A hemoglobin assay, often called a hemoglobin test, is a routine blood examination that measures the amount of hemoglobin in your blood. This test is typically performed as part of a complete blood count (CBC), which assesses various components of your blood. It serves as a fundamental diagnostic tool, offering insights into your overall health and helping to screen for a range of conditions.
Understanding Hemoglobin Assays
Hemoglobin is an iron-containing protein located within your red blood cells, giving blood its characteristic red color. Its primary role involves binding to oxygen in the lungs and transporting it to tissues and organs throughout the body, which then use oxygen for cellular metabolism and energy production. Hemoglobin also carries carbon dioxide, a waste product, from the body’s tissues back to the lungs to be exhaled.
A hemoglobin assay is performed for various reasons, including routine health check-ups. It helps evaluate symptoms such as fatigue, weakness, dizziness, or shortness of breath, which may suggest conditions like anemia. The test can also monitor existing medical conditions, such as chronic kidney disease or certain cancers, or assess the effectiveness of treatments.
The procedure for a hemoglobin assay involves drawing a blood sample. For adults and older children, blood is collected from a vein in the arm or hand. The healthcare professional cleans the skin, applies an elastic band, and inserts a small needle to collect the blood. For infants, a small blood sample may be taken from a heel stick. The process takes less than five minutes.
What Hemoglobin Assay Results Indicate
Hemoglobin levels are reported in grams per deciliter (g/dL) or grams per liter (g/L). Normal ranges can vary slightly depending on the laboratory, age, sex, and other factors. For adult males, a range is 13.8 to 17.2 g/dL, while for adult females, it is 12.1 to 15.1 g/dL. Newborns have higher levels (14-24 g/dL), which decrease in infants (9.5-13 g/dL).
Low hemoglobin levels, known as anemia, mean your body may not be getting enough oxygen. This can lead to symptoms like fatigue, weakness, pale skin, dizziness, and cold hands and feet. Common causes include iron deficiency, vitamin B12 and folate deficiencies, chronic diseases (e.g., kidney disease, cancer), and blood loss (e.g., injuries, heavy menstrual periods, gastrointestinal bleeding).
Conversely, high hemoglobin levels can indicate an underlying health issue. This can result from the body needing more oxygen, such as living at high altitudes or smoking. Certain medical conditions, such as polycythemia vera (a bone marrow disorder), chronic lung diseases (e.g., COPD, emphysema), heart failure, and severe dehydration, can also lead to elevated hemoglobin. While high levels may not always cause symptoms, they can lead to headaches, dizziness, fatigue, and an increased risk of blood clots.
It is important to distinguish a standard hemoglobin assay from a hemoglobin A1c test. The hemoglobin A1c test measures the percentage of hemoglobin in red blood cells that is coated with glucose, providing an average blood sugar level over the past two to three months. This test is specifically used to screen for and diagnose prediabetes and type 2 diabetes, and to monitor blood sugar control in individuals with diabetes. Unlike a general hemoglobin test that assesses oxygen-carrying capacity, the A1c test focuses on glucose attachment to hemoglobin, and the two tests serve different diagnostic purposes.