What is anemia?
Anemia is a condition in which the body has fewer red blood cells than normal. Red blood cells carry oxygen to tissues and organs throughout the body so that they can use the energy in food. With anemia, red blood cells deliver less oxygen to tissues and organs (especially the heart and brain), which may prevent these tissues and organs from functioning at the level they should.
How is anemia related to chronic kidney disease?
Patients with chronic kidney disease are more likely to develop anemia, either with complete or partial loss of kidney function. Anemia may begin to develop early in CKD, such as when having 20 to 50 percent of normal kidney function. As CKD progresses, the anemia tends to worsen. Most people with complete loss of kidney function or kidney failure have anemia.
How do the kidneys work?
The kidneys are two bean-shaped organs, each the size of a fist. They are located directly below the rib cage, on either side of the spine. Each day, the kidneys filter about 120 to 150 liters of blood and produce about 1-2 liters of urine.
Healthy kidneys produce a hormone called erythropoietin (EPO). Hormones are chemicals produced by the body and released into the bloodstream that help trigger or regulate specific body functions. EPO prompts the bone marrow to produce red blood cells, which are then carried throughout the body.
What causes anemia in chronic kidney disease?
When the kidneys are diseased or damaged, they do not have enough EPO. As a result, the bone marrow produces fewer red blood cells, which causes anemia. When there are fewer red blood cells in the blood, the body does not have enough oxygen it needs.
Other common causes of anemia in people with kidney disease include blood loss from hemodialysis and low levels of the following nutrients in food.
- Iron
- Vitamin B12
- Folic acid
These nutrients are necessary for red blood cells to produce hemoglobin, which is the main oxygen-carrying protein in red blood cells.
If treatment for kidney-associated anemia does not help, health care providers should look for other causes of the anemia, including:
- Other problems with the bone marrow
- Inflammatory problems such as arthritis, lupus or inflammatory bowel disease - these diseases cause the body's immune system to attack the body's own cells and organs
- Chronic infections, such as diabetic ulcers
- Malnutrition
What are the signs and symptoms of anemia in patients with chronic kidney disease?
Signs and symptoms of anemia in people with CKD may include:
- Weakness
- Fatigue or feeling tired
- Headaches
- Difficulty concentrating
- Pale complexion
- Dizziness
- Difficulty breathing or shortness of breath
- Chest pain
You should seek medical attention immediately if you have difficulty breathing or shortness of breath or chest pain.
What are the complications of anemia in patients with chronic kidney disease?
Heart disease is a complication of anemia and includes:
- An irregular heart rhythm or abnormally fast heartbeat, especially during exercise.
- Harmful expansion of the heart muscle.
Heart failure, does not mean that the heart suddenly stops working. Rather, heart failure is a long-term condition in which the heart is unable to pump enough blood to meet the body's needs.
How is anemia diagnosed in chronic kidney disease?
Health care providers diagnose anemia based on the following:
- medical history
- physical examination
- blood tests
Medical history
Taking a medical history is the first step for a doctor to diagnose whether or not there is anemia. The doctor will usually ask about the patient's symptoms.
Physical examination
A physical examination helps diagnose anemia. During the physical examination, the doctor will usually examine the patient's body, including checking for changes in skin color.
Blood tests
To diagnose anemia, the doctor will ask the patient to undergo a routine blood test, in which the concentration of hemoglobin (Hb) is used to determine whether the patient is anemic. The diagnostic criteria for anemia in China are: in the sea level area, anemia is present in adult males with Hb <120 g/L, adult females with Hb <110 g/L, and pregnant women with Hb <100 g/L. It should be noted that infants, children and pregnant women have lower hemoglobin concentrations than adults, and people who live on highlands for a long time have higher normal values of hemoglobin than those at sea level. Also, in hypoproteinemia, congestive heart failure, splenomegaly and macroglobulinemia, the plasma volume increases, and at this time, even though the red blood cell volume is normal, the hemoglobin concentration decreases because the blood is diluted, and it is easy to be misdiagnosed as anemia; when the circulating blood volume decreases such as dehydration or blood loss, the hemoglobin concentration increases due to blood concentration, and even though the red blood cell volume decreases and there is anemia, it is not easy to show.
The severity of anemia is as follows:
- Mild anemia: >90 g/L
- Moderate: 60~90 g/L
- Severe: 30~59 g/L
- Very severe: <30 g/L
If there is at least 50% loss of normal kidney function and the hemoglobin is low, the cause of the anemia is most likely decreased erythropoietin production.
Two other blood tests help measure iron levels:
Ferritin levels help to assess the amount of iron stored in the body. Ferritin values below 200 nanograms (ng) per milliliter may indicate an iron deficiency that requires treatment.
A transferrin saturation value indicates how much iron is available for making red blood cells. A transferrin saturation score of less than 30% may also mean that iron levels are low and need to be treated.
In addition to blood tests, patients will need to undergo other tests, such as fecal blood loss tests, to look for other causes of anemia.
Anemia is highly prevalent in patients with chronic kidney disease and can worsen as kidney function declines.
How should anemia in chronic kidney disease be treated?
Depending on the cause, doctors may treat anemia with one or more of the following treatments.
Iron
The first step in treating anemia is to raise the level of iron in the blood. Iron supplement tablets may help improve iron and hemoglobin levels. However, for patients undergoing hemodialysis, many studies have shown that oral tablets are not as effective as intravenous injections. Generally, non-dialysis patients and peritoneal dialysis patients can be treated with oral iron supplementation first or apply intravenous iron therapy depending on the iron deficiency status; intravenous iron supplementation should be preferred for hemodialysis patients.
Erythropoietin
If blood tests indicate that kidney disease is the most likely cause of anemia, treatment may include injections of man-made EPO. health care providers (usually nurses) will inject EPO subcutaneously or subcutaneously into patients as needed. some patients can learn how to inject EPO themselves. hemodialysis patients may receive EPO intravenously during hemodialysis.
Studies have shown that the use of EPO can increase the chance of cardiovascular events, such as heart attacks and strokes, in patients with chronic kidney disease. Physicians should carefully examine the patient's medical history and determine if EPO is the best way to treat the patient's anemia. Some experts recommend using the lowest possible dose of EPO to reduce the need for red blood cell transfusions. Patients receiving EPO should have regular blood tests to monitor their hemoglobin so that the physician can adjust the EPO dose if levels are too high or too high. Doctors should discuss the benefits and risks of EPO with patients.
Many people with kidney disease need iron and EPO supplements to increase their red blood cell counts to levels that will reduce the need for red blood cell transfusions. Some patients may improve their anemia symptoms with iron supplements and EPO.
Red blood cell transfusions
If a patient's hemoglobin drops too low, the patient may need a red blood cell transfusion. Infusion of red blood cells into the patient's vein will increase the percentage of red blood cells in the blood, thus increasing the amount of oxygen available to the body.
Vitamin B12 and Folic Acid Supplements
Some patients can improve their anemia with the use of vitamin B12 and folic acid supplements. It is best to have asked your doctor before using them.
Diet and Nutrition
If the anemia is caused by a deficiency of iron, vitamin B12 and folic acid supplements, the anemia can be improved by eating foods that contain these nutrients. If some of these foods are high in sodium or phosphorus, people with chronic kidney disease should restrict their diet. Patients with chronic kidney disease should talk with their doctor before making any dietary changes.
The following chart lists some of the foods that contain iron, vitamin B12 and folic acid (1 cup is about the size of a tennis ball):
| Foods | amount | iron | vitamin B12 | folic acid |
| Beans | 1 cup (240g) | 8 mg | 6 µg | 37 µg |
| Beef | 100 g | 2 mg | 2 µg | 8 µg |
| Beef liver | 100 g | 5 mg | 67 µg | 211 µg |
| Clam | 120 g | 3 mg | 1 µg | 66 µg |
| Spinach | 100 g | 2 mg | 0 µg | 115 µg |
| Canned tuna | 100 g | 1 µg | 1 µg | 2 µg |
See also:
2. How to choose the at-home kidney test？
3. 9 Best At-Home Kidney Tests Buyers Guide In 2022
4. Can I take anemia tests at home?
5. What Is Blood Test For Iron Called?
7. Chronic Kidney Disease: Causes, Symptoms And Management
8. 2022 Best Home Hemoglobin Meter Buyers Guide