Serum iron as a trace element biomarker of nutritional status in nondialysis chronic kidney disease

A BSTRACT Objectives: Iron is a vital trace element involved in oxygen transport, energy metabolism, and muscle function. In chronic kidney disease (CKD), anemia and malnutrition are common, with iron deficiency being a key contributor to anemia. However, the role of iron status in nutritional health remains less defined. Materials and Methods: In this cross-sectional study of patients with nondialysis CKD stages 3–5, nutritional status was comprehensively assessed using anthropometry, multifrequency bioelectrical impedance analysis, serum albumin, handgrip strength, the malnutrition–inflammation score (MIS), and dietary intake. Iron status was evaluated using serum iron, ferritin, and transferrin saturation (TSAT). Patients were categorized according to serum iron levels (<70 vs. ≥70 μg/dL), and associations between iron indices and nutritional parameters were examined using linear regression analyses with adjustment for relevant covariates, including sex, diabetes, and estimated glomerular filtration rate (eGFR). Results: We enrolled 157 patients (mean age: 64 ± 12 years; 93 men and 64 women) who had a mean eGFR of 24.4 ± 13.4 mL/min/1.73 m 2 . Compared with patients with high serum iron ( n = 104), those with low serum iron ( n = 53) were more frequently female and had lower eGFR, hemoglobin, lean tissue index, handgrip strength, serum albumin, and dietary protein intake, along with higher MIS (all P < 0.05). In adjusted linear regression, serum iron was independently associated with handgrip strength and serum albumin (both P < 0.05). Ferritin showed no association with nutritional parameters, while TSAT demonstrated a borderline association with handgrip strength. Conclusion: Beyond its conventional role in anemia management, serum iron may serve as a practical and underrecognized marker of nutritional status in nondialysis CKD, highlighting the interplay between trace element biology and protein-energy malnutrition.