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Changes in Thyroid Metabolites after Liothyronine Administration: A Secondary Analysis of Two Clinical Trials That Incorporated Pharmacokinetic Data

Open access
Diab, Nour, Desale, Sameer, Danielsen, Mark, Köhrle, Josef, Shara, Nawar, Jonklaas, Jacqueline·2022·Metabolites
DOI 10.3390/metabo12060476PMC PMC9227779
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Abstract

We examined relationships between thyroid hormone (TH) metabolites in humans by measuring 3,5-diiodothyronine (3,5-T2) and 3-iodothyronamine (3-T1AM) levels after liothyronine administration. In secondary analyses, we measured 3,5-T2 and 3-T1AM concentrations in stored samples from two clinical trials. In 12 healthy volunteers, THs and metabolites were documented for 96 h after a single dose of 50 mcg liothyronine. In 18 patients treated for hypothyroidism, levothyroxine therapy was replaced by daily dosing of 30–45 mcg liothyronine. Analytes were measured prior to the administration of liothyronine weekly for 6 weeks, and then hourly for 8 h after the last liothyronine dose of the study. In the weekly samples from the hypothyroid patients, 3,5-T2 was higher by 0.033 nmol/L with each mcg/dL increase in T4 and 0.24 nmol/L higher with each ng/dL increase in FT4 (p-values = 0.007, 0.0365). In hourly samples after the last study dose of liothyronine, patients with T3 values higher by one ng/dL had 3-T1AM values that were lower by 0.004 nmol/L (p-value = 0.0473); patients with 3,5-T2 higher by one nmol/L had 3-T1AM values higher by 2.45 nmol/L (p-value = 0.0044). The positive correlations between weekly trough levels of 3,5-T2 and T4/FT4 during liothyronine therapy may provide insight into 3,5-T2 production, possibly supporting some production of 3,5-T2 from endogenous T4, but not from exogenous liothyronine. In hourly sampling after liothyronine administration, the negative correlation between T3 levels and 3-T1AM, but positive correlation between 3,5-T2 levels and 3-T1AM could support the hypothesis that 3-T1AM production occurs via 3,5-T2 with negative regulation by T3.

AI snapshot

Written from the paper’s full text.

TL;DR

This secondary analysis of stored samples from two liothyronine (LT3) trials measured 3,5-T2 and 3-T1AM and found no within-person trends after LT3, but identified relationships between metabolites and T4/FT4/T3 in hypothyroid patients. The authors suggest possible production of 3,5-T2 from endogenous T4, and 3-T1AM production via 3,5-T2 with negative regulation by T3.

Key findings

  • In 12 healthy volunteers given a single 50 mcg LT3 dose, 3,5-T2 and 3-T1AM remained stable: no trend for 3,5-T2 over the first 5 h (p = 0.75) or all 96 h (p = 0.19), and no trend for 3-T1AM over the first 5 h (p = 0.3687) or all 96 h (p = 0.1859). There was no correlation between 3,5-T2 and 3-T1AM, and no relationship between either metabolite and TSH, T4, FT4, T3, or FT3. Females had 3.9-fold higher 3-T1AM than males (p = 0.034).
  • In 18 hypothyroid patients switched to daily LT3, weekly trough 3,5-T2 was higher by 0.033 nmol/L per mcg/dL increase in T4 (p = 0.007) and by 0.24 nmol/L per ng/dL increase in FT4 (p = 0.03; abstract reports p = 0.0365). No weekly associations were found between 3-T1AM and TSH, T4, FT4, T3, or FT3.
  • In hourly samples after the last LT3 dose, higher 3,5-T2 was associated with higher 3-T1AM: 1 nmol/L higher 3,5-T2 corresponded to 3-T1AM higher by 2.45 nmol/L (p = 0.0041; abstract reports p = 0.0044). Higher T3 was associated with lower 3-T1AM: each ng/dL increase in T3 corresponded to 3-T1AM lower by 0.004 nmol/L (p = 0.047; abstract reports p = 0.0473).
  • Both healthy volunteers and hypothyroid patients appeared to have individual setpoints for 3,5-T2 and 3-T1AM; no effects of sex, race, age, or BMI were found on metabolites in the hypothyroid patients.

Methods

  • Secondary analysis of stored samples from two prior clinical trials: NCT01581463 included 12 healthy volunteers who received a single 50 mcg LT3 dose with sampling over 96 h; NCT01800617 included 18 hypothyroid patients whose LT4 was replaced by daily LT3 (15 mcg initially, then 30–45 mcg) for 6 weeks, with weekly trough samples and hourly sampling for 8 h after the final LT3 dose.
  • 3,5-T2 and 3-T1AM were measured in 2017 at Charité–Universitätsmedizin Berlin using a monoclonal antibody-based chemiluminescence immunoassay; TSH, T4, FT4, T3, and FT3 were measured at Georgetown University Laboratory using a Siemens Dimension Vista Analyzer.
  • Statistical analysis used linear regression with repeated measures and autoregressive covariance structure, adjusted for time, with interaction terms for time and 3,5-T2; analyses were conducted in SAS 9.4, and missing data were handled with Proc Mixed assuming missing at random. No formal power analysis was performed.

Limitations

  • The paper states: tandem mass spectrometry was not used; samples had been stored for several years, though at −80°C with continuous monitoring and no thawing; participant numbers were very small; this was a secondary analysis of two prior studies with different designs; multiple comparisons could not exclude multiple testing bias; sex and age composition differed between studies; varying degrees of endogenous thyroid function complicated separating endogenous versus exogenous T4 sources; hypothyroid participants were transitioning off LT4 to LT3; the study was uncontrolled and could not assess therapy satisfaction.
  • The text also makes evident: immunoassay-based metabolite measurements may not correlate with mass spectrometry data, and reported concentrations of 3,5-T2 and 3-T1AM vary widely across methods; the novel sex difference in 3-T1AM among healthy volunteers may not be a true finding given the small number of individuals studied.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/metabo12060476

Cites

27 of 27 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

3 of 8 cited sources checked · 3 supported · 0 flagged

  • Premisecitation

    These setpoints also seem to extend to LT4-treated patients.

    “These setpoints also seem to extend to LT4-treated patients [14,15,16].”
    Quote in the paperNot a substantial claim3 of 3 sources checked
    • cites [14] Hoermann, 2019, Functional and Symptomatic Individuality in the Response to Levothyroxine Treatment, Front. Endocrinol. source
    • cites [15] Hoermann, 2017, Recent Advances in Thyroid Hormone Regulation: Toward a New Paradigm for Optimal Diagnosis and Treatment, Front. Endocrinol. source
    • cites [16] Leow, 2014, The homeostatic set point of the hypothalamus-pituitary-thyroid axis--maximum curvature theory for personalized euthyroid targets, Biol. Med. Model. source
  • Findingown data

    In healthy volunteers after a single dose of LT3, there was no correlation between 3,5-T2 and 3-T1AM concentrations.

    “There was also no correlation between 3,5-T2 and 3-T1AM concentrations (see Table 2).”
    Quote in the paperNot a substantial claim
  • Findingown data

    In hypothyroid patients receiving daily LT3, there was no significant trend in 3,5-T2 levels in either weekly (p=0.4982) or hourly sampling (p=0.1256).

    “There was no significant trend in 3,5-T2 levels in either the weekly (p = 0.4982) or hourly sampling (p value = 0.1256).”
    Quote in the paperNot a substantial claim
  • Findingown data

    In weekly samples of hypothyroid patients, there were no associations between 3-T1AM and TSH, T4, FT4, T3 and FT3.

    “There were no associations between 3-T1AM and TSH, T4, FT4, T3 and FT3 in the weekly samples.”
    Quote in the paperNot a substantial claim
  • Findingown data

    In healthy volunteers, there was no effect of race, age and BMI on 3-T1AM concentrations.

    “For 3-T1AM, there was also no effect of race, age and BMI.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 17
  • Classified as probably not a substantial claim. 12
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data

    In 12 healthy volunteers given a single 50 mcg dose of LT3, 3-T1AM levels remained stable, with no change over the first 5 h (p=0.3687) or over all 96 h (p=0.1859).

    “Similarly, there was no change in 3-T1AM either over the first 5 h (p value = 0.3687) or over all 96 h (p value = 0.1859) (see Table 1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In 12 healthy volunteers given a single 50 mcg dose of LT3, 3,5-T2 levels remained stable, with no trend for change over the first 5 h (p=0.75) or over all 96 h (p=0.19).

    “3,5-T2 and 3-T1AM levels remained stable after the administration of 50 mcg LT3. There was also no trend for a change in 3,5-T2, either over the first 5 h (p value = 0.75) or over all 96 h (p value = 0.19).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In hourly samples after the last dose of LT3 in hypothyroid patients, T3 levels and 3-T1AM levels were negatively correlated; for each ng/dL increase in T3, 3-T1AM levels were lower by 0.004 nmol/L (p=0.047).

    “However, T3 levels and 3-T1AM levels were negatively correlated. For each ng/dL increase in T3, 3-T1AM levels were lower by 0.004 nmol/L (p value = 0.047).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    For hourly sampling after the last dose of LT3 in hypothyroid patients, 3,5-T2 and 3-T1AM were positively associated; patients with 1 nmol/L higher 3,5-T2 had 3-T1AM higher by 2.45 nmol/L (p=0.0041).

    “However, for the hourly sampling after the last dose of LT3, 3,5-T2 and 3-T1AM were positively associated, with higher 3,5-T2 levels being associated with higher 3-T1AM levels. Patients with 1 nmol/L higher 3,5-T2 levels on average had 3-T1AM levels that were higher by 2.45 nmol/L (p value = 0.0041) (see Table 5).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The study did not utilize the very specific tandem mass spectrometry methodology for measuring TH metabolites.

    “Foremost, we did not utilize the very specific tandem mass spectrometry methodology for measuring TH metabolites.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductreasoning

    The study was uncontrolled and so could not assess satisfaction with therapy during the transition.

    “In addition, our study was uncontrolled and so could not assess satisfaction with therapy during the transition.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    No relationship observed between 3,5-T2 and 3-T1AM levels during weekly sampling in hypothyroid patients suggests tight regulation of metabolites.

    “No relationship was observed between 3,5-T2 and 3-T1AM levels during the weekly sampling in the hypothyroid patients, suggesting the tight regulation of metabolites.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductnone given

    Participant numbers were very small and this was a secondary analysis of two prior studies with different designs performed for other purposes.

    “Additionally, our participant numbers were very small and this was a secondary analysis of two prior studies with different designs performed for other purposes.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductnone given

    Samples were appropriately stored in a −80° centigrade freezer with continuous monitoring, with no intervening episodes of thawing prior to use, thus ensuring sample quality.

    “However, the samples were appropriately stored in a −80° centigrade freezer with continuous monitoring, thus ensuring sample quality. There were no intervening episodes of thawing prior to use.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationown data

    The positive correlation between 3,5-T2 and 3-T1AM during dynamic sampling after the last LT3 dose could suggest that 3-T1AM production is via 3,5-T2.

    “However, during the dynamic sampling after the administration of the last LT3 dose, there was a positive correlation between 3,5-T2 and 3-T1AM which could suggest that 3-T1AM production is via 3,5-T2.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    This could raise the possibility that 3,5-T2 can also be made from endogenous T4, but does not support the concept of 3,5-T2 production from exogenous T3.

    “This could raise the possibility that 3,5-T2 can also be made from endogenous T4, but does not support the concept of 3,5-T2 production from exogenous T3.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Study design and conductnone given

    The sex and age composition of the participants in the two studies differed.

    “The sex and age composition of the participants in the two studies differed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The hypothyroid patients in the second study retained at least some degree of residual endogenous thyroid function and were exclusively receiving LT3; they would have had some remaining T4 from exogenous LT4 at the beginning of the study, which then declined, so that by the end of the study any T4 would be from endogenous sources.

    “However, the hypothyroid patients in our second study retained at least some degree of residual endogenous thyroid function and were exclusively receiving LT3. They would have had some remaining T4 from exogenous LT4 at the beginning of the study, which then declined, so that by the end of the study any T4 would be from endogenous sources.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Similar individual setpoints have been observed for TSH, T4 and T3.

    “Similar individual setpoints have been observed for TSH, T4 and T3 [12,13].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [12] Andersen, 2002, Narrow individual variations in serum T(4) and T(3) in normal subjects: A clue to the understanding of subclinical thyroid disease, J. Clin. Endocrinol. Metab source
    • cites [13] Andersen, 2003, Biologic variation is important for interpretation of thyroid function tests, Thyroid source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Samples had been stored for several years prior to their use for this secondary analysis.

    “Our samples had been stored for several years prior to their use for this secondary analysis.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    No acute changes in 3,5-T2 or 3-T1AM after exogenous LT3 administration in individuals with intact thyroid function, despite mean T3 concentrations rising from 120 ng/dL to 346 ng/dL, suggests that these metabolites are not produced via exogenous T3 or that metabolite concentrations are tightly and rapidly regulated.

    “The fact that no acute changes in 3,5-T2 or 3-T1AM were observed after exogenous LT3 administration in individuals with intact thyroid function, despite the fact that their mean T3 concentrations rose from 120 ng/dL to 346 ng/dL, either suggests that these metabolites are not produced via exogenous T3 or that metabolite concentrations are tightly and rapidly regulated.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Higher T3 levels were associated with lower 3-T1AM levels unless T3 negatively regulated 3-T1AM production from 3,5-T2.

    “However, such a hypothesis does not explain why higher T3 levels were associated with lower 3-T1AM levels unless T3 negatively regulated 3-T1AM production from 3,5-T2.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    The distribution of data points for 3,5-T2 and 3-T1AM from individuals with intact thyroid function suggests that there is a distinct setpoint for these metabolites for each individual participant that is composed of closely grouped values and is not subject to perturbations caused by exogenous LT3.

    “The distribution of the data points for 3,5-T2 and 3-T1AM from individuals with intact thyroid function suggests that there is a distinct setpoint for these metabolites for each individual participant that is composed of closely grouped values and is not subject to perturbations caused by exogenous LT3.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing), S4 (based). The quote only partly states this claim.

    Interpretationown data

    Each hypothyroid patient had an apparent setpoint for their 3,5-T2 and 3-T1AM concentrations.

    “It can be seen that each participant had an apparent setpoint for their 3,5-T2 and 3-T1AM concentrations.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    TH metabolite measurement was not pre-planned at the time of the initial studies and a formal power analysis was not performed.

    “TH metabolite measurement was not pre-planned at the time of the initial studies and a formal power analysis was not performed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The first study was approved by the Institutional Review Board and registered at ClinicalTrials.gov as NCT01581463.

    “The trial was approved by the Institutional Review Board and registered at ClinicalTrials.gov as clinical trial NCT01581463”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The detailed assay methodology using a monoclonal antibody-based chemiluminescence immunoassay has been previously described.

    “The detailed assay methodology using a monoclonal antibody-based chemiluminescence immunoassay has been previously described [2,6,7]”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [2] Lehmphul, 2019, 3,5-T2-A Janus-Faced Thyroid Hormone Metabolite Exerts Both Canonical T3-Mimetic Endocrine and Intracrine Hepatic Action, Front. Endocrinol.

      Not checked in the free run.

    • cites [6] Homuth, 2014, Detection of 3,5-diiodothyronine in sera of patients with altered thyroid status using a new monoclonal antibody-based chemiluminescence immunoassay, Thyroid source
    • cites [7] Hoefig, 2011, Evidence for extrathyroidal formation of 3-iodothyronamine in humans as provided by a novel monoclonal antibody-based chemiluminescent serum immunoassay, J. Clin. Endocrinol. Metab. source

  • May combine two claims.

    Interpretationreasoning

    These findings possibly support some production of 3,5-T2 from endogenous T4, but not from exogenous liothyronine.

    “These findings possibly support some production of 3,5-T2 from endogenous T4, but not from exogenous liothyronine.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The second study was approved by the Institutional Review Board and registered at ClinicalTrials.gov as NCT01800617.

    “This study was approved by the Institutional Review Board and registered at ClinicalTrials.gov as clinical trial NCT01800617”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Samples from both studies were pooled together and placed in a randomized order prior to analysis to avoid between-run bias.

    “The samples from both studies were pooled together and placed in a randomized order prior to analysis to avoid between-run bias.”
    Quote in the paperNot a substantial claim
25 of 25

  • The authors state this as an assumption.

    Missing data are missing at random.

    “This analyzes all of the data that are present with the assumption that the data are missing at random.”
1 of 1

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Conflicting p-values for the weekly FT4-3,5-T2 association

    Minor

    The abstract gives p = 0.0365 for the FT4 association, whereas the results give p = 0.03. The latter is not the value obtained by rounding 0.0365 to two decimal places.

  • Conflicting p-values for the hourly 3,5-T2-3-T1AM association

    Minor

    The abstract reports p = 0.0044 for this association, while the results report p = 0.0041.

2 of 2

Cites

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Related

Authors
Diab, N., Desale, S., Danielsen, M., Köhrle, J., Shara, N., & Jonklaas, J.
Affiliations
  • Marshall High School, Falls Church, VA 22043, USA
  • MedStar Health Research Institute (US)
  • Georgetown University (US)
  • Humboldt-Universität zu Berlin (DE)
Corresponding author
Jonklaas, Jacqueline
ORCID
Venue
Metabolites
Publisher
MDPI AG
Published
2022-05-24
Volume
12
Issue
6
Pages
476
ISSN
2218-1989 (ISSN-L)
DOI
10.3390/metabo12060476
PMC
PMC9227779
OpenAlex
W4281492895
Cited by
1
References
27
Citations by year
2024: 1
FWCI
0.19
Type
journal article
Language
en
Open access
Licence
Locations
  • Metabolites (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
federal funds (UL1TR001409)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Hormonal and reproductive studies
Keywords
liothyronine, thyroid hormone metabolites, 3,5-diiodothyronine, 3-iodothyronamine, triiodothyronine, thyroxine, hypothyroidism, levothyroxine replacement, pharmacokinetics

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