Serum Intact Fibroblast Growth Factor Research Articles

#2524 Impact of sevelamer hydrochloride on fibroblast growth factor-23 levels in patients undergoing hemodialysis

Abstract Background and Aims Serum intact fibroblast growth factor 23 (FGF23) levels are progressively increased in relation to the severity of kidney dysfunction. High serum intact FGF23 concentration is associated with the increased cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). Clinically, phosphate binders are commonly used to reduce serum intact FGF23 levels in CKD patients by lowering serum phosphate levels. Reduction of high intact FGF23 concentration is a strategy, possibly improving the consequences of CKD. We aimed to Assessing the Impact of Sevelamer Carbonate on Fibroblast Growth Factor-23 Levels. Method This case-control study enrolled 100 pre-existing hemodialysis patients, evenly divided into two groups of 50. Group I received a specific sevelamer hydrochloride (Renagel)® dose (2 tablets every 8 hrs), while Group II served as the control group and did not receive (Renagel)®. All patients received the same modality of dialysis with a consistent dialysate calcium concentration. Additionally, they received comprehensive dietary phosphate counseling as part of the standard dietary education provided to our dialysis patients. The levels of phosphorus, calcium, alkaline phosphatase, and FGF23 were assessed in all individuals at the beginning of the study (baseline) and again following 3 months of sevelamer therapy. Results While baseline FGF-23 levels were not statistically different, a highly significant divergence emerged after 3 months of treatment. The sevelamer group experienced a remarkable 38.4% decrease in FGF-23, compared to a mere 0.5% change in the control group, highlighting the pronounced effect of sevelamer on this key protein. Analysis of PO4 levels revealed a remarkable difference between the groups following treatment. While initial PO4 measurements were statistically comparable, the sevelamer group experienced a significantly larger decrease compared to the control group (p < 0.001). Both baseline and follow-up FGF-23 levels displayed highly statistically significant positive correlations with PO4, PTH, alkaline phosphatase, and hsCRP. Conclusion This study found that non-calcium-based phosphate binders were associated with a substantial reduction in FGF-23 in hemodialysis patients. This finding suggests that utilizing such binders may offer protection against the adverse effects of high FGF-23 levels, which are prevalent in this population.

Serum Intact Fibroblast Growth Factor 23 Levels Are Negatively Associated with Bone Mineral Density in Chronic Hemodialysis Patients

(1) Background: Fibroblast growth factor 23 (FGF23) is predominantly secreted from bone and plays an important role in mineral balance in chronic kidney disease. However, the relationship between FGF23 and bone mineral density (BMD) in chronic hemodialysis (CHD) patients remains unclear. (2) Methods: This was a cross-sectional observational study that involved 43 stable outpatients on CHD. A linear regression model was used to determine risk factors for BMD. Measurements included serum hemoglobin, intact FGF23 (iFGF23), C-terminal FGF23 (cFGF23), sclerostin, Dickkopf-1, α-klotho, 1,25-hydroxyvitamin D, intact parathyroid hormone levels and dialysis profiles. (3) Results: Study participants had a mean age of 59.4 ± 12.3 years, and 65% were male. In the multivariable analysis, cFGF23 levels showed no significant associations with the BMD of the lumbar spine (p = 0.387) nor that of the femoral head (p = 0.430). However, iFGF23 levels showed a significant negative association with the BMD of the lumbar spine (p = 0.015) and that of the femoral neck (p = 0.037). (4) Conclusions: Among patients on CHD, higher serum iFGF23 levels, but not serum cFGF23 levels, were associated with lower BMD values of the lumbar spine and femoral neck. However, further research is required to validate our findings.

Intact Fibroblast Growth Factor 23 Regulates Chronic Kidney Disease-Induced Myocardial Fibrosis by Activating the Sonic Hedgehog Signaling Pathway.

Background Clinically, myocardial fibrosis is one of the most common complications caused by chronic kidney disease (CKD). However, the potential mechanisms of CKD-induced myocardial fibrosis have not been clarified. Methods and Results In our in vivo study, a rat model of CKD with 5/6 nephrectomy was established. The CKD model was treated with the glioma 1 (Gli-1) inhibitor GANT-61, and myocardial fibrosis and serum intact fibroblast growth factor 23 levels were assessed 16 weeks after nephrectomy. Finally, we found that Gli-1 and Smoothened in the Sonic Hedgehog (Shh) signaling pathway were activated and that collagen-1 and collagen-3, which constitute the fibrotic index, were expressed in CKD myocardial tissue. After administering the Gli-1 inhibitor GANT-61, the degree of myocardial fibrosis was reduced, and Gli-1 expression was also inhibited. We also measured blood pressure, cardiac biomarkers, and other indicators in rats and performed hematoxylin-eosin staining of myocardial tissue. Furthermore, in vitro studies showed that intact fibroblast growth factor 23 promoted cardiac fibroblast proliferation and transdifferentiation into myofibroblasts by activating the Shh signaling pathway, thereby promoting cardiac fibrosis, as manifested by increased expression of the Shh, Patch 1, and Gli-1 mRNAs and Shh, Smoothened, and Gli-1 proteins in the Shh signaling pathway. The protein and mRNA levels of other fibrosis indicators, such as α-smooth muscle actin, which are also markers of transdifferentiation, collagen-1, and collagen-3, were increased. Conclusions On the basis of these results, intact fibroblast growth factor 23 promotes CKD-induced myocardial fibrosis by activating the Shh signaling pathway.

18-year change in serum intact fibroblast growth factor 23 from midlife to late life and risk of mortality: the ARIC Study.

Fibroblast growth factor 23 (FGF23) concentration increases in response to declining kidney function to preserve normal phosphate concentrations. However, the etiological association of change in FGF23 concentration with mortality has not been examined in the general population. We analyzed 5458 participants of the Atherosclerosis Risk in Communities Study who had intact FGF23 and estimated glomerular filtration rate (eGFR) assessed during midlife (visit 3, 1993-1995, mean age: 58 years) and late life (visit 5, 2011-2013, 76 years) to examine the association of FGF23 change over 18 years from mid-life to late life with the subsequent risk of mortality in late life using Cox regression models. The median 18-year change in intact FGF23 was +17.3 pg/mL. During a median follow-up of 7.2 years following visit 5, 1176 participants died. In multivariable Cox models, elevated mortality was seen in the highest quartile of FGF23 change (ΔFGF23: ≥31.3 pg/mL) (adjusted hazard ratio (aHR): 1.61 (95%CI: 1.36-1.90), or 1.37 (1.15-1.64) after additionally adjusting for eGFR change, compared with the lowest quartile (≤6.4 pg/mL)). When both FGF23 change and FGF23 in late life were simultaneously entered into the Cox model, FGF23 in late life, but not FGF23 change, was an independent predictor of mortality; however, we observed a high correlation between FGF23 change from midlife to late life and FGF23 in late life (r = 0.77). Serum intact FGF23 change from midlife to late life was associated with subsequent risk of mortality independent of decline in kidney function. Our findings further support the implications of FGF23 beyond its association with kidney function.

Changes in Serum Intact Fibroblast Growth Factor 23 Concentrations From Midlife to Late Life and Their Predictors in the Community: The ARIC Study.

ObjectiveTo investigate longitudinal changes in the blood concentration of fibroblast growth factor 23 (FGF23) from midlife to late life and their major predictors in the general population.Patients and MethodsIn 14,444 participants of the Atherosclerosis Risk in Communities Study, we analyzed the association of 31,095 measurements of serum intact FGF23 with age using data from 3 visits (visit 2 [N=13,460; mean age, 57 years]; visit 3 [N=12,323; mean age, 60 years]; and visit 5 [N=6122; mean age, 76 years]) and a linear mixed-effects model. Among 5804 participants who had FGF23 measurements at both visits 3 and 5, we explored predictors of FGF23 change from midlife to late life using linear regression models. Prespecified risk factors were estimated glomerular filtration rate, body mass index, ever smoking, ever drinker, diabetes, hypertension, history of cardiovascular disease, total cholesterol, and high-density lipoprotein cholesterol.ResultsMedian FGF23 concentrations were 41.9 pg/mL (interquartile interval [IQI], 33.9 to 51.8 pg/mL) at visit 2, 38.3 pg/mL (IQI, 30.6 to 48.3 pg/mL) at visit 3, and 55.0 pg/mL (IQI, 44.4 to 70.3 pg/mL) at visit 5. A linear mixed-effects model showed that the association of FGF23 with age was nonlinear, with a slight decline or no change in age 45-60 years and a monotonic increase in age greater than or equal to 65 years (FGF23, +10 to 15 pg/mL per 10 years of age). In a multivariable linear regression model, significantly greater increases in FGF23 were noted, with midlife estimated glomerular filtration rate less than 60 mL/min per 1.73 m2 vs more than or equal to 60 mL/min per 1.73 m2 (ΔFGF23, +4.4 pg/mL [95% CI, 0.9 to 8.0]), diabetes vs no diabetes (ΔFGF23, +6.2 pg/mL [95% CI, 4.1 to 8.3]), and hypertension vs no hypertension (ΔFGF23, +4.1 pg/mL [95% CI, 2.7 to 5.4]).ConclusionFGF23 did not show any major changes in midlife but increased linearly in late life. Reduced kidney function, diabetes, and hypertension were robustly associated with a greater increase in FGF23. Further investigations are needed to understand the potential mechanisms linking these conditions to an increase in FGF23 concentrations.

Effect of different phosphate binders on fibroblast growth factor 23 levels in patients with chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials.

Serum intact fibroblast growth factor 23 (FGF23) levels are progressively increased in relation to the severity of kidney dysfunction. High serum intact FGF23 concentration is associated with the increased cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). Clinically, phosphate binders are commonly used to reduce serum intact FGF23 levels in CKD patients by lowering serum phosphate levels. It is not clear whether all kinds of phosphate binders can reduce serum intact FGF23 levels, or which kind of phosphate binders is more effective in reducing serum intact FGF23 levels in patients with CKD. The aim of this systematic review and meta-analysis was to compare the efficiency of different kinds of commonly used phosphate binders on serum intact FGF23 levels in patients with CKD. Systematic searches were performed through PubMed, Cochrane Central Register of Controlled Trials and Embase from 1999 to 2020. We included the studies performed only in human subjects. All randomized clinical trials (RCTs) were included. Reviews, case reports, letters, commentaries, abstracts and unpublished articles were excluded. Risk of bias was assessed by the Cochrane Collaboration's tool. Random effect was performed in meta-analysis. Meta-regression was used to investigate heterogeneity. Of 1,895 articles, 15 RCTs (comprising 1,098 participants) were included. Common sources of bias were selection bias. Phosphate binders could reduce serum intact FGF23 levels in patients with CKD [standard mean difference (SMD) of total change in serum intact FGF23 levels was 0.91 PG/mL (95% confidence interval: 0.38 to 1.44 PG/mL]. Meta-regression explained 89.02% of heterogeneous sources, indicating that dietary phosphate intake could weaken the effect of phosphate binders on reducing serum intact FGF23 levels, and the effect of phosphate binders on reducing serum intact FGF23 levels in dialysis patients was better than that in early-to-middle CKD patients. Phosphate binders can effectively reduce serum intact FGF23 levels in CKD patients, and iron-based phosphate binders have better effect on reducing serum intact FGF23 levels than other phosphate binders.

Serum intact fibroblast growth factor 23 in healthy paediatric population.

IntroductionIt is believed that fibroblast growth factor 23 (FGF23) can become an early biomarker of chronic kidney disease progression. Data on FGF23 age dependency are inconsistent. We present the results of the cross-sectional study concerning FGF23 levels in healthy Polish children.Material and methodsThis study was conducted in 121 children aged 0–18 years. Kidney function and intact FGF23 levels in serum were assessed. Differences between age groups and according to gender were analysed.ResultsThe difference in FGF23 between age groups and according to gender was statistically insignificant. In the youngest and the oldest group, a trend to higher FGF23 levels was observed. FGF23 level in girls tended to be higher than boys, apart from the age group between 1 and 4 years. There was a negative correlation between eGFR and FGF23 (r = −0.26, p < 0.05) – strong in girls (r = −0.38, p < 0.05), but not in boys. In each age group, we found no significant correlation between eGFR and FGF23.ConclusionsOur study supports the evidence that the FGF23 level in paediatric population is not age or sex dependent. The results can serve as a reference point under clinical conditions and for other studies on the topic.

Inositol hexakisphosphate kinases 1 and 2 (IP6K1/2) are involved in renal control of phosphate homeostasis

Phosphate (Pi) is an indispensable component of living organisms. In the body, Pi homeostasis is tightly regulated by four main tissues: intestine, kidney, bone and parathyroid glands. There are multiple complex mechanisms underlying the regulation of serum Pi including hormones and transporters. Although plenty of studies have analysed Pi regulation, the mechanism with which Pi levels are sensed by mammalian cells remains elusive. Molecular mechanisms of Pi-sensing have been elucidated in detail in yeast and bacteria. However, most of the Pi-sensing proteins identified in yeast and bacteria are encoded by genes that are not conserved in mammals. As a major exception, inositol polyphosphates—which respond to changes in ambient Pi in yeast and, in turn, regulate the expression of Pi transporters—are also found in mammals. Here, we addressed the role of inositol polyphosphates and their biogenic enzymes, the IP6Ks (especially IP6K1 and 2), in cellular Pi sensing in mammals. Human and mouse kidneys express the IP6K1 and IP6K2 isoforms. Likewise, Opossum Kidney (OK) cells, a model for renal proximal tubules express IP6K1 and 2. Pharmacological inhibition of IP6K1/2 or CRISPR/Cas9 mediated knockout in OK cells downregulates Pi transporter mRNA, particularly NaPi-IIa/c. Ip6k1-/-2-/- KO cells also exhibited decreased Pi uptake (by 70%) and an abrogated adaptation to ambient Pi. To study the role of IP6K1 and 2 in vivo, we generated renal tubule-specific inducible ip6k1-/-2-/- KO mice: the mice had strongly reduced expression of renal Pi transporters, at the protein and mRNA levels, and lower serum Pi (by 20%) together with the transcriptional downregulation of many other transporters. Serum intact fibroblast growth factor 23—a principal phosphaturic hormone—was also substantially reduced (10-fold) in these mice. Our data indicate that the deletion of IP6K1 and 2 decreases transcription of renal Pi transporters both in vivo and in vitro, and that Ip6k1-/-2-/- cells are unable to adapt to ambient Pi. Therefore, IP6K1 and 2 play a critical role in renal Pi metabolism and, potentially, sensing.

Phosphatemic Index Is a Novel Evaluation Tool for Dietary Phosphorus Load: A Whole-Foods Approach

Dietary phosphorus (P) restriction is crucial to treat hyperphosphatemia and reduce cardiovascular disease risk and mortality in patients with chronic kidney disease (CKD) and the wider population. Various methods for dietary P restriction exist, but the bioavailability of P in food should also be considered when making appropriate food choices to maintain patients' quality of life. Here, we propose the "Phosphatemic Index" (PI) as a novel tool for evaluating dietary P load based on P bioavailability; we also evaluated the effect of continuous intake of different PI foods in mixed meals on serum intact fibroblast growth factor 23 concentration. A 2-stage crossover study was conducted: Study 1: 20 healthy participants consumed 10 different foods containing 200mg of P, and the PI was calculated from the area under the curve of a time versus serum P concentration curve; Study 2: 10 healthy participants consumed 4 different test meals (low, medium, or high PI meals or a control) over a 5-day period. Study 1 showed milk and dairy products had high PI values, pork and ham had medium PI values, and soy and tofu had low PI values. In Study 2, ingestion of high PI test meals showed higher fasting serum intact fibroblast growth factor 23 levels and lower serum 1,25-dihydroxyvitamin D levels compared with ingestion of low PI test meals. These findings suggest that the PI can usefully evaluate the dietary P load of various foods and may help to make appropriate food choices for dietary P restriction in CKD patients.

Interactions between FGF23 and Genotype in Autosomal Dominant Polycystic Kidney Disease.

Higher serum intact fibroblast growth factor 23 (iFGF23) was associated with disease progression in participants with autosomal dominant polycystic kidney disease (ADPKD) in the HALT-PKD Studies. PKD mutation is also an important determinant of progression. We hypothesized that serum levels of iFGF23 and vitamin D metabolites (1,25-dihydroxyvitamin D [1,25(OH)2D] and 25-hydroxyvitamin D [25[OH]D]) differ according to ADPKD mutation and differentially predict clinical end points according to genotype (significant interaction between genotype and mineral metabolites). A total of 864 individuals with ADPKD who participated in the HALT-PKD Study A or B and had measurements of mineral metabolites (1,25[OH]2D, 25[OH]D, iFGF23) were categorized by PKD mutation (PKD1 truncating, PKD1 nontruncating, PKD2, or no mutation detected [NMD]). The association of the interactions of genotype × iFGF23, genotype × 1,25(OH)2D, and genotype × 25(OH)D with (1) annualized change in eGFR; (2) mean annualized percentage change in height-corrected total kidney volume (Study A only); and (3) time to a composite of 50% reduction in eGFR, ESKD, or death were evaluated using linear regression and Cox proportional hazards regression. Median (interquartile range) iFGF23 differed (PKD1 truncating, 55.8 [40.7-76.8]; PKD1 nontruncating, 49.9 [37.7-71.0]; PKD2, 49.0 [33.8-70.5]; NMD, 50.3 [39.7-67.4] pg/ml; P=0.03) and mean±SD 1,25(OH)2D differed (PKD1 truncating, 32.8±12.8; PKD1 nontruncating, 33.4±12.5; PKD2, 34.1±13.1; NMD, 38.0±14.6 pg/ml; P=0.02) according to PKD genotype. There was a significant interaction between iFGF23 and genotype (P=0.02) for the composite end point in fully adjusted models, but no significant interaction between 1,25(OH)2D or 25(OH)D and genotype for clinical end points. ADPKD genotype interacts significantly with FGF23 to influence clinical end points. Whereas the worst outcomes were in individuals with a PKD1-truncating or -nontruncating mutation and the highest iFGF23 tertile, risk of the composite end point differed according to iFGF23 the most in the PKD1-nontruncating and PKD2 groups.

Clinical and metabolic features in childhood hypophosphatemic rickets

Background: Hypophosphatemic rickets is a rare disease, related to renal phosphate waste, which cause bone deformities, and lead to walking abnormalities and to the reduction in the quality of life. Clinical recommendations in different countries vary in medications, recommended doses and surgery approach. The main aim was to analyze phosphate metabolism in children with hypophosphatemic rickets and to evaluate results of conservative and surgical therapy. Methods: We analyzed medical histories of 15 children with hypophosphatemic rickets and investigated phosphate metabolism, including the measurement of serum intact fibroblast growth factor 23 and X-ray bone densitometry. Routine biochemical tests were assessed with our laboratory reference data, the level of iFGF-23 in hypophosphatemic children was compared with the same values in 18 healthy children. Results: We investigated 15 girls with hypophosphatemic rickets, aged of from 3 years 9 months to 18 years 7 months. All children were treated with alphacalcidol and inorganic phosphate (in dose from 16.21 to 103.3 mg/kg, during from 1 to 114 months). Eleven (73%) children had surgical correction of bone deformations, starting at the age of from 3 to 12 years. Ten (91%) of them had the relapse of bone deformations. Two of four children undergone to the correction of bone abnormalities on alphacalcidol and phosphate therapy without surgery. The level of iFGF-23 in children with hypophosphatemic rickets was 73.11 pg/ml, and exceed iFGF-23 in control group (22.92 pg/ml), p =0,009. Conclusion: Early surgical treatment of bone deformations is not indicated in hypophosphatemic rickets because of risk of recurrence, observed in 91% of our patients. There could be spontaneous correction of bone deformation during conservative therapy, when it is started early.

Randomized Clinical Trial of Sevelamer Carbonate on Serum Klotho and Fibroblast Growth Factor 23 in CKD.

Epidemiologic studies suggest that higher serum phosphaturic hormone fibroblast growth factor 23 levels are associated with increase morbidity and mortality. The aim of the FGF23 Reduction Efficacy of a New Phosphate Binder in CKD Trial was to evaluate the effect of sevelamer carbonate on serum C-terminal fibroblast growth factor 23 levels in normophosphatemic patients with CKD stage 3b/4. Patients with CKD, eGFR between 45 and 15 ml/min per 1.73 m2, fasting serum phosphate concentration >3.1 mg/dl, and serum C-terminal fibroblast growth factor 23 >80 relative units/ml were included in our double-blind, placebo-controlled, randomized multicenter study. All patients received 100,000 IU cholecalciferol at time of randomization. Participants received either placebo or sevelamer carbonate 4.8 g daily during a 12-week period. Biologic parameters, including serum C-terminal fibroblast growth factor 23, intact fibroblast growth factor 23, and α-klotho, were evaluated at baseline and 12 weeks after inclusion. Of 96 screened patients, 78 (mean±SD age: 63±13 years old; 70% men; mean eGFR: 27±9 ml/min per 1.73 m2) met the inclusion criteria. At baseline, mean eGFR was 27±9 ml/min per 1.73 m2, mean serum phosphate level was 3.8±0.5 mg/dl, and median (interquartile range) serum C-terminal fibroblast growth factor 23 level was 157 (120-241) relative units/ml. After 12 weeks of treatment, urinary phosphate-to-creatinine ratio fell significantly in the sevelamer group. The sevelamer and placebo groups did not differ significantly in terms of median change in serum C-terminal fibroblast growth factor 23 levels: the median (interquartile range) change was 38 (-13-114) relative units/ml in the placebo group and 37 (-1-101) relative units/ml in the sevelamer group (P=0.77). There was no significant difference in serum intact fibroblast growth factor 23, α-klotho, or phosphate levels changes between the two groups. Serum total and LDL cholesterol levels fell significantly in the sevelamer group. In our double-blind, placebo-controlled, randomized study performed in normophosphatemic patients with CKD, a 12-week course of sevelamer carbonate significantly reduced phosphaturia without changing serum phosphorus but did not significantly modify serum C-terminal fibroblast growth factor 23 and intact fibroblast growth factor 23 or α-klotho levels.

Association of serum intact fibroblast growth factor 23 with left ventricular mass and different echocardiographic findings in patients on hemodialysis.

To determine the association of fibroblast growth factor 23 (FGF23) with left ventricular hypertrophy (LVH) through the assessment of left ventricular (LV) mass and left ventricular mass index (LVMI) in patients on hemodialysis, this study was done. All patients on hemodialysis who are older than 18 years and in whom hemodialysis vintage was at least 6 months were enrolled. All patients were on hemodialysis thrice a week for 4 h using low-flux dialysis filters, polysulfone membranes, reverse osmosis purified water, and bicarbonate-base hemodialysis solution. The exclusion criteria were any respiratory illness or pulmonary infection, cigarette smoking, and the presence of pericarditis or pericardial effusion. Additionally, patients with a known coronary artery disease, any form of cardiac arrhythmias, any cardiomyopathy or severe valvular heart disease diagnosed by echocardiography, acute congestive heart failure (CHF), and acute myocardial infarction were not included. Echocardiography was conducted by an experienced operator for all the enrolled patients using the ACUSON SC2000™ ultrasound system transducer (Siemens), with a frequency bandwidth of: 1.5-3.5 MHz. Patients were considered to have LVH if the LVMI was greater than 134 g/m2 for men and greater than 110 g/m2 for women. A total of 61 patients (19 female and 42 male) were enrolled to the study. Mean (± SD) age of the patients was 59.6 ± 13.1 years. The median duration of hemodialysis was 23 (range: 6-120) months. The median predialysis level of FGF23 was 1,977 pg/mL (range: 155-8,870). LVH was seen in 73.8% of the patients (n = 45) and of them 66.7% were male. There was a statistically significant direct correlation between FGF23 and left ventricle diameter in end systole (LVDs) (r = 0.29, P = 0.027). However, the association of FGF23 with LV mass, LVMI, and left ventricular ejection fraction (LVEF) was not significant. This study does not show the correlation between FGF23 and LV mass in stable hemodialysis patients.

Relationship of FGF23 to indexed left ventricular mass in children with non-dialysis stages of chronic kidney disease.

The aim of this study was to evaluate the association of serum intact fibroblast growth factor 23 (FGF23) concentrations with indexed left ventricular mass in children with non-dialysis stages 3-5 of chronic kidney disease (CKD). The study cohort comprised 83 children (51 boys; mean age 12.1 ± 3.2 years) with a mean estimated glomerular filtration rate (eGFR) of 32.3 ± 14.6 ml/min/1.73 m(2) who underwent clinic and ambulatory blood pressure measurement (ABPM), echocardiography and evaluation of biochemical markers of CKD-associated mineral bone disease. The mean left ventricular mass index (LVMI) was 35.9 ± 8.5 g/m(2.7) (± standard deviation), with 30 (36.1 %) children showing left ventricular hypertrophy (LVH), all eccentric, as defined using age-specific criteria. For all subjects, the mean FGF23 concentration was 142.2 ± 204.4 ng/l and the normalised distribution following log transformation was 1.94 ± 0.39. There was significant univariate correlation of LVMI with GFR, body mass index (BMI) z-score and calcium intake, but not with 24-h systolic ABPM z-score, log intact parathyroid hormone or log FGF23. On multivariate analysis following adjustment for confounders, only elemental calcium content (g/kg/day) estimated from prescribed calcium-based phosphate binder dose (β = 154.9, p < 0.001) and BMI z-score (β = 2.397, p = 0.003) maintained a significant positive relationship with LVMI (model r (2) = 0.225). We observed no significant relationship of FGF23 with LVMI. Larger studies in children are needed to clarify the roles of calcium-containing phosphate binders and FGF23 with LV mass and their roles in the evolution of the development of adverse cardiovascular outcomes.

Fibroblast growth factor 23 and incident CKD in type 2 diabetes.

High levels of fibroblast growth factor 23 are associated with accelerated progression of CKD. Whether high fibroblast growth factor 23 levels also predict incident CKD is uncertain. A prospective case-cohort study was conducted within the Action to Control Cardiovascular Risk in Diabetes Trial. The analytic sample consisted of a random subcohort of 590 patients with type 2 diabetes without prevalent CKD at baseline, 124 of whom developed incident CKD during follow-up, and 520 additional patients with incident CKD outside the random subcohort. The association between serum intact fibroblast growth factor 23 and incident CKD, defined as the new onset of eGFR<60 ml/min per 1.73 m(2) that represented a ≥25% decrease from baseline in an individual with eGFR≥60 ml/min per 1.73 m(2) and no microalbuminuria (<30 mg/g creatinine) at baseline, was tested. The mean baseline eGFR in the random subcohort was 90.9±22.7 ml/min per 1.73 m(2). During a median follow-up of 4.7 years, there was a total of 644 patients with incident CKD. The median baseline fibroblast growth factor 23 level was modestly higher among patients with incident CKD versus controls (43.5, interquartile range=34.7-55.1 versus 39.8, interquartile range=31.9-49.5 pg/ml; P<0.001). Higher baseline fibroblast growth factor 23 levels were associated with higher risk of incident CKD in unadjusted and demographics-adjusted models, but the effect was attenuated after additional adjustment for clinical risk factors and baseline eGFR (hazard ratio per SD of natural log fibroblast growth factor 23, 1.09; 95% confidence interval, 0.94 to 1.27), which was the strongest predictor of incident CKD. Consistent with the results of primary analyses, baseline fibroblast growth factor 23 was not associated with eGFR slope. Higher fibroblast growth factor 23 levels are not independently associated with higher risk of incident CKD in patients with type 2 diabetes.

Production and Conditioning of Winterfat Seeds (Krascheninnikovia lanata)

Background: Higher serum intact fibroblast growth factor 23 (iFGF23) was associated with disease progression in participants with autosomal dominant polycystic kidney disease (ADPKD) in the HALT-PKD Studies. PKD mutation is also an important determinant of progression. We hypothesized that serum levels of iFGF23 and vitamin D metabolites (1,25-dihydroxyvitamin D [1,25(OH)₂D] and 25-hydroxyvitamin D [25[OH]D]) differ according to ADPKD mutation and differentially predict clinical endpoints according to genotype (significant interaction between genotype and mineral metabolites). Methods: 864 individuals with ADPKD who participated in the HALT-PKD Study A or B and had measurement of mineral metabolites (1,25(OH)2D, 25(OH)D, iFGF23) were categorized by PKD mutation (PKD1 truncating, PKD1 non-truncating, PKD2, or no mutation detected [NMD]). The association of the interactions of genotype * iFGF23, genotype * 1,25(OH)2D, and genotype * 25(OH)D with 1) annualized change in estimated glomerular filtration rate; 2) mean annualized percent change in height-corrected total kidney volume (Study A only); 3) time to a composite of 50% reduction in eGFR, end-stage renal disease (ESRD), or death were evaluated using linear regression and Cox proportional hazards regression. Results: Median [IQR] iFGF23 differed (PKD1 truncating: 55.8 [40.7, 76.8]; PKD1 non-truncating: 49.9 [37.7, 71.0]; PKD2: 49.0 [33.8, 70.5]; NMD: 50.3 [39.7, 67.4] pg/ml; p=0.03) and mean±S.D. 1,25(OH)₂D differed (PKD1 truncating: 32.8±12.8; PKD1 non-truncating: 33.4±12.5, PKD2: 34.1±13.1; NMD: 38.0±14.6 pg/ml; p=0.02) according to PKD genotype. There was a significant interaction between iFGF23 and genotype (p=0.02) for the composite endpoint in fully adjusted models, but no significant interaction between 1,25(OH)₂D or 25(OH)D and genotype for clinical endpoints. Conclusions: ADPKD genotype interacts significantly with FGF23 to influence clinical endpoints. While the worst outcomes were in individuals with a PKD1 truncating or non-truncating mutation and the highest iFGF23 tertile, risk of the composite endpoint differed according to iFGF23 the most in the PKD1 non-truncating and PKD2 groups.