AUTHOR=Spaggiari Giorgia , Brigante Giulia , De Vincentis Sara , Cattini Umberto , Roli Laura , De Santis Maria Cristina , Baraldi Enrica , Tagliavini Simonetta , Varani Manuela , Trenti Tommaso , Rochira Vincenzo , Simoni Manuela , Santi Daniele 

TITLE=Probiotics Ingestion Does Not Directly Affect Thyroid Hormonal Parameters in Hypothyroid Patients on Levothyroxine Treatment

JOURNAL=Frontiers in Endocrinology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2017.00316

DOI=10.3389/fendo.2017.00316

ISSN=1664-2392

ABSTRACT=<sec id="ST1"><title>Purpose</title><p>The relationship between probiotics and levothyroxine (LT<sub>4</sub>) requirement has not yet been investigated. The aim of this study was to assess whether a mixture of highly charged <italic>Lactobacilli</italic> and <italic>Bifidobacteria</italic> (VSL#3<sup>®</sup>) is able to influence LT<sub>4</sub> metabolism acting on the gut microbiota.</p></sec><sec id="ST2"><title>Methods</title><p>A prospective, randomized, single-blind, controlled, investigator-started clinical trial was carried out. Patients with primary hypothyroidism were randomly assigned to the study (VSL#3<sup>®</sup> + LT<sub>4</sub>) and the control group (LT<sub>4</sub>). A 2-month treatment phase was followed by 2 months of follow-up. Clinical examination, blood tests for thyroid function and for peripheral tissue markers of thyroid hormones (PTM) were performed monthly. LT<sub>4</sub> dose adjustments were performed when necessary.</p></sec><sec id="ST3"><title>Results</title><p>Thirty-nine patients were enrolled in the study group and 41 in the control group. No difference in thyroid function [thyroid-stimulating hormone (TSH), free triiodothyronine (fT<sub>3</sub>), and free thyroxine (fT<sub>4</sub>)] and PTM was found between groups and among visits. FT<sub>3</sub>/fT<sub>4</sub> ratio was directly correlated to TSH at each visit in both groups, with the exception of the first evaluation of probiotics-treated subjects (rho = 0.287, <italic>p</italic> = 0.076). LT<sub>4</sub> daily dose adjustments occurred more frequently in the control than in the study group (<italic>p</italic> = 0.007), despite no differences in the mean LT<sub>4</sub> daily dose. In particular, LT<sub>4</sub> doses were increased six times in the control group and decreased four times in the study group.</p></sec><sec id="ST4"><title>Conclusion</title><p>VSL#3<sup>®</sup> does not directly alter thyroid functional compensation. A probiotics-mediated influence on thyroid hormones homeostasis is suggested since probiotics supplementation could be able to prevent serum hormonal fluctuations.</p></sec><sec id="ST5"><title><uri xlink:href="http//ClinicalTrials.gov" xmlns:xlink="http://www.w3.org/1999/xlink">ClinicalTrials.gov</uri> ID</title><p>Registration number NCT03095963.</p></sec>