MedlinePlus, a patient information service jointly maintained by the National Institutes of Health and the National Library of Medicine, estimates that two out of every 1,000 Americans suffer from some form of renal disease. The term "renal disease" refers to kidney diseases. The kidneys play a key role in your body's ability to manufacture red blood cells from stored iron. Kidney disease also affects iron intake by limiting the types and quantities of foods you can eat.
Significance
A hormone called erythropoietin, or EPO, stimulates bone marrow to produce red blood cells. Your kidneys produce 90 percent of the EPO in your body. As renal disease progresses, the kidneys gradually stop producing EPO and production of new red blood cells drops dramatically. Treatment for renal disease often compounds the problem. Hemodialysis, in particular, involves chronic blood loss because some of your blood remains in the tubing that connects you to the dialyzer machine after you have completed a treatment.
Time Frame
Iron problems usually begin during stage three renal disease, when your kidney function falls to one- to two-thirds normal function. You may not notice symptoms, such as shortness of breath, fatigue, weakness, fast heartbeat, pale skin, brittle nails, swollen tongue, cold hands and feet or unusual food cravings, until you reach stage four renal disease when kidney function falls to 17 to 33 percent of normal. At stage five renal disease, your kidney function falls below 17 percent; however, most patients have started treatment by this time. Depending on the cause of your renal disease, this progression may occur over years, months or weeks in most extreme cases.
Treatment
Treatment for anemia due to renal disease begins with drugs that stimulate the production of erythropoietin. These so-called erythropoietin-stimulating agents, or ESAs, are usually administered by an injection under the skin. However, erythropoietin does not work if you do not have enough iron. Your doctor will probably recommend that you take an iron supplement by mouth three times per day between meals. If you do not absorb enough oral iron, you may require intravenous iron. Intravenous iron must be administered at a hospital, clinic or doctor's office. Ask your doctor if you can receive intravenous iron during your regular dialysis appointment.
Monitoring
If you have renal disease, your doctor may order regular blood tests to monitor your levels of hemoglobin, hematocrit, ferritin, transferrin and reticulocytes. Hemoglobin is the part of the red blood cell that carries iron while hematocrit describes the amount of red blood cells within a sample of blood. Ferritin is a measure of the amount of iron your body stores. Transferrin is a protein that ferries stored iron to the bone marrow so that it can be used to produce new red blood cells. Low transferrin signals that you are not consuming enough protein to use your iron effectively. Reticulocytes are new or immature red blood cells. Red blood cells circulate for two months, so monitoring reticulocytes tells your doctor about recent changes in your iron status.
Complications
When your body does not have enough iron, your heart must work harder to make sure all the cells in the body receive enough oxygen. If you have renal disease, your heart is already working hard to accommodate extra fluid and electrolytes that you cannot excrete as urine. Plus, many of the conditions that predispose you to renal disease -- such as diabetes and hypertension -- also affect your heart. Working with your doctor to treat anemia and iron deficiency may reduce your risk of serious heart-related complications, such as heart failure and heart attack.
References
- "Modern Nutrition in Health and Disease"; Maurice E. Shils, M.D. et al.; 2005
- "Harrison's Principles of Internal Medicine, 23rd Edition"; Anthony S. Fauci, M.D. et al.; 2008
- MedlinePlus: Chronic Kidney Disease
- National Anemia Action Council: I (Heart) My Kidneys
