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 Sickle cell is caused by a mutation in a gene that carries instructions to make hemoglobin, the molecule found inside red blood cells that carries oxygen throughout the human body. Julie Washington, cleveland, 16 June 2021 The therapy, jointly developed by Vertex Pharmaceuticals and CRISPR Therapeutics, is designed to treat sickle cell disease and beta-thalassemia by boosting the body’s production of hemoglobin. Damian Garde, STAT, 12 June 2021 Sickle cell disease and beta thalassemia interfere with how hemoglobin carries oxygen in the body, and usually considerably shorten the lives of patients who have them. BostonGlobe.com, 20 Apr. 2021 Her research published in the British Journal of Sports Medicine in March show that hemoglobin levels in transgender women fall to levels in line with cisgender women in the space of three to four months on average. Scott Gleeson, USA TODAY, 9 June 2021 Four atoms of iron help form the molecule hemoglobin, the protein in a red blood cell that stores and transports oxygen. Sharman Apt Russell, Scientific American, 20 May 2021 He had been hospitalized twice for low hemoglobin levels, and was awaiting results from a coronavirus test. BostonGlobe.com, 1 Jan. 2021 Dan Oren, a professor of psychiatry at Yale who credits Cook with pioneering light therapy, points to the quasi-identical molecular structures of the light-catching parts of chlorophyll and of hemoglobin. Julian Sancton, Time, 12 May 2021 Most doctors use the hemoglobin A1C test, which looks at the blood sugar over the past couple of months, rather than a fasting blood glucose, which will not become abnormal until the diabetes is considerably more advanced. Dr. Keith Roach, oregonlive, 8 Apr. 2021

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.

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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

Time Traveler

The first known use of hemoglobin was in 1869

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Statistics for hemoglobin

Last Updated

6 Jul 2021

Cite this Entry

“Hemoglobin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hemoglobin. Accessed 25 Jul. 2021.

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More Definitions for hemoglobin



English Language Learners Definition of hemoglobin

technical : the part of blood that contains iron, carries oxygen through the body, and gives blood its red color


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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