Hemoglobin

Hemoglobin or haemoglobin (frequently abbreviated as Hb, {{PDB|1A3N}}) is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. The molecule consists of globin, the apoprotein, and four heme (or haem) groups, which are organic molecules with an iron atom in each.

Role in disease

Decreased levels of hemoglobin, with or without an absolute decrease of red blood cells, leads to symptoms of anemia. Anemia has many different causes, although iron deficiency and its resultant iron deficiency anemia are the most common causes in the Western world. As absence of iron decreases heme synthesis, red blood cells in iron deficiency anemia are hypochromic (lacking the red hemoglobin pigment) and microcytic (smaller than normal). Other anemias are rarer. In hemolysis (accelerated breakdown of red blood cells), associated jaundice is caused by the hemoglobin metabolite bilirubin, and the circulating hemoglobin can cause renal failure.

Related Topics:
Red blood cell - Anemia - Iron deficiency - Iron deficiency anemia - Heme - Hemolysis - Jaundice - Bilirubin - Renal failure

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Mutations in the globin chain are associated with the haemoglobinopathies, such as Sickle-cell disease and thalassemia.

Related Topics:
Haemoglobinopathies - Thalassemia

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There is a group of genetic disorders, known as the porphyrias that

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are characterized by errors in metabolic pathways of heme synthesis.

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King George III of the United Kingdom was probably the most famous porphyria sufferer.

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To a small extent, hemoglobin A slowly combines with glucose at a certain location in the molecule. The resulting molecule is often referred to as Hb A1c. As the concentration of glucose in the blood increases, the percentage of Hb A that turns into Hb A1c increases. In diabetics whose glucose usually runs high, the percent Hb A1c also runs high. Because of the slow rate of Hb A combination with glucose, the Hb A1c percentage is representative of glucose level in the blood averaged over a longer time, such as weeks or months.

Related Topics:
Glucose - '''Hb A_1c''' - Concentration - Diabetics

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