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class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Common causes of elevated methemoglobin</span> </div> </a> <ul id="toc-Common_causes_of_elevated_methemoglobin-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Therapeutic_uses" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Therapeutic_uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Therapeutic uses</span> </div> </a> <ul id="toc-Therapeutic_uses-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Methemoglobin_saturation" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Methemoglobin_saturation"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Methemoglobin saturation</span> </div> </a> <ul id="toc-Methemoglobin_saturation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Blood_stains" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Blood_stains"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Blood stains</span> </div> </a> <ul id="toc-Blood_stains-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" 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Available in 25 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-25" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">25 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%85%D8%AA%D9%87%D9%8A%D9%85%D9%88%D8%BA%D9%84%D9%88%D8%A8%D9%8A%D9%86" title="متهيموغلوبين – Arabic" lang="ar" hreflang="ar" data-title="متهيموغلوبين" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Metahemoglobina" title="Metahemoglobina – Catalan" lang="ca" hreflang="ca" data-title="Metahemoglobina" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Methemoglobin" title="Methemoglobin – Czech" lang="cs" hreflang="cs" data-title="Methemoglobin" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/M%C3%A6th%C3%A6moglobin" title="Mæthæmoglobin – Danish" lang="da" hreflang="da" data-title="Mæthæmoglobin" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Meth%C3%A4moglobin" title="Methämoglobin – German" lang="de" hreflang="de" data-title="Methämoglobin" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Metahemoglobina" title="Metahemoglobina – Spanish" lang="es" hreflang="es" data-title="Metahemoglobina" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Metahemoglobina" title="Metahemoglobina – Basque" lang="eu" hreflang="eu" data-title="Metahemoglobina" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%85%D8%AB%DB%8C%D9%85%D9%88%DA%AF%D9%84%D9%88%D8%A8%DB%8C%D9%86" title="مثیموگلوبین – Persian" lang="fa" hreflang="fa" data-title="مثیموگلوبین" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/M%C3%A9th%C3%A9moglobine" title="Méthémoglobine – French" lang="fr" hreflang="fr" data-title="Méthémoglobine" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Metahemoglobina" title="Metahemoglobina – Galician" lang="gl" hreflang="gl" data-title="Metahemoglobina" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EB%A9%94%ED%8A%B8%ED%97%A4%EB%AA%A8%EA%B8%80%EB%A1%9C%EB%B9%88" title="메트헤모글로빈 – Korean" lang="ko" hreflang="ko" data-title="메트헤모글로빈" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Methemoglobin" title="Methemoglobin – Indonesian" lang="id" hreflang="id" data-title="Methemoglobin" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Metaemoglobina" title="Metaemoglobina – Italian" lang="it" hreflang="it" data-title="Metaemoglobina" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%9C%D0%B5%D1%82%D0%B3%D0%B5%D0%BC%D0%BE%D0%B3%D0%BB%D0%BE%D0%B1%D0%B8%D0%BD" title="Метгемоглобин – Kazakh" lang="kk" hreflang="kk" data-title="Метгемоглобин" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9C%D0%B5%D1%82%D1%85%D0%B5%D0%BC%D0%BE%D0%B3%D0%BB%D0%BE%D0%B1%D0%B8%D0%BD" title="Метхемоглобин – Macedonian" lang="mk" hreflang="mk" data-title="Метхемоглобин" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Methemoglobine" title="Methemoglobine – Dutch" lang="nl" hreflang="nl" data-title="Methemoglobine" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%A1%E3%83%88%E3%83%98%E3%83%A2%E3%82%B0%E3%83%AD%E3%83%93%E3%83%B3" title="メトヘモグロビン – Japanese" lang="ja" hreflang="ja" data-title="メトヘモグロビン" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Methemoglobina" title="Methemoglobina – Polish" lang="pl" hreflang="pl" data-title="Methemoglobina" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Meta-hemoglobina" title="Meta-hemoglobina – Portuguese" lang="pt" hreflang="pt" data-title="Meta-hemoglobina" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Methemoglobiini" title="Methemoglobiini – Finnish" lang="fi" hreflang="fi" data-title="Methemoglobiini" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Methemoglobin" title="Methemoglobin – Swedish" lang="sv" hreflang="sv" data-title="Methemoglobin" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9C%D0%B5%D1%82%D0%B3%D0%B5%D0%BC%D0%BE%D0%B3%D0%BB%D0%BE%D0%B1%D1%96%D0%BD" title="Метгемоглобін – Ukrainian" lang="uk" hreflang="uk" data-title="Метгемоглобін" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D9%85%DB%8C%D9%B9_%DB%81%DB%8C%D9%85%D9%88_%DA%AF%D9%84%D9%88%D8%A8%D9%86" title="میٹ ہیمو گلوبن – Urdu" lang="ur" hreflang="ur" data-title="میٹ ہیمو گلوبن" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Methemoglobin" title="Methemoglobin – Vietnamese" lang="vi" hreflang="vi" data-title="Methemoglobin" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" 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class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Hemoglobin with ferric iron unable to carry oxygen</div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:NADH_cytochrome_B5_reductase_1UMK.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9e/NADH_cytochrome_B5_reductase_1UMK.png/220px-NADH_cytochrome_B5_reductase_1UMK.png" decoding="async" width="220" height="196" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9e/NADH_cytochrome_B5_reductase_1UMK.png/330px-NADH_cytochrome_B5_reductase_1UMK.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9e/NADH_cytochrome_B5_reductase_1UMK.png/440px-NADH_cytochrome_B5_reductase_1UMK.png 2x" data-file-width="1000" data-file-height="891" /></a><figcaption>The structure of <a href="/wiki/Cytochrome_b5_reductase" title="Cytochrome b5 reductase">cytochrome b5 reductase</a>, the enzyme that converts methemoglobin to hemoglobin.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></figcaption></figure><p><b>Methemoglobin</b> (British: <b>methaemoglobin</b>, shortened <b>MetHb</b>) (pronounced "met-hemoglobin") is a <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a> <i>in the form of <a href="/wiki/Metalloprotein" title="Metalloprotein">metalloprotein</a></i>, in which the <a href="/wiki/Iron" title="Iron">iron</a> in the <a href="/wiki/Heme" title="Heme">heme</a> group is in the Fe<sup>3+</sup> (<a href="/wiki/Ferric" title="Ferric">ferric</a>) state, not the Fe<sup>2+</sup> (<a href="/wiki/Ferrous" title="Ferrous">ferrous</a>) of normal hemoglobin. Sometimes, it is also referred to as ferrihemoglobin.<sup id="cite_ref-MeSH_2-0" class="reference"><a href="#cite_note-MeSH-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Methemoglobin cannot bind <a href="/wiki/Oxygen" title="Oxygen">oxygen</a>, which means it cannot carry oxygen to tissues. It is bluish chocolate-brown in color. In human <a href="/wiki/Blood" title="Blood">blood</a> a trace amount of methemoglobin is normally produced spontaneously, but when present in excess the blood becomes abnormally dark bluish brown. The <a href="/wiki/NADH" class="mw-redirect" title="NADH">NADH</a>-dependent enzyme <a href="/wiki/Methemoglobin_reductase" class="mw-redirect" title="Methemoglobin reductase">methemoglobin reductase</a> (<a href="/wiki/Diaphorase" title="Diaphorase">a type of diaphorase</a>) is responsible for converting methemoglobin back to <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a>. </p><p>Normally one to two percent of a person's hemoglobin is methemoglobin; a higher percentage than this can be genetic or caused by exposure to various chemicals and depending on the level can cause health problems known as <a href="/wiki/Methemoglobinemia" title="Methemoglobinemia">methemoglobinemia</a>. A higher level of methemoglobin will tend to cause a <a href="/wiki/Pulse_oximeter" class="mw-redirect" title="Pulse oximeter">pulse oximeter</a> to read closer to 85% regardless of the true level of <a href="/wiki/Oxygen_saturation" title="Oxygen saturation">oxygen saturation</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Etymology">Etymology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=1" title="Edit section: Etymology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The word methemoglobin derives from the <a href="/wiki/Ancient_Greek" title="Ancient Greek">Ancient Greek</a> prefix <i>μετα-</i> (meta-: behind, later, subsequent) and the word <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a>. </p><p>The name <i>hemoglobin</i> is itself derived from the words <i><a href="/wiki/Heme" title="Heme">heme</a></i> and <i><a href="/wiki/Globin" title="Globin">globin</a></i>, each <a href="/wiki/Protein_subunit" title="Protein subunit">subunit</a> of hemoglobin being a <a href="/wiki/Globular_protein" title="Globular protein">globular protein</a> with an embedded <a href="/wiki/Heme" title="Heme">heme</a> group. </p> <div class="mw-heading mw-heading2"><h2 id="Common_causes_of_elevated_methemoglobin">Common causes of elevated methemoglobin</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=2" title="Edit section: Common causes of elevated methemoglobin"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>Reduced cellular defense mechanisms <ul><li>Children younger than 4 months exposed to various environmental agents</li> <li>Pregnant women are considered vulnerable to exposure of high levels of nitrates in drinking water<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Cytochrome_b5_reductase" title="Cytochrome b5 reductase">Cytochrome b5 reductase</a> deficiency</li> <li><a href="/wiki/Glucose-6-phosphate_dehydrogenase_deficiency" title="Glucose-6-phosphate dehydrogenase deficiency">G6PD deficiency</a></li> <li><a href="/wiki/Hemoglobin_M_disease" title="Hemoglobin M disease">Hemoglobin M disease</a></li> <li><a href="/wiki/Pyruvate_kinase_deficiency" title="Pyruvate kinase deficiency">Pyruvate kinase deficiency</a></li></ul></li> <li>Various pharmaceutical compounds <ul><li>Local anesthetic agents, especially prilocaine and <a href="/wiki/Benzocaine" title="Benzocaine">benzocaine</a>.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Amyl_nitrite" title="Amyl nitrite">Amyl nitrite</a>, <a href="/wiki/Chloroquine" title="Chloroquine">chloroquine</a>, <a href="/wiki/Dapsone" title="Dapsone">dapsone</a>, <a href="/wiki/Nitrates" class="mw-redirect" title="Nitrates">nitrates</a>, <a href="/wiki/Nitrites" class="mw-redirect" title="Nitrites">nitrites</a>, <a href="/wiki/Nitroglycerin" title="Nitroglycerin">nitroglycerin</a>, <a href="/wiki/Nitroprusside" class="mw-redirect" title="Nitroprusside">nitroprusside</a>, <a href="/wiki/Phenacetin" title="Phenacetin">phenacetin</a>, <a href="/wiki/Phenazopyridine" title="Phenazopyridine">phenazopyridine</a>, <a href="/wiki/Primaquine" title="Primaquine">primaquine</a>, <a href="/wiki/Quinones" class="mw-redirect" title="Quinones">quinones</a> and <a href="/wiki/Sulfonamide_(medicine)" title="Sulfonamide (medicine)">sulfonamides</a></li></ul></li> <li>Environmental agents <ul><li>Aromatic <a href="/wiki/Amine" title="Amine">amines</a> (e.g. <a href="/wiki/4-Nitroaniline" title="4-Nitroaniline"><i>p</i>-nitroaniline</a>, <a rel="nofollow" class="external text" href="http://www.gtfch.org/cms/images/stories/media/tk/tk73_2/Bakdash.pdf">patient case</a>)</li> <li><a href="/wiki/Arsine" title="Arsine">Arsine</a></li> <li><a href="/wiki/Chlorobenzene" title="Chlorobenzene">Chlorobenzene</a></li> <li><a href="/wiki/Chromates" class="mw-redirect" title="Chromates">Chromates</a></li> <li><a href="/wiki/Nitrates" class="mw-redirect" title="Nitrates">Nitrates</a>/<a href="/wiki/Nitrites" class="mw-redirect" title="Nitrites">nitrites</a><sup id="cite_ref-:0_5-0" class="reference"><a href="#cite_note-:0-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Umbellulone" title="Umbellulone">Umbellulone</a></li></ul></li> <li>Inherited disorders <ul><li>Some family members of the <a href="/wiki/Blue_Fugates" title="Blue Fugates">Fugate family</a> in Kentucky, due to a recessive gene, had blue skin from an excess of methemoglobin.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup></li></ul></li> <li>In cats <ul><li>Ingestion of <a href="/wiki/Paracetamol" title="Paracetamol">paracetamol</a> (i.e. acetaminophen, tylenol)<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup></li></ul></li></ul> <div class="mw-heading mw-heading2"><h2 id="Therapeutic_uses">Therapeutic uses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=3" title="Edit section: Therapeutic uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Amyl_nitrite" title="Amyl nitrite">Amyl nitrite</a> is administered to treat <a href="/wiki/Cyanide_poisoning" title="Cyanide poisoning">cyanide poisoning</a>. It works by converting <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a> to methemoglobin, which allows for the binding of <a href="/wiki/Cyanide" title="Cyanide">cyanide</a> (CN<sup>–</sup>) <a href="/wiki/Anion" class="mw-redirect" title="Anion">anions</a> by <a href="/wiki/Ferric" title="Ferric">ferric</a> (Fe<sup>3+</sup>) <a href="/wiki/Cation" class="mw-redirect" title="Cation">cations</a> and the formation of <a href="/w/index.php?title=Cyanomethemoglobin&action=edit&redlink=1" class="new" title="Cyanomethemoglobin (page does not exist)">cyanomethemoglobin</a>. The immediate goal of forming this cyanide adduct is to prevent the binding of free cyanide to the <a href="/wiki/Cytochrome" title="Cytochrome">cytochrome</a> a<sub>3</sub> group in <a href="/wiki/Cytochrome_c_oxidase" title="Cytochrome c oxidase">cytochrome c oxidase</a>.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Methemoglobin_saturation">Methemoglobin saturation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=4" title="Edit section: Methemoglobin saturation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Methemoglobinemia" title="Methemoglobinemia">Methemoglobinemia</a></div> <p>Methemoglobin is expressed as a concentration or a percentage. Percentage of methemoglobin is calculated by dividing the concentration of methemoglobin by the concentration of total hemoglobin. Percentage of methemoglobin is likely a better indicator of illness severity than overall concentration, as underlying medical conditions play an important role. For example, a methemoglobin concentration of 1.5 g/dL may represent a percentage of 10% in an otherwise healthy patient with a baseline hemoglobin of 15 mg/dL, whereas the presence of the same concentration of 1.5 g/dL of methemoglobin in an anemic patient with a baseline hemoglobin of 8 g/dL would represent a percentage of 18.75%. The former patient will be left with a functional hemoglobin concentration of 13.5 g/dL and potentially remain asymptomatic while the latter patient with a functional hemoglobin concentration 6.5 g/dL may be severely symptomatic with a methemoglobin of less than 20%.<sup id="cite_ref-Wilkerson_Nappe_2019_9-0" class="reference"><a href="#cite_note-Wilkerson_Nappe_2019-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <ul><li>1–2% Normal</li> <li>Less than 10% metHb - No symptoms</li> <li>10–20% metHb - Skin discoloration only (most notably on <a href="/wiki/Mucous_membrane" title="Mucous membrane">mucous membranes</a>)</li> <li>20–30% metHb - <a href="/wiki/Anxiety" title="Anxiety">Anxiety</a>, <a href="/wiki/Headache" title="Headache">headache</a>, <a href="/wiki/Dyspnea" class="mw-redirect" title="Dyspnea">dyspnea</a> on exertion</li> <li>30–50% metHb - <a href="/wiki/Fatigue_(medical)" class="mw-redirect" title="Fatigue (medical)">Fatigue</a>, <a href="/wiki/Confusion" title="Confusion">confusion</a>, <a href="/wiki/Dizziness" title="Dizziness">dizziness</a>, <a href="/wiki/Tachypnea" title="Tachypnea">tachypnea</a>, <a href="/wiki/Palpitations" title="Palpitations">palpitations</a></li> <li>50–70% metHb - <a href="/wiki/Coma" title="Coma">Coma</a>, <a href="/wiki/Seizures" class="mw-redirect" title="Seizures">seizures</a>, <a href="/wiki/Arrhythmias" class="mw-redirect" title="Arrhythmias">arrhythmias</a>, <a href="/wiki/Acidosis" title="Acidosis">acidosis</a></li> <li>Greater than 70% metHb - High risk of <a href="/wiki/Death" title="Death">death</a><sup id="cite_ref-:0_5-1" class="reference"><a href="#cite_note-:0-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup></li></ul> <p>This may be further compounded by the "functional hemoglobin's" decreased ability to release oxygen in the presence of methemoglobin. <a href="/wiki/Anemia" title="Anemia">Anemia</a>, <a href="/wiki/Congestive_heart_failure" class="mw-redirect" title="Congestive heart failure">congestive heart failure</a>, <a href="/wiki/Chronic_obstructive_pulmonary_disease" title="Chronic obstructive pulmonary disease">chronic obstructive pulmonary disease</a>, and essentially any pathology that impairs the ability to deliver oxygen may worsen the symptoms of methemoglobinemia.<sup id="cite_ref-Wilkerson_Nappe_2019_9-1" class="reference"><a href="#cite_note-Wilkerson_Nappe_2019-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Blood_stains">Blood stains</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=5" title="Edit section: Blood stains"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Increased levels of methemoglobin are found in blood stains. Upon exiting the body, <a href="/wiki/Bloodstain_pattern_analysis" title="Bloodstain pattern analysis">bloodstains</a> transit from bright red to dark brown, which is attributed to oxidation of oxy-hemoglobin (HbO<sub>2</sub>) to methemoglobin (met-Hb) and <a href="/wiki/Hemichrome" title="Hemichrome">hemichrome</a> (HC).<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=6" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Blue_baby_syndrome" title="Blue baby syndrome">Blue baby syndrome</a></li> <li><a href="/wiki/Carboxyhemoglobin" title="Carboxyhemoglobin">Carboxyhemoglobin</a></li> <li><a href="/wiki/Methemoglobinemia" title="Methemoglobinemia">Methemoglobinemia</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Methemoglobin&action=edit&section=7" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFBandoTakanoYubisuiShirabe2004" class="citation journal cs1">Bando, S.; Takano, T.; Yubisui, T.; Shirabe, K.; Takeshita, M.; Nakagawa, A. (2004). 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abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Hemeproteins" title="Template:Hemeproteins"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Hemeproteins" title="Template talk:Hemeproteins"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Hemeproteins" title="Special:EditPage/Template:Hemeproteins"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Proteins_that_contain_heme_(hemoproteins)178" style="font-size:114%;margin:0 4em"><a href="/wiki/Protein" title="Protein">Proteins</a> that contain <a href="/wiki/Heme" title="Heme">heme</a> (<a href="/wiki/Hemoprotein" title="Hemoprotein">hemoproteins</a>)</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Globin" title="Globin">Globins</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Hemoglobin" title="Hemoglobin">Hemoglobin</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Subunits</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><i>Alpha locus on <a href="/wiki/Chromosome_16" title="Chromosome 16">16</a>:</i></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><i>α</i> <ul><li><a href="/wiki/Hemoglobin_subunit_alpha" title="Hemoglobin subunit alpha">HBA1</a></li> <li><a href="/wiki/Hemoglobin,_alpha_2" title="Hemoglobin, alpha 2">HBA2</a></li> <li><a href="/wiki/HBAP1" title="HBAP1">pseudo</a></li></ul></li> <li><i>ζ</i> <ul><li><a href="/wiki/Hemoglobin_subunit_zeta" title="Hemoglobin subunit zeta">HBZ</a></li></ul></li> <li><i>θ</i> <ul><li><a href="/wiki/HBQ1" title="HBQ1">HBQ1</a></li></ul></li> <li><i>μ</i> <ul><li><a href="/wiki/Mu_hemoglobin" title="Mu hemoglobin">HBM</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><i><a href="/wiki/Human_%CE%B2-globin_locus" title="Human β-globin locus">Beta locus</a> on <a href="/wiki/Chromosome_11" title="Chromosome 11">11</a>:</i></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><i>β</i> <ul><li><a href="/wiki/Hemoglobin_subunit_beta" title="Hemoglobin subunit beta">HBB</a></li></ul></li> <li><i>δ</i> <ul><li><a href="/wiki/HBD" title="HBD">HBD</a></li></ul></li> <li><i>γ</i> <ul><li><a href="/wiki/HBG1" title="HBG1">HBG1</a></li> <li><a href="/wiki/HBG2" title="HBG2">HBG2</a></li></ul></li> <li><i>ε</i> <ul><li><a href="/wiki/HBE1" title="HBE1">HBE1</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Tetrameric_protein" title="Tetrameric protein">Tetramers</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><i>stages of <br />development:</i></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Embryonic</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Embryonic_hemoglobin" title="Embryonic hemoglobin">HbE Gower 1</a> (ζ<sub>2</sub>ε<sub>2</sub>)</li> <li><a href="/wiki/Embryonic_hemoglobin" title="Embryonic hemoglobin">HbE Gower 2</a> (α<sub>2</sub>ε<sub>2</sub>)</li> <li><a href="/wiki/Embryonic_hemoglobin" title="Embryonic hemoglobin">HbE Portland I</a> (ζ<sub>2</sub>γ<sub>2</sub>)</li> <li><a href="/wiki/Embryonic_hemoglobin" title="Embryonic hemoglobin">HbE Portland II</a> (ζ<sub>2</sub>β<sub>2</sub>)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fetal</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fetal_hemoglobin" title="Fetal hemoglobin">HbF/Fetal</a> (α<sub>2</sub>γ<sub>2</sub>)</li> <li><a href="/wiki/Hemoglobin_A" title="Hemoglobin A">HbA</a> (α<sub>2</sub>β<sub>2</sub>)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Adult</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Hemoglobin_A" title="Hemoglobin A">HbA</a> (α<sub>2</sub>β<sub>2</sub>)</li> <li><a href="/wiki/Hemoglobin_A2" title="Hemoglobin A2">HbA<sub>2</sub></a> (α<sub>2</sub>δ<sub>2</sub>)</li> <li><a href="/wiki/Fetal_hemoglobin" title="Fetal hemoglobin">HbF/Fetal</a> (α<sub>2</sub>γ<sub>2</sub>)</li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><i>pathology:</i></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alpha-thalassemia" title="Alpha-thalassemia">HbH</a> (β<sub>4</sub>)</li> <li><a href="/wiki/Hemoglobin_Barts" title="Hemoglobin Barts">Barts</a> (γ<sub>4</sub>)</li> <li><a href="/wiki/HbD" class="mw-redirect" title="HbD">HbD</a> (α<sub>2</sub>β<sup>D</sup><sub>2</sub>)</li> <li><a href="/wiki/Sickle_cell_disease" title="Sickle cell disease">HbS</a> (α<sub>2</sub>β<sup>S</sup><sub>2</sub>)</li> <li><a href="/wiki/Hemoglobin_C" title="Hemoglobin C">HbC</a> (α<sub>2</sub>β<sup>C</sup><sub>2</sub>)</li> <li><a href="/wiki/Hemoglobin_E" title="Hemoglobin E">HbE</a> (α<sub>2</sub>β<sup>E</sup><sub>2</sub>)</li> <li><a href="/wiki/Hemoglobin_O" title="Hemoglobin O">HbO</a> (α<sub>2</sub>β<sup>O</sup><sub>2</sub>)</li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Compounds</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Carboxyhemoglobin" title="Carboxyhemoglobin">Carboxyhemoglobin</a></li> <li><a href="/wiki/Carbaminohemoglobin" title="Carbaminohemoglobin">Carbaminohemoglobin</a></li> <li><a href="/wiki/Hemoglobin" title="Hemoglobin">Oxyhemoglobin</a>/<a href="/wiki/Deoxyhemoglobin" class="mw-redirect" title="Deoxyhemoglobin">Deoxyhemoglobin</a></li> <li><a href="/wiki/Sulfhemoglobinemia" title="Sulfhemoglobinemia">Sulfhemoglobin</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other human</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Glycated_hemoglobin" title="Glycated hemoglobin">Glycated hemoglobin</a></li> <li><a class="mw-selflink selflink">Methemoglobin</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Nonhuman</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Erythrocruorin" title="Erythrocruorin">Chlorocruorin</a></li> <li><a href="/wiki/Erythrocruorin" title="Erythrocruorin">Erythrocruorin</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><i>human:</i></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Myoglobin" title="Myoglobin">Myoglobin</a> <ul><li><a href="/wiki/Metmyoglobin" title="Metmyoglobin">Metmyoglobin</a></li></ul></li> <li><a href="/wiki/Neuroglobin" title="Neuroglobin">Neuroglobin</a></li> <li><a href="/wiki/Cytoglobin" title="Cytoglobin">Cytoglobin</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><i>plant:</i></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Leghemoglobin" title="Leghemoglobin">Leghemoglobin</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cytochrome" title="Cytochrome">Cytochrome</a> <ul><li><a href="/wiki/Cytochrome_b" title="Cytochrome b">Cytochrome b</a></li> <li><a href="/wiki/Cytochrome_P450" title="Cytochrome P450">Cytochrome P450</a></li></ul></li> <li><a href="/wiki/Methemalbumin" title="Methemalbumin">Methemalbumin</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="background: transparent; padding: 0px;"><div><i>see also <a href="/wiki/Template:Disorders_of_globin_and_globulin_proteins" title="Template:Disorders of globin and globulin proteins">disorders of globin and globulin proteins</a></i></div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Methemoglobin&oldid=1268831864">https://en.wikipedia.org/w/index.php?title=Methemoglobin&oldid=1268831864</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" 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