Date Published: 
Wednesday, 22 May, 2013

Diagnosing iron deficiency in patients with chronic kidney disease

Recent guidelines for management of anaemia in CKD recommend regular testing for iron deficiency in both non-anaemic and anaemic patients, with the frequency of testing dependent on the stage of disease and treatment (Table 2)1. Reliance on haemoglobin level alone for diagnosis should be avoided, as this could potentially lead to delay in the identification and treatment of iron deficiency in CKD.

Table 2. Frequency of testing for anaemia in patients with chronic kidney disease1

Diagnosing iron deficiency in CKD

A diagnosis of iron deficiency is made on the basis of TSAT and ferritin levels (see ‘Diagnosing iron deficiency’). Management guidelines for anaemia from the Kidney Disease Outcomes Quality Initiative (KDOQI) suggest that patients with CKD should have sufficient iron to maintain TSAT at >20% and serum ferritin levels >100 ng/mL (>200 ng/mL for haemodialysis patients)2. The guidelines, supported by the European Renal Best Practice (ERBP) group, have proposed specific criteria for initiating iron therapy in CKD (see Treating iron deficiency and iron deficiency anaemia in patients with CKD)1,3

Diagnosing iron deficiency anaemia in CKD

A diagnosis of iron deficiency anaemia is made when the iron deficiency parameters (see 'Diagnosing iron deficiency in CKD') are accompanied by haemoglobin concentrations below 13.0 g/dL for males and 12.0 g/dL for females with CKD aged >15 years1. The ERBP group sets a slightly higher haemoglobin threshold for males <70 years (<13.5 g/dL) compared with those >70 years (13.2 g/dL). The group also notes that a diagnosis of anaemia can be considered in patients who do not reach these thresholds if haemoglobin is falling from a normal level3.

Thresholds defining anaemia may be lower for children with CKD aged <15 years1.

Monitoring iron deficiency with ESA therapy

Iron status should be evaluated by TSAT and ferritin measurement at least once every 3 months during ESA therapy, and more frequently when initiating or increasing the ESA dose, when there is blood loss, when monitoring response after a course of IV iron, and in other circumstances where iron stores may become depleted1.

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