Table 3 Iron deficiency-associated outcome in patients with chronic kidney disease (CKD)

Kaneko et al. (2003) [75]

ID/IDA and HD-CKD*, treated with rhEPO, iv iron

TSAT level < 20%

• Higher CRP > 5 mg/L level; associated with inflammatory process and EPO resistance

   → iron marker for iron supplementation therapy

Kalantar-Zadeh et al. (2004) [70]

ID and MHD-CKD, treated with epoetin-alfa, iv iron

Serum iron < 45.3 μg/dL [< 8.1 μmol/L]

• Higher risk of mortality^†

• Higher risk of hospitalization^†

Pollak et al. (2009) [69]

IDA and HD-CKD, treated with epoetin-alfa, iv iron

Serum ferritin ≤ 100 μg/L + TSAT ≤ 16%

• Worst long-time survival

Serum ferritin > 600 μg/L + TSAT > 25%

• Best long-time survival

Koo et al. (2014) [72]

IDA and HD-CKD

TSAT ≤ 20%

• Higher risks of composite cardiovascular and all-cause mortality^§

Gaweda et al. (2014) [74]

IDA and HD-CKD

TSAT 34%

• Max. Hb response

Hamano et al. (2015) [76]

ID/IDA and HD-CKD*

Serum ferritin > 100 µg/L + TSAT < 20%

• Higher ERIs (ESA resistance index)

   → iron marker for ESA response

Eisenga et al. (2018) [73]

ID and ND-CKD

TSAT < 10%

• Higher risk of all-cause mortality

• Higher risk of cardiovascular mortality

• Higher risk for developing anemia

Cho et al. (2019) [66]

ID and ND-CKD with/without diabetic issues

Abnormal iron balance:

TSAT 0.4–16% or 28–99.6%, serum ferritin 0.4–55 μg/L or 205–4941 μg/L

FID: TSAT 0.8–16%, serum ferritin 109–2783 μg/L

• Higher risk of all-cause mortality**

Awan et al. (2019) [67]

IDA and ND-CKD

AID: serum ferritin < 100 μg/L + TSAT ≤ 20%

• Higher risk of cardiovascular hospitalization

FID: serum ferritin > 100–500 µg/L + TSAT ≤ 20%

• Higher risk of mortality

• Higher risk of cardiovascular hospitalization

Sato et al. (2019) [68]

MHD-CKD*

(evaluated iron profiles)

TSAT < 20%

• Higher risk of all-cause mortality^#

Yeh et al. (2019) [71]

HD-CKD with/without PKD

(evaluated iron profiles)

TSAT ≤ 20%

• Higher risk of mortality^‡

Mehta et al. (2021) [65]

ID/iron status in CKD

ID: serum ferritin 4.85–82.48 µg/L + TSAT 1.28–17.24%

FID: serum ferritin 157.7–3769.0 µg/L + TSAT 1.28–17.24%

Iron-replete: serum ferritin 82.49–284.4 µg/L + TSAT 17.25–28.018%

Mixed ID: serum ferritin 82.49–157.6 µg/L + TSAT 1.28–17.24%

High iron: serum ferritin 284.4–3769.0 µg/L + TSAT 28.019–87.12%

Nonclassified: serum ferritin 4.85–82.48 µg/L + TSAT 17.25–87.12 or

serum ferritin 82.49–284.4 µg/L + TSAT 28.019–87.12% or serum ferritin 284.4–3769.0 µg/L + TSAT 17.25–28.018%

• ID independently associated with mortality and heart failure

• Mixed ID associated with mortality and ESKD

• High iron associated with mortality, heart failure and ESKD

• FGF23 mediated the risks of mortality and heart failure conferred by ID

Guedes et al. (2021) (45)

ID and ND-dependent CKD

AID: serum ferritin < 50 µg/L + TSAT < 20%

FID: serum ferritin > 300 µg/L + TSAT < 20%

• Worse physical HRQoL