Iron deficiency is prevalent in patients with nonaninemia and nondialysis-dependent CKD

Iron deficiency frequently appears in patients with chronic renal disease (CKD), including anemia. Despite this knowledge, the effect of iron deficiency on CKD progression and all-cause mortality in patients with anemia-free nondialysis-dependent (NDD)-CKD (NDD-CKD) is unknown. Authors of the research published in Nutritional Journal We investigated the association between iron deficiency and the risk of CKD progression and all-cause mortality.

This multicenter, retrospective, national cohort study included adult patients with nonaninemia NDD-CKD from 24 hospitals across China until January 1, 2000 and December 31, 2022. I did. This study investigated the association between serum ferritin or transfrin saturation (TSAT) levels of CKD progression and the risk of all-cause mortality.

All enrolled patients were over 18 years of age with CKD who had at least one serum ferritin test or TSAT test in the Chinese Renal Data System. The investigator defined CKD based on one of the following criteria: International Statistical Classification of Disease, 10th Revised, Clinical Modification (ICD-10-cm) Code. Estimated glomerular filtration rate (EGFR) less than 60 ml/min/min/1.73 m² Over 3 months. Or at least two abnormal urine protein tests over three months or more.

EGFR was calculated using the Epidemiological Collaboration Equation for Chronic Renal Disease (CKD-EPI). Abnormal urinary proteins were defined as one of the following: Qualitative urinary protein detection greater than 1+. Urine protein determination over 0.3 g for 24 hours. Or creatinine above 300 mg/g from urinary albumin. Patients with either ferritin or TSAT, or both, were included in the study. Additionally, baseline was defined as the first hospitalization using available ferritin or TSAT.

The investigator used two datasets for analysis purposes. The dataset for analysis of kidney disease progression did not include patients without repeated EGFR measurements after discharge. Additionally, the dataset for analysis of all-cause mortality did not include patients without identifiable information from the national electronic and electronic cause reporting system. China Centers for Disease Control and Prevention.

The main outcome was progression of CKD, which was defined as the combined continuous reduction in EGFR above 40% from baseline (except for the development of acute kidney injury) or the onset of end-stage renal disease (ESKD; EGFR <15 <15 ml/min/1.73 m² or the need for maintenance dialysis or kidney transplantation). Patients were abolished when the patient reached the results of the study or when the last available serum creatinine measurement was recorded. The secondary outcome was all-cause mortality, which was determined using records from the national electronic cause of death reporting system. Follow-up began upon discharge and continued until the last day when he was killed or recorded in the electronic medical record.

Of the 18,878 patients enrolled with NDD-CKD, 9,989 patients were included in the kidney outcome analysis, and 18,481 patients were included in the all-cause mortality analysis. Of the patients measured, approximately 27.2% (n = 2450) had ferritin levels below 100 ng/ml, and 13.1% (n = 2440) had TSAT levels of 20% or less than 20%. Compared with patients with TSAT levels >20%, patients with TSAT levels below 20% were significantly more at a higher risk of both CKD progression (AHR: 1.66, 95% CI: 1.16–2.37; p= .005) and all-cause mortality rate (AHR: 2.21, 95% CI: 1.36–3.57; p= .001).

Interestingly, patients with ferritin levels below 100 ng/mL were more likely to be younger and female, with lower EGFR levels and lower hemoglobin levels. Patients with TSAT levels below 20% were also likely female, with lower levels of both proteinuria and hemoglobin.

Iron deficiency was prevalent in patients with NDD-CKD and those without anemia. Furthermore, the authors believe that TSAT may be a modifiable risk factor for CKD progression and all-cause mortality. Screening of iron biomarkers in the early stages of NDD-CKD, particularly with TSAT, is important for assessing and improving prognosis. The strength of the results was supported by subgroup analysis. However, we found no significant association between ferritin levels and the risk of CKD progression or all-cause mortality (p>0.05), according to the author.

reference

Yu H, Shao X, Guo Z, and others Association of iron deficiency with renal outcome and all-cause mortality in patients with chronic renal disease without anemia. Nutr j. 2025; 24 (7). doi:10.1186/s12937-025-01072-1