Red blood cells contain a protein known as hemoglobin, whose primary function is to carry oxygen. Oxygen bound to hemoglobin is delivered to all the tissues in the body. This oxygen is central to the execution of biochemical life processes in the cells. Anemia refers to a blood disorder in which there are insufficient number of red blood cells in the bloodstream, resulting in inadequate delivery of oxygen to tissues throughout the body. Anemia could also occur if hemoglobin levels are lower than normal.
The primary effect of anemia is hypoxia, which refers to inadequate oxygen supply to the tissues of the body. Tissues cannot function properly in hypoxic conditions. However, with time, a person may adapt to life under hypoxic conditions (for example, life at high altitudes in the mountains). The signs and symptoms of anemia are dependent on the extent of hypoxia in the body. There are different types of anemia but the effect is largely the same – the oxygen-carrying capacity of the blood is reduced. Iron-deficiency anemia is the most common type.
Read more on iron deficiency anemia.
Severity of Anemia
Depending upon the severity of hypoxia, anemia can be classified into two types.
1. Mild anemia
Mild anemia causes mild hypoxia. Therefore, the signs and symptoms of mild anemia may not be obvious to the individual who has it. Under conditions of high oxygen demand, such as during physical exertion, a person with mild anemia may notice some vague symptoms. However, these symptoms are often ignored since the body returns to normal at rest. A person with mild anemia may remain asymptomatic for a period of many months or years. Therefore, many cases of mild anemia may remain undiagnosed.
2. Severe anemia
In severe anemia, the level of hypoxia is great enough to cause adverse signs and symptoms even when the body is at rest. The signs and symptoms worsen even with a little bit of physical exertion. Normal daily tasks become difficult to execute. Even mental functioning is impaired, leading to a general feeling of lethargy.
Signs and Symptoms
The following are some of the common signs and symptoms associated with anemia.
Fatigue is the most common symptom of anemia. It is present in all cases but varies in intensity depending on the extent of the anemia.
Fatigue is a very prominent feature of severe anemia, whereas it might not be easily discernible in mild anemia. Even though fatigue is present in anemia, it is not a symptom that is specific to anemia. Fatigue is characterized by a reduction in energy, stamina and interest in daily activities. These symptoms are also present when a person is stressed, lacks physical fitness, and has a poor diet. Therefore, anemia cannot be diagnosed on the basis of fatigue alone.
Fatigue due to anemia is caused by reduced supply of oxygen to the muscles and tissues of the body. Biochemical processes that produce energy aerobically are affected adversely. Since increased physical exertion requires additional energy, the body is unable to cope with the increased demands for energy production due to lack of sufficient oxygen supply. This results in the feeling of fatigue.
The normal pinkish hue of the skin and the mucus membranes in the body is imparted by the red blood cells flowing through the capillaries in the skin. The red color of the blood is due to the hemoglobin protein. Lack of sufficient red blood cells in anemia results in paleness of the skin and the mucus membranes.
During exercise, the skin may even start displaying a bluish hue (a condition known as cyanosis) due to the presence of severely deoxygenated blood in the capillaries. Apart from the skin, the paleness may also be visible in the sclera (white part) of the eyes, inside surface of the mouth, fingernails and toenails.
Shortness of breath
The low oxygen carrying capacity of the blood in anemia can also cause shortness of breath (technically known as dyspnea). During dyspnea, a person may have rapid yet shallow breathing. This is caused by the body’s effort to increase the oxygen supply to the muscles and tissues of the body. However, due to the low hemoglobin levels in anemia, oxygen supply to the tissues may remain insufficient despite the rapid breathing pattern. This is especially the case with severe anemia or increased physical activity.
Rapid or irregular heartbeat
In order to compensate for hypoxia in anemia, the heart starts pumping blood faster in an attempt to increase the blood flow and the oxygen supply to the tissues. In adults, the heart rate may even exceed 100 beats per minute, a condition referred to as tachycardia. As the heart attempts to circulate blood faster by beating faster and harder, the rhythm of the heartbeat starts getting affected. Irregular heartbeats, especially during physical exertion, may occur in anemia.
Low blood pressure
Due to decrease in the number of red blood cells in anemia, the viscosity of the blood decreases. This leads to decrease in peripheral resistance to blood flow, resulting in low blood pressure. Low blood pressure in anemia may not be compensated by increased heart rate.
Headaches may occur in anemia due to many different reasons. The headache may be due to pain in the arteries that are supplying blood to the brain. These arteries are sensitive to low blood pressure and low oxygen state. Due to lack of sufficient oxygen, the muscles may also go into spasm. When the muscles of the head and neck region are affected this way, tension-headache might occur.
Dizziness in anemia is caused by a lack of sufficient oxygen supply to the brain. People suffering from anemia may experience dizziness when indulging in moderate to severe physical activity. In some severe cases of anemia, dizziness may occur constantly. Fainting may also occur if the body is unable to meet the its oxygen demands.
Anemia does not affect only physical functions of the body. Mental faculties are also affected adversely. This is not surprising because a large chunk of the oxygen supply from blood is used by the brain. People suffering from anemia may report difficulty in remembering things and in executing tasks requiring mental effort. It is important to note that learning difficulties and psychiatric disorders may also produce similar symptoms.
In an attempt to increase oxygen supply to the tissues, peripheral vasodilation occurs in anemia. This leads to heat loss from the peripheral parts of the body, such as the fingers and the toes. In cold conditions, severe vasoconstriction may occur in the peripheral circulatory system to conserve body heat. This may lead to the fingers and toes becoming very cold.
Other signs and symptoms
Other signs and symptoms that may be reported in anemia include chest pain, nausea, constipation, tingling or numbness in hands and feet, hair loss, loss of sexual desire, mood swings, anxiety, irritability, depression, sweaty hands and feet, brittle nails, and difficulty in gaining weight.