Fibroblast growth factor 21 and protein energy wasting in hemodialysis patients

Higher circulating FGF21, lower protein intake, and lower muscle mass: Associations with a higher risk of mortality

BACKGROUND AND OBJECTIVES

This population-based study explores associations of fibroblast growth factor 21 (FGF21), a key modulator of processes linked to protein metabolism, with protein intake and muscle mass, and their relationships with all-cause mortality.

METHODS

In 6395 participants (mean age 54 years; 50% women), circulating FGF21 (immunoassay), protein intake (Maroni equation using 24-h urinary urea excretion; low intake defined as <0.8 g/kg/day), and muscle mass (24-h creatinine excretion rate indexed to height squared (CERI)) were documented.

RESULTS

FGF21 concentration was 896 (540-1384) pg/mL, protein intake was 1.01 (0.85-1.19) g/kg/day, and CERI was 4.1 ± 0.9 mmol/day/m2. Higher FGF21 was associated with higher odds of low protein intake (odds ratio per doubling: 1.48; 95% confidence interval [CI]: 1.38-1.58; p < 0.0001) and lower muscle mass (standardized beta: -0.08; 95% CI: -0.10; -0.06; p < 0.001). Over 10.4 years of follow-up, 955 deaths were registered. Higher FGF21 was associated with increased mortality (hazard ratio (HR) per doubling: 1.09; 95% CI: 1.02-1.16; p = 0.009). Conversely, higher protein intake (HR per doubling: 0.67; 95% CI: 0.56-0.81; p < 0.0001) and higher CERI (HR per standard deviation increase: 0.83; 95% CI: 0.76-0.90; p < 0.0001) were associated with a lower risk of mortality, independent of potential confounders. However, the FGF21-mortality association became non-significant after adjusting for protein intake.

CONCLUSION

Higher FGF21 was associated with higher odds of low protein intake. The observed association of higher FGF21 concentrations and risk mortality was predominantly attributable to lower protein intake. In contrast, both higher protein intake and higher muscle mass were independently associated with lower mortality risk, highlighting the potential relevance of protein intake and maintenance of muscle mass in long-term health.

Association between objectively measured protein intake and muscle status, health-related quality of life, and mortality in hemodialysis patients

BACKGROUND

Protein intake is known to be associated with muscle mass, health-related quality of life (HRQoL), and mortality in patients with stage 5 chronic kidney disease undergoing dialysis. However, most studies evaluated protein intake based on 24 h dietary recall or food frequency questionnaire, and these methods are prone to bias. Therefore, this study aimed to evaluate the association of objectively measured protein intake with muscle mass and strength, HRQoL, and mortality.

METHODS

Dietary protein intake was calculated based on the combined (urinary and dialysate) urea excretion rate according to the Maroni formula and indexed to body weight. Muscle mass was calculated based on the combined dialysate and urinary creatinine excretion rate, and muscle strength was assessed by handgrip strength. HRQoL was based on the Short Form 36. Linear and Cox regression were used for the analyses.

RESULTS

We included 59 hemodialysis patients (mean age 65 ± 15 years, 37% female, median hemodialysis vintage 15 [6-39] months). Mean protein intake was 0.82 ± 0.23 g/kg/day, and 76% had a low protein intake (<1.0 g/kg/day). Higher protein intake was independently associated with higher muscle mass (Standardized beta (St. β) [95% confidence interval (95%CI) = 0.56 [0.34 to 0.78]) and higher scores on the physical functioning domain of HRQoL (St. β [95%CI] = 0.49 [0.25 to 0.73]), but not with muscle strength (St. β [95%CI] = 0.17 [-0.10 to 0.43]). During a median follow-up of 21.6 [8.6-36.6] months, 16 (27.1%) patients died. Higher protein intake was associated with lower mortality risk (hazard ratio [95%CI] = 0.34 [0.16-0.73]). This association remained significant after adjustment for potential confounders.

CONCLUSIONS

Protein intake is independently associated with muscle mass, physical functioning domain of HRQOL, and mortality. Clinicians and dietitians should closely monitor the protein intake of hemodialysis patients.

Urinary Endotrophin and Long-term Outcomes in Kidney Transplant Recipients

Background

Kidney fibrosis is a suggested cause of kidney failure and premature mortality. Because collagen type VI is closely linked to kidney fibrosis, we aimed to evaluate whether urinary endotrophin, a collagen type VI fragment, is associated with graft failure and mortality among kidney transplant recipients (KTR).

Methods

In this prospective cohort study, KTR with a functioning graft ≥1-y posttransplantation were recruited; 24-h urinary endotrophin excretion was measured using an ELISA method. Multivariate Cox regression analyses were performed.

Results

A total of 621 KTR (mean age 53 y old, 43% female) at a median of 5.2 y posttransplantation were included. Median 24-h urinary endotrophin excretion was 5.6 (3.1-13.6) µg/24h. During a median follow-up of 7.5 y, 87 KTR (14%) developed graft failure and 185 KTR (30%) died; 24-h urinary endotrophin excretion was associated with increased risk of graft failure (hazard ratio [95% confidence interva] per doubling = 1.24 [1.08-1.42]) and all-cause mortality (hazard ratio [95% confidence intervals] per doubling = 1.14 [1.03-1.25]) independent of potential confounders including plasma endotrophin concentration. Twenty-four-hour urinary protein excretion was a significant effect modifier for the association with mortality (Pinteraction = 0.002). Twenty-four-hour urinary endotrophin excretion was only significantly associated with mortality in KTR with low levels of proteinuria.

Conclusions

Urinary endotrophin is independently associated with an increased risk of graft failure in all KTR and mortality only in KTR with low levels of proteinuria. Further studies with different KTR populations are needed to confirm these findings.

Fibroblast Growth Factor 21: A Fascinating Perspective on the Regulation of Muscle Metabolism

Fibroblast growth factor 21 (FGF21) plays a vital role in normal eukaryotic organism development and homeostatic metabolism under the influence of internal and external factors such as endogenous hormone changes and exogenous stimuli. Over the last few decades, comprehensive studies have revealed the key role of FGF21 in regulating many fundamental metabolic pathways, including the muscle stress response, insulin signaling transmission, and muscle development. By coordinating these metabolic pathways, FGF21 is thought to contribute to acclimating to a stressful environment and the subsequent recovery of cell and tissue homeostasis. With the emphasis on FGF21, we extensively reviewed the research findings on the production and regulation of FGF21 and its role in muscle metabolism. We also emphasize how the FGF21 metabolic networks mediate mitochondrial dysfunction, glycogen consumption, and myogenic development and investigate prospective directions for the functional exploitation of FGF21 and its downstream effectors, such as the mammalian target of rapamycin (mTOR).

Elevated serum FGF21 is an independent predictor for adverse events in hemodialysis patients from two large centers: a prospective cohort study

Introduction: We explored the relationship and the predictive value of serum fibroblast growth factor 21 (FGF21) with all-cause mortality, major adverse cardiovascular events (MACEs) and pneumonia in hemodialysis (HD) patients.Methods: A total of 388 Chinese HD patients from two HD centers were finally enrolled in this prospective cohort study (registration number: ChiCTR 1900028249) between January 2018 and December 2018. Serum FGF21 was detected. Patients were followed up with a median period of 47 months to record the MACEs and pneumonia until death or 31 December 2022.Results: The incidence of all-cause mortality, MACEs and pneumonia in HD patients were 20.6%, 29.6%, and 34.8%, respectively. The optimal cutoffs for FGF21 to predict all-cause mortality, MACEs and pneumonia were 437.57 pg/mL, 216.99 pg/mL and 112.79 pg/mL. Multivariate Cox regression analyses showed that FGF21, as a categorical variable, was an independent predictor for all-cause mortality, MACEs and pneumonia (HR, 3.357, 95% CI, 2.128-5.295, p < 0.001; HR, 1.575, 95% CI, 1.046-2.371, p = 0.029; HR, 1.784; 95% CI, 1.124-2.830; p = 0.014, respectively). The survival nomogram, MACEs-free survival nomogram and pneumonia-free survival nomogram based on FGF21 constructed for individualized assessment of HD patients had a high C-index with 0.841, 0.706 and 0.734.Conclusion: Higher serum FGF21 is an independent predictor of all-cause mortality, MACEs and pneumonia in HD patients.