Anemia could be beneficial response to chronic disease, study says

OTTAWA, Ontario—Anemia associated with chronic diseases, such as renal failure, could be a beneficial, adaptive response to the disease rather than a negative effect of the illness, according to a study in the Aug. 12 issue of the Canadian Medical Association Journal.

Read the study here.

“The prevailing opinion is that anemia of chronic disease is an adverse consequence of systemic illness,” the authors wrote. “The general assumption is that anemia is a disorder and that patients would be better of without it.”

Instead, the authors argued that anemia of chronic disease is a beneficial and adaptive response to a patient’s disease. The authors made the following three arguments in favor of their hypothesis:

• “The observation that anemia is associated with a poor prognosis in many disorders is not sufficient reason to attribute causation.
• Anemia of chronic disease has the characteristics of an adaptive physiologic response.
• Treatment of mild to moderate anemia of chronic disease appears to increase mortality.”

“The body has adapted over thousands of years to be anemic at times of stress because it needs to conserve energy,” Ryan Zarychanski, MD, the study’s coauthor, and scientist at the Ottawa Health Research Institute, told the Ottawa Citizen on Aug. 11. “It needs help to fight infection. And when you’re anemic, bacteria doesn’t grow so well in the blood. It’s probably an evolutionary response to infection before we had antibiotics.”

In terms of renal disease, the authors say that the anemia treatment with erythropoiesis-stimulating agents (ESAs) has improved patient’s well-being and decreased the need for blood transfusions.

The kidneys create a protein called erythropoietin (EPO), which stimulates the bone marrow to create new red blood cells. This, in turn, causes the body to call on its iron stores to aid in hemoglobin production. And with kidney failure, the body loses its ability to produce EPO, which has a cascading effect on the rest of the body as fewer red blood cells are produced and causes anemia, which is often treated with ESAs.

However, the authors point to a number of studies that question the treatments safety. For example, a 2007 study in the Lancet found that ESA treatment was associated with higher mortality and increased thrombosis.

“It may be plausible that physiologic correction of the erythropoietin deficiency may be beneficial; however, pharmacologic override of anemia of chronic disease may confer harm,” the authors wrote.

In the study, the authors call for better characterization of the cause of individual patient’s anemia is future clinical trials and careful monitoring of adverse outcomes, including mortality.

“Even if anemia of chronic disease is a beneficial adaptive response, it must be recognized that any adaptive response may at time be excessive or insufficient, and thus maladaptive,” the authors wrote. “Nevertheless, we believe there is sufficient evidence to advocate restraint regarding the treatment of mild to moderate anemia of chronic disease.”