FGF23 levels as a marker of physical performance and falls in community-dwelling very old individuals.

Objective: The fibroblast growth factor 23 (FGF23) has been related to biological aging, but data in elderly individuals are scant. We determined the profile of serum FGF23 levels in a population of very-old individuals and studied their correlations with parameters of bone metabolism and health markers, as functional performance. Methods: This cross-sectional study was performed on 182 community dwellers aged ≥ 80 years. Serum levels of FGF23, PTH, calcium, albumin, phosphorus, creatinine, bone markers, and bone mineral density data were analyzed. Physical performance was evaluated with the stationary march (Step), Flamingo, and functional reach tests, along with questionnaires to assess falls and fractures in the previous year, energy expenditure (MET), and the Charlson index (CI). Physical activity was evaluated with the International Physical Activity Questionnaire (IPAQ). Results: Most participants (75%) had FGF23 levels between 30-120 RU/mL (range: 6.0-3,170.0 RU/mL). FGF23 levels correlated with estimated glomerular filtration rate (eGFR; r = -0.335; p = 0.001) and PTH (r = 0.318; p < 0.0001). Individuals with FGF23 in the highest tertile had more falls in the previous year (p = 0.032), worse performance in the Flamingo (p = 0.009) and Step (p < 0.001) tests, worse CI (p = 0.009) and a trend toward sedentary lifestyle (p = 0.056). On multiple regression, FGF23 tertiles remained significant, independently of eGFR, for falls in the previous year, performance in the Flamingo and stationary march tests, lean mass index, and IPAQ classification. Conclusion: In a population of very elderly individuals, FGF23 levels were inversely associated with neuromuscular and functional performances. Higher concentrations were related to more falls, lower muscle strength and aerobic capacity, and poorer balance, regardless of renal function, suggesting a potentially deleterious role of high FGF23 concentrations in musculoskeletal health.

Association between fibroblast growth factor 23 and functional capacity among independent elderly individuals.

OBJECTIVE: To examine the association of between serum fibroblast growth factor 23 and the functional capacity among independent individuals, aged 80 or older. METHODS: The functional capacity of 144 elderly was assessed by Instrumental Activities of Daily Living, cognitive tests, handgrip strength and the timed ability to rise from a chair and sit down five times. Fibroblast growth factor 23 was measured using an ELISA assay. RESULTS: Participants in the lowest fibroblast growth factor 23 tertile had the highest mean±standard deviation estimated glomerular filtration rate, the highest mean hemoglobin level, the lowest average number of diseases and the lowest number of medications used. In participants with the estimated glomerular filtration rate >45mL/minute/1.73m2, mean fibroblast growth factor 23 level was higher in those with 25(OH) vitamin D <20ng/mL than in those with 25(OH) vitamin D ≥20ng/mL (75.6RU/mL±42.8 versus 68.5RU/mL±41.7; p<0.001). There was an increase in the mean serum cystatin C (from 1.3mg/mL±0.3 to 1.5mg/mL±0.3 to 1.7mg/mL±0.4) as function of higher fibroblast growth factor 23 tertile (p<0.001). Fibroblast growth factor 23 levels were not significantly associated with capacity in physical or cognitive tests. CONCLUSION: In independent community-dwelling elderly, aged ≥80 years, fibroblast growth factor 23 was associated with aged-related comorbidities and renal function but not with functional capacity.

FGF23 levels as a marker of physical performance and falls in community-dwelling very old individuals

ABSTRACT Objective: The fibroblast growth factor 23 (FGF23) has been related to biological aging, but data in elderly individuals are scant. We determined the profile of serum FGF23 levels in a population of very-old individuals and studied their correlations with parameters of bone metabolism and health markers, as functional performance. Materials and methods: This cross-sectional study was performed on 182 community dwellers aged ≥ 80 years. Serum levels of FGF23, PTH, calcium, albumin, phosphorus, creatinine, bone markers, and bone mineral density data were analyzed. Physical performance was evaluated with the stationary march (Step), Flamingo, and functional reach tests, along with questionnaires to assess falls and fractures in the previous year, energy expenditure (MET), and the Charlson index (CI). Physical activity was evaluated with the International Physical Activity Questionnaire (IPAQ). Results: Most participants (75%) had FGF23 levels between 30-120 RU/mL (range: 6.0-3,170.0 RU/mL). FGF23 levels correlated with estimated glomerular filtration rate (eGFR; r = -0.335; p = 0.001) and PTH (r = 0.318; p < 0.0001). Individuals with FGF23 in the highest tertile had more falls in the previous year (p = 0.032), worse performance in the Flamingo (p = 0.009) and Step (p < 0.001) tests, worse CI (p = 0.009) and a trend toward sedentary lifestyle (p = 0.056). On multiple regression, FGF23 tertiles remained significant, independently of eGFR, for falls in the previous year, performance in the Flamingo and stationary march tests, lean mass index, and IPAQ classification. Conclusion: In a population of very elderly individuals, FGF23 levels were inversely associated with neuromuscular and functional performances. Higher concentrations were related to more falls, lower muscle strength and aerobic capacity, and poorer balance, regardless of renal function, suggesting a potentially deleterious role of high FGF23 concentrations in musculoskeletal health.