Comparing Reticulocyte Hemoglobin and Transferrin Saturation to Guide Iron Treatment in People on Dialysis

Participants in this arm will receive intravenous (IV) iron therapy guided by reticulocyte hemoglobin equivalent (RET-He) levels. Iron dosing will follow a protocol based on RET-He values: * RET-He \< 26 pg: IV iron 100 mg weekly * RET-He ≥ 26 pg and \< 30 pg: IV iron 100 mg every 2 weeks * RET-He ≥ 30 pg and ≤ 36 pg: IV iron 100 mg every 4 weeks * RET-He \> 36 pg or ferritin ≥ 800 ng/mL: Discontinue iron supplementation to prevent iron overload

Participants in this arm will receive IV iron therapy guided by transferrin saturation (TSAT) and serum ferritin, as per the Thai Clinical Practice Guidelines for Anemia in CKD (2021). Iron dosing will follow this TSAT-based protocol: * TSAT \< 30% and ferritin \< 200 ng/mL: IV iron 100 mg weekly * TSAT \< 30% and ferritin 200-500 ng/mL: IV iron 100 mg every 2 weeks * TSAT \< 30% and ferritin 500-800 ng/mL or TSAT 30-40%: IV iron 100 mg every 4 weeks * TSAT ≥ 40% or ferritin ≥ 800 ng/mL: Discontinue iron supplementation

All participants will receive erythropoiesis-stimulating agents (ESAs) according to a standardized dose adjustment protocol based on hemoglobin levels. Oral iron supplements will be discontinued.