Hemoglobin, or Hb, is a component of red blood cells and has the primary function of transporting oxygen to the tissues and organs of the body. Hb consists of the heme group, which is formed by iron, and globin chains, which can be alpha, beta, gamma or delta, resulting in the main types of hemoglobin, such as:
- HbA1, which is formed by two alpha chains and two beta chains and is present in higher concentration in the blood;
- HbA2, which is formed by two alpha chains and two delta chains;
- HbF, which is formed by two alpha chains and two gamma chains and is present in higher concentrations in newborns, but its concentration decreases along with the baby's growth.
In addition to these major types, there are still Hb Gower I, Gower II and Portland, which are present during embryonic life. As birth approaches they decrease in concentration and there is an increase in HbF.
There are also some variant or abnormal hemoglobins that may be present due to structural or functional changes in hemoglobin, and may indicate some diseases, such as sickle cell anemia and thalassemia, for example. Therefore, it is important to perform hemoglobin electrophoresis, in addition to other tests, to check the possibility of hemoglobin synthesis related diseases.
The concentration of hemoglobin in the red blood cells can be measured by a conventional blood test, blood count, or by means of a rapid measuring device similar to the diabetes apparatus. According to the amount of hemoglobin present in the erythrocyte and with the result of the other hematological examinations, it is possible to know the general state of a person's health.
Reference range for hemoglobin
The hemoglobin reference ranges are:
- Children from 2 to 6 years old: 11.5 to 13.5 g / dL;
- Children from 6 to 12 years old: 11.5 to 15.5 g / dL;
- Men: 14 to 18 g / dL;
- Women: 12 to 16 g / dL;
- Pregnant women: 11 g / dL.
These values may vary between clinical laboratories.
Causes for low hemoglobin
Low hemoglobin can indicate various problems like:
- Renal insufficiency;
- Iron and vitamin deficiency;
- Medications to treat cancer and AIDS.
A low hemoglobin count in the blood can cause symptoms such as frequent tiredness, shortness of breath and pallor, and the cause must be identified and treatment should be done following medical recommendation.
Causes for high hemoglobin
High hemoglobin can be caused by:
- Use of tobacco;
- Pulmonary emphysema;
- Pulmonary fibrosis;
- Kidney tumor;
- Use of anabolic or hormone erythropoietin.
High hemoglobin is characterized by symptoms such as dizziness, bluish-colored skin on the lips and fingertips, and in rare cases, temporary loss of vision and hearing.
Glycated hemoglobin can be used to diagnose diabetes and evaluate the severity of this disease, but it is more commonly used to evaluate the effectiveness of the treatment of diabetes. So, it can be used after the treatment has been implemented for 3 months to see if it is necessary to do adjustments. This type of hemoglobin is identified through a blood test and it's normal reference range is up to 5.7%.
Hemoglobin in the urine
Hemoglobin in the urine, or hemoglobinuria, can be detected by a urine test and can indicate problems such as kidney infection, malaria or lead poisoning, for example.
In addition to hemoglobin, hematocrit values also indicate changes in blood such as anemia and leukemia. See what is a hematocrit and how to interpret the result.