Hemoglobin, often abbreviated as HGB, is a protein within your red blood cells. It is composed of a component called heme, which binds to oxygen. This protein is rich in iron, a mineral that gives blood its characteristic red color. Hemoglobin makes up a significant portion of the dry weight of a red blood cell, constituting about 96% of it.
The Role of Hemoglobin in the Body
The primary responsibility of hemoglobin is to transport gases throughout the body. In the lungs, where oxygen concentration is high, hemoglobin molecules bind to oxygen. Each hemoglobin molecule can carry up to four oxygen molecules, which increases the blood’s oxygen-carrying capacity up to seventy times. This oxygen-rich blood is then circulated to all tissues and organs, providing fuel for metabolic processes.
This process is an efficient delivery service. After hemoglobin delivers oxygen to the cells, it does not return empty-handed. It picks up a portion of the cellular waste product, carbon dioxide, and transports it back to the lungs to be removed from the body when you exhale.
Understanding Hemoglobin Test Results
Hemoglobin levels are measured with a blood test, frequently included as part of a Complete Blood Count (CBC). The test determines the amount of hemoglobin in your blood, expressed in grams per deciliter (g/dL). These results are compared against established reference ranges to assess whether your levels are healthy, though these ranges can vary slightly between laboratories.
For adult males, a normal hemoglobin range is between 13.2 and 16.6 g/dL. For adult, non-pregnant females, the normal range is from 11.6 to 15 g/dL. These values can differ based on age, with healthy ranges for children being lower than for adults, and a slight decrease is often observed after middle age.
Pregnancy also affects normal hemoglobin levels due to a significant increase in the body’s blood volume to support the fetus. For individuals in their first and third trimesters, a hemoglobin level of 11 g/dL or higher is considered normal. During the second trimester, this value adjusts to 10.5 g/dL or higher.
Implications of Low Hemoglobin
When hemoglobin levels fall below the normal range, it can lead to a condition known as anemia. This means the blood has a reduced ability to carry oxygen to the body’s tissues. The lack of adequate oxygen supply causes the common symptoms, which often include persistent fatigue, weakness, shortness of breath, dizziness, and pale skin.
Several factors can cause hemoglobin levels to drop, including:
- A deficiency in nutrients needed for red blood cell production, such as iron, vitamin B12, or folate.
- Blood loss, which can be acute from an injury or chronic from conditions like stomach ulcers or heavy menstrual periods.
- Certain chronic diseases, such as kidney disease or cancer.
- Bone marrow disorders that impair the body’s ability to produce enough healthy red blood cells.
Other potential signs might include headaches, cold hands and feet, or an unusual desire to eat non-food items, a condition known as pica. If you experience these symptoms, consulting a healthcare provider is recommended to identify the underlying cause.
Implications of High Hemoglobin
Elevated hemoglobin levels indicate an excess of red blood cells in the blood, a condition called polycythemia. This abundance of red blood cells causes the blood to become thicker than normal. The increased thickness can slow down blood flow and raises the risk of developing blood clots, which could lead to serious health issues like a stroke.
Several situations can lead to a high hemoglobin count. Dehydration is a common, temporary cause, as the reduced fluid volume in the blood makes the red cell concentration appear higher. Living at high altitudes can also prompt the body to produce more red blood cells to compensate for less oxygen in the air. Lifestyle factors, such as cigarette smoking, can also result in elevated levels.
Underlying medical conditions are another source of high hemoglobin, including lung diseases like COPD or certain heart conditions. In some cases, a rare bone marrow disorder called polycythemia vera directly causes the overproduction of red blood cells. Symptoms of high hemoglobin may include headaches, dizziness, and excessive sweating.