Nephrogenic Anaemia
Anemia of chronic kidney disease, Anemia of chronic renal disease, Anemia of CKD, Renal anemia
Nephrogenic anaemia is a common blood condition that affects people with kidney disease, occurring when damaged kidneys cannot produce enough of a special hormone needed to make healthy red blood cells.
Table of contents
- What is nephrogenic anaemia?
- How kidney disease causes anaemia
- How common is this condition?
- Signs and symptoms
- What causes nephrogenic anaemia?
- How doctors identify this condition
- Treatment options
- Lifestyle and dietary support
What is nephrogenic anaemia?
Anaemia is a condition in which your blood has a lower-than-normal amount of red blood cells or hemoglobin. Hemoglobin is the iron-rich protein that allows red blood cells to carry oxygen from your lungs to the rest of your body.[1] With fewer red blood cells or less hemoglobin, your tissues and organs—such as your heart and brain—may not get enough oxygen to work properly.[1]
Nephrogenic anaemia is a type of normocytic and normochromic anaemia, meaning the red blood cells are normal in size and color, but there are simply not enough of them.[10]
How kidney disease causes anaemia
Anaemia is a common complication of chronic kidney disease (CKD). CKD means your kidneys are damaged and can’t filter blood the way they should. This damage can cause wastes and fluid to build up in your body. CKD can also cause other health problems.[1]
The connection between kidney disease and anaemia is direct and important. When healthy, kidneys produce about 90% of a hormone called erythropoietin, or EPO. This hormone tells the bone marrow to produce the amount of red blood cells that the body needs to carry oxygen to vital organs.[5] When the kidneys are damaged, they often do not make enough EPO. As a result, the bone marrow makes too few red blood cells.[17]
Damaged kidneys lead to impaired production of erythropoietin, which leads to a reduced number of red blood cells, which leads to anaemia.[4]
How common is this condition?
Anaemia is less common in early kidney disease, and it often gets worse as kidney disease progresses and more kidney function is lost.[1] As kidney disease advances, the prevalence of anaemia increases, affecting almost all patients with stage 5 CKD.[10]
Anaemia occurs when creatinine clearance (a measure of kidney function) is less than 45 mL/minute.[5] The severity of anaemia does not always correlate with the extent of kidney dysfunction. Kidney diseases affecting the filtering units of the kidney (such as those due to diabetes or amyloidosis) generally result in the most severe anaemia for their degree of kidney failure.[5]
Signs and symptoms
Common symptoms of nephrogenic anaemia include loss of energy and shortness of breath.[4] You may also become irritable and frustrated at the difficulty experienced in doing daily tasks.[4]
Other symptoms may include:
- Feeling very tired all or most of the time
- Muscle weakness
- Feeling dizzy or lightheaded
- Being short of breath after even a little bit of activity
- Feeling cold when others around you are not
- Confusion or trouble thinking clearly
- Very pale skin and/or bluish fingernails or lips
- Loss of appetite
- A more rapid heart rate
- Trouble sleeping
- Headaches[14][17]
The symptoms of chronic kidney disease—such as lethargy, mood changes, disturbed sleep patterns, and impaired sexual function—may be made worse by anaemia.[4]
What causes nephrogenic anaemia?
The most common cause of nephrogenic anaemia is the lack of EPO production by damaged kidneys.[5] However, the anemia in chronic kidney disease is often caused by multiple factors working together.
The main mechanisms include:
- Decreased production of erythropoietin by damaged kidneys
- Lack of EPO leading to reduced red blood cell production
- Iron deficiency and problems with iron storage in the body
- Shortened red blood cell lifespan due to uremia (buildup of waste products in the blood)
- Bone marrow resistance to EPO
- Blood loss due to problems with blood clotting, dialysis procedures, or bleeding in the digestive system[5][10]
The lack of EPO leads to loss of erythroferrone production, which causes loss of hepcidin suppression and increased iron sequestration. This is similar to what happens in anemia of chronic disease.[5]
Other factors that may contribute include infections, vitamin B12 or folic acid deficiency, and secondary hyperparathyroidism.[4][5]
How doctors identify this condition
Your doctor can check your hemoglobin level through a blood test. The normal range is 130-170 grams per liter (g/L) for men and 120-150 g/L for women. These levels are reduced in anaemia, sometimes as low as 40 g/L.[4]
Diagnosis is based on demonstrating kidney disease, normocytic anaemia, and a low number of young red blood cells called reticulocytes.[5]
Blood tests should be performed to measure:
- Complete blood count with differential
- Hemoglobin levels
- Iron levels in the blood
- Ferritin (a protein that stores iron)
- Transferrin saturation (TSAT)
- Vitamin B12 and folic acid levels
- Reticulocyte count[4][5]
A peripheral blood smear may also be examined. The bone marrow may show reduced red blood cell production.[5]
Treatment options
Treatment of nephrogenic anaemia is directed at improving kidney function when possible and increasing red blood cell production.[5]
If kidney function returns to normal, anaemia is slowly corrected. However, most treatment focuses on managing the anaemia while addressing the underlying kidney disease.[5]
Erythropoietin replacement
Recombinant erythropoietin (EPO) improves anaemia and reduces the need for blood transfusions in patients with chronic kidney disease. It is generally started when hemoglobin is less than 9 to 10 g/dL (less than 90 to 100 g/L) in patients on dialysis.[5]
In patients receiving long-term dialysis, recombinant erythropoietin (such as epoetin alfa or darbepoetin alfa) along with iron supplements is the treatment of choice.[5] These medicines are called Erythropoiesis Stimulating Agents (ESAs).[17]
The goal is a hemoglobin of 10 to 11.5 g/dL (100 to 115 g/L). Careful monitoring of hemoglobin response is needed because adverse effects such as blood clots, heart attack, or death may occur when hemoglobin rises above 12 to 13 g/dL.[5]
Lower doses of EPO are used in patients with chronic kidney disease who are not on dialysis.[5] In almost all cases, maximum increases in red blood cells are reached by 8 to 12 weeks.[5]
Iron supplementation
Iron is the building block your body uses to make red blood cells. Adequate iron stores are required to ensure a good response to recombinant EPO, and iron supplementation is often needed.[5][14]
If there is a deficiency of iron, vitamin B12, or folic acid, supplements can be given.[4] Iron pills are not often absorbed well enough to give high enough iron levels. Instead, a liquid iron elixir or intravenous iron is used.[14]
The addition of intravenous iron is considered in patients receiving dialysis with hemoglobin less than 10 g/dL, ferritin 500 ng/mL or less, and transferrin saturation (TSAT) 30% or less.[5]
Blood transfusions
Immediate treatment of anaemia may require blood transfusions. Adding red blood cells to the body’s low stocks gives better oxygen-carrying capacity and improves the anaemia. However, blood transfusions alone do not address the underlying problem and carry their own risks.[4]
Treating other contributing factors
Infections may cause or worsen anaemia. Recurring infections such as urinary tract infections or infections around a dialysis catheter may need treatment.[4]
It is also important to detect any blood loss from the bowel. Any indigestion should be reported to the doctor, as well as any change in stools, either with visible blood or blackening of the stool.[4]
Lifestyle and dietary support
Nutrition and diet
A well-balanced diet for anaemia includes:
- Whole grains: oats, enriched pasta, and fortified cereals
- Animal protein: chicken, beef, pork, and fish
- Nuts: almonds, pistachios, and sesame seeds
- Beans and legumes: soybeans, lentils, and garbanzo beans
- Iron-rich fruits and vegetables: broccoli, collard greens, peas, raisins, spinach, strawberries, and tomatoes[16]
How these foods are paired and prepared can affect their effectiveness. Foods high in vitamin C allow easier iron absorption. This makes fish with lemon juice or marinara sauce with enriched pasta beneficial pairings for anemic patients.[16]
Foods to limit
You may need to avoid or limit certain milk and dairy products, such as ice cream, butter, and cow’s milk. Despite being high in calcium, they can make iron absorption harder.[16]
Tannin has the same effect. Examples of high-tannin foods and drinks include pomegranate, dark chocolate, coffee, black tea, and red wine. You do not have to give these up completely, but wait a few hours after eating an iron-rich meal before consuming them.[16]
Exercise and rest
Research shows that endurance exercise like walking, swimming, biking, or jogging can help anyone to have stronger muscles, a healthier heart, and more energy—including people with kidney disease. If you have kidney disease, exercise does even more: it helps spur the growth of more red blood cells, which can reduce anaemia.[14]
However, it is important to take time to rest. Anaemia can make a person feel fatigued, weak, and dizzy. For patient safety, always take breaks when symptoms occur. Stop exercising immediately if dizziness, chest pain, or shortness of breath develop.[16]
Talk to your doctor about starting an exercise program if you are not active now.[14]
