What is anaemia?
There are three types of blood cell: red cells (carry oxygen), white cells (fight infection) and platelets (clot blood). A person whose blood is low in red blood cells has anaemia. Without oxygen, tissues and organs - particularly the heart and brain - do not do function well. For this reason, anaemic people may get tired easily and look pale. Anaemia also contributes to heart problems.
Anaemia is common in people with kidney disease, and one of its most important complications. Healthy kidneys produce erythropoietin (EPO), a hormone that stimulates the bone marrow to produce red blood cells. Diseased kidneys, however, often don’t make enough EPO. As a result, the bone marrow makes fewer red blood cells. Other common causes of anaemia include blood loss from haemodialysis and low levels of iron and folic acid. Anaemia occurs in patients before dialysis (predialysis), on dialysis, and with a transplant.
Anaemia occurs in patients before dialysis (predialysis), on dialysis, and with a transplant
How does kidney disease cause anaemia?
Anaemia is a common side effect of chronic kidney disease (CKD).
If your kidneys are damaged, they produce less of a hormone called erythropoietin which is needed to make red blood cells. This results in fewer cells being made and causes anaemia. Red blood cells contain haemoglobin which carries oxygen around your body.
Kidney disease also effects the way in which your body uses iron. If you have kidney disease you may therefore need more iron to make the same amount of haemoglobin as people without kidney disease.
You can also become anaemic for the same reasons as people without kidney disease - blood loss, inflammation, infections, poor nutrition, or problems with your bone marrow. Your doctor might think about these causes of anaemia as well.
What are the symptoms of anaemia?
Symptoms can include:
- Feeling more tired than normal
- Lacking energy
- Shortness of breath, especially after exercise
- Awareness of the heart beating
- Chest pain
- Feeling cold
These symptoms can happen for other reasons and you should discuss them with your doctor.
Diagnosing anaemia early is important because it can affect your quality of life. Anaemia can also put extra strain on your other organs, including the heart.
How is anaemia diagnosed?
Anaemia is diagnosed by blood tests. These will measure your blood count (haemoglobin; Hb), iron levels (including ferritin), and levels of vitamin B12 and folate (a type of vitamin B). This can confirm the type and severity of anaemia.
If you are receiving dialysis you will have regular blood tests to monitor your anaemia. If you are not having dialysis you will probably just have your blood count measured in clinic, so if you experience any of the above symptoms you should discuss them with your doctor.
How is anaemia treated?
Mild anaemia may not need any treatment, particularly if you do not have any symptoms. If you are low on vitamin B12 or folate your doctor may prescribe you supplements as either tablets or injections.
For more severe anaemia, the main treatments are iron supplements and, if needed, injections of ESA (also called EPO), a replacement for the erythropoietin hormone that was previously made by your kidneys.
In earlier stages of kidney disease, iron may be given in tablet form. However, if you have advanced kidney disease or if you are receiving dialysis, you are likely to need iron infusions given into a vein (intravenously), rather than as tablets.
ESA treatment can be injected just underneath your skin, but for convenience it can be given via your dialysis machine for haemodialysis patients.
ESA injections can also be done at home. You can inject yourself or a family member or nurse can do it for you.
You are likely to have regular blood pressure monitoring at either your GPs or in clinic. This will probably be monthly at first until your results are stable and then every 6-12 weeks.
Many people with kidney disease need both an ESA and iron supplements to raise their Hb to a satisfactory level.
If iron levels are too low, the ESA won’t work well and the person will continue to experience anaemia. Some people take iron tablets. For others, iron is injected into a vein in the arm, or into the tube thatreturns blood to the body during haemodialysis. Another blood test – to measure the ferritin in your blood – should also be done. This reflects the iron levels in the body; the higher the better. The normal level offerritin is 15–350 mcg/L. Doctors will aim to keep it over 200, with a combination of iron tablets and injections.
We have a booklet that details the medicines that can be used to help the symptoms of chronic kidney disease (CKD), including anaemia and mineral bone disease.
Are there any side effects of anaemia treatment?
Iron tablets can cause nausea (feeling sick), indigestion, constipation and dark stools (black poo). Iron injections can give you a temporary metallic taste in your mouth, and, rarely, an allergic reaction, which can be serious.
Most people respond well to ESA but some people can develop high blood pressure, flu-like symptoms and skin reactions at the injection site. People with kidney disease can vary in how well they respond to ESA and frequently require dose adjustments.
The main aim of iron and ESA treatment is to improve your quality of life by reducing your symptoms.
What about blood transfusions?
If you have severe anaemia, suffer complications or the treatments described above are not working, then your doctor may recommend a blood transfusion to replace the red blood cells your body cannot produce.
Blood transfusions are avoided, where possible, due to the risk of allergic reactions, iron overload and to reduce the risk of producing antibodies that might limit the donors you could receive a transplant from.
What can I do to help manage my anaemia?
Changes to diet can sometimes help to prevent anaemia, but you should talk to your doctor or dietitian before making changes. The Renal Nutrition Group does not recommend a high iron diet for patients with CKD.
It is important to follow the treatment recommended by your doctor. You should store ESA injections or iron as recommended by the manufacturer - some products need to be stored in the fridge for example.
You should let your doctor or nurse know immediately if you notice any bleeding or if you experience symptoms of anaemia.
A full blood count (FBC) is a blood test that measures the number of red cells, white cells and platelets in the blood. The haemoglobin (Hb) reflects the number of red cells in the blood; the higher the number, the more red cells. Usually, the higher the Hb the better. It should be 11–15 g/dL (women) and 13–18 g/dL (men). Any results below these levels indicate anaemia, which may need treatment. Higher results may also cause problems (such as clotting of fistulas). The ‘target Hb’ for patients with kidney disease is 11–12 g/dL.
When does anaemia begin?
Anaemia may begin to develop in the early stages of kidney disease; for example in CKD Stage 2 when you still have 60–90% of normal kidney function. The blood creatinine level may only be marginally raised at this point, at 120–150 mcmol/L for example (normal range 60–120 mcmol/L). Anaemia worsens as kidney disease progresses. End-stage kidney disease (ESRD), the point at which dialysis or a kidney transplant becomes necessary, doesn’t occur until you have only about 10% of your kidney function remaining. Nearly everyone with end-stage kidney disease has anaemia, and will need treatment.