Diagnostic utility of reticulocyte hemoglobin for iron-restricted anemia in patients with end-stage kidney disease on hemodialysis

TL;DR

This study shows that reticulocyte hemoglobin (MCHr) is a better indicator of iron deficiency in hemodialysis patients than traditional markers like ferritin and TSAT.

Contribution

The study demonstrates that MCHr outperforms conventional iron biomarkers in detecting iron deficiency in patients with end-stage kidney disease.

Findings

MCHr showed an AUC of 0.98 with 100% specificity and 72.41% sensitivity for detecting iron deficiency anemia when TSAT was < 20%.

In patients with ferritin < 200 ng/mL, MCHr had 89.47% sensitivity and 100% specificity with a cut-off of < 31.20 pg.

MCHr outperformed ferritin and TSAT in identifying functional iron deficiency in hemodialysis patients.

Abstract

Chronic kidney disease (CKD) is a serious, long-term illness that damages kidneys and lowers glomerular filtration rate. CKD often causes anemia. Iron deficiency (ID) is common in these patients and worsens illness symptoms. Modern hematology analysers can measure reticulocyte mean cell hemoglobin (MCHr), which directly measures iron integration into erythrocyte hemoglobin. MCHr can improve iron deficiency detection in CKD patients, who have aberrant iron indicators due to chronic inflammation. This research aims to evaluate the effectiveness of MCHr as a marker for ID in patients with CKD.

To obtain data for this study, CBC, reticulocyte profile, and iron biomarkers were collected from King Khalid National Guard Hospital (Ref No. IRB/1861/23). Transferring saturation was calculated using (Serum iron/TIBC) × 100. GraphPad Prism 9 software was used to analyze the data, and Mann-Whitney, Spearman correlation, and ROC plots were used to determine MCHr's diagnostic performance. A p-value < 0.05 was considered significant.

The study compared 190 individuals undergoing hemodialysis (HD) with 165 healthy blood donors. The HD group showed lower levels of RBC, Hb, MCHr, serum iron, and total iron-binding capacity (TIBC). Despite anemia, the HD group had higher levels of ferritin and transferrin saturation (TSAT). MCHr demonstrated excellent diagnostic performance in identifying iron deficiency anemia (IDA), particularly in functional iron deficiency. When TSAT was < 20%, MCHr showed an AUC of 0.98, with 100% specificity and 72.41% sensitivity, significantly outperforming ferritin and TSAT in inflammatory settings. In the HD group with ferritin levels < 200 ng/mL, the MCHr cut-off value of < 31.20 pg had a sensitivity and specificity of 89.47% and an AUC of 0.89. When TSAT was < 20%, the MCHr cut-off value of < 23.95 pg had a sensitivity of 72.41%, specificity of 100%, and AUC of 0.98.

Based on the findings, MCHr is more effective than ferritin and TSAT in detecting iron deficiency in hemodialysis patients. Future research should use MCH to investigate the impact of iron therapy with or without rHuEPO.

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