Determination of iron status in patients with CKD

• diagnostic tests to determine iron status and predict response to iron therapy in CKD
  • carry out testing to diagnose iron deficiency and determine potential responsiveness to iron therapy and long-term iron requirements every 3 months (every 1-3 months for people receiving haemodialysis)
    
    
    • percentage of hypochromic red blood cells (% HRC; more than 6%) should be used, but only if processing of blood sample is possible within 6 hours
      
      
    • if using percentage of hypochromic red blood cells is not possible, use reticulocyte haemoglobin (Hb) content (CHr; less than 29 pg) or equivalent tests - for example, reticulocyte Hb equivalent
      
      
    • only if these tests are not available or the person has thalassaemia or thalassaemia trait, use a combination of transferrin saturation (less than 20%) and serum ferritin measurement (less than 100micrograms/litre)
      
      
  • therefore a clinician should not routinely request transferrin saturation or serum ferritin measurement alone to assess iron deficiency status in people with anaemia of chronic kidney disease (CKD)
    
    
  • measurement of erythropoietin levels for the diagnosis or management of anaemia should not be routinely considered for people with anaemia of CKD

Note:

• serum ferritin is an acute-phase reactant and frequently raised in CKD, the diagnostic cut-off value should be interpreted differently to non-CKD patients
• in people treated with iron, serum ferritin levels should not rise above 800 micrograms/litre. In order to prevent this, review the dose of iron when serum ferritin levels reach 500micrograms/litre

Reference:

1. NICE (August 2021). Chronic kidney disease: assessment and management