Complications

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.

Complications of Severe or Prolonged Anemia

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.

Certain inherited forms of anemia, including thalassemia major, pernicious anemia, and sickle-cell anemia can be life threatening. Thalassemia major and sickle-cell anemia affect children and are particularly devastating.

Effects of Anemia in Pregnant Women

Pregnant women who are anemic have an increased risk for poor pregnancy outcomes, particularly if they are anemic in the first trimester.

Complications from Anemia in Children and Adolescents

One study reported a higher incidence of ear infections in infants with iron deficiency anemia. Some experts have also identified an anemia in children that may be caused by inflammation from ear, urinary tract, and other infections.

In children, severe anemia can impair growth and motor and mental development. One small, well-conducted trial suggested that iron therapy in anemic children younger than 2 years may help reverse some of these problems. Iron deficiency in vegetarian children without anemia may cause mental impairment, but it appears to be temporary.

A long-term study reported that 11- to 15-year old children who had been severely iron-deficient during their infant years scored lower than normal children in all subjects, but particularly in written expression. They also tended to have more behavioral, general health, and emotional problems. Another study reported that teenage girls with iron deficiency, even without anemia, may have temporary memory and concentration loss.

Effects of Anemia in the Elderly

Anemia is common in older people and can have significantly more severe complications than anemia in younger adults. Some studies have reported higher mortality rates in anemic individuals 85 and older compared to their nonanemic peers. (The rates were higher in anemic men than in women.) The following are examples of its effects from different studies:

• 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. Elderly patients who are anemic for more than 2 days before heart surgery may have a greater risk for complications and death.
• Anemia may predict the development of other serious problems. In one study, 13% of elderly people with anemia developed cancer over a 10-year period compared to 5% of nonanemic individuals. Rates of infection and peptic ulcer rates were also higher in anemic patients.
• Elderly people with lower levels of hemoglobin are at an increased risk of death.
• Anemia may be associated with an increased incidence of falls.
• There may be an association between anemia and vascular dementia. This form of dementia is caused by lack of oxygen to the brain and is not related to Alzheimer's disease.

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. People with pernicious anemia, which results in an inability to absorb the vitamin, are not only at risk for neurologic damage, but also have a higher risk for stomach cancer and possibly cancer of the throat and mouth.

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 may worsen the toxicity of chemotherapy in elderly cancer patients.

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 by 30 – 60%. Patients with heart failure whose hemoglobin levels decline do worse than patients with stable levels.