he·​mo·​glo·​bin | \ ˈhē-mə-ˌglō-bən How to pronounce hemoglobin (audio) \

Definition of hemoglobin

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 Instead, blood donation staff commonly measure hemoglobin levels, which determine whether a person is anemic or not. Brittany Trang, STAT, 21 Sep. 2022 The next parameter is tissue oxygenation in the leg muscles, as measured with near-infrared spectroscopy, which basically involves shining infrared light through the skin and measuring how much is absorbed by oxygen-rich hemoglobin. Alex Hutchinson, Outside Online, 25 Nov. 2020 Since iron is an important component of hemoglobin, iron loss often accompanies a lot of bleeding. Jason Karp, Outside Online, 14 Mar. 2014 These diseases impair hemoglobin, a protein in red blood cells that carries oxygen. New York Times, 27 June 2022 Sickle cell disease is caused by a mutation in the gene for hemoglobin, an oxygen-carrying protein in the blood. Ryan Cross, BostonGlobe.com, 28 June 2022 By the spring of 2019, her hemoglobin level was back to normal. Beth Bragg, Anchorage Daily News, 10 Sep. 2021 When chemotherapy during an arduous battle with leukemia destroyed much of her platelets and hemoglobin in 2019, transfusions helped replace the proteins needed to carry oxygen throughout her body. Abigail Hasebroock, Orlando Sentinel, 20 June 2022 In truth, the Teichmann Test had been in use since 1853, a conclusive test based on microcrystal formation in reaction to hemoglobin. Roy Schwartz, CNN, 20 May 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'hemoglobin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of hemoglobin

1869, in the meaning defined at sense 1

History and Etymology for hemoglobin

International Scientific Vocabulary, short for earlier hematoglobulin

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Time Traveler for hemoglobin

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The first known use of hemoglobin was in 1869

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Dictionary Entries Near hemoglobin



hemoglobin A

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Statistics for hemoglobin

Last Updated

28 Sep 2022

Cite this Entry

“Hemoglobin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hemoglobin. Accessed 1 Oct. 2022.

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More Definitions for hemoglobin


he·​mo·​glo·​bin | \ ˈhē-mə-ˌglō-bən How to pronounce hemoglobin (audio) \

Kids Definition of hemoglobin

: a protein of red blood cells that contains iron and carries oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs


variants: or chiefly British haemoglobin \ ˈhē-​mə-​ˌglō-​bən How to pronounce hemoglobin (audio) \

Medical Definition of hemoglobin

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)

Other Words from hemoglobin

hemoglobinic or chiefly British haemoglobinic \ ˌhē-​mə-​glō-​ˈbin-​ik How to pronounce hemoglobin (audio) \ adjective
hemoglobinous or chiefly British haemoglobinous \ -​ˈglō-​bə-​nəs How to pronounce hemoglobin (audio) \ adjective

More from Merriam-Webster on hemoglobin

Nglish: Translation of hemoglobin for Spanish Speakers

Britannica English: Translation of hemoglobin for Arabic Speakers

Britannica.com: Encyclopedia article about hemoglobin


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