hemoglobin

noun

he·​mo·​glo·​bin ˈhē-mə-ˌglō-bən How to pronounce hemoglobin (audio)
1
: an iron-containing respiratory pigment of vertebrate red blood cells that consists of a globin composed of four subunits each of which is linked to a heme molecule, that functions in oxygen transport to the tissues after conversion to oxygenated form in the gills or lungs, and that assists in carbon dioxide transport back to the gills or lungs after surrender of its oxygen
2
: any of numerous iron-containing respiratory pigments of various organisms (such as invertebrates and yeasts)

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When filled with oxygen, the hemoglobin in your blood is bright red; returning to the lungs without its oxygen, it loses its brightness and becomes somewhat bluish. Hemoglobin levels can change from day to day, and may be affected by such factors as a lack of iron in the diet, a recent loss of blood, and being pregnant. When you give blood, a nurse first pricks your finger to test your hemoglobin level; a low hemoglobin count indicates anemia and may mean that you shouldn't give blood that day. Mild anemia is generally of little importance, but some types can be very serious.

Examples of hemoglobin in a Sentence

Recent Examples on the Web Low values of red blood cell count, or RBC, hemoglobin, or Hb, and hematocrit, or HCT, would indicate that the patient is suffering from anemia. Brad Reisfeld, Discover Magazine, 12 Feb. 2024 More recently, a WIC nurse recommended that Missouri get her hemoglobin checked. The Enquirer, 30 Jan. 2024 Her body is making its own hemoglobin for the first time in her life. Brittany Trang, STAT, 13 Dec. 2023 The culprit is abnormal hemoglobin, the protein that carries oxygen through the body. Emily Mullin, WIRED, 8 Dec. 2023 This transforms normal adult hemoglobin (HbA) to sickle hemoglobin (HbS). Beth Mole, Ars Technica, 8 Dec. 2023 This difference depends on the diameter of the artery, the blood volume and the concentration of hemoglobin (the oxygen-carrying protein) at the measurement site. Smithsonian Magazine, 25 Oct. 2023 Iron supports hemoglobin production, an important protein in red blood cells that delivers oxygen to cells in the body. Casey Seiden, Parents, 26 Feb. 2024 Fossils resembling modern horseshoe crabs have been found as found back as far as 200 million years ago and their blue blood (caused by a copper-containing molecule where humans use hemoglobin) is used to test the safety of a wide variety of medicines. Andrew Wight, Forbes, 22 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'hemoglobin.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

International Scientific Vocabulary, short for earlier hematoglobulin

First Known Use

1869, in the meaning defined at sense 1

Time Traveler
The first known use of hemoglobin was in 1869

Dictionary Entries Near hemoglobin

Cite this Entry

“Hemoglobin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hemoglobin. Accessed 19 Mar. 2024.

Kids Definition

hemoglobin

noun
he·​mo·​glo·​bin ˈhē-mə-ˌglō-bən How to pronounce hemoglobin (audio)
: a protein that contains iron, is the chief means of transporting oxygen in the body of vertebrate animals, occurs in the red blood cells, and is able to combine loosely with oxygen in regions (as the lungs) where it is in high concentration and release it in regions (as the tissues of the internal organs) where it is in low concentration

Medical Definition

hemoglobin

noun
he·​mo·​glo·​bin
variants or chiefly British haemoglobin
1
: an iron-containing respiratory pigment of vertebrate red blood cells that functions primarily in the transport of oxygen from the lungs to the tissues of the body, that consists of four polypeptide chains of which two are of the type designated alpha and two are of one of the types designated beta, gamma, or delta and each of which is linked to a heme molecule, that combines loosely and reversibly with oxygen in the lungs or gills to form oxyhemoglobin and with carbon dioxide in the tissues to form carbaminohemoglobin, that in humans is present normally in blood to the extent of 14 to 16 grams in 100 milliliters expressed sometimes on a scale of 0 to 100 with an average normal value (as 15 grams) taken as 100, and that is determined in blood either colorimetrically or by quantitative estimation of the iron present see fetal hemoglobin, hemoglobin a compare carboxyhemoglobin, methemoglobin
2
: any of numerous iron-containing respiratory pigments of various organisms (as invertebrates and yeasts)
hemoglobinic adjective
or chiefly British haemoglobinic
hemoglobinous adjective
or chiefly British haemoglobinous

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