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Hemoglobin facts for kids

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1GZX Haemoglobin
Structure of human hemoglobin.
The α and β subunits are in red and blue.
The iron-containing heme groups in green

Hemoglobin is a protein found in red blood cells that is responsible for carrying oxygen throughout the body. It is composed of a protein called heme, which binds to oxygen. Hemoglobin levels are measured in a blood test and are expressed in grams per deciliter (g/dl). Normal levels of hemoglobin in the blood are 12 to 18 g/dl for males and 12 to 16 g/dl for females.

Low hemoglobin levels can be a sign of various health conditions, including anemia and cancer. Symptoms of low hemoglobin levels may include fatigue, weakness, and dizziness. The underlying cause of low hemoglobin levels can be diagnosed through medical tests, and treatment depends on the specific condition causing the decrease in hemoglobin

Structure

The most common type of hemoglobin in mammals contains four such subunits. Each subunit of hemoglobin is a globular protein (globin) with a heme group inside it. Each heme group has one iron atom. This binds one oxygen molecule. So the complete hemoglobin molecule has four globin chains, four heme molecules, and four iron atoms. When hemoglobin is in the lungs, it picks up oxygen in its hemes, and carries it to the rest of the body.

Its structure took years to work out. Max Perutz and John Kendrew worked out the structure of myoglobin first. That muscle globin is smaller, with only one heme group.

Diagnostic uses

Hemoglobin Test American Red Cross
A hemoglobin concentration measurement being administered before a blood donation at the American Red Cross Boston Blood Donation Center.

Hemoglobin concentration measurement is among the most commonly performed blood tests, usually as part of a complete blood count. For example, it is typically tested before or after blood donation. Results are reported in g/L, g/dL or mol/L. 1 g/dL equals about 0.6206 mmol/L. Normal levels are:

  • Men: 13.8 to 18.0 g/dL (138 to 180 g/L, or 8.56 to 11.17 mmol/L)
  • Women: 12.1 to 15.1 g/dL (121 to 151 g/L, or 7.51 to 9.37 mmol/L)
  • Children: 11 to 16 g/dL (110 to 160 g/L, or 6.83 to 9.93 mmol/L)
  • Pregnant women: 11 to 14 g/dL (110 to 140 g/L, or 6.83 to 8.69 mmol/L) (9.5 to 15 usual value during pregnancy)

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See also

Kids robot.svg In Spanish: Hemoglobina para niños

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