You received a form with the letters HGB and a number next to them. Or you heard the word "hemoglobin" from a doctor and want to understand what it means. Let's go through it step by step and without unnecessary terms.
Hemoglobin: what it is
It is a protein rich in iron. It is found in erythrocytes — red blood cells. It has one job, but everything else depends on it.
Hemoglobin carries oxygen from the lungs to the tissues. Cells need oxygen to grow, divide, and give you energy.
The molecule is large, with a mass of about 66.8 kDa. Inside are four subunits, each with its own heme group. Each heme contains one iron atom. It is this atom that binds oxygen.
Hemoglobin in erythrocytes: how it works
The bond with oxygen is reversible. In the lungs, where there is a lot of oxygen, the protein captures it. In the tissues, where there is little oxygen, it releases it.
One hemoglobin molecule carries up to 4 oxygen molecules. One gram of hemoglobin transports up to 1.331 milliliters of oxygen. Across the whole blood volume, this is enough for tissue respiration.
In adults, the main form is hemoglobin A. The alpha chains are encoded by the HBA1 and HBA2 genes, and the beta chain by the HBB gene. Mutations in these genes cause hemoglobinopathies. The best known are sickle cell anemia and thalassemia.
How hemoglobin is designated in a test: HGB and Hb
On the form, hemoglobin is labeled with Latin letters. Most often this is Hb or HGB. Sometimes the designation H&H is also found.
Units of measurement and the reference interval are printed next to it. Do not compare your number with someone else's from the internet. The normal range depends on the laboratory, age, sex, and even race.
Blood test for hemoglobin: what it shows
The test measures the level of hemoglobin in the blood. It is usually done as part of a complete blood count. This is a set of tests: the number and types of blood cells are counted.
Do not confuse this test with glycated hemoglobin A1C. A1C shows the average glucose level. These are different tests.
Blood is drawn from a vein in the arm with a thin needle. The procedure takes less than five minutes. No preparation is needed unless the doctor has ordered other fasting tests.
It is ordered in the following cases:
- routine health check;
- weakness, dizziness, cold hands and feet;
- hereditary blood diseases in the family — thalassemia, sickle cell anemia;
- a diet lacking iron and other minerals;
- a long-lasting infection or major blood loss after trauma and surgery.
The result itself does not name the cause of the deviation. But it shows how pronounced the problem is. Next, the doctor looks at symptoms, medical history, and other indicators.
What a hemoglobin deviation from normal means
A low level occurs in anemia. There are many causes: different types of anemia, thalassemia, iron deficiency, liver disease, oncological diseases. Also blood loss — after trauma or with heavy periods. And a lack of iron or vitamin B-12 in the diet.
A high level also occurs. It is associated with lung and heart diseases. With polycythemia vera, when the bone marrow makes too many erythrocytes. With sleep apnea, when breathing stops for short periods.
Sometimes the number goes beyond the normal range without disease. In high-altitude residents, hemoglobin is higher. Diet, activity, medications, dehydration, smoking, and hereditary characteristics also have an effect.
Iron deficiency anemia is the most common type of anemia. Its causes are heavy periods and pregnancy. Another common cause is bleeding in the stomach and intestines. It is caused by NSAID painkillers, stomach ulcers, inflammation of the intestines or esophagus, and hemorrhoids.
Without treatment, such anemia increases the risk of infections. The risk of heart and lung complications grows. For example, rapid heartbeat or heart failure. In pregnant women, there is a greater risk of complications before and after childbirth.
When to see a doctor because of hemoglobin
A reason for a visit is signs of anemia. Fatigue and lack of energy, shortness of breath, noticeable heartbeat. Skin paler than usual, and headaches may occur.
Less often there is ringing in the ears, a strange taste of food, itching, a painful tongue, and hair loss. A craving for non-food items — paper or ice. Difficulty swallowing, and sores appear at the corners of the mouth. Nails become concave, and the legs become restless.
The doctor will ask about lifestyle and past illnesses. Usually they will order a complete blood count. If the cause is unclear, they will test the blood in stool with a FIT test. Or refer you to a specialist.
A hemoglobin deviation by itself is not a reason to call an ambulance. 103 or 112 — for a life-threatening condition, for example signs of stroke or heart attack.
Show the form to a doctor and discuss the result with them. The material is for reference and does not replace a doctor's consultation.
Sources
Update history
Reader reviews
No reviews yet — tell us whether this article was helpful.
Leave a review
This content is for reference and does not replace a doctor's consultation. Medical disclaimer