Association of Increased Serum Ferritin With Impaired Muscle Strength/Quality in Hemodialysis Patients

Objective: We reported previously that muscle quality and muscle strength provide clinically relevant predictors for better survival in hemodialysis patients. Iron overload might impair muscle function by its accumulation in muscle in such patients. Methods: Serum ferritin, a marker for body iron store, was examined for its association with handgrip strength (HGS) and muscle quality which was defined as the ratio of HGS to arm lean mass measured with dual-energy X-ray absorptiometry. Results: In 300 Japanese hemodialysis patients, age, hemodialysis duration, body mass index, and serum albumin were 58.0 +/- 12.0 (mean +/- standard deviation) years, 4.2 (1.8-10.4) (median [25th-75th percentile]) years, 20.4 +/- 2.8 kg/m(2), 4.0 +/- 0.3 g/dL, respectively. Hemoglobin and hematocrit were 8.9 +/- 1.2 g/dL, and 28.8 +/- 3.9%, respectively, whereas transferrin saturation and serum ferritin were 29.8 +/- 11.0% and 100 (54-172) ng/mL, respectively. Serum ferritin significantly correlated in a positive manner with the total dose of iron orally administered during the previous 6 months (r=0.185, P=.0013). HGS and muscle quality were 23.1 +/- 10.4 kg and 11.6 +/- 3.8 kg/kg, respectively. In multivariate analysis to elucidate the factors associated with HGS and muscle quality in 300 hemodialysis patients, which included transferrin saturation and log serum ferritin, in addition to age, gender, hemodialysis duration, the presence/absence of diabetes, body mass index as independent variables, log serum ferritin emerged as a significant and independent factor which associated in a negative fashion with HGS (beta=-0.091, P=.0395) and tendency toward negative association with muscle quality (beta=-0.100, P =.0754). Conclusion: In summary, the present study demonstrated the significant association of serum ferritin with HGS and muscle quality in hemodialysis patients and thus suggested that we should be careful of iron overload to avoid its possible harmful effect on muscle in such patients. (C) 2016 by the National Kidney Foundation, Inc. All rights reserved.