improved HOMA-IR [P = 0.04], and elevated IGF1/IGFBP3 ratio [P = 0.04], SGLT2i showed a tendency of increasing IGF1 (P = 0.10), but this was not statistically meaningful. There was no effect on GH and IGFBP3. Correlation analysis showed that blood IGF1 was negatively correlated with FPG, HBA1c, HOMA-IR, TyG index and positively correlated with IGFBP3. Regression analysis indicated that FPG and testosterone had a negative effect on blood IGF1 level, while HOMA-IR had no obvious effect.

CONCLUSION

In male patients with newly diagnosed T2D, SGLT2i can increase IGF1/IGFBP3 ratio, alleviate insulin resistance, but has no significant effect on GH and IGF1 levels. Additionally, our study showed that Metformin+SGLT2i treatment resulted in an increase in blood IGF1 levels and improved insulin resistance, suggesting a potentially beneficial role of IGF1 in newly diagnosed T2D.

Estimating the impact of drug addiction causes heart damage

To date, few studies have investigated the toxicological effects of the combined use of amphetamine and heroin in the heart. Hence, the aim of this study was to identify indicators for clinical evaluation and prevention of cardiac injury induced by the combined use of amphetamine and heroin. Four different groups were analyzed: (1) normal group (n＝25；average age＝35 ± 6.8); (2) heart disease group (n＝25；average age＝58 ± 17.2); (3) drug abusers (n = 27; average age = 37 ± 7.7); (4) drug abstainers (previous amphetamine-heroin users who had been drug-free for more than two weeks; n = 22; average age = 35 ± 5.6). The activity of MMPs, and levels of TNF-α, IL-6, GH, IGF-I, and several serum biomarkers were examined to evaluate the impact of drug abuse on the heart. The selected plasma biomarkers and classic cardiac biomarkers were significantly increased compared to the normal group. The zymography data showed the changes in cardiac-remodeling enzymes MMP-9 and MMP-2 among combined users of amphetamine and heroin. The levels of TNF-α and IL-6 only increased in the heart disease group. Growth hormone was increased; however, IGF-I level decreased with drug abuse and the level was not restored by abstinence. We speculated that the amphetamine-heroin users might pose risk to initiate heart disease even though the users abstained for more than two weeks. The activity change of MMP-9 and MMP-2 can be a direct reason affecting heart function. The indirect reason may be related to liver damage by drug abuse reduce IGF-1 production to protect heart function.

Asymmetric tri-layer sponge-nanofiber wound dressing containing insulin-like growth factor-1 and multi-walled carbon nanotubes for acceleration of full-thickness wound healing

To more closely resemble the structure of natural skin, multi-layered wound dressings have been developed. Herein, a tri-layer wound dressing was prepared containing a polyacrylamide (PAAm)-Aloe vera (Alo) sponge that had been incorporated with insulin-like growth factor-1 (IGF1) to provide a porous absorbent layer, which was able to promote angiogenesis. Alo nanofibers with multi-walled carbon nanotubes (MWCNT) were electrospun into the bottom layer to increase cell behavior, and a small film of stearic acid was put as a top layer to avoid germy penetration. In comparison to bilayer dressing, the tensile strength increased by 17.0 % (from 0.200 ± 0.010 MPa to 0.234 ± 0.022 MPa) and the elastic modulus by 45.6 % (from 0.217 ± 0.003 MPa to 0.316 ± 0.012 MPa) in the presence of Alo nanofibers containing 0.5 wt% of MWCNT at the bottom layer of Trilayer0.5 dressing. The release profile of IGF1, the antibacterial activity and the degradability of different wound dressings were investigated. Trilayer0.5 indicated the highest cell viability, cell adhesion and angiogenic potential among the prepared dressing materials. In-vivo rat model revealed that the Trilayer0.5 dressing treated group had the highest rate of wound closure and wound healing within 10 days compared to other groups.

Cell non-autonomous regulation of cerebrovascular aging processes by the somatotropic axis

Age-related cerebrovascular pathologies, ranging from cerebromicrovascular functional and structural alterations to large vessel atherosclerosis, promote the genesis of vascular cognitive impairment and dementia (VCID) and exacerbate Alzheimer's disease. Recent advances in geroscience, including results from studies on heterochronic parabiosis models, reinforce the hypothesis that cell non-autonomous mechanisms play a key role in regulating cerebrovascular aging processes. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) exert multifaceted vasoprotective effects and production of both hormones is significantly reduced in aging. This brief overview focuses on the role of age-related GH/IGF-1 deficiency in the development of cerebrovascular pathologies and VCID. It explores the mechanistic links among alterations in the somatotropic axis, specific macrovascular and microvascular pathologies (including capillary rarefaction, microhemorrhages, impaired endothelial regulation of cerebral blood flow, disruption of the blood brain barrier, decreased neurovascular coupling, and atherogenesis) and cognitive impairment. Improved understanding of cell non-autonomous mechanisms of vascular aging is crucial to identify targets for intervention to promote cerebrovascular and brain health in older adults.

IGF-1 and IGFBP3 as indirect markers of hepatic insulin resistance and their relation to metabolic syndrome parameters in liver steatosis patients

Objective. The aim of the present study was to assess insulin-like growth factor 1 (IGF-1) and IGF-binding protein 3 (IGFBP3) as markers of insulin resistance in patients with prediabetes and type 2 diabetes mellitus (TDM2). Patients and Methods. This observational clinical study included 76 obese/overweight patients at the age of 45-75 years with T2DM on oral diabetic medication and ultrasonographically or by a computerized tomography (CT) diagnosed liver steatosis. Correlation analysis was performed between plasma levels of insulin, C-peptide, IGF-1, IGFBP3 and HOMA indexes on the one hand and between plasma levels of ALT, AST, triglyceride, cholesterol, and HDL cholesterol and body mass index (BMI) of patients on the other hand. In case of significant partial correlation coefficients, a multiple linear regression model with IGF-1 and IGFBP3 used as outcome variables adjusted for age and sex groups was calculated. According to these regression models, ROC curves were prepared with HOMA index=3 used as a classificator of insulin resistance. Results. Significant correlation was found between C-peptide and IGF-1 (r=0.24, p≤0.05), C-peptide and IGFBP3 (r=0.24, p≤0.05), IGFBP3 and cholesterol (r=0.22, p≤0.05) IGFBP3 and ALT (r=0.19, p≤0.05), HOMA index and triglycerides (r=0.22, p≤0.05), and HOMA index and ALT (r=0.23, p≤0.05). Significant correlation adjusted for age and gender was found between C-peptide and IGF-1 plasma levels (R2=0.20, p<0.05) with AUROC 0.685 (p≤0.01) and C-peptide and IGFBP3 plasma levels (R2=0.28, p<0.05) with AUROC 0.684 (p≤0.01). Significant correlation adjusted for age and gender was found between triglyceride and IGFBP3 plasma levels (R2=0.28, p<0.05) with AUROC 0.616 (p≤0.01). After the distribution of patients according to their IGFBP3 levels, we found a difference between the 1st and the 4th quartiles in terms of triglyceride levels. Conclusion. Our results demonstrate a fundamental role of IGF-1 and IGFBP3 in the patho-physiology of hepatic insulin resistance and suggest them as indirect indicators of the hepatic insulin resistance.

Machine learning analysis of the UK Biobank reveals IGF-1 and inflammatory biomarkers predict Parkinson's disease risk

INTRODUCTION

Parkinson's disease (PD) is the most common movement disorder, and its prevalence is increasing rapidly worldwide with an ageing population. The UK Biobank is the world's largest and most comprehensive longitudinal study of ageing community volunteers. The cause of the common form of PD is multifactorial, but the degree of causal heterogeneity among patients or the relative importance of one risk factor over another is unclear. This is a major impediment to the discovery of disease-modifying therapies.

METHODS

We used an integrated machine learning algorithm (IDEARS) to explore the relative effects of 1,753 measured non-genetic variables in 334,062 eligible UK Biobank participants, including 2,719 who had developed PD since their recruitment into the study.

RESULTS

Male gender was the highest-ranked risk factor, followed by elevated serum insulin-like growth factor 1 (IGF-1), lymphocyte count, and neutrophil/lymphocyte ratio. A group of factors aligned with the symptoms of frailty also ranked highly. IGF-1 and neutrophil/lymphocyte ratio were also elevated in both sexes before PD diagnosis and at the point of diagnosis.

DISCUSSION

The use of machine learning with the UK Biobank provides the best opportunity to explore the multidimensional nature of PD. Our results suggest that novel risk biomarkers, including elevated IGF-1 and NLR, may play a role in, or are indicative of PD pathomechanisms. In particular, our results are consistent with PD being a central manifestation of a systemic inflammatory disease. These biomarkers may be used clinically to predict future PD risk, improve early diagnosis and provide new therapeutic avenues.

Dirty Jobs: Macrophages at the Heart of Cardiovascular Disease

Cardiovascular disease (CVD) is one of the greatest public health concerns and is the leading cause of morbidity and mortality in the United States and worldwide. CVD is a broad yet complex term referring to numerous heart and vascular conditions, all with varying pathologies. Macrophages are one of the key factors in the development of these conditions. Macrophages play diverse roles in the maintenance of cardiovascular homeostasis, and an imbalance of these mechanisms contributes to the development of CVD. In the current review, we provide an in-depth analysis of the diversity of macrophages, their roles in maintaining tissue homeostasis within the heart and vasculature, and the mechanisms through which imbalances in homeostasis may lead to CVD. Through this review, we aim to highlight the potential importance of macrophages in the identification of preventative, diagnostic, and therapeutic strategies for patients with CVD.

The Exosomal lncRNA KLF3-AS1 From Ischemic Cardiomyocytes Mediates IGF-1 Secretion by MSCs to Rescue Myocardial Ischemia-Reperfusion Injury

The purpose of the study was to explore the mechanism by which myocardial ischemia-reperfusion (I/R) injury-induced exosomes modulate mesenchymal stem cells (MSCs) to regulate myocardial injury. In this study, we established an I/R injury model in vivo and a hypoxia-reoxygenation (H/R) model in vitro. Then, exosomes isolated from H/R-exposed H9c2 cells were characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot analysis. CCK-8 assays and flow cytometry were performed to assess cell injury. ELISA was applied to determine the level of insulin-like growth factor 1 (IGF-1). Echocardiography was used to assess cardiac function in vivo. HE staining and TUNEL assays were conducted to analyze myocardial injury in vivo. In the present study, H/R-exposed H9c2 cells induced IGF-1 secretion from MSCs to inhibit cell myocardial injury. Moreover, exosomes derived from H/R-exposed H9c2 cells were introduced to MSCs to increase IGF-1 levels. The lncRNA KLF3-AS1 was dramatically upregulated in exosomes derived from H/R-treated H9c2 cells. Functional experiments showed that the exosomal lncRNA KLF3-AS1 promoted IGF-1 secretion from MSCs and increased H9c2 cell viability. In addition, miR-23c contains potential binding sites for both KLF3-AS1 and STAT5B, and miR-23c directly bound to the 3'-UTRs of KLF3-AS1 and STAT5B. Furthermore, the lncRNA KLF3-AS1 promoted IGF-1 secretion from MSCs and rescued myocardial cell injury in vivo and in vitro by upregulating STAT5B expression. The lncRNA KLF3-AS1 may serve as a new direction for the treatment of myocardial I/R injury.

Association between insulin-like growth factor-1 and systolic blood pressure in children and adolescents with short stature

The relationship between insulin‐like growth factor‐1 (IGF‐1) and systolic blood pressure (SBP) is controversial in adults and children. The purpose of this study was to investigate the relationship between the IGF‐1 standard deviation score (IGF‐1 SDS) and SBP in children with short stature. A cross‐sectional analysis including 1315 children with short stature was conducted from March 2013 to October 2020. We estimated IGF‐1, blood pressure and other laboratory tests, and anthropometric indicators were also evaluated. Subgroup analyses of the pubertal stage, sex, growth hormone levels, thyroid hormone levels, fasting blood glucose levels, and triglyceride levels were performed. A positive association between the IGF‐1 SDS and SBP was observed by univariate analysis (p < .001). We further found a nonlinear association between the IGF‐1 SDS and SBP. The inflection point for the curve was found at an IGF‐1 SDS level of −2.91. In multivariate piecewise linear regression, there was a positive association between the IGF‐1 SDS and SBP when the IGF‐1 SDS was greater than −2.91 (β 1.56, 95% CI: 0.91, 2.22; p < .001). However, we did not observe a significant relationship between the IGF‐1 SDS and SBP when the IGF‐1 SDS level was less than −2.91 (β −0.95, 95% CI −3.17, 1.28; p = .379). This association was consistent across subgroup analyses. The present study demonstrated that there is a nonlinear relationship between the IGF‐1 SDS and SBP in children with short stature. Increased serum IGF‐1 levels were associated with elevated SBP when the IGF‐1 levels reached the inflection point.

HMGB1 is increased in adolescents with polycystic ovary syndrome (PCOS) and decreases after treatment with myo-inositol (MYO) in combination with alpha-lipoic acid (ALA)

PCOS treatment should be based on pathophysiology. High-mobility-group-box-1 (HMGB1) was shown to increase in PCOS patients as a consequence of reduced cystic-fibrosis-transmembrane-conductance-regulator (CFTR) expression in the ovary, and was associated with insulin resistance and inflammation, both features of PCOS. Inositols and ALA derivatives could have positive effects on insulin sensitivity, reduce androgens, and improve ovulation rhythm. The aim of this study was to verify changes in HMGB1, in metabolic and endocrine parameters in adolescents with PCOS compared with controls and after treatment with a combination of MYO + ALA. Twenty-three PCOS adolescents and 21 controls matched for age and BMI were enrolled. In all subjects, metabolic and hormonal parameters were assayed. Homeostatic index (HOMA-IR) and the triglyceride/HDL-cholesterol ratio were calculated. Ovarian volumes were evaluated. Patients were treated with MYO + ALA for 6 months. HMGB1 was measured using a specific ELISA assay. HMGB1 was increased in PCOS compared with controls (19.76 ± 5.99 versus 5.65 ± 1.88 ng/ml; p < .05) and normalized after treatment (2.27 ± 0.36 ng/ml, p < .05). Treatment significantly reduced insulin (24.0 ± 4.11 versus 12.13 ± 2.13 uU/ml), HOMA-IR (3.91 ± 0.41 versus 2.42 ± 0.45), and 17-hydroxyprogesterone (1.20 ± 0.15 versus 0.78 ± 0.11 ng/ml). Cholesterol, luteinizing hormone, 17-β-estradiol, delta 4-androstenedione, and testosterone were unchanged. Circulating HMGB1 was increased in PCOS adolescents, and treatment was effective in normalizing HMGB1.

Insulin-like growth factor-1 levels predict myocardial injury and infarction after elective percutaneous coronary intervention: an optical coherence tomography study

INTRODUCTION

Periprocedural myocardial necrosis, which can range from a low level elevation of cardiac biomarkers to a large myocardial infarction (MI), is a common complication after percutaneous coronary intervention (PCI).

AIM

We hypothesized that insulin-like growth factor-1 (IGF-1) levels may play a protective role in myocardial injury after coronary stent placement and aimed to investigate the relationship between IGF-1 levels and plaque characteristics assessed by optical coherence tomography (OCT).

MATERIAL AND METHODS

Between May 2015 and December 2015 we prospectively enrolled 74 patients with stable angina pectoris in whom single de novo coronary artery stenosis was present. PCI was performed according to standard methods. OCT was applied to all patients. TnT was analyzed at admission, before PCI and at 6, 12, 24 and 48 h after PCI. Serum IGF-1 was measured prior to PCI.

RESULTS

A total of 25 (33.7%) patients had periprocedural myocardial injury or type 4a myocardial infarction, and 49 (66.2%) patients had no events. IGF-1 level and reference intimal thickness, medial thickness, and plaque fibrous cap thickness in OCT had strong correlations (r = 0.88, 0.80 and 0.88 respectively, p < 0.001). IGF-1 was an independent predictor of periprocedural myocardial injury or type 4a MI in univariate (OR = 0.929, 95% CI: 0.895-0.964, p < 0.001) and multivariate regression analysis (OR = 0.757, 95% CI: 0.575-0.998, p = 0.04). Based on ROC analysis, the best cut-off value of IGF-1 for predicting periprocedural myocardial injury or type 4a myocardial infarction was 144.5 ng/ml, with a maximum sensitivity of 88% and specificity of 77.6% (AUC = 0.80, 95% CI: 0.69-0.88, p < 0.0001).

CONCLUSIONS

The results from this study indicate that low IGF-1 levels are associated with plaque instability assessed by OCT. Low IGF-1 levels may identify patients who are at increased risk for periprocedural myocardial injury/infarction.

Is insulin-like growth factor-1 involved in Parkinson's disease development?

Parkinson's disease (PD) is a neurodegenerative disorder that results in the death of dopaminergic neurons within the substantia nigra pars compacta and the reduction in dopaminergic control over striatal output neurons, leading to a movement disorder most commonly characterized by akinesia or bradykinesia, rigidity and tremor. Also, PD is less frequently depicted by sensory symptoms (pain and tingling), hyposmia, sleep alterations, depression and anxiety, and abnormal executive and working memory related functions. On the other hand, insulin-like growth factor 1 (IGF-1) is an endocrine, paracrine and autocrine hormone with several functions including tissue growth and development, insulin-like activity, proliferation, pro-survival, anti-aging, antioxidant and neuroprotection, among others. Herein this review tries to summarize all experimental and clinical data to understand the pathophysiology and development of PD, as well as its clear association with IGF-1, supported by several lines of evidence: (1) IGF-1 decreases with age, while aging is the major risk for PD establishment and development; (2) numerous basic and translational data have appointed direct protective and homeostasis IGF-1 roles in all brain cells; (3) estrogens seem to confer women strong protection to PD via IGF-1; and (4) clinical correlations in PD cohorts have confirmed elevated IGF-1 levels at the onset of the disease, suggesting an ongoing compensatory or "fight-to-injury" mechanism.

Circulating IGF-1 Independently Predicts Blood Pressure in Children With Higher Calcium-Phosphorus Product Levels

OBJECTIVE

To study the association between insulin-like growth factor 1 (IGF-1) and blood pressure in children, in particular, the potential interaction with the serum calcium-phosphorus product (Ca*P).

METHODS

A longitudinal study included 521 children (age 8.8 ± 0.1) from northeastern Spain, of whom 158 were followed-up after 5 years. IGF-1, insulin-like growth factor-binding protein 3 (IGFBP-3), and serum calcium and phosphorus were measured at baseline. Anthropometric (body-mass index [BMI] and waist) and cardiometabolic variables (systolic [SBP] and diastolic blood pressure), pulse pressure, insulin, homeostatic model assessment of insulin resistance [HOMA-IR], high-density lipoprotein [HDL]-cholesterol, and triglycerides) were assessed at baseline and at the end of follow-up. Statistical analysis included Pearson correlations followed by multivariable linear regression analyses.

RESULTS

Baseline IGF-1 and IGF-1/IGFBP-3 molar ratio positively correlated with baseline and follow-up BMI, waist, SBP, pulse pressure, insulin, HOMA-IR and triglycerides (r 0.138-0.603; all P < 0.05). The associations with SBP were stronger with increasing Ca*P (r 0.261-0.625 for IGF-1; and r 0.174-0.583 for IGF-1/IGFBP-3). After adjusting for confounding variables, baseline IGF-1 and IGF-1/IGFBP-3 remained independently associated with both baseline and follow-up SBP in children in the highest Ca*P tertile (β = 0.245-0.381; P < 0.01; model R2 = 0.246-0.566).

CONCLUSIONS

Our results suggest that IGF-1 in childhood is an independent predictor of SBP in apparently healthy children, especially in those with high Ca*P levels.