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General Practice 2023

High or low hemoglobin: what it means and reference valuesê

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High or low hemoglobin: what it means and reference valuesê
High or low hemoglobin: what it means and reference valuesê

Hemoglobin, or Hb, is a component of red blood cells and its main function is to transport oxygen to the tissues. Hb is constituted by 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 greater concentration in the blood;
  • HbA2, which is made up of two alpha chains and two delta chains;
  • HbF, which is formed by two alpha chains and two gamma chains and is present in greater concentration in newborns, with its concentration decreasing according to development.

In addition to these main types, there is still Hb Gower I, Gower II and Portland, which are present during embryonic life, with a decrease in their concentration and an increase in HbF as birth approaches.

Red blood cells that carry hemoglobin

Red blood cells that carry hemoglobin

There are still some variant or abnormal hemoglobins that may be present due to structural or functional changes in hemoglobin, which 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 verify the possibility of diseases related to hemoglobin synthesis. Understand how hemoglobin electrophoresis is performed.

The concentration of hemoglobin in the red blood cell can be measured by means of a conventional blood test, the hemogram, or by means of a rapid measuring device, similar to the diabetes device.According to the amount of hemoglobin present in the red blood cell and the results of other hematological tests, it is possible to know the general state of he alth of the person.

Hemoglobin Reference Values

Hemoglobin reference values ​​are:

  • Children aged 2 to 6: 11.5 to 13.5 g/dL;
  • Children aged 6 to 12: 11.5 to 15.5 g/dL;
  • Men: 14 to 18 g/dL;
  • Women: 12 to 16 g/dL;
  • Pregnant: 11 g/dL.

These values ​​may vary between clinical analysis laboratories.

What can high hemoglobin be

High hemoglobin in the blood can be caused by:

  • Tobacco use;
  • Dehydration;
  • Lung emphysema;
  • Pulmonary fibrosis;
  • Polycythemia;
  • Kidney tumor;
  • Use of anabolic steroids or the hormone erythropoietin.

High hemoglobin is characterized by symptoms such as dizziness, bluish skin on the lips and fingertips, and, in rarer cases, temporary loss of vision and hearing.

Causes of low hemoglobin

The decrease in the amount of hemoglobin can happen in case of anemia, cirrhosis, lymphoma, leukemia, hypothyroidism, renal failure, thalassemia, porphyria and hemorrhage, for example. In addition, low hemoglobin can also happen due to iron and vitamin deficiency, in addition to the use of drugs to treat cancer and AIDS, for example.

A low number of hemoglobin in the blood can cause symptoms such as frequent tiredness, shortness of breath and pallor, and the cause should be identified and treatment started according to medical advice.

If you have recently had a blood test and want to know what it could mean, enter your details below:

Glycated hemoglobin

Glycated hemoglobin, also called glycosylated hemoglobin, is a diagnostic test that aims to check the amount of medical glucose in the blood for 3 months, being very suitable for diagnosis and monitoring of diabetes, as well as evaluation of its gravity.

The normal value of glycated hemoglobin is 5.7% and the confirmation of diabetes is made when the value is equal to or greater than 6.5%. Learn more about glycated hemoglobin.

Hemoglobin in urine

The presence of hemoglobin in the urine is called hemoglobinuria and is usually indicative of kidney infection, malaria or lead poisoning, for example. The identification of hemoglobin in the urine is done through a simple urine test, called EAS.

In addition to hemoglobin, hematocrit values ​​also indicate blood changes such as anemia and leukemia. See what the hematocrit is and how to understand its result.

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