{"id":3132,"date":"2025-08-05T12:00:20","date_gmt":"2025-08-05T12:00:20","guid":{"rendered":"http:\/\/i-base.info\/qa\/?page_id=3132"},"modified":"2025-08-06T11:15:49","modified_gmt":"2025-08-06T11:15:49","slug":"units-of-measure","status":"publish","type":"page","link":"https:\/\/i-base.info\/qa\/factsheets\/units-of-measure","title":{"rendered":"Units of measure &#8211; mm3, mL, \u03bcL etc"},"content":{"rendered":"<p>CD4 and viral load are measured in different volumes.<\/p>\n<h2>CD4 counts are measured in cells per cubic millimetre = cells\/mm3<\/h2>\n<p>A cubic millimetre (mm<sup>3<\/sup>)\u00a0= mm3\u00a0 = mm<sup>3\u00a0<\/sup>= 1 mm x 1 mm x 1 mm.<\/p>\n<p>= microlitre (\u00b5L).<\/p>\n<p>= a metric measure of volume or capacity equal to a cube that is 1 millimeter on each edge.<\/p>\n<p>Sometimes CD4 is written as cells\/\u00b5L = cells\/<em>micro<\/em>litre = millionth of a litre.<\/p>\n<p>Sometimes CD4 results are written as cells \/ log\u00a0x 10<sup>6 <\/sup>(ie x 10 x 10 x 10 x 10 x 10 x 10).<\/p>\n<p>If your CD4 count is 200, this can be written:<\/p>\n<ul>\n<li>200 cells\/mm3<\/li>\n<li>200 cells\/\u00b5L<\/li>\n<li>200 x log<sub>10<\/sub><sup>6<\/sup> cells\/L<\/li>\n<li>0.2 x log<sub>10<sup>9<\/sup><\/sub>\u00a0cells\/L<\/li>\n<\/ul>\n<h2>Viral load is measured in copies per millilitre = copies\/mL<\/h2>\n<p>A cubic centimetre (cm<sup>3<\/sup>) = millilitre (mL)<\/p>\n<p>= one cubic centimetre = 1cm x 1cm x 1 cm = cm3 = cm<sup>3<\/sup>.<\/p>\n<p>= one mL\u00a0\u00a0= 1000\u00a0\u00b5L.<\/p>\n<p>= a metric unit of volume equal to one thousandth of a litre.<\/p>\n<p>Viral load of 20,000 is written:<\/p>\n<ul>\n<li>20,000 copies\/mL<\/li>\n<li>20,000 c\/mL HIV RNA.<\/li>\n<li>This is sometimes\u00a0written 2.0\u00a0x 10<sup> (x)<\/sup>. The letter &#8220;x&#8221; can be any number from 1 to 8 to show whether you are multiplying by 10, 100, 1000, 10 000, 100 000 etc. In this case it would be 2.0 x 10<sup>4<\/sup> &#8211; ie 2.0 x 10,000.<\/li>\n<li>Using a log scale this would be 4.3 log10\u00a0copies\/mL.<\/li>\n<\/ul>\n<p><a href=\"https:\/\/i-base.info\/qa\/factsheets\/viral-load-converting-log-values-to-numbers\">Conversion table between viral load as numbers and logs<\/a>.<\/p>\n<div class=\"border\">\n<p><strong>1,000 microlitres = <\/strong><strong>1 millilitre<\/strong><\/p>\n<p><strong>1,000 millilitres = 1 litre<\/strong><\/p>\n<p><strong>1,000,000 microlitres = 1 litre<\/strong><\/p>\n<p><strong>[1 US pint = 0.47 litres]<\/strong><\/p>\n<p><strong>If there are 5.5 litres of blood in your body:<\/strong><\/p>\n<p><strong>Q1.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 How many millilitres (mL) of blood are in your body? \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/strong><\/p>\n<p>A.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 _______<\/p>\n<p><strong>Q2.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 How many microlitres (\u00b5L) of blood are in your body? \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/strong><\/p>\n<p>A.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 _______<\/p>\n<p>[Answers: Q1: 1000 x 5.5 = 5,500; Q2: 1000 x 1000 x 5.5 = 5,500,000]<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>CD4 and viral load are measured in different volumes. CD4 counts are measured in cells per cubic millimetre = cells\/mm3 A cubic millimetre (mm3)\u00a0= mm3\u00a0 = mm3\u00a0= 1 mm x 1 mm x 1 mm. = microlitre (\u00b5L). = a &hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":7201,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3132","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/pages\/3132","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/comments?post=3132"}],"version-history":[{"count":3,"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/pages\/3132\/revisions"}],"predecessor-version":[{"id":26192,"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/pages\/3132\/revisions\/26192"}],"up":[{"embeddable":true,"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/pages\/7201"}],"wp:attachment":[{"href":"https:\/\/i-base.info\/qa\/wp-json\/wp\/v2\/media?parent=3132"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}