Higher Fibroblast Growth Factor 23 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.

#2611 Development of a predictive model for FGF-23 levels in children with chronic kidney disease

Abstract Background and Aims The global prevalence of Chronic Kidney Disease (CKD) among the population is approximately 10%, with this rate steadily increasing. Epidemiological data on CKD in childhood are scarce and show significant variability across different countries. One of the most serious complications is mineral and bone disorders (CKD-MBD), which worsen the clinical course and prognosis of patients. The understanding of the pathogenesis of CKD-MBD has undergone substantial changes since the discovery of Fibroblast growth factor 23 (FGF-23), a 32 kDa peptide produced by osteocytes and osteoblasts, has emerged as a key regulator of phosphate metabolism. It is acknowledged that FGF-23 levels in the serum gradually increase as renal function declines, i.e., with the progression of CKD. According to various studies, FGF-23 may also be associated with cardiovascular complications, such as left ventricular hypertrophy (LVH). There is evidence indicating that FGF-23 may be regarded as an independent risk factor for mortality. Considering the predictive abilities of FGF-23 in relation to the onset of complications and mortality in children with CKD, there is a need for its assessment in serum or plasma. However, the availability of the FGF-23 assay kit in Kazakhstan is not consistently ensured in clinical practice, and its logistics may be time-consuming and financially burdensome. Therefore, we aimed to develop a predictive model to estimate FGF-23 levels based on accessible clinical and laboratory parameters. Method 73 children with CKD were enrolled in the pilot study. The average age was 9.79 ± 0.58 years, 52.1% males and 47.9% females. The study adhered to the principles outlined in the Declaration of Helsinki. A comprehensive evaluation of all clinical and necessary laboratory characteristics was conducted. The estimated glomerular filtration rate (eGFR) was calculated according to the Schwartz formula. FGF-23 levels were measured in serum using a multimatrix ELISA kit (Biomedica Medizinprodukte GmbH, Austria). For the development of the predictive model, we employed the decision tree learning approach. Statistical analysis and modeling were conducted using SPSS version 27 (IBM, USA). Results Initially, we included all clinical and laboratory parameters showing statistically significant associations with FGF-23 as independent variables and created various models. Then, we selected the most accurate predictive model which included 3 predictors: phosphate, eGFR and LVH. We found out a correlation between FGF-23 with eGFR (r = −0,826, p = 0.000), with phosphate (r = 0.473, p = 0.000). LVH is also associated with high FGF-23 (p = 0.000). At the start of the algorithm, the phosphate level should be estimated, and if it is normal, the next step is to determine eGFR. When eGFR is more than 85.7 ml/min, in 92.9% of cases FGF-23 will be within normal limits. eGFR less than 28.3 ml/min predicts a 100% chance of high FGF-23 levels. If the eGFR is in the range from 28.3 to 85.7 ml/min, the next we should determine the presence of LVH in the child. So, if a patient has been diagnosed with LVH, this indicates a high level of FGF-23 in 100% of cases. On the contrary, if the patient does not have LVH, then this probability is reduced to 52.9%. In the case of initially elevated phosphate, there is a need to evaluate if the patient has LVH or not regardless of eGFR. If it is present, the probability of a high level of FGF-23 is 100%, and if absent, it is 55.6%. Our predictive model demonstrated a high sensitivity of 98%, an overall percentage of accuracy is 82.2 ± 4.5%. Conclusion A decision tree algorithm based on a limited set of available clinical and laboratory characteristics such as phosphate, eGFR and LVH might be considered as a useful tool for predicting FGF-23 levels. This algorithmic approach enables the identification and evaluation of individuals with elevated FGF-23 who are at high risk for complications associated with CKD.

#2421 Kidney injury in scleroderma: serum level of fibroblast growth factor-23, klotho and neutrophil gelatinase-associated lipocalin after iloprost infusion

Abstract Background and Aims Systemic sclerosis (SSc) is characterized by progressive derangement of the microcirculation leading to a state of chronic tissue hypoxia with release of several inflammatory cytokines such as neutrophil gelatinase-associated lipocalin (NGAL), fibroblast growth factor-23 (FGF-23) and Klotho. Renal scleroderma associated-vasculopathy is characterized by vascular damage with normal renal function and increased intrarenal stiffness, assessed by renal resistive index (RRI) Aim of this study was to evaluate at baseline serum levels of FGF-23, Klotho and NGAL in SSc patients and healthy controls (HC) and to correlate the serum levels of these markers with microvascular damage of skin and kidney. Secondary aim was to evaluate the serum levels of FGF-23, Klotho and NGAL after Iloprost infusion. Method Twenty-one SSc patients and 20 HC were enrolled. All patients had a 2-months wash-out of Iloprost infusion before of clinical, laboratory and instrumental assessment. Peripheral venous blood was collected at three different time points for SSc patients: t0 immediately before the first Iloprost infusion (after 2-months wash-out period), t1 immediately after the first Iloprost infusion and t2 the day of the next Iloprost infusion (about 14 days from the last infusion). Results SSc patients had higher serum level of FGF-23 [18.7 pg/mL (± 6.4) vs 3.6 pg/mL (± 2.2), p < 0.001], Klotho [5.1 pg/mL (±0.8) vs 2.3 pg/mL (±0.6), p < 0.001] and NGAL [20.9 pg/mL (±2.6) vs 14.5 pg/mL (±1.7), p < 0.001] compared to HC. The one-way repeated-measures ANOVA showed that mean FGF-23 [F (2,40) = 71.255, p < 0.001], Klotho [F (1.405, 28.103) = 195.095, p < 0.001] and NGAL [F (2,40) = 48.024, p < 0.001] differed significantly between time points. Conclusion SSc patients had higher FGF-23, Klotho and NGAL than HC. Our present data demonstrate that microvascular damage is associated to chronic hypoperfusion with increased circulating markers such as FGF-23, Klotho and NGAL. For the first time, we demonstrated that Iloprost infusion reduces significantly serum level of FGF-23, Klotho and NGAL and it has showed to be a key role in renal vasculopathy in SSc patients. In literature, there are no data about the modification of these serum markers before and after vasoactive treatment, especially of Iloprost infusion.

Iloprost infusion reduces serological cytokines and hormones of hypoxia and inflammation in systemic sclerosis patients

IntroductionSystemic sclerosis (SSc) is characterized by microvascular damage of skin and internal organs with chronic hypoxia and release of cytokines and hormones such as neutrophil gelatinase-associated lipocalin (NGAL), fibroblast growth factor-23 (FGF-23) and Klotho. Aim of the study was to evaluate FGF-23, Klotho and NGAL serum levels in SSc patients and healthy controls (HC) and to evaluate serum levels changes of FGF-23, Klotho and NGAL after Iloprost.MethodsTwenty-one SSc patients and 20 HC were enrolled. In SSc patients, peripheral venous blood samples were collected at the first day before the autumn Iloprost infusion (t0), 60 min (t1) and 14 days after Iloprost infusion (t2).ResultsSSc patients had higher serum level of FGF-23 [18.7 ± 6.4 pg/ml versus 3.6 ± 2.2 pg/ml, p < 0.001], Klotho [5.1 ± 0.8 pg/ml versus 2.3 ± 0.6 pg/ml, p < 0.001] and NGAL [20.9 ± 2.6 pg/ml versus 14.5 ± 1.7 pg/ml, p < 0.001] than HC.Iloprost infusion reduces serum level of FGF-23 (18.7 ± 6.4 pg/ml versus 10.4 ± 5.5 pg/ml, p < 0.001), Klotho (5.1 ± 0.8 pg/ml versus 2.5 ± 0.6 pg/ml, p < 0.001) and NGAL (20.9 ± 2.6 pg/ml versus 15.1 ± 2.3 pg/ml, p < 0.001) between t0 and t1. The Iloprost infusion reduces serum level of FGF-23 (18.7 ± 6.4 pg/ml versus 6.6 ± 5.1 pg/ml), Klotho (5.1 ± 0.8 pg/ml versus 2.3 ± 0.4 pg/ml) and NGAL (20.9 ± 2.6 pg/ml versus 15.5 ± 1.9 pg/ml) between t0 and t2.ConclusionsSSc patients had higher FGF-23, Klotho and NGAL than HC. Iloprost reduces serum levels of FGF-23, Klotho and NGAL.

Emerging concepts on the FGF23 regulation and activity.

Fibroblast growth factor 23 (FGF23) discovery has provided new insights into the regulation of Pi and Ca homeostasis. It is secreted by osteoblasts and osteocytes, and acts mainly in the kidney, parathyroid, heart, and bone. The aim of this review is to highlight the current knowledge on the factors modulating the synthesis of FGF23, the canonical and non-canonical signaling pathways of the hormone, the role of FGF23 in different pathophysiological conditions, and the anti-FGF23 therapy. This is a narrative review based on the search of PubMed database in the range of years 2000-2023 using the keywords local and systemic regulators of FGF23 synthesis, FGF23 receptors, canonical and non-canonical pathways, pathophysiological conditions and FGF23, and anti-FGF23 therapy, focusing the data on the molecular mechanisms. The regulation of FGF23 synthesis is complex and multifactorial. It is regulated by local factors and systemic regulators mainly involved in bone mineralization. The excessive FGF23 production is associated with different congenital diseases and with diseases occurring with a secondary high FGF23 production such as in chronic disease kidney and tumor-induced osteomalacia (TIO). The anti-FGF23 therapy appears to be useful to treat chromosome X-linked hypophosphatemia and TIO, but there are doubts about the handle of excessive FGF23 production in CKD. FGF23 biochemistry and pathophysiology are generating a plethora of knowledge to reduce FGF23 bioactivity at many levels that might be useful for future therapeutics of diseases associated with high-serum FGF23 levels.

A retrospective cohort of tumor-induced osteomalacia and case series of malignant disease.

We aimed to describe the clinical characteristics of a large cohort of patients diagnosed with tumor-induced osteomalacia (TIO), with a focus on patients with non-localizing and malignant TIO. This is a retrospective cohort of TIO patients in an academic medical center, diagnosed between January 1998 to May 2023. We described their demographics, biochemistries, tumor features, localization, treatment and complications. Of 68 patients diagnosed with TIO, 49 (72%) were localizing and 5 (7.4%) were malignant. Of 50 patients who attempted localizing procedures, 29 (58%) achieved cure. 20 (40%) had persistent disease due to wrong tumor targeted, or refractory or recurrent tumors, despite up to 6 procedural attempts. There was no difference in demographics, phosphorus or baseline fibroblast growth factor-23 (FGF23) levels between localizing versus non-localizing groups, and malignant versus non-malignant groups. Lower extremity was the commonest site of localization (37%), with 47% in bone and 53% in soft tissue. 60% of malignant cases were located in the trunk. Tumor size correlated with peak FGF23 (R=0.566, p<0.001) but was not associated with malignancy risk (p=0.479). A cut-off FGF23 of >20 times upper limit of normal in the presence of normal renal function (p=0.025), and recurrence after initial cure (p=0.013) were factors significantly associated with malignancy. The non-localizing group had lower survival than localizing group (p=0.0097). TIO is a condition with significant morbidity. Very high FGF23 level and disease recurrence are associated with malignant disease. Reasons behind the observation of higher mortality in non-localizing TIO should be further explored.

Serum fibroblast growth factor 23 concentration and the risk of mortality in patients undergoing peritoneal dialysis.

Fibroblast growth factor 23 (FGF23) is a phosphate-regulating hormone that is secreted in large amounts early in chronic kidney disease. In this cohort, we aimed to investigate the association between serum FGF23 concentration and mortality in patients undergoing peritoneal dialysis (PD). Serum FGF23 level was determined by enzyme-linked immunosorbent assay (ELISA) in a large 15-year prospective cohort study of PD patients with stored serum samples at baseline. Kaplan-Meier survival curves and Cox proportional hazards models were performed to characterise the relationship of FGF23 with mortality. A total of 737 incident PD patients were analysed. The baseline median FGF23 concentration was 683.2 (518.5-896.2) pg/mL. Age, serum phosphorus, high-density lipoprotein cholesterol and high-sensitivity C-reactive protein were independently correlated with serum FGF23 concentration. During a median follow-up of 66.7 (41.1-95.4) months, 171 of the 737 participants (23.2%) died, including 84 (49.1%) cardiovascular disease-related and 50 (29.2%) infection-related deaths. Multivariable Cox regression analysis showed that the adjusted hazard ratios of the highest tertile of serum FGF23 compared with those in the lowest tertile were 1.36 (95% confidence interval (CI): 0.89-2.07; p = 0.154), 0.75 (95% CI: 0.40-1.38; p = 0.353) and 2.66 (95% CI: 1.15-6.15; p = 0.022) for all-cause, cardiovascular disease-related and infection-related mortality, respectively. High serum FGF23 concentration is associated with a higher risk of infection-related death for incident PD patients.

C-terminal fragment of fibroblast growth factor 23 improves heart function in murine models of high intact fibroblast growth factor 23.

Cardiovascular disease (CVD) is the major cause of death in chronic kidney disease (CKD) and is associated with high circulating fibroblast growth factor (FGF)23 levels. It is unresolved whether high circulating FGF23 is a mere biomarker or pathogenically contributes to cardiomyopathy. It is also unknown whether the C-terminal FGF23 peptide (cFGF23), a natural FGF23 antagonist proteolyzed from intact FGF23 (iFGF23), retards CKD progression and improves cardiomyopathy. We addressed these questions in three murine models with high endogenous FGF23 and cardiomyopathy. First, we examined wild-type (WT) mice with CKD induced by unilateral ischemia-reperfusion and contralateral nephrectomy followed by a high-phosphate diet. These mice were continuously treated with intraperitoneal implanted osmotic minipumps containing either iFGF23 protein to further escalate FGF23 bioactivity, cFGF23 peptide to block FGF23 signaling, vehicle, or scrambled peptide as negative controls. Exogenous iFGF23 protein given to CKD mice exacerbated pathological cardiac remodeling and CKD progression, whereas cFGF23 treatment improved heart and kidney function, attenuated fibrosis, and increased circulating soluble Klotho. WT mice without renal insult placed on a high-phosphate diet and homozygous Klotho hypomorphic mice, both of whom develop moderate CKD and clear cardiomyopathy, were treated with cFGF23 or vehicle. Mice treated with cFGF23 in both models had improved heart and kidney function and histopathology. Taken together, these data indicate high endogenous iFGF23 is not just a mere biomarker but pathogenically deleterious in CKD and cardiomyopathy. Furthermore, attenuation of FGF23 bioactivity by cFGF23 peptide is a promising therapeutic strategy to protect the kidney and heart from high FGF23 activity.NEW & NOTEWORTHY There is a strong correlation between cardiovascular morbidity and high circulating fibroblast growth factor 23 (FGF23) levels, but causality was never proven. We used a murine chronic kidney disease (CKD) model to show that intact FGF23 (iFGF23) is pathogenic and contributes to both CKD progression and cardiomyopathy. Blockade of FGF23 signaling with a natural proteolytic product of iFGF23, C-terminal FGF23, alleviated kidney and cardiac histology, and function in three separate murine models of high endogenous FGF23.

High pretransplant FGF23 level is associated with persistent vitamin D insufficiency and poor graft survival in kidney transplant patients

Vitamin D3 (25[OH]D3) insufficiency and fibroblast growth factor 23 (FGF23) elevation are usually attenuated after kidney transplantation (KT). However, elevated FGF23 may be associated with poor graft outcomes and vitamin D insufficiency after KT. This study investigated the effect of pretransplant FGF23 levels on post-KT 25(OH)D3 status and graft outcomes. Serum FGF23 levels from 400 participants of the KoreaN Cohort Study for Outcome in Patients With Kidney Transplantation were measured. Annual serum 25(OH)D3 levels, all-cause mortality, cardiovascular event, and graft survival were assessed according to baseline FGF23 levels. Serum 25(OH)D3 levels were initially increased 1 year after KT (12.6 ± 7.4 vs. 22.6 ± 6.4 ng/mL). However, the prevalence of post-KT vitamin D deficiency increased again after post-KT 3 years (79.1% at baseline, 30.8% and 37.8% at 3 and 6 years, respectively). Serum FGF23 level was decreased 3 years post-KT. When participants were categorized into tertiles according to baseline FGF23 level (low, middle, high), 25(OH)D3 level in the low FGF23 group was persistently low at a median follow-up of 8.3 years. Furthermore, high baseline FGF23 level was a risk factor for poor graft survival (HR 5.882, 95% C.I.; 1.443–23.976, P = 0.013). Elevated FGF23 levels are associated with persistently low post-transplant vitamin D levels and poor graft survival.

THU466 XLH During Pregnancy: A Closer Look Based On Real-World Experience

Abstract Disclosure: D.S. Ali: None. A.A. Khan: Advisory Board Member; Self; Amgen Inc, Takeda. Grant Recipient; Self; Alexion Pharmaceuticals, Inc., Amgen Inc, Radius Health, Inc, Takeda, Ultragenyx. Background: X-linked hypophosphatemia (XLH) is a genetic disorder caused by mutation in the PHEX gene leading to excess serum levels of the phosphate-regulating hormone fibroblast growth factor 23 (FGF23). High FGF23 causes renal phosphate wasting, decreased production of serum 1,25-dihydroxy vitamin D, and increased metabolism of 1,25-dihydroxy vitamin D, leading to hypophosphatemia. Maintaining normal serum phosphorus levels in pregnant women with XLH is critically important to ensure mineralization of the fetal skeleton. Multiple factors may influence phosphorus homeostasis in pregnancy, including an increase in PTHrP production and a tripling of calcitriol beginning in the first trimester. Case study: 30 years old Gravida 1 Para 0 with XLH, diagnosed at the age of 18 months. She has a pathogenic heterozygous mutation of the PHEX gene (c.1645+1G&amp;gt;A). Treated with phosphate and calcitriol since diagnosis. Had no history of neonatal seizure or respiratory distress, and no dental or renal manifestations. No prior fractures or corrective surgeries and has a normal BMD. No history of enthesopathy, however, has chronic joint pain &amp;gt; 1 year. The pregnancy progressed well with no issues; the patient chose not to undergo amniocentesis for fetal diagnosis. She was monitored closely every 3 weeks, aiming to maintain the serum phosphorus within the normal range to ensure adequate mineralization of the fetal skeleton. The requirements for phosphate increased by 50% in the 2nd trimester and by 125% in the 3rd trimester compared to baseline. While the calcitriol dose increased by 25% in the 3 trimesters compared to baseline. Because further increases in the calcitriol dose were associated with hypercalciuria, the dose was carefully titrated. The mean serum phosphorus level was maintained in the low normal reference range at 0.79 - 0.8 mmol/L (NR: 0.8-1.45), mean TmP/GFR 0.611 (NR: 0.96-1.44). She was induced at 37 weeks due to cholestasis, and delivered with a vaginal delivery. The baby boy weighed 2.690 kg and had slightly low serum phosphorus and calcium levels at birth, which corrected spontaneously. DNA analysis confirmed that the baby also has a pathogenic mutation of the PHEX gene. Conclusion: There was a noticeable variation in the serum phosphorus levels during the 1st and 2nd trimesters and less so in the 3rd trimester and during lactation. The dose of phosphate and active vitamin D required careful upward titration to maintain a normal serum phosphorus level. Therefore, close monitoring is essential. Although the rate of c-sections is higher (76%) amongst the XLH patient population compared to the normal population 27.1%, our patient delivered vaginally with no adverse skeletal outcomes in the mother or neonate. Presentation: Thursday, June 15, 2023

Impaired 1,25-dihydroxyvitamin D3 action underlies enthesopathy development in the Hyp mouse model of X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is characterized by high serum fibroblast growth factor 23 (FGF23) levels, resulting in impaired 1,25-dihydroxyvitamin D3 (1,25D) production. Adults with XLH develop a painful mineralization of the tendon-bone attachment site (enthesis), called enthesopathy. Treatment of mice with XLH (Hyp) with 1,25D or an anti-FGF23 Ab, both of which increase 1,25D signaling, prevents enthesopathy. Therefore, we undertook studies to determine a role for impaired 1,25D action in enthesopathy development. Entheses from mice lacking vitamin D 1α-hydroxylase (Cyp27b1) (C-/-) had a similar enthesopathy to Hyp mice, whereas deletion of Fgf23 in Hyp mice prevented enthesopathy, and deletion of both Cyp27b1 and Fgf23 in mice resulted in enthesopathy, demonstrating that the impaired 1,25D action due to high FGF23 levels underlies XLH enthesopathy development. Like Hyp mice, enthesopathy in C-/- mice was observed by P14 and was prevented, but not reversed, with 1,25D therapy. Deletion of the vitamin D receptor in scleraxis-expressing cells resulted in enthesopathy, indicating that 1,25D acted directly on enthesis cells to regulate enthesopathy development. These results show that 1,25D signaling was necessary for normal postnatal enthesis maturation and played a role in XLH enthesopathy development. Optimizing 1,25D replacement in pediatric patients with XLH is necessary to prevent enthesopathy.

Maternal overweight and obesity modify the association of serum fibroblast growth factor 21 levels with gestational diabetes mellitus: A nested case-control study.

To examine the prospective association between fibroblast growth factor 21 (FGF21) and risk of gestational diabetes mellitus (GDM) and the modifying effect of overweight/obesity for this association. Serum FGF21 levels were measured at 6-15weeks of gestation among 332 GDM cases and 664 matched controls. Conditional logistic regression was used to evaluate its association with GDM risk. Interaction analyses on multiplicative and additive scales were conducted to investigate the modifying effect of overweight/obesity. Elevated FGF21 levels were associated with a higher risk of GDM in multivariable models, but the positive association was attenuated after further adjustment for pre-pregnancy body mass index (BMI). A significant multiplicative interaction was noted between FGF21 (both continuous and dichotomous) and pre-pregnancy BMI (p for interaction=0.049 and 0.03), and the association was only significant in participants with pre-pregnancy BMI ≥24kg/m2 . When participants were grouped based on pre-pregnancy BMI (≥24 and <24kg/m2 ) and FGF21 levels (≥median and <median), a significant association was observed in those with higher BMI and FGF21 levels (odds ratio, 2.12; 95% CI: 1.41, 3.20) but not in those with either higher BMI or higher FGF21, with a significant additive interaction (relative excess risk due to interaction=1.23; 95% CI: 0.27, 2.20). FGF21 was also correlated with unfavourable glucose and lipid biomarkers as well as adipokines. Elevated serum FGF21 levels in early pregnancy were associated with a higher risk of GDM, particularly among those with overweight/obesity.

Insight to the association among fibroblast growth factor 21, non-alcoholic fatty liver disease and cardiovascular outcomes: A population-based study

ObjectiveWe aimed to investigate whether there was a joint effect of fibroblast growth factor 21 (FGF21) and non-alcoholic fatty liver disease (NAFLD) or interaction on the incidence of cardiovascular diseases based on a community-dwelling population. MethodsSerum FGF21 levels were determined using an enzyme-linked immunosorbent method. NAFLD was diagnosed via ultrasonography. Multivariable-adjusted cox proportional hazards models were used to assess the joint effects of FGF21 and NAFLD on the major adverse cardiovascular events (MACE). ResultsA total of 1194 participants were enrolled in the final analysis. The multivariable-adjusted hazard ratio (HR) of MACE was 1.84 (95% confidence interval (CI) 1.18–2.86) in participants with diagnosed NAFLD at baseline, compared with those without NAFLD at baseline. The multivariable-adjusted HRs of MACE across quintiles of serum FGF21 levels at baseline were 1.00, 1.48 (95%CI 0.68–3.21), 2.01 (95%CI 0.98–4.13), 1.94 (95%CI 0.94–4.02) and 2.14 (95%CI 1.03–4.44) respectively. Participants with high FGF21 levels and NAFLD at baseline showed the highest risk of MACE with a significant interaction between the presence of NAFLD and serum FGF21 levels. ConclusionsBoth FGF21 and NAFLD were associated with MACE, while the association between FGF21 and MACE may be interacted by the presence of NAFLD at baseline.

#3959 ASSOCIATION BETWEEN AMORPHOUS CALCIUM-PHOSPHATE RATIOS IN CIRCULATING CALCIPROTEIN PARTICLES AND PROGNOSTIC BIOMARKERS IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Calciprotein particles (CPPs) are circulating colloidal mineral-protein complexes containing crystalline and/or non-crystalline (amorphous) calcium-phosphate (CaPi). Serum CPP levels correlate with vascular stiffness and calcification in patients with chronic kidney disease (CKD). In vitro studies showed that CPPs containing crystalline CaPi were more arteriosclerogenic and inflammogenic than CPPs without containing crystalline CaPi. Thus, we hypothesized that not only the quantity but also the quality of CPPs (the phase of CaPi) might affect clinical outcomes. Method To test this hypothesis, we quantified amorphous CaPi ratio defined as the ratio of the amorphous CaPi amount to the total CaPi amount in serum CPPs from 183 hemodialysis patients and explored its possible correlation with serum parameters associated with prognosis of hemodialysis patients. Results Multivariate analysis revealed that the amorphous CaPi ratio correlated positively with hemoglobin and negatively with fibroblast growth factor-21 (FGF21), which remained significant after adjusting for the total CaPi amount. Because, low hemoglobin and high FGF21 were associated with increased mortality. Patients with low amorphous CaPi rate tended to have lower 2-year survival rates (p = 0.07). Conclusion This study suggests that low amorphous CaPi ratio in circulating CPPs is associated with poor prognosis in hemodialysis patients. Further investigation of the association with prognosis is warranted.

Abstract #1405323: A Rare Case of Multiple Fragility Fractures Caused by Tumor-Induced Osteomalacia

Tumor-induced osteomalacia (TIO) is a rarely encountered paraneoplastic syndrome caused by a small, usually benign tumor of mesenchymal origin. It can present with severe hypophosphatemia and osteomalacia, usually in adulthood, but also in adolescence. The rarity of these tumors often leads to a late or missed diagnosis. Here we present a case of TIO with missed diagnosis for many years, which as a result, presented with multiple fractures. A 54-year-old Asian woman presented to the emergency department with complaints of progressive lower back pain, weakness, and chronic myalgias. Imaging revealed diffuse osteoporosis, multiple rib and pelvic fractures, and bilateral coxa vera. Labs revealed normal corrected serum calcium 9.0 mg/dl (8.7-10.5), high PTH 144.9 mg/ml (9-77), low serum phosphorus 1.1 mg/dl (2.5-4.9), high alkaline phosphatase 474 u/ml (55-135), and normal 25-hydroxyvitamin D (25 Vit D) 45.8 ng/ml (30-100). Further labs showed high urinary phosphorus >90 mg/dl and low serum 1,25-Dihydroxyvitamin D (1,25 Vit D) 18 pg/ml (20-79). Genetic testing for hypophosphatemic rickets was negative. Serum fibroblast growth factor 23 (FGF23) level was found to be elevated to 218 pg/ml (< 59). She was later found to have a left mandibular fracture. A 68Ga-DOTATATE PET/CT scan revealed gastric wall thickening. Several months after her initial presentation she reported ongoing left jaw pain and an enlarging left mandibular mass. Repeat PET scan revealed a hypermetabolic mandibular lesion. Pathologic analysis of the biopsied lesion was consistent with a phosphaturic mesenchymal tumor, and the lesion was resected. Labs three months following tumor resection revealed normalization of serum phosphorus, 1,25 Vit D, and PTH. TIO is caused by overproduction of FGF23 and other phosphaturic proteins by a mesenchymal tumor. High serum FGF23 causes decreased renal phosphate reabsorption and increased 1,25 vit D production. This results in development of rickets/osteomalacia. These tumors are usually benign, small, slow growing neoplasms making them difficult to diagnose. Delay in diagnosis can result in complications such as fractures. TIO, although rare, should be on the differential for patients with hypophosphatemia and progressive osteopenia. Analysis of serum 1,25 vit D, FGF23, and urine phosphorous levels is indicated, followed by tumor localization with PET/CT, CT, or MRI. Tumor resection is often curative, as in this case. Increased awareness of this condition may help to reduce the proportion of missed TIO cases and improve outcomes in recognized cases via earlier recognition and treatment.

Fibroblast growth factor 21 may be a strong biomarker for renal outcomes: a meta-analysis

Background Fibroblast growth factor 21 (FGF21) is deemed to play an important role in kidney outcomes, while the association between FGF21 and various kidney diseases remains largely unclear and inconsistent. Therefore, we conducted this meta-analysis to find out the role of FGF21 in various renal diseases. Methods The outcome indicator of our study was assessed by the pooled standard mean difference (SMD) with 95% confidence intervals (CIs) which were calculated by random-effect model analysis. The risk of bias was assessed by Non-Randomized Studies of Interventions (ROBINS-I) tool. Funnel plot combined with Egger’s and Begg’s tests was performed to estimate the publication bias that existed in the study. Results A total of 28 eligible studies with 19348 participants were included in our research. The agreement between authors reached a kappa-value of 0.88. Overall, the serum FGF21 level was strongly higher in CKD patients (SMD = 0.97 (ng/L); 95% CI, 0.70—1.24 (ng/L)) and the renal outcomes in T2DM patients (SMD = 0.54 (ng/L); 95% CI, 0.39–0.70 (ng/L)) compared with the control group. Consistent with this, the incidence of CKD (OR = 2.56; 95% CI, 1.72–3.81) and the incidence of renal outcomes (OR = 1.63; 95% CI, 1.31–2.01) in T2DM patients was significantly higher in the patients with high FGF21 concentration, indicating that high serum FGF21 level may predict the incidence of CKD and the renal outcomes in T2DM patients. Conclusion Serum FGF21 may be one of the strong predictors for various kidney diseases including the progression of CKD and the hard renal outcomes in type 2 diabetes patients, but more large-scale clinical research are needed to confirm this finding.

PD03-01 FGF-23 PRODUCTION COUPLING WITH ALDOSTERONE AND PREDICTING CLINICAL OUTCOMES IN PRIMARY ALDOSTERONISM

You have accessJournal of UrologyCME1 Apr 2023PD03-01 FGF-23 PRODUCTION COUPLING WITH ALDOSTERONE AND PREDICTING CLINICAL OUTCOMES IN PRIMARY ALDOSTERONISM Jeff Chueh, Shuo-Meng Wang, VinCent Wu, and Kang-Yung Peng Jeff ChuehJeff Chueh More articles by this author , Shuo-Meng WangShuo-Meng Wang More articles by this author , VinCent WuVinCent Wu More articles by this author , and Kang-Yung PengKang-Yung Peng More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003220.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Higher fibroblast growth factor-23 (FGF-23) levels are associated with activating renin-angiotensin-aldosterone system (RAAS), more volume overload, and hypertension. The roles of FGF-23 in primary aldosteronism (PA) haven't been studied. METHODS: Unilateral PA (uPA) patients who underwent adrenalectomy were enrolled and followed for their clinical outcomes from Aug 15 to Jan 19. The FGF-23 expression in a rat osteoblast-like cell culture was evaluated after the addition of aldosterone. RESULTS: A total of 121 uPA patients & 69 matched essential hypertension (EH) controls were enrolled. The log [carboxyl-terminal FGF-23 (cFGF-23)] level was higher in uPA patients (p=0.001).] In Cox proportional hazard model, the preoperative Log [plasma cFGF-23]>1.98 was a risk factor for either all-cause mortality and cardiovascular or kidney events (HR, 4.01, p=0.038). Plasma cFGF-23 levels were increased in a nonlinear manner re: plasma aldosterone concentration (PAC). Log [plasma cFGF-23]>1.75 independently predicted post-op remission of hypertension (odds ratio (OR), 3.8, p=0.004). The plasma total FGF-23 level was significantly higher in PA patients (p<0.001), and it was significantly reduced post-op (p<0.001). When osteoblast-like UMR-106 cells were cultured with aldosterone, the cFGF-23 concentration in the culture medium was elevated (p=0.028), but it was abrogated after family with sequence similarity 20, member C (FAM20c) short hairpin RNA was added (p= 0.659). Docking experiments showed that aldosterone may bind to the potential drug binding pocket of FAM20c (Pdb: 5YH3; Figure 1A, B). CONCLUSIONS: Compared with EH controls, uPA patients had higher cFGF-23 levels--associated with a higher risk of cardiovascular composite outcomes, though such higher cFGF-23 levels predicted hypertension remission after adrenalectomy. Their total FGF-23 levels were significantly attenuated after adrenalectomy. An increase in cFGF-23 production among the uPA patients was secondary to increased cleavage of intact FGF-23 evidenced by higher FAM20c activity modulated by aldosterone. Source of Funding: Taiwan (NSC 101-2314-B-002-132-MY3, NSC100-2314-B-002-119, NSC 101-2314-B-002-085-MY3, MOST 104-2314-B-002 -125 -MY3; 111-2314-B-002-232-MY3) and NTUH 100-N1776, 101-M1953, 102-S2097 © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e74 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jeff Chueh More articles by this author Shuo-Meng Wang More articles by this author VinCent Wu More articles by this author Kang-Yung Peng More articles by this author Expand All Advertisement PDF downloadLoading ...

Circulating leukocyte cell-derived chemotaxin 2 and fibroblast growth factor 21 are negatively associated with cardiorespiratory fitness in healthy volunteers

Leukocyte cell-derived chemotaxin-2 (LECT2) and fibroblast growth factor 21 (FGF21) are hepatokines that are regulated by energy balance and mediate insulin sensitivity and glycaemic control. This cross-sectional study examined the independent associations of cardiorespiratory fitness (CRF), moderate-to-vigorous intensity physical activity (MVPA), and sedentary time with circulating LECT2 and FGF21. Data were combined from two previous experimental studies in healthy volunteers (n = 141, male = 60%, mean ± SD age = 37 ± 19 years, body mass index (BMI) = 26.1 ± 6.3 kg·m-2). Sedentary time and MVPA were measured via an ActiGraph GT3X + accelerometer, while magnetic resonance imaging quantified liver fat. CRF was assessed using incremental treadmill tests. Generalized-linear models examined the association of CRF, sedentary time, and MVPA with LECT2 and FGF21 while controlling for key demographic and anthropometric variables. Interaction terms explored the moderating influence of age, sex, BMI, and CRF. In the fully adjusted models, each SD increase in CRF was independently associated with a 24% (95% CI: -37% to-9%, P = 0.003) lower plasma LECT2 concentration and 53% lower FGF21 concentration (95% CI: -73% to -22%, P = 0.004). Each SD increase in MVPA was independently associated with 55% higher FGF21 (95% CI: 12% to 114%, P = 0.006), and this relationship was stronger in those with lower BMI and higher levels of CRF. These findings demonstrate that CRF and wider activity behaviours may independently modulate the circulating concentrations of hepatokines and thereby influence inter-organ cross-talk.

Tumor-induced Osteomalacia Secondary to Phosphaturic Mesenchymal Tumor.

HomeRadiology: Imaging CancerVol. 5, No. 2 PreviousNext Images in CancerFree AccessTumor-induced Osteomalacia Secondary to Phosphaturic Mesenchymal TumorAmit Agarwal , Girish Bathla, Vivek GuptaAmit Agarwal , Girish Bathla, Vivek GuptaAuthor AffiliationsFrom the Departments of Radiology (A.A.) and Neuroradiology (V.G.), Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224; and Department of Radiology, Mayo Clinic, Rochester, Minn (G.B.).Address correspondence to A.A. (email: [email protected]).Amit Agarwal Girish BathlaVivek GuptaPublished Online:Mar 10 2023https://doi.org/10.1148/rycan.220170MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Tumor-induced osteomalacia (TIO), or oncogenic osteomalacia, is an uncommon paraneoplastic syndrome characterized by urinary phosphate wasting due to an increased production of fibroblast growth factor 23 (FGF23), secondary to an underlying phosphaturic mesenchymal tumor (PMT). Patients usually present with bone pain and pathologic fractures caused by hypophosphatemic hyperphosphaturic osteomalacia (Fig 1), characterized by high serum FGF23 levels (Fig 2) and low serum calcitriol levels. Given the rarity of this entity and nonspecific clinical and imaging features, these tumors are challenging to diagnose and can go undetected for many years (1). Tumors can be found in any osseous or soft-tissue location, however, and are typically observed in the extremities, most commonly the femur, of middle-aged adults. TIO is also associated with other mesenchymal tumors, including solitary fibrous tumors and giant cell tumors, primarily due to FGF23 secretion. A combination of nuclear scans using somatostatin analogs, such as gallium-68 tetraazacyclododecane tetraacetic acid octreotate (68Ga-DOTATATE) and indium-111 (111In)-pentetreotide (OctreoScan), provides the highest sensitivity for detecting tumors, which are usually small in size and not evident at clinical examination. These lesions appear to be moderately fluorodeoxyglucose avid, potentially aiding in diagnosis, but have wide variability in uptake and limited specificity. CT and MRI are noncontributory for initial location but are usually needed later to evaluate anatomic extent. Surgical resection of PMTs is typically curative, resulting in complete resolution of the syndrome (2,3). While few cases of PMT have been reported, it is important to consider this diagnosis in all patients with hypophosphatemic osteomalacia.Figure 1: (A) Methylene diphosphonate bone scan in a 65-year-old female patient with bone pain reveals multiple foci of increased uptake (arrowheads) over bilateral femur and sternum, along with prominent costochondral beadings (rosary), suggesting metabolic bone disease (osteomalacia). Serologic workup revealed a high serum fibroblast growth factor 23 (FGF23) level of 1155 reference unit (RU)/mL (reference range, ≤180 RU/mL) with low serum phosphate level and elevated alkaline phosphatase level. (B) Coronal noncontrast CT image of the lumbar spine reveals a lytic lesion in the right transverse process of L3 (arrow) with (C) increased fluorodeoxyglucose uptake (standardized uptake value, 9.8) (arrow) on the axial PET/CT image.Figure 1:Download as PowerPointOpen in Image Viewer Figure 2: Histopathologic features of phosphaturic mesenchymal tumors, with predominantly spindled cells on hematoxylin-eosin (H&E) stains and strong expression of fibroblast growth factor 23 (FGF-23) mRNA on in situ hybridization (ISH).Figure 2:Download as PowerPointOpen in Image Viewer Disclosures of conflicts of interest: A.A. Consulted for and expert testimony for Authnetic4D in 2020; institutional CME fund (attending meetings/travel); stocks in Gilead Pharma. G.B. Grant from Foundation of Sarcoidosis Research, unrelated to current work. V.G. No relevant relationships.Keywords: Osteomalacia, Phosphaturic, Spine, Tumor MicroenvironmentAuthors declared no funding for this work.

High Plasma Levels of Fibroblast Growth Factor 23 Are Associated with Increased Risk of COVID-19 in End-Stage Renal Disease Patients on Hemodialysis: Results of a Prospective Cohort.

We performed a prospective cohort of ESRD patients in hemodialysis who had measurements of plasma intact FGF23 in 2019. We determined COVID-19 infections, hospitalizations, and mortality between January 2020 and December 2021. We evaluated 243 patients. Age: 60.4 ± 10.8 years. Female: 120 (49.3%), diabetes: 110 (45.2%). During follow-up, 45 patients developed COVID-19 (18.5%), 35 patients were hospitalized, and 12 patients died (mortality rate: 26.6%). We found that patients with higher FGF23 levels (defined as equal or above median) had a higher rate of SARS-CoV-2 infection versus those with lower levels (18.8% versus 9.9%; Hazard ratio: 1.92 [1.03-3.56], p = 0.039). Multivariate analysis showed that increased plasma FGF23 was independently associated with SARS-CoV-2 infection and severe COVID-19. Our results suggest that high plasma FGF23 levels are a risk factor for developing COVID-19 in ESRD patients. These data support the potential immunosuppressive effects of high circulating FGF23 as a factor implicated in the association with worse clinical outcomes. Further data are needed to confirm this hypothesis.