Total Hemoglobin: What High and Low Levels Mean

Hemoglobin is a protein produced by bone marrow and stored within red blood cells. A “total hemoglobin” measurement quantifies the amount of this protein in the blood, expressed in grams per deciliter (g/dL). This value is an important indicator of a person’s overall health.

The Function of Hemoglobin

The primary role of hemoglobin is to carry oxygen from the lungs to all the body’s tissues and organs. This function is enabled by its structure, which consists of a protein called globin and a compound called heme, which holds iron. This iron component binds to oxygen in the lungs, where oxygen levels are high.

After releasing oxygen to the body’s cells, hemoglobin picks up carbon dioxide, a waste product of metabolic processes. Hemoglobin transports the carbon dioxide back to the lungs, where it is removed from the body through exhalation. This protein also gives red blood cells their characteristic color.

How Total Hemoglobin is Measured

The total hemoglobin level is measured as part of a standard blood test known as a complete blood count, or CBC. A healthcare provider will order a CBC for routine check-ups or to diagnose and monitor health conditions. The procedure involves a blood draw, where a sample is typically taken from a vein in the arm.

In the laboratory, the blood sample is mixed with a solution containing cyanide, which binds tightly to the hemoglobin molecules. By shining a light through the resulting mixture and measuring the amount of light absorbed, technicians can accurately determine the concentration of hemoglobin in the blood.

Normal Hemoglobin Ranges

Normal hemoglobin ranges vary based on age and sex. The range for adult males is 13.8 to 17.2 g/dL, while for adult females, it is 12.1 to 15.1 g/dL. These values can differ slightly between laboratories, so it is important to consult the specific reference range provided by the lab that performed the test.

Pregnancy can also affect hemoglobin levels, and a result greater than 11 g/dL is often considered normal for pregnant individuals. Normal ranges for children also change significantly with age. Newborns have the highest levels (14-24 g/dL), which stabilize as they approach adulthood.

Causes and Symptoms of Low Hemoglobin

A lower-than-normal hemoglobin level is known as anemia, which means the blood has a reduced oxygen-carrying capacity. Common causes include nutritional deficiencies like a lack of iron, vitamin B12, or folate. Chronic blood loss from conditions such as stomach ulcers or heavy menstrual periods, and certain chronic illnesses like kidney disease or lupus, can also cause anemia.

The symptoms of low hemoglobin are related to the body’s tissues not receiving enough oxygen. Fatigue and weakness are the most common complaints. Other signs include:

• Pale skin
• Shortness of breath during physical activity
• Dizziness or lightheadedness
• Cold hands and feet
• Headaches or problems with concentration

Causes and Symptoms of High Hemoglobin

High hemoglobin can occur when the body produces too many red blood cells (erythrocytosis) or when blood becomes concentrated. Dehydration is a frequent cause, as reduced fluid volume makes hemoglobin appear more concentrated. Living at high altitudes can also prompt the body to produce more hemoglobin to improve oxygen delivery. Other causes include smoking, chronic lung diseases like COPD, and heart conditions. In rarer cases, a bone marrow disorder called polycythemia vera causes the body to overproduce red blood cells.

The symptoms of high hemoglobin are often subtle. They can include headaches, dizziness, a flushed or reddish complexion, and itchiness, particularly after a warm bath.