Hemoglobin is a protein found within red blood cells, which are responsible for transporting substances throughout the body. This protein is what gives red blood cells their characteristic color. One can think of hemoglobin as a highly specialized delivery service, ensuring that various parts of the body receive what they need to operate.
Hemoglobin’s Primary Function
Hemoglobin plays a dual role in the body’s gas exchange. In the lungs, hemoglobin efficiently picks up oxygen, where it binds to the iron atom located within each of its four heme groups. Each hemoglobin molecule has the capacity to bind up to four oxygen molecules.
Once oxygenated, the hemoglobin molecules travel through the bloodstream to various tissues and organs, releasing oxygen where it is needed for cellular metabolism. After delivering oxygen, hemoglobin then collects carbon dioxide, a waste product generated by the body’s cells. This carbon dioxide binds to the globin protein part of hemoglobin. The hemoglobin then transports this carbon dioxide back to the lungs, completing the cycle of gas exchange.
Normal Hemoglobin Levels
Measuring hemoglobin levels is a common part of a complete blood count (CBC). These levels are expressed in grams per deciliter (g/dL) of blood. Normal ranges can vary based on factors like age, biological sex, and environmental conditions such as living at high altitudes.
For adult males, a hemoglobin range is between 13.5 to 17.5 g/dL. Non-pregnant adult females have levels ranging from 12.0 to 15.5 g/dL. Children’s normal hemoglobin levels vary more widely by age, with a general range for those aged 2-12 years being between 11.0 and 13.5 g/dL, though infants and teenagers have different specific ranges. These figures serve as a general guide.
Issues with Low and High Hemoglobin
When hemoglobin levels fall below the normal range, a condition known as anemia can occur. Common causes of low hemoglobin include insufficient iron intake, which is necessary for hemoglobin production. Deficiencies in vitamins like B12 and folate can also impair red blood cell formation, leading to lower hemoglobin. Chronic diseases and ongoing blood loss, such as from heavy menstrual periods or internal bleeding, are additional contributors to anemia. Symptoms of low hemoglobin often include persistent fatigue, shortness of breath, pale skin, and dizziness.
Conversely, an unusually high hemoglobin count, sometimes referred to as polycythemia. This can cause the blood to thicken, making circulation more challenging. Potential causes for elevated hemoglobin include dehydration, as a reduced plasma volume concentrates the blood. Living at high altitudes can also lead to higher hemoglobin as the body produces more red blood cells to compensate for lower oxygen availability. Smoking and certain underlying medical conditions, such as chronic lung diseases or bone marrow disorders like polycythemia vera, can also result in elevated hemoglobin levels. Individuals with high hemoglobin may experience headaches, blurred vision, and dizziness.
Inherited Hemoglobin Conditions
Some conditions affecting hemoglobin are inherited. These are broadly categorized as hemoglobinopathies. Unlike acquired low or high levels, these conditions are present from birth due to specific gene defects.
One such condition is Sickle Cell Anemia, where a single amino acid error causes the hemoglobin molecules to form rigid, crescent or “sickle” shapes. These misshapen red blood cells are less flexible and can obstruct small blood vessels, hindering oxygen delivery and causing pain and organ damage. Another inherited condition is Thalassemia, which involves reduced or absent production of one of the globin chains that make up hemoglobin. This leads to fewer healthy red blood cells and can result in varying degrees of anemia.