{"id":15494,"date":"2026-11-07T16:00:00","date_gmt":"2026-11-07T16:00:00","guid":{"rendered":"https:\/\/bioprofile.com\/?page_id=15494"},"modified":"2026-11-07T16:16:10","modified_gmt":"2026-11-07T16:16:10","slug":"free-t3","status":"publish","type":"page","link":"https:\/\/bioprofile.com\/en\/biomarkers\/free-t3\/","title":{"rendered":"Free T3"},"content":{"rendered":"\n<div id=\"content\" tabindex=\"-1\"><\/div>\n<style>@import url('https:\/\/fonts.googleapis.com\/css2?family=Poppins:ital,wght@0,400;0,600;0,700;0,800;1,400&display=swap');\n\/* ===========================================================================\n   BioProfile advertorial, the design Jesse approved on 2026-07-30, expressed\n   as a WordPress design system.\n\n   THE @import IS LOAD BEARING and must stay the first thing in this sheet (a\n   CSS @import after any rule is dropped by the parser). elementor_canvas does\n   not enqueue the theme's fonts, so without it the whole page falls back to the\n   system font. Caught by LOOKING at the live page on 2026-07-30, right after\n   the template was switched to canvas.\n\n   Everything is scoped to `.bp-adv`, so nothing here can reach the rest of\n   bioprofile.com, and core blocks are styled BY ELEMENT so a heading, a\n   paragraph, a quote, a list, an image or a button inserted by hand inside the\n   advertorial comes out on-design with no class to remember.\n\n   Jesse's design feedback, 2026-07-29 23:38, point by point:\n   1. the light green and the dark green are the preferred colours; grey may be\n      used but the page must NOT open grey;\n   2. more colour and variation across sections, e.g. a colour block on the left\n      or the right side of a section, without overdesign;\n   3. ONE H1, plain text on white; everything else H2 or H3; an H2 may carry its\n      own background colour so the page can be read from the headings alone; an\n      H3 keeps its section background and gets a bigger font size;\n   4. reuse the results page design feel;\n   5. Written by \/ Verified by, the placeholder blocks and noindex stay.\n\n   COLOUR PROVENANCE. Not one hex is invented.\n   - #b7cb32  LIGHT GREEN, brand manual \"colours rejuvenation protocol\"\n              (R183 G203 B51). Same value as --bp-lime in\n              brands\/bioprofile\/brand\/tokens.md.\n   - #006b62  DARK GREEN, brand manual, nourish the cells (R0 G107 B98).\n   - #005859  brand manual primary teal, the value the brand is built on.\n   - #228a62  brand manual, challenge the body (R34 G138 B98).\n   - #7ca64c  brand manual, calm the mind (R124 G166 B76).\n   - #dbd4cd  brand manual \"additional color\", the warm neutral.\n   - #B7CB3329 is the brand token --bp-lime-soft (light green at 16 percent).\n   - the gradients are the brand token layer's own, copied verbatim.\n\n   SPECIFICITY NOTE. Elementor's global kit emits `.elementor-kit-6 h2` style\n   rules at (0,1,1). Element rules below are written `.bp-adv h2`, also (0,1,1),\n   and win on source order because this sheet is inline in the body while the\n   kit is a <link> in the head. Component rules that MUST NOT lose carry two\n   classes, e.g. `.bp-adv .wp-block-button__link`.\n\n   LAYOUT NOTE. Vertical rhythm uses `margin-block` and never the `margin`\n   shorthand, so the measure rule `.bp-adv-sec > * { margin-inline: auto }` can\n   centre a block without being outranked by its own element rule.\n   =========================================================================== *\/\n\n.bp-adv {\n  --bp-ink: #212527;\n  --bp-teal: #005859;\n  --bp-forest: #006B62;\n  --bp-emerald: #228A62;\n  --bp-olive: #7CA64C;\n  --bp-lime: #B7CB33;\n  --bp-lime-soft: #B7CB3329;\n  --bp-sand: #DBD4CB;\n  --bp-white: #FFFFFF;\n  --bp-foot: #6b6b6b;\n  --bp-grad-dark: linear-gradient(237deg, rgba(0,88,89,0.00) 62.94%, #005859 100%), linear-gradient(90deg, rgba(34,138,98,0.00) 40%, #228A62 100%), #006B62;\n  --bp-grad-lime: linear-gradient(110deg, rgba(183,203,51,0.00) 36.06%, rgba(183,203,51,0.25) 97.65%), #FFFFFF;\n  --bp-font: 'Poppins','Segoe UI',Arial,sans-serif;\n  --bp-fs-h1: 44px; --bp-fs-h2: 31px; --bp-fs-h3: 24px; --bp-fs-pre: 15px;\n  --bp-fs-body: 17px; --bp-fs-small: 14px; --bp-fs-foot: 13px; --bp-fs-btn: 17px;\n  --bp-lh-body: 1.75;\n  --bp-s-1: 4px; --bp-s-2: 8px; --bp-s-3: 12px; --bp-s-4: 16px;\n  --bp-s-5: 24px; --bp-s-6: 32px; --bp-s-7: 44px; --bp-s-8: 72px;\n  --bp-measure: 760px; --bp-side: 40px;\n  --bp-radius-photo: 16px; --bp-radius-btn: 10px; --bp-radius-card: 20px;\n  --bp-shadow: 0 10px 30px rgba(0,88,89,0.10);\n  font-family: var(--bp-font);\n  font-size: var(--bp-fs-body);\n  line-height: var(--bp-lh-body);\n  color: var(--bp-ink);\n  background: var(--bp-white);\n  -webkit-font-smoothing: antialiased;\n}\n.bp-adv, .bp-adv * { box-sizing: border-box; }\n.bp-adv p, .bp-adv li, .bp-adv h1, .bp-adv h2, .bp-adv h3, .bp-adv blockquote,\n.bp-adv a, .bp-adv cite, .bp-adv span { overflow-wrap: break-word; min-width: 0; }\n\n\/* THE TOGGLE. One word in the block's own \"Additional CSS class(es)\" field\n   hides an optional component on the front end without deleting anything. *\/\n.bp-adv .bp-off { display: none !important; }\n\n\/* the page opens on green, never on grey (his point 1) *\/\n.bp-adv .bp-adv-rule {\n  height: 6px; border: 0; margin-block: 0; max-width: none;\n  background: linear-gradient(90deg, #005859 0%, #006B62 38%, #228A62 66%, #B7CB33 100%);\n}\n\n\/* --- section surfaces ------------------------------------------------------ *\/\n.bp-adv-sec { position: relative; background: var(--bp-white);\n  padding: var(--bp-s-8) var(--bp-side); margin-block: 0; }\n\/* the measure: every direct child of a section is the 760px text column *\/\n.bp-adv-sec > * { max-width: var(--bp-measure); margin-inline: auto; }\n.bp-adv-sec > *:last-child { margin-block-end: 0; }\n.bp-adv-sec--wash  { background: linear-gradient(180deg, #B7CB331F 0%, #B7CB3312 100%), #FFFFFF; }\n.bp-adv-sec--dark  { background: var(--bp-grad-dark); color: var(--bp-white); }\n.bp-adv-sec--dark p, .bp-adv-sec--dark cite, .bp-adv-sec--dark li { color: var(--bp-white); }\n.bp-adv-sec--offer { background: var(--bp-grad-lime); text-align: center; }\n.bp-adv-sec--hero  { padding-block-start: var(--bp-s-6); }\n.bp-adv-sec--disclosure { padding-block: var(--bp-s-6);\n  border-top: 1px solid var(--bp-sand); }\n\n\/* --- the side accent bar, his own example (\"a colour block on the left or the\n       right side of a section\"), design rev 3: a slim vertical bar hugging the\n       text column rather than a wide margin panel. Below 1100px the margin is\n       gone, so it becomes a slim top edge. ---------------------------------- *\/\n.bp-adv-rail { overflow: hidden; }\n.bp-adv-rail::before {\n  content: \"\"; position: absolute; top: var(--bp-s-7); bottom: var(--bp-s-7);\n  width: 6px; border-radius: 3px;\n  background: linear-gradient(180deg, var(--bp-forest) 0%, var(--bp-lime) 100%);\n}\n.bp-adv-rail--left::before  { left: calc((100% - var(--bp-measure)) \/ 2 - 34px); }\n.bp-adv-rail--right::before { right: calc((100% - var(--bp-measure)) \/ 2 - 34px); }\n@media (max-width: 1099px) {\n  .bp-adv-rail::before { left: 0; right: 0; width: auto; bottom: auto; top: 0;\n    height: 4px; border-radius: 0; background: var(--bp-lime); }\n}\n\n\/* --- CORE BLOCKS, styled by element. This is the part that makes an inserted\n       block come out on-design with no class. --------------------------------- *\/\n.bp-adv p { font-size: var(--bp-fs-body); line-height: var(--bp-lh-body);\n  margin-block: 0 var(--bp-s-5); }\n.bp-adv h1 { font-size: var(--bp-fs-h1); font-weight: 700; line-height: 1.22;\n  margin-block: 0 var(--bp-s-4); }\n\/* an H2 is its own colour band, so the page can be read from the headings\n   alone (his point 3). Dark green on light sections, light green on the dark\n   one, so a heading always wins against its own background. *\/\n.bp-adv h2 {\n  font-size: var(--bp-fs-h2); font-weight: 700; line-height: 1.28;\n  margin-block: 0 var(--bp-s-5);\n  background: var(--bp-grad-dark); color: var(--bp-white);\n  padding: var(--bp-s-4) var(--bp-s-5);\n  border-radius: var(--bp-radius-btn);\n  border-left: 6px solid var(--bp-lime);\n}\n.bp-adv-sec--dark h2 { background: var(--bp-lime); color: var(--bp-ink);\n  border-left-color: var(--bp-forest); }\n\/* H3: same background as its section, bigger font (his point 3, verbatim) *\/\n.bp-adv h3 { font-size: var(--bp-fs-h3); font-weight: 700; line-height: 1.35;\n  color: var(--bp-forest); background: transparent; margin-block: 0 var(--bp-s-3); }\n.bp-adv-sec--dark h3 { color: var(--bp-lime); }\n.bp-adv ul, .bp-adv ol { font-size: var(--bp-fs-body); line-height: var(--bp-lh-body);\n  margin-block: 0 var(--bp-s-5); padding-left: var(--bp-s-5); }\n.bp-adv li { margin-block-end: var(--bp-s-2); }\n.bp-adv a { color: var(--bp-teal); text-decoration: underline; }\n.bp-adv a:hover { color: var(--bp-olive); }\n.bp-adv-sec--dark a, .bp-adv-sec--dark strong { color: var(--bp-lime); }\n.bp-adv strong { font-weight: 700; }\n\/* the highlight pill. Colours ride on the inline style core writes, so only\n   the shape lives here and any <mark> in the article picks it up. *\/\n.bp-adv mark {\n  padding: 0 10px; border-radius: 10px; display: inline;\n  -webkit-box-decoration-break: clone; box-decoration-break: clone;\n}\n\/* figures match the approved page exactly: card radius plus the soft shadow,\n   and a left-aligned caption rather than core's centred one *\/\n.bp-adv .wp-block-image { margin-block: var(--bp-s-5); margin-inline: auto; }\n.bp-adv .wp-block-image img { display: block; width: 100%; height: auto;\n  border-radius: var(--bp-radius-card); box-shadow: var(--bp-shadow); }\n.bp-adv .wp-block-image figcaption { font-size: var(--bp-fs-foot); line-height: 1.55;\n  color: var(--bp-foot); text-align: left; margin-block: var(--bp-s-2) 0; }\n.bp-adv .wp-block-embed, .bp-adv .wp-block-video { margin-block: var(--bp-s-5); }\n.bp-adv .wp-block-embed iframe, .bp-adv .wp-block-video video {\n  width: 100%; border-radius: var(--bp-radius-photo); }\n.bp-adv .wp-block-separator:not(.bp-adv-rule) { border: 0; border-top: 1px solid var(--bp-sand);\n  margin-block: var(--bp-s-5); }\n\n\/* quotes: core pullquote and core quote both land on the lime rule. The\n   font-size reset undoes core's own 1.5em on the figure, which would otherwise\n   leak into anything inside the quote that has no size of its own. *\/\n\/* margin-inline is load bearing, and it must be `auto` rather than `0`.\n   `blockquote` and `figure` carry a 40px side margin in the browser's own\n   default stylesheet, which indents the quote inside its rule and makes the\n   copy wrap early on a phone. But these blocks are direct children of a\n   section, so zeroing the side margin also defeats the measure rule\n   `.bp-adv-sec > * { margin-inline: auto }` and pins them to the left edge. *\/\n.bp-adv .wp-block-pullquote, .bp-adv .wp-block-quote {\n  border: 0; border-left: 5px solid var(--bp-lime); background: transparent;\n  padding: var(--bp-s-2) 0 var(--bp-s-2) var(--bp-s-5);\n  margin-block: var(--bp-s-5); margin-inline: auto;\n  text-align: left; font-size: var(--bp-fs-body);\n}\n.bp-adv .wp-block-pullquote blockquote { border: 0; margin: 0; padding: 0; }\n.bp-adv .wp-block-pullquote p, .bp-adv .wp-block-quote p {\n  font-size: 24px; line-height: 1.45; font-weight: 600;\n  margin-block: 0 var(--bp-s-2); color: var(--bp-forest); }\n.bp-adv .wp-block-pullquote cite, .bp-adv .wp-block-quote cite {\n  display: block; margin: 0; font-size: var(--bp-fs-small); color: var(--bp-foot);\n  font-style: normal; text-transform: none; }\n\n\/* buttons: two classes so core's own .wp-block-button__link cannot win *\/\n.bp-adv .wp-block-buttons { display: flex; justify-content: center;\n  margin-block: 0 var(--bp-s-4); }\n.bp-adv .wp-block-button__link {\n  display: inline-flex; align-items: center; justify-content: center; min-height: 48px;\n  background: var(--bp-teal); color: var(--bp-white); font-size: var(--bp-fs-btn);\n  font-weight: 700; line-height: 1.2; border-radius: var(--bp-radius-btn);\n  padding: 15px 44px; text-decoration: none; transition: background 250ms ease;\n  box-shadow: var(--bp-shadow);\n}\n.bp-adv .wp-block-button__link:hover { background: var(--bp-olive); color: var(--bp-white); }\n\n\/* --- slot 1: pre-headline, headline, sub-headline (Jesse's headline skill) --- *\/\n.bp-adv .bp-adv-preheadline {\n  color: var(--bp-forest); font-size: var(--bp-fs-pre); font-weight: 600; line-height: 1.5;\n  border-left: 4px solid var(--bp-lime); padding-left: var(--bp-s-3);\n  margin-block: 0 var(--bp-s-4);\n}\n.bp-adv .bp-adv-subheadline { font-size: 21px; line-height: 1.5; font-weight: 600;\n  color: var(--bp-forest); margin-block: 0 var(--bp-s-5); }\n.bp-adv .bp-adv-standfirst { font-size: 19px; line-height: 1.65;\n  margin-block: 0 var(--bp-s-5); }\n.bp-adv .bp-adv-lede { font-size: 18px; line-height: 1.7;\n  margin-block: 0 var(--bp-s-5); }\n.bp-adv .bp-adv-byline { font-size: var(--bp-fs-small); color: var(--bp-foot);\n  line-height: 1.6; margin-block: 0 var(--bp-s-5); }\n.bp-adv .bp-adv-socialproof { font-size: var(--bp-fs-small); color: var(--bp-foot);\n  margin-block: 0 var(--bp-s-5); }\n\/* the offer headline above the CTA. Jesse asked for a second H1 here; the brand\n   doc's accessibility rule is one h1 per page, so it is rendered at H1 size and\n   stays an h2 element. Named in the close as the one design conflict. *\/\n.bp-adv h2.bp-adv-offerhead {\n  font-size: var(--bp-fs-h1); font-weight: 700; line-height: 1.22;\n  margin-block: 0 var(--bp-s-4); text-align: center; color: var(--bp-ink);\n  background: none; padding: 0; border: 0; border-radius: 0;\n}\n\n\/* --- Written by + Verified by. The avatar is the first child and spans the\n       three text rows, so the whole box is four ordinary paragraphs and stays\n       editable without nested columns. ---------------------------------------- *\/\n.bp-adv .bp-adv-authors {\n  background: var(--bp-white); border: 1px solid var(--bp-sand);\n  border-top: 4px solid var(--bp-lime); border-radius: var(--bp-radius-card);\n  box-shadow: var(--bp-shadow); padding: var(--bp-s-5);\n  margin-block: 0 var(--bp-s-4);\n  \/* auto-fit, so switching the verified box off leaves one full-width author\n     rather than a half-empty card *\/\n  display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));\n  gap: var(--bp-s-5); align-items: start;\n}\n.bp-adv .bp-adv-author {\n  display: grid; grid-template-columns: 62px 1fr; gap: 0 var(--bp-s-3);\n  align-items: start; min-width: 0;\n}\n.bp-adv .bp-adv-avatar {\n  grid-row: 1 \/ span 3; width: 62px; height: 62px; border-radius: 50%;\n  background: #B7CB331F; border: 2px dashed var(--bp-olive);\n  display: flex; align-items: center; justify-content: center;\n  font-size: 10px; font-weight: 700; letter-spacing: 0.06em; color: var(--bp-forest);\n  margin-block: 0;\n}\n.bp-adv .bp-adv-author.is-placeholder .bp-adv-avatar {\n  border-color: var(--bp-sand); background: #fff; color: var(--bp-foot); }\n.bp-adv .bp-adv-author-role {\n  font-size: 11px; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase;\n  color: var(--bp-forest); line-height: 1.6; margin-block: 0; }\n.bp-adv .bp-adv-author.is-placeholder .bp-adv-author-role { color: var(--bp-foot); }\n.bp-adv .bp-adv-author-name { font-size: 17px; font-weight: 700; line-height: 1.35;\n  margin-block: 0; }\n.bp-adv .bp-adv-author-cred { font-size: var(--bp-fs-foot); color: var(--bp-foot);\n  line-height: 1.55; margin-block: 0; }\n\/* the optional wrapper must not break the two-column grid of the box *\/\n.bp-adv .bp-adv-authors > .bp-optional { display: contents; }\n.bp-adv .bp-adv-authors > .bp-optional.bp-off { display: none !important; }\n\n\/* --- placeholders: image slot, video slot ---------------------------------- *\/\n.bp-adv .bp-slot {\n  display: flex; align-items: center; justify-content: center; text-align: center;\n  min-height: 180px; padding: var(--bp-s-4); margin-block: var(--bp-s-5) 0;\n  border: 2px dashed var(--bp-olive); border-radius: var(--bp-radius-photo);\n  background: #B7CB331F; color: var(--bp-forest);\n}\n.bp-adv .bp-slot p { font-size: var(--bp-fs-small); font-weight: 700; margin-block: 0; }\n.bp-adv .bp-slot--video { min-height: 260px; }\n\n\/* --- mid-article CTA band --------------------------------------------------- *\/\n.bp-adv .bp-adv-midcta {\n  background: var(--bp-grad-lime); border: 1px solid var(--bp-lime);\n  border-radius: var(--bp-radius-card); padding: var(--bp-s-5) var(--bp-s-4);\n  margin-block: var(--bp-s-6); text-align: center;\n}\n.bp-adv .bp-adv-midcta .wp-block-buttons { margin-block-end: var(--bp-s-2); }\n.bp-adv .bp-adv-midcta .bp-adv-foot { margin-block: 0; }\n\n\/* the closing CTA is one named unit in List View, so it moves and toggles as a\n   whole. It carries no box of its own: the spacing must read exactly as it does\n   on the approved page, where the three parts are plain siblings. *\/\n.bp-adv .bp-adv-ctablock { margin-block: 0 var(--bp-s-5); }\n.bp-adv .bp-adv-ctablock .wp-block-buttons { margin-block-end: var(--bp-s-4); }\n.bp-adv .bp-adv-ctablock .bp-adv-foot { margin-block: 0; }\n\n\/* --- the condition, slot 8: the results page reference-card shape ----------- *\/\n.bp-adv .bp-adv-condition {\n  background: var(--bp-white); border: 1px solid var(--bp-sand);\n  border-left: 5px solid var(--bp-lime); border-radius: var(--bp-radius-btn);\n  padding: var(--bp-s-4) var(--bp-s-5); font-weight: 600; box-shadow: var(--bp-shadow);\n}\n\n\/* --- the numbers card: the results page focus panel, same gradient, same\n       radius, same lime figures (\"use more of that design\") ------------------ *\/\n.bp-adv .bp-adv-numcard {\n  background: linear-gradient(135deg, var(--bp-teal) 0%, var(--bp-forest) 100%);\n  border-radius: var(--bp-radius-card);\n  padding: var(--bp-s-6) var(--bp-s-5) var(--bp-s-5);\n  box-shadow: var(--bp-shadow); margin-block: var(--bp-s-5) 0;\n  position: relative; overflow: hidden;\n}\n.bp-adv .bp-adv-numcard::after {\n  content: \"\"; position: absolute; right: -70px; top: -70px; width: 240px; height: 240px;\n  border-radius: 50%; background: rgba(255,255,255,0.05); pointer-events: none;\n}\n.bp-adv .bp-adv-numcard .wp-block-columns {\n  position: relative; z-index: 1; gap: var(--bp-s-5); margin-block: 0; }\n.bp-adv .bp-adv-numcard .wp-block-column { min-width: 0; }\n.bp-adv .bp-adv-num-v { font-size: 44px; font-weight: 700; line-height: 1.12;\n  color: var(--bp-lime); text-align: center; margin-block: 0 var(--bp-s-2); }\n.bp-adv .bp-adv-num-l { font-size: var(--bp-fs-small); line-height: 1.5;\n  color: rgba(255,255,255,0.92); text-align: center; margin-block: 0; }\n.bp-adv .bp-adv-numsrc { margin-block: var(--bp-s-5) 0; }\n\n\/* --- the proof slot: a dashed card until a consented quote exists. 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Uitleg op basis van MedlinePlus en het lab.\",\"inLanguage\":\"nl-NL\",\"dateModified\":\"2026-11-05\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/bioprofile.com\/biomarkers\/vrij-t3\/\"},\"isPartOf\":{\"@id\":\"https:\/\/bioprofile.com\/biomarkers\/vrij-t3\/\"},\"publisher\":{\"@id\":\"https:\/\/bioprofile.com\/#organization\"},\"about\":{\"@id\":\"https:\/\/bioprofile.com\/biomarkers\/vrij-t3\/#biomarker\"},\"citation\":[{\"@type\":\"CreativeWork\",\"name\":\"MedlinePlus, U.S. National Library of Medicine. Triiodothyronine (T3) Tests. Geraadpleegd op 5 november 2026.\",\"url\":\"https:\/\/medlineplus.gov\/lab-tests\/triiodothyronine-t3-tests\/\"},{\"@type\":\"CreativeWork\",\"name\":\"Labplusarts, het laboratorium waarmee BioProfile werkt: referentiewaarde bij de bepaling vrij t3 (FT3), 3,5 tot 5,9 pmol\/l. Lijst van 24 september 2026.\"},{\"@type\":\"CreativeWork\",\"name\":\"BioProfile, de pakketten van het bloedonderzoek en de waarden in elk pakket.\",\"url\":\"https:\/\/bioprofile.com\/bloedonderzoek\/\"}]},{\"@type\":\"MedicalTest\",\"@id\":\"https:\/\/bioprofile.com\/biomarkers\/vrij-t3\/#biomarker\",\"name\":\"Vrij T3\",\"alternateName\":[\"Free T3\"]}]}<\/script>\n\n\n\n<section class=\"wp-block-group bp-adv bp-biomarker bp-biomarker--page is-layout-flow wp-block-group-is-layout-flow\">\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity bp-adv-rule\"\/>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--hero is-layout-flow wp-block-group-is-layout-flow\">\n\n<p class=\"bp-bm-crumbs wp-block-paragraph\"><a href=\"https:\/\/bioprofile.com\/en\/\">Home<\/a> \u203a <a href=\"https:\/\/bioprofile.com\/en\/biomarkers\/\">Biomarkers<\/a> \u203a <span>Free T3<\/span><\/p>\n\n\n\n<h1 class=\"wp-block-heading bp-adv-h1\">Free T3 (FT3): the active thyroid hormone in your blood<\/h1>\n\n\n\n<p class=\"bp-adv-standfirst wp-block-paragraph\">This level shows how much active thyroid hormone is circulating freely in your blood. A high level can point to a thyroid that makes too much hormone, a low level to a thyroid that makes too little.<sup>[1]<\/sup><\/p>\n\n\n\n<p class=\"bp-adv-lede wp-block-paragraph\">On this page you can read what Free T3 is, what the guidelines say about a level that is too low or too high, what affects your level and which levels are best to look at alongside it.<\/p>\n\n\n\n<p class=\"bp-bm-names wp-block-paragraph\">Also known as: free triiodothyronine, free T3. At the lab: FT3.<\/p>\n\n\n\n<p class=\"bp-adv-byline wp-block-paragraph\">Updated on 10 October 2026<\/p>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--wash is-layout-flow wp-block-group-is-layout-flow\">\n\n<div class=\"wp-block-group bp-bm-toc is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-inhoud\">On this page<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li><a href=\"#bp-in-het-kort\">In short<\/a><\/li>\n\n\n<li><a href=\"#bp-wat-is-vrij-t3\">What is Free T3?<\/a><\/li>\n\n\n<li><a href=\"#bp-waarom-het-ertoe-doet\">Why this value matters<\/a><\/li>\n\n\n<li><a href=\"#bp-wat-je-waarde-zegt\">What your Free T3 level tells you<\/a><\/li>\n\n\n<li><a href=\"#bp-wat-het-beinvloedt\">What affects your Free T3<\/a><\/li>\n\n\n<li><a href=\"#bp-welke-pakketten\">Which BioProfile packages measure Free T3<\/a><\/li>\n\n\n<li><a href=\"#bp-waarden-die-erbij-horen\">Related values<\/a><\/li>\n\n\n<li><a href=\"#bp-hoe-gemaakt\">How this page was made<\/a><\/li>\n\n\n<li><a href=\"#bp-bronnen\">Sources<\/a><\/li>\n\n<\/ul>\n\n<\/div>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-in-het-kort\">In short<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Free T3 is the active form of T3, a hormone your thyroid makes.<sup>[1]<\/sup><\/li>\n\n\n<li>A high level can point to a thyroid that makes too much hormone.<sup>[1]<\/sup><\/li>\n\n\n<li>A low level can point to a thyroid that makes too little hormone.<sup>[1]<\/sup><\/li>\n\n\n<li>Your doctor usually looks at the result alongside your TSH and your Free T4.<sup>[1]<\/sup><\/li>\n\n<\/ul>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--wash is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-wat-is-vrij-t3\">What is Free T3?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Free T3 is the active part of the thyroid hormone T3 in your blood. Your thyroid is a small, butterfly-shaped gland at the bottom of your throat. It makes two hormones: T3 and T4. Free T3 is the form that can enter your tissues, right where it is needed.<sup>[1]<\/sup><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Together, thyroid hormones control how your body uses energy. They affect your weight, your heart, your body temperature, your muscle strength and even your mood. Most of your T3 is bound to certain proteins and cannot enter your tissues. A Free T3 test measures only the free part.<sup>[1]<\/sup><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Free T3 is measured in blood taken from a vein in your arm. The doctor usually looks at the result together with your TSH and T4. A high value can point to a thyroid that makes too much hormone, and a low value to one that makes too little. A normal value on its own does not rule out a thyroid condition.<sup>[1]<\/sup><\/p>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-waarom-het-ertoe-doet\">Why this value matters<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A T3 test mainly helps to check whether your thyroid is making too much hormone. The test can also help find what is causing it.<sup>[1]<\/sup><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The pituitary gland is a pea-sized gland at the base of your brain. It makes TSH, the hormone that tells your thyroid how much T3 and T4 to make. That is why an abnormal T3 level can also point to a problem with the pituitary gland.<sup>[1]<\/sup><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Your doctor may ask for a T3 test if you have symptoms that fit too much thyroid hormone. Think of restlessness, shaky hands, heavy sweating, poor sleep, tiredness or an irregular heartbeat.<sup>[1]<\/sup><\/p>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--wash is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-wat-je-waarde-zegt\">What your Free T3 value tells you<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">The lab's reference range<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Labplusarts, the lab BioProfile works with, uses a reference range of 3.5 to 5.9 pmol\/l for Free T3. The lab calls a level between those limits normal.<sup>[2]<\/sup><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What MedlinePlus says<\/h3>\n\n\n\n<figure class=\"wp-block-table bp-bm-table\"><table><thead><tr><th>Free T3<\/th><th>Can point to<\/th><th>Alongside which other results<\/th><\/tr><\/thead><tbody><tr><td>High<sup>[1]<\/sup><\/td><td>A thyroid that makes too much hormone<\/td><td>In general<\/td><\/tr><tr><td>High<sup>[1]<\/sup><\/td><td>A problem in the thyroid itself that leads to too much hormone<\/td><td>With a low TSH and a high Free T4<\/td><\/tr><tr><td>High<sup>[1]<\/sup><\/td><td>A pituitary condition that leads to too much thyroid hormone<\/td><td>With a normal or high TSH and a high Free T4<\/td><\/tr><tr><td>Low<sup>[1]<\/sup><\/td><td>A thyroid that makes too little hormone<\/td><td>In general<\/td><\/tr><tr><td>Low or normal<sup>[1]<\/sup><\/td><td>A problem in the thyroid itself that leads to too little hormone<\/td><td>With a high TSH and a low Free T4<\/td><\/tr><tr><td>Low or normal<sup>[1]<\/sup><\/td><td>A pituitary condition that leads to too little thyroid hormone<\/td><td>With a low TSH and a low Free T4<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"bp-bm-caption wp-block-paragraph\">Source: MedlinePlus, U.S. National Library of Medicine. Patterns for T3, free or total, together with TSH and Free T4, without fixed numbers.<sup>[1]<\/sup><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">A level that is too low<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A low Free T3 can point to a thyroid that makes too little hormone. Even so, a T3 test is usually not the first choice for this. Other thyroid tests show it sooner.<sup>[1]<\/sup><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">A level that is too high<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A high Free T3 can point to a thyroid that makes too much hormone. If your TSH or T4 result is abnormal or unclear, your doctor can use a T3 test to confirm or rule this out. Ask your doctor what your combination of results means.<sup>[1]<\/sup><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.<\/p>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-wat-het-beinvloedt\">What affects your Free T3<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Medicines and supplements<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Certain medicines and supplements can affect your result. Your doctor will let you know if you need to stop taking anything before the test. Do not stop taking a medicine on your own unless your doctor tells you to.<sup>[1]<\/sup><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Thyroid hormone as a medicine<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">If you take thyroid hormone as a medicine, a T3 test can show whether your dose is keeping your hormone levels within a healthy range.<sup>[1]<\/sup><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Your pituitary gland<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">How much T3 your thyroid makes depends on TSH from your pituitary gland. That way, a pituitary condition can lead to too much or too little thyroid hormone.<sup>[1]<\/sup><\/p>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--wash is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-welke-pakketten\">Which BioProfile packages measure Free T3<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Free T3 is included in BioProfile 121 and 150.<sup>[3]<\/sup><\/p>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-3e41869c wp-block-buttons-is-layout-flex\">\n\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/bioprofile.com\/en\/blood-testing\/\">View the packages<\/a><\/div>\n\n<\/div>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-waarden-die-erbij-horen\">Values that go with it<\/h2>\n\n\n\n<ul class=\"wp-block-list bp-bm-related\">\n\n<li><a href=\"https:\/\/bioprofile.com\/en\/biomarkers\/tsh\/\">TSH<\/a>: the hormone from your pituitary gland that tells your thyroid how much T3 and T4 to make.<sup>[1]<\/sup><\/li>\n\n\n<li><strong>Selenium<\/strong>: a level you can look at alongside your thyroid levels.<\/li>\n\n\n<li><a href=\"https:\/\/bioprofile.com\/en\/biomarkers\/free-t4\/\">Free T4<\/a>: the second thyroid hormone, which your doctor usually looks at together with your T3 and TSH.<sup>[1]<\/sup><\/li>\n\n\n<li><strong>TPO antibodies<\/strong>: a level that belongs with your thyroid levels and that you can look at alongside them.<\/li>\n\n\n<li><strong>Iodine<\/strong>: a level you can look at alongside your thyroid levels.<\/li>\n\n<\/ul>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--wash is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-hoe-gemaakt\">How this page was made<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.<\/p>\n\n<\/div>\n\n\n\n<div class=\"wp-block-group bp-adv-sec bp-adv-sec--disclosure is-layout-flow wp-block-group-is-layout-flow\">\n\n<h2 class=\"wp-block-heading\" id=\"bp-bronnen\">Sources<\/h2>\n\n\n\n<ol class=\"wp-block-list bp-adv-srclist bp-bm-src\">\n\n<li>MedlinePlus, U.S. National Library of Medicine. Triiodothyronine (T3) Tests. Accessed on 5 November 2026. <a href=\"https:\/\/medlineplus.gov\/lab-tests\/triiodothyronine-t3-tests\/\" target=\"_blank\" rel=\"noopener\">https:\/\/medlineplus.gov\/lab-tests\/triiodothyronine-t3-tests\/<\/a><\/li>\n\n\n<li>Labplusarts, the laboratory BioProfile works with: reference range for the Free T3 (FT3) test, 3.5 to 5.9 pmol\/l. List of 24 September 2026.<\/li>\n\n\n<li>BioProfile, the blood test packages and the values in each package. <a href=\"https:\/\/bioprofile.com\/en\/blood-testing\/\" target=\"_blank\" rel=\"noopener\">https:\/\/bioprofile.com\/en\/blood-testing\/<\/a><\/li>\n\n<\/ol>\n\n<\/div>\n\n<\/section>\n\n","protected":false},"excerpt":{"rendered":"<p>Home \u203a Biomarkers \u203a Free T3 Free T3 (FT3): the active thyroid hormone in your blood This level shows how much active thyroid hormone is circulating freely in your blood. A high level can point to a thyroid that makes too much hormone, a low level to a thyroid that makes too little.[1] On this [&hellip;]<\/p>\n","protected":false},"author":18,"featured_media":0,"parent":6592,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"_yoast_wpseo_title":"Free T3 (FT3): what your level tells you | BioProfile","_yoast_wpseo_metadesc":"What is Free T3, what can a level that is too low or too high point to, and which levels do you look at alongside it? 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