Symptoms of anaemia
Anaemia can affect many body systems, including the central nervous system (CNS), the vascular system, the cardiorespiratory system, and the genital tract. (NAAC)
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Cardiorespiratory system effects
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CNS effects
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The vascular system effects
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Genital tract effects
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Haemoglobin levels in renal anaemia
A diagnosis of renal anaemia is made when haemoglobin falls below certain threshold levels. These have been defined by the National Kidney Foundation Kidney Disease Outcome Quality Initiative (NKF-KDOQI), the World Health Organization (WHO), and the European Best Practice Guidelines (EBPG) for the Management of Renal Anaemia in Patients with Chronic Renal Failure.
| Organization | Threshold haemoglobin concentrations for the diagnosis of anaemia (g/dL) | |
| Adult males | Adult females | |
| NKF-KDOQI1 | 13.5 | 12 |
| WHO2 | 13 | 12 (11*) |
| EBPG3 | 13.5 (12†) | 11.5 |
*Pregnant women
†Men > 70 years old
Chronic kidney disease (CKD) and anaemia
Anaemia is a major complication of CKD, even affecting patients with early stage disease. Haemoglobin levels progressively decrease with increasing degree of renal impairment4. Renal anaemia occurs even earlier in patients with diabetes5.
Early CKD (Stage 1) is characterised by kidney damage and normal renal function. As CKD progresses (Stages 2–5), kidney damage progressively increases and estimated glomerular filtration rate (eGFR) decreases1.
| Stage | Description | eGFR (mL/min/1.73 m2) |
| 1 | Kidney damage* with normal or increased eGFR | >90 |
| 2 | Kidney damage with mild decrease in eGFR | 60–89 |
| 3 | Moderate decrease in eGFR | 30–59 |
| 4 | Severe decrease in eGFR | 15–29 |
| 5 | Kidney failure | <15 or dialysis |
*Defined by the National Kidney Foundation as ‘pathologic abnormalities or markers of damage, including abnormalities in blood or urine tests or imaging studies’
How is CKD linked with renal anaemia?
Haemoglobin is carried by the red blood cells in the blood. Red blood cells derive from myeloid stem cells (burst-forming unit–erythroid [BFU-E] and colony-forming unit–erythroid [CFU-E] cells) in the bone marrow through the process of erythropoiesis. As a crucial first step, the hormone erythropoietin (produced by the kidney) binds to BFU-E and CFU-E cells, triggering them to divide and differentiate into ‘proerythroblasts’. After numerous stages of cell division and differentiation, haemoglobin-rich mature red blood cells are formed.
Renal anaemia can have a number of causes:
- Reduced stimulation of erythropoiesis – As the kidneys become progressively damaged in CKD, they lose the ability to produce erythropoietin, leading to renal anaemia.6
- Loss of red blood cells – Patients with CKD are at risk of blood loss due to poorly functioning platelets, resulting in bleeding. One of the causes of blood loss in CKD patients is dialysis.7
- Shortened red blood cell lifespan – While the average life span of a red blood cell is 120 days, this is reduced by approximately one-third in CKD patients who undergo dialysis.7
These effects contribute to iron deficiency. For example, dialysis patients may lose 3–5 g of iron per year.7 Find out more about the causes of renal anaemia.
Diagnostic work-up
Shown below is a flow-chart describing diagnosis of renal anaemia in patients presenting with CKD.1
References
- KDOQI (United States National Kidney Foundation ‘Kidney Disease Outcomes Quality Initiative’). Available at http://www.kidney.org/professionals/KDOQI/guidelines_anemia/index.htm
[Accessed December 2006]. - Iron Deficiency Anaemia. Assessment, Prevention, and Control. A guide for programme managers. World health organization 2001.
- Revised European Best Practice Guidelines for the Management of Anaemia in Patients with Chronic Renal Failure. SECTION I. Anaemia Evaluation. Nephrol Dial Transplant 2004;19:ii2–ii5.
- Jungers PY, Robino C, Choukroun G, et al. Incidence of anaemia, and use of epoetin therapy in pre-dialysis patients: a prospective study in 403 patients. Nephrol Dial Transplant 2002;17:1621–1627.
- Bosman DR, Winkler AS, Marsden JT, et al. Anemia with erythropoietin deficiency occurs early in diabetic nephropathy. Diabetes Care 2001; 24:495–499.
- National Institute of Diabetes and Digestive and Kidney Diseases. National Institutes of Health. Anemia in Kidney Disease and Dialysis. NIH Publication No. 05–4619.
- Nurko S. Anemia in chronic kidney disease: causes, diagnosis, treatment. Cleve Clin J Med 2006;73:289–97.
