Most cases of anemia are mild, including those that occur as a result of chronic disease. Nevertheless, even mild anemia can reduce oxygen transport in the blood, causing fatigue and a diminished physical capacity. Moderate-to-severe iron-deficiency anemia is known to reduce endurance. Some studies indicate that even iron deficiency without anemia can produce a subtle but still lower capacity for exercise.
Because a reduction in red blood cells decreases the ability to absorb oxygen from the lungs, serious problems can occur in prolonged and severe anemia that is not treated. Anemia can lead to secondary organ dysfunction or damage, including heart arrhythmia and heart failure.
Effects of Anemia in Pregnant Women
Pregnant women with significant anemia may have an increased risk for poor pregnancy outcomes, particularly if they are anemic in the first trimester. Mild-to-moderate anemia does not pose any increased risk.
Complications from Anemia in Children and Adolescents
In children, severe anemia can impair growth and motor and mental development. Children may exhibit a shortened attention span and decreased alertness. Children with severe iron-deficiency anemia may also have an increased risk for stroke.
Effects of Anemia in the Elderly
Anemia is common in older people and can have significantly more severe complications than anemia in younger adults. Effects of anemia in the elderly include decreased strength and increased risk for falls. Anemia may have adverse effects on the heart and increase the severity of cardiac conditions, including reducing survival rates from heart failure and heart attacks. Even mild anemia may possibly lead to cognitive impairment or worsen existing dementia.
Effects of Vitamin B12 Deficiencies and Pernicious Anemia
In addition to anemia, vitamin B12 deficiency can cause neurologic damage, which can be irreversible if it continues for long periods without treatment.
Anemia in Patients with Cancer
Anemia is particularly serious in cancer patients. In people with many common cancers, the presence of anemia is associated with a shorter survival time.
Anemia in Patients with Kidney Disease
Anemia is associated with higher mortality rates and possibly heart disease in patients with kidney disease.
Anemia in Patients with Heart Failure
The combination of anemia and heart failure can increase the risk of hospitalization or death. Patients with heart failure whose hemoglobin levels decline do worse than patients with stable levels.
Effects of Excess Iron
Patients with certain types of anemia need frequent blood transfusions. These transfusions can cause iron overload. [For more information, see "Transfusions" in Treatment section of this report.]
Review Date: 01/13/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.