Anemia in the patient with chronic kidney disease

Anemia is a common condition in patients with chronic kidney disease and is caused by poor regulation of iron metabolism and erythropoiesis. It has been associated with an increased risk of hospitalization, cardiovascular disease, cognitive deficits and mortality.

To treat anemia, it is essential to assess iron status. With regard to iron, it is important to say that it is an essential component because of its ability to transport oxygen throughout the body and, in addition, it is also an essential element of hemoglobin for erythropoiesis.

What are the causes of anemia?

A person is anemic when the hemoglobin level is less than 13 g/dL in men and 12 g/dL in non-pregnant women.

In this sense, the causes of anemia can be:

  • Low iron levels
  • Inadequate iron level regulation (as occurs in chronic kidney disease).

In 15-24% of cases of chronic kidney disease, anemia is generated by:

  • Inadequate erythropoietin production
  • Poor regulation of iron homeostasis (by functional deficit or impaired absorption)
  • By a decreased survival of red blood cells.

Thus, chronic kidney disease is related to a negative iron balance due to decreased food intake, reduced intestinal absorption and increased losses. The functional deficit is multifactorial, caused mainly by iron sequestration by macrophages.

Treatment with intravenous iron

Treatment of anemia in chronic kidney disease is often challenging, especially in patients with inflammation, type 2 diabetes or cancer. In patients with heart failure, administering iron is beneficial regardless of hemoglobin levels. However, the preferred treatment in chronic kidney disease is partial correction of anemia with erythropoiesis-stimulating agents.

When there is functional or absolute iron deficiency, treatment with intravenous or oral iron is essential because of poor intestinal iron absorption and poor tolerance of oral treatment.

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The new erythropoiesis stimulating agents are oral drugs and can be very useful in patients with difficulties to be treated, being equally effective in those with underlying inflammation. Anemia caused by inflammation is prevalent in different chronic diseases (cancer, heart disease, inflammatory bowel disease, rheumatoid arthritis and chronic kidney disease). Inflammation is associated with a functional iron deficit, which occurs when iron is sequestered in organs and the availability of this stored iron is restricted. In patients with chronic kidney disease, inflammation can lead to poor response to iron therapy, especially oral iron, due to reduced intestinal absorption. For this reason, intravenous iron is recommended to correct anemia if ferritin is

On the other hand, the most frequent cause of CKD is diabetes, which is related to inflammation generated by high glucose levels, increased cholesterol levels and arterial hypertension. Anemia in CKD secondary to diabetes is more frequent than in non-diabetic CKD. In this case, erythropoietin deficiency contributes to the development of anemia in diabetes. Iron therapy is usually indicated before erythropoiesis-stimulating agents to maintain hemoglobin levels. This is associated with less hospitalization and less need for blood transfusions. Treatment with empagliflozin, canagliflozin, or dapagliflozin has been observed to improve anemia in these patients.