Anemia & Chronic Kidney Disease (CKD) Primer
If you are new to kidney dialysis and dealing with anemia or just need a refresher on anemia and chronic kidney disease read on... this is for you!
What is anemia?
Anemia is a condition that occurs when you have a lower than normal amount of red blood cells (RBCs) or hemoglobin (Hgb) in the bloodstream. Hemoglobin is the oxygen carrying protein found in RBCs that carries oxygen from the lungs to the tissues of the body including heart, brain and muscles which help you function normally. Therefore, when Hgb levels are low, you can end up feeling weak and tired.
CKD & RBC production
Normally kidneys produce a hormone called erythropoietin (EPO), which stimulates red blood cell production in the bone marrow. However, when your kidney is damaged or not functioning properly (not making enough EPO) fewer RBCs are created. Because of this, it is common for people with chronic kidney disease to be anemic, and therefore monitoring Hgb levels becomes an important part of care management.
In addition to low EPO production from non-functioning kidneys, blood loss from hemodialysis, low iron, vitamin B12 and folic acid levels are all common causes of anemia in people with chronic kidney disease.
How is anemia diagnosed?
Anemia is typically diagnosed through a combination of a physical exam and blood tests. There are many types of anemia, each with its own cause. For stage 5 CKD patients, regular blood testing is part of the routine to ensure that the treatment being provided is effective. Tests that evaluate CKD associated anemia are typically done on a monthly basis and are included in the CBC (complete blood count) test.
Hint: When getting a blood test done outside of your dialysis center, double check the range used for Hemoglobin (Hgb) and other tests as what is in “normal” range for a kidney dialysis patient is not the same as someone without CKD.
Red blood cells (RBCs) are created in the bone marrow and contain the oxygen carrying protein hemoglobin (Hgb), which provides oxygen to your cells and is important for normal function of your heart and brain as well as other organs. Hemoglobin’s ability to bind oxygen is dependent on the presence of the heme group which contains iron. Human hemoglobin consists of 4 subunits, each of which contains a heme group. (1)
What are “Normal Hgb levels” for a person with CKD:
When on kidney dialysis, medical professionals typically want to keep your Hgb levels between 10-11.5g/L. (2) The medicare.gov site evaluates centers on their ability to keep Hgb levels between 10-12 g/L, and the centers are themselves reimbursed for anemia treatment based on this information as well. (3)
Why keeping track of Hgb levels is important for a person with CKD:
Too low and too high Hgb levels can be dangerous for someone on kidney dialysis. High Hgb levels can lead to cardiovascular problems, your levels should not be higher than 12 g/L absolute max.
If you get test results back with abnormal Hgb levels and a clinician hasn't spoken to you yet, make sure you bring it to their attention. Dialysis centers are evaluated based on their ability to manage CKD associated anemia among other things, so they should be keeping a close eye on your levels via the regular CBC tests that are done, but they are human.
Reminder: It is your body, it is best to keep on top of your test results and be your own advocate if possible. Keeping track of your test results is extremely important to managing your health; A mobile app can help with that :).
Treatments for Anemia (Hgb levels below 10g/L)(4)
1. Erythropoiesis‑stimulating agents (ESAs) - manufactured recombinant proteins that work by stimulating the bone marrow to produce red blood cells, resulting in the same biological effect as endogenous erythropoietin (EPO).
Before prescribing treatment with an ESA your Dr. will look at your overall health profile as ESA’s have been shown to increase the chance of cardiovascular events, such as heart attack and stroke. Your doctor should provide you with the risk evaluation and strategy document (REMS) so that you understand the pros and cons of using ESAs. If you have not been given this information you can ask for it.
FDA cleared ESA’s: Epoetin alfa (marketed as Procrit® and Epogen®), and Darbepoetin alfa (marketed as Aranesp®)
Where done: ESA treatment is typically done intravenously when you are in the center for your dialysis treatment.
When effects seen: changes will not be immediate, it takes time for new red blood cells (also called erythrocytes) to be created from their erythroid progenitors. “Because of the length of time required for erythropoiesis- several days for erythroid progenitors to mature and be released into the circulation- a clinically significant increase in hematocrit is usually not observed in less than 2 weeks and may require up to 6 weeks in some patients”. (5) Hgb levels should not be greater than 11 g/dL when using Procrit®. (6)
2. Iron supplements- intravenous iron has been shown to be more effective than iron pills for hemodialysis patients (7)
3. Vitamin B12 and Folic Acid supplements. Read more about vitamin B12 and folic acid on the MedlinePlus website at www.nlm.nih.gov/medlineplus about complementary and alternative medicine at www.nccam.nih.gov/
4. Red Blood Cell Transfusions- this should be last resort.
If these treatments aren’t effective, your doctor will look for other causes of anemia including looking at other bone marrow issues, inflammatory problems, chronic infections and malnutrition.
Why iron supplements? How is iron and anemia connected?
Human adult hemoglobin consists of 4 protein subunits, each of which contains a heme group and a central iron atom (see figure).(1) The iron within the heme group of each Hgb subunit is able to bind and release one molecule of oxygen (O2), thus providing each hemoglobin with the ability to carry 4 molecules of oxygen. The binding of oxygen by Hgb occurs in a cooperative fashion, so that the binding of one oxygen actually changes the structure making it easier for the remaining heme/iron centers to bind oxygen. Bottom line: Iron plays a central role in the ability of hemoglobin to catch and release oxygen.
What you can do today:
Eat well. Remember some iron rich foods for example might be high in other things like sodium or phosphorous, which is not healthy for a person with CKD.
Education is key: Read more about nutrition for people with CKD on the National Kidney Disease Education Program website.
Maintaining an appropriately healthy diet for someone on hemo or peritoneal dialysis is a very important. You can help yourself and your care providers by eating the appropriate foods.
The following chart from the NIH/NIDDK illustrates some good dietary sources of iron, vitamin B12, and folic acid.
Communicate with your Nephrologist: Your nephrologist typically will come to you to address changes seen in your blood test results and provide recommendations and/or treatment plans, but keeping yourself or your loved one informed on what is needed to stay as healthy as possible while living with CKD, will help both you and your doctor manage your health.
If you found this primer on Anemia & CKD helpful, please pass it on!
All the best,
Berg JM, Tymoczko JL, Stryer L. Biochemistry 5th edition. W.H Freeman: 2002. Chapter 10.2.1. Oxygen bnding induces substantial structural changes at the iron sites in hemoglobin
Brugnara C, Eckardt KU. Hematologic aspects of kidney disease. In: Taal MW, ed. Brenner and Rector’s The Kidney. 9th ed. Philadelphia: Saunders; 2011: 2081–2120.
Medicare.gov evaluates dialysis centers Hgb levels 10-12 g/L
NIDDK- erythropoietin section.
PROCRIT®EPOETIN ALFA Full Prescribing information 11/05.
Revised 2012 Procrit® Prescribing information. In controlled trials, patients experienced greater risks for death, serious adverse cardiovascular reactions, and stroke when administered erythropoiesis-stimulating agents (ESAs) to target a hemoglobin level of greater than 11 g/dL (5.1). No trial has identified a hemoglobin target level, ESA dose, or dosing strategy that does not increase these risks. Use the lowest PROCRIT dose
Kidney Disease: Improving Global Outcomes (KDIGO) Anemia Work Group. KDIGO clinical practice guideline for anemia in chronic kidney disease. Kidney International Supplements. 2012;2(4):279–335