MONDAY, Aug. 8 (HealthDay News) -- One in five patients who are hospitalized for heart attacks develop anemia because so much of their blood is drawn for routine diagnostic tests, researchers have found.
Often, this anemia persists for a month or more after discharge and could spell worse outcomes -- even death -- down the line, according to a study in the Aug. 8 online edition of the Archives of Internal Medicine.
"This is not just a lab abnormality," said study senior author Dr. Mikhail Kosiborod, a cardiologist with St. Luke's Hospital Mid-America Heart & Vascular Institute in Kansas City, Mo. "These patients actually feel worse after they leave the hospital. Mortality is higher, too."
People with anemia have too-low numbers of the red blood cells that carry critical oxygen to different parts of the body.
The researchers had previously found that about half of heart attack patients who are admitted to the hospital with normal red blood cell, or hemoglobin, counts actually leave with new anemia.
But the majority of these patients had no bleeding complications that could account for the condition.
That led Kosiborod and his colleagues to hypothesize that it was due to the amounts of blood drawn for routine diagnostic tests.
"Drawing blood in a hospital is typically a very common occurrence, particularly in the intensive care unit," said Kosiborod, who is also an associate professor of medicine at the University of Missouri in Kansas City.
The study authors looked at electronic medical records for almost 18,000 patients who'd had a heart attack at one of 57 U.S. hospitals.
While all had normal hemoglobin levels when they were admitted, 20 percent developed moderate-to-severe anemia by the time they left the hospital.
The risk of anemia rose 18 percent for each 50 milliliters (mL) drawn.
"That was probably somewhat mor
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