Anemia in Kidney Disease and Dialysis
If your blood is low in red blood cells, you have anemia. Red blood cells
carry oxygen (O2) to tissues and organs
throughout your body and enable them to use the energy from food. Without
oxygen, these tissues and organs—particularly the heart and brain—may not do
their jobs as well as they should. For this reason, if you have anemia, you may
tire easily and look pale. Anemia may also contribute to heart problems.
Anemia is common in people with kidney disease. Healthy kidneys produce a
hormone called erythropoietin, or EPO, which stimulates the bone marrow to
produce the proper number of red blood cells needed to carry oxygen to vital
organs. Diseased kidneys, however, often don’t make enough EPO. As a result, the
bone marrow makes fewer red blood cells. Other common causes of anemia include
loss of blood from hemodialysis and low levels of iron and folic acid. These
nutrients from food help young red blood cells make hemoglobin (Hgb), their main
A complete blood count (CBC), a laboratory test performed on a sample of your
blood, includes a determination of your hematocrit (Hct), the percentage of the
blood that consists of red blood cells. The CBC also measures the amount of Hgb
in your blood. The range of normal Hct and Hgb in women who menstruate is
slightly lower than for healthy men or healthy postmenopausal women. The Hgb is
usually about one-third the value of the Hct.]
When Anemia Begins
Anemia may begin to develop in the early stages of kidney disease, when you
still have 20 percent to 50 percent of your normal kidney function. This partial
loss of kidney function is often called chronic renal insufficiency. Anemia
tends to worsen as kidney disease progresses. End-stage kidney failure, the
point at which dialysis or kidney transplantation becomes necessary, doesn’t
occur until you have only about 10 percent of your kidney function remaining.
Nearly everyone with end-stage kidney failure has anemia.
If you have lost at least half of normal kidney function (based on your
glomerular filtration rate calculated using your serum creatinine measurement)
and have a low Hct, the most likely cause of anemia is decreased EPO production.
The National Kidney Foundation’s Dialysis Outcomes Quality Initiative (DOQI)
recommends that doctors begin a detailed evaluation of anemia in men and
postmenopausal women on dialysis when the Hct value falls below 37 percent. For
women of childbearing age, evaluation should begin when the Hct falls below 33
percent. The evaluation will include tests for iron deficiency and blood loss in
the stool to be certain there are no other reasons for the anemia.
|Hematocrit (Hct)||Hemoglobin (Hgb)|
|Women who menstruate||less than 33%||less than 11 g/dL|
|All men and postmenopausal women||less than 37%||less than 12 g/dL|
If no other cause for EPO deficiency is found, it can be treated with a
genetically engineered form of the hormone, which is usually injected under the
skin two or three times a week. Hemodialysis patients who can’t tolerate EPO
shots may receive the hormone intravenously during treatment, but this method
requires a larger, more expensive dose and may not be as effective. DOQI
recommends that patients treated with EPO therapy should achieve a target Hgb of
11 to 12 g/dL.
Many people with kidney disease need both EPO and iron supplements to raise
their Hct to a satisfactory level. If your iron levels are too low, EPO won’t
help and you’ll continue to experience the effects of anemia. You may be able to
take an iron pill, but many studies show that iron pills don’t work as well in
people with kidney failure as iron given intravenously. Iron is injected
directly into an arm or into the tube that returns blood to your body during
A nurse or doctor will give you a test dose because a very small number of
people (less than 1 percent) have a bad reaction to iron injections. If you
begin to wheeze or have trouble breathing, your health care provider can
administer epinephrine or corticosteroids to counter the reaction. Even though
the risk is small, you’ll be asked to sign a form stating that you understand
the possible reaction and that you agree to have the treatment. Talk with your
health care provider if you have any questions.
In addition to measuring your Hct and Hgb, your tests will also include two
measurements to show whether you have enough iron.
- Your ferritin level indicates the amount of iron stored in your body.
According to DOQI guidelines, your ferritin score should be no less than 100
micrograms per liter (mcg/L) and no more than 800 mcg/L.
- TSAT stands for transferrin saturation, a score that indicates how much iron
is available to make red blood cells. DOQI guidelines call for a TSAT score
between 20 percent and 50 percent.
Other Causes of Anemia
In addition to EPO and iron, a few people may also need vitamin B12 and folic acid supplements.
If EPO, iron, vitamin B12, and folic acid
all fail, your doctor should look for other causes such as sickle cell disease
or an inflammatory problem. At one time, aluminum poisoning contributed to
anemia in people with kidney failure because many phosphate binders used to
treat bone disease caused by kidney failure were antacids that contained
aluminum. But aluminum-free alternatives are now widely available. Be sure your
phosphate binder and your other drugs are free of aluminum.
Anemia keeps many people with kidney disease from feeling their best. But EPO
treatments help most patients raise their Hgb, feel better, live longer, and
have more energy.
Hope Through Research
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK),
through its Division of Kidney, Urologic, and Hematologic Diseases, supports
several programs and studies devoted to improving treatment for patients with
progressive kidney disease and end-stage kidney failure, which is sometimes
called end-stage renal disease or ESRD, i