How Kidney Disease Causes Anemia

Chronic Kidney Disease (CKD) could cause your red cell count to drop

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Anemia, or low red cell/hemoglobin count is a common problem in Chronic Kidney Disease (CKD). Kidneys are not just excretory  organs, sitting up in your flanks quietly making urine. They serve multiple other functions, one of which is making sure that your red cell count stays up in the normal range.


The general rule of thumb is that your chances of developing anemia worsen with the severity of your kidney disease.

Hence anemia would be seen in a far greater proportion of patients in stage 4 or 5 kidney disease, as opposed to stage 3 disease. According to data, prevalence of anemia is strongly associated with declining glomerular filtration rate (GFR). The percentage of patients with hemoglobin under 12 increases from about 27% in patients with GFR over 60, to about 75% in patients with GFR under 15 (or stage 5 disease).


Besides the general symptoms of CKD that could be present in patients, anemia of kidney disease specifically can cause the following symptoms (which might not be different from anemia from any other cause):

  • fatigue
  • shortness of breath
  • malaise
  • decrease in appetite
  • lack of energy
  • feeling "cold"
  • chest pain and congestive heart failure in persistent severe cases 
  • increased risk of death

The fact is that red cells in the blood serve such a fundamental function important to life (carrying oxygen).

Hence, low counts are likely to have profound effects on every single organ.  


Red cell/hemoglobin count drops in patients with kidney disease due to multiple reasons. A partial list would be:

  1. REDUCED ERYTHROPOIETIN PRODUCTION: Red cells are made by the bone marrow. However, to do that, an hormone called erythropoietin is an essential requirement. The production of red cells is a complicated process which proceeds through multiple stages until a mature red cell with its hemoglobin content is produced.  Immature cells that are eventually going to turn into a red cells are highly susceptible to dying young (a process called apoptosis). One of the ways erythropoietin acts is by preventing this process from happening. It sees to it that immature "precursor" cells eventually grow up to become strapping red cells. This is a somewhat simplistic explanation but further details would be beyond the scope of this auricle. Erythropoietin is produced primarily by the kidneys in adults, although liver is the main site of production in the fetus. In CKD, production of this hormone goes down and the resultant deficiency can cause anemia. This anemia worsens with advancing stages of kidney disease.
  1. SHORTENED LIFE SPAN OF RED CELLS: Not only are fewer red cells produced in patients with kidney disease, they also die sooner. A normal red cell can typically live up to about 120 days. In patients with kidney disease, owing to multiple factors, this can be shortened to about 70 days. Hence not only you make less red cells, you also destroy more. 
  2. ROLE OF CHRONIC INFLAMMATION: Kidney disease is a de-facto state of chronic inflammation. Chemicals whose production goes up in states of inflammation are often found to be high in patients with kidney disease. I don't want to get too technical for this article, but these include some with scary names such as "tumor necrosis factor" and "interleukins". These in turn can lead to increased level of another substance called "hepcidin". Hepcidin has a major role in controlling absorption of iron (one of the raw materials required for hemoglobin production) from the gut and high levels interfere with the iron availability for red cell production.  

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