Anaemia in Renal Disease

This textbook page aims to provide some educational information about anaemia in CKD.  To see our unit protocols for managing anaemia, please see our handbook.

Anaemia in CKD

Anaemia is a common complication of chronic kidney disease (CKD) and is associated with adverse outcomes. Investigation of anaemia for adults with CKD is recommended when haemoglobin falls below 110 g/L, or when symptoms attributable to anaemia develop. For further information on the possible causes of anaemia in renal disease and suggested baseline investigations, click here.   EPO-replacement therapy with an erythropoiesis-stimulating agent (ESA) can be instigated for patients with CKD who have had other causes of anaemia investigated and excluded.

To download the Renal Association Clinical Practice Guideline (2017) on Anaemia of Chronic Kidney Disease, please click here.

 

Iron Deficiency and Supplementation

It is important to remember that CKD in itself is not a cause of iron deficiency, and patients with iron deficiency anaemia require appropriate investigation to determine the cause of this, usually involving investigation of the gastrointestinal tract.

Patients with CKD should be iron-replete irrespective of whether or not they are receiving ESA therapy. Assessing iron status is therefore mandatory. Doing so, however, is difficult and there is not a single fool-proof method. A ferritin of < 50μg/l is highly suggestive of iron deficiency, and <150μg/l is also likely to warrant supplementation. However, ferritin is an acute phase protein, and therefore higher levels may be found despite an underlying iron deficiency. Transferrin saturation (TSAT) is a measure of the ability to mobilise stored iron for red cell production. TSAT < 20% is indicative of a functional iron deficiency, even if the ferritin levels are normal / raised. This may respond to treatment with IV iron.

Iron supplementation for patients with CKD can be oral or intravenous. The choice between these routes largely depends upon the severity of iron deficiency, previous response to treatment, and tolerability of oral iron supplements. Many patients with CKD and iron-deficiency will maintain their haemoglobin with oral iron supplements in the early stages,  however, the absorption of oral preparations of iron often becomes insufficient as CKD advances, and therefore treatment with IV iron becomes increasingly necessary. 

In our department, we no longer routinely give test doses for IV iron as reactions, although serious, are rare. 

 

Erythropoesis-Stimulating Agents (“Epo”)

In their 2017 clinical practice guideline, the Renal Association recommend that Erythropoiesis-Stimulating Agents (ESAs) should be offered to patients with anaemia of CKD who are likely to benefit in term of quality of life and physical function and to avoid blood transfusion; especially in patients considered suitable for transplantation. The recommended target haemoglobin for adult patients receiving ESAs is between 100 and 120g/L1; the target without our department is 105 – 125g/L.

ESA Resistance

Some patients may require ever increasing doses of ESAs to result in an increment in haemoglobin, and a few will fail to respond to ESAs at all. The potential causes include:

  • iron, B12 or folate deficiency
  • active blood loss (e.g. from GI tract)
  • active haemolysis
  • chronic inflammation (e.g in infection or cancer)
  • uncontrolled hyperparathyroidism
  • inadequate small molecular clearance on dialysis
  • rarely, anti-epo antibodies


Blood Transfusions

Blood transfusions should be avoided as far as possible in patients who are on, or who in the future may be on, the transplant list. All blood products given to patients with renal disease who may be future transplant candidates should be treated to remove white blood cells. Our Blood Transfusion Service now routinely provides leucocyte-depleted products for all patients. When blood transfusion is felt to be necessary for renal patients, careful consideration should be given to volume status. If blood is being given on haemodialysis, each unit is usually given over 1 hour and the equivalent fluid volume removed by ultrafiltration.

Education
References
  1. The Renal Association Clinical Practice Guideline for Anaemia of Chronic Kidney Disease, 2017. Available from Renal Assoc guidelines page

 

Acknowledgements: John Webster and Sue Mann were the original authors for this page, revised by Paddy Gibson and Wendy King. This page was reviewed and updated by Ashley Simpson in 2019. The date it was last modified is shown in the footer.