<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Recently, a trial with 353 subjects on steady-state L-T4 replacement dose for autoimmune thyroiditis or after surgery for malignant or benign thyroid disease was published in Endocrine Connections.<div><br></div><div>It revealed that substitution dose was independently associated with gender, age, aetiology and deiodinase capacity (all p<0.001). Stratifying patients by deiodinase activity (SPINA-GD) categories of <23, 23-29 and >29 nmol/s revealed an increasing FT3-FT4 dissociation; the poorest converters showed the lowest FT3 levels in spite of highest dose and circulating FT4 (p<0.001).</div><div><br></div><div>As the authors state these findings imply that a) thyroid hormone conversion efficiency is an important modulator of the biochemical response to levothyroxine, b) measuring FT3 may be an additional treatment target, and c) L-T4 dose escalation may have limited success to raise FT3 appropriately in some cases.</div><div><br></div><div>The full text of the paper is available for free from <a href="http://dx.doi.org/10.1530%2FEC-15-0056">http://dx.doi.org/10.1530%2FEC-15-0056</a> .</div><div><br></div><div>Reference</div><div><pre><font class="Apple-style-span" face="Helvetica"><span class="Apple-style-span" style="white-space: normal;">Midgley JE, Larisch R, Dietrich JW, Hoermann R. Variation in the Biochemical
Response to L-Thyroxine Therapy and Relationship with Peripheral Thyroid Hormone
Conversion. Endocr Connect. 2015 Aug 11. pii: EC-15-0056. [Epub ahead of print]
PubMed PMID: 26265111</span></font></pre><div apple-content-edited="true"> <div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="font-size: small; "><div><br class="Apple-interchange-newline">-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --</div><div>-- Dr. med. Johannes W. Dietrich</div><div>-- Oberarzt / Consultant Endocrinologist</div><div>-- Laboratory XU44, Endocrine Research</div><div>-- Medical Hospital I, Bergmannsheil University Hospitals</div><div>-- Ruhr University of Bochum</div><div>-- Buerkle-de-la-Camp-Platz 1, D-44789 Bochum, NRW, Germany</div><div>-- Phone: +49:234:302-6400, Fax: +49:234:302-6403</div><div>-- eMail: "<a href="mailto:j.w.dietrich@medical-cybernetics.de">j.w.dietrich@medical-cybernetics.de</a>"</div><div>-- <a href="http://www.thyreologie.com.de">http://www.thyreologie.com.de</a></div><div>-- GND 123571073 | VIAF 69838628 | Researcher ID C-3498-2009</div><div>-- ISNI: 0000 0000 1275 0811 | ORCID ID: 0000-0002-1185-3549</div><div>-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --</div><div><br></div></span><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"> </div><br></div></body></html>