Dataset Information

Is a Normal TSH Synonymous With "Euthyroidism" in Levothyroxine Monotherapy?

ABSTRACT:

Context

Levothyroxine (LT₄) monotherapy is the standard of care for hypothyroidism.

Objective

To determine whether LT₄ at doses that normalize the serum TSH is associated with normal markers of thyroid status.

Design

Cross-sectional data from the US National Health and Nutrition Examination Survey (2001-2012) was used to evaluate 52 clinical parameters. LT₄ users were compared to healthy controls and controls matched for age, sex, race, and serum TSH. Regression was used to evaluate for correlation with T₄ and T₃ levels.

Participants

A total of 9981 participants with normal serum TSH were identified; 469 were LT₄-treated.

Results

Participants using LT₄ had higher serum total and free T₄ and lower serum total and free T₃ than healthy or matched controls. This translated to approximately 15-20% lower serum T₃:T₄ ratios in LT₄ treatment, as has been shown in other cohorts. In comparison to matched controls, LT₄-treated participants had higher body mass index despite report of consuming fewer calories/day/kg; were more likely to be taking beta-blockers, statins, and antidepressants; and reported lower total metabolic equivalents. A serum TSH level below the mean in LT₄-treated participants was associated with a higher serum free T₄ but similar free and total T₃; yet those with lower serum TSH levels exhibited higher serum high-density lipoprotein and lower serum low-density lipoprotein, triglycerides, and C-reactive protein. Age was negatively associated with serum free T₃:free T₄ ratio in all participants; caloric intake was positively associated in LT₄-treated individuals.

Conclusions

In a large population study, participants using LT₄ exhibited lower serum T₃:T₄ ratios and differed in 12/52 objective and subjective measures.

SUBMITTER: Peterson SJ

PROVIDER: S-EPMC6287526 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Is a Normal TSH Synonymous With "Euthyroidism" in Levothyroxine Monotherapy?

Peterson Sarah J SJ McAninch Elizabeth A EA Bianco Antonio C AC

The Journal of clinical endocrinology and metabolism 20161004 12

<h4>Context</h4>Levothyroxine (LT<sub>4</sub>) monotherapy is the standard of care for hypothyroidism.<h4>Objective</h4>To determine whether LT<sub>4</sub> at doses that normalize the serum TSH is associated with normal markers of thyroid status.<h4>Design</h4>Cross-sectional data from the US National Health and Nutrition Examination Survey (2001-2012) was used to evaluate 52 clinical parameters. LT<sub>4</sub> users were compared to healthy controls and controls matched for age, sex, race, and ...[more]

PMID: 27700539

Similar Datasets

Project description:ImportanceWhether the use of generic vs brand levothyroxine affects thyrotropin levels remains unclear.ObjectiveTo compare the effectiveness of generic vs brand levothyroxine in achieving and maintaining normal thyrotropin levels among new users.Design, setting, and participantsThis retrospective, 1:1 propensity score-matched longitudinal cohort study used the OptumLabs Data Warehouse administrative claims database linked to laboratory results from commercially insured and Medicare Advantage enrollees throughout the United States. Eligible patients were adults (aged ≥18 years) with thyrotropin levels ranging from 4.5 to 19.9 mIU/L who initiated use of generic or brand-name levothyroxine from January 1, 2008, to October 1, 2017. Data were analyzed from August 13, 2018, to October 25, 2019.ExposurePatients received generic or brand-name levothyroxine.Main outcomes and measuresProportion of patients with normal vs markedly abnormal thyrotropin levels (<0.1 or >10 mIU/L) within 3 months and with stable thyrotropin levels within 3 months after the thyrotropin value fell into the normal range.ResultsA total of 17 598 patients were included (69.0% female; 74.0% White; mean [SD] age, 55.1 [16.0] years), of whom 15 299 filled generic and 2299 filled brand-name levothyroxine prescriptions during the study period. Among 4570 propensity score-matched patients (mean [SD] age, 50.3 [13.8] years; 3457 [75.6%] female; 3510 [76.8%] White), the proportion with normal thyrotropin levels within 3 months of filling levothyroxine prescriptions was similar for patients who received generic vs brand-name levothyroxine (1722 [75.4%; 95% CI, 71.9%-79.0%] vs 1757 [76.9%; 95% CI, 73.4%-80.6%]; P = .23), as was the proportion with markedly abnormal levels (94 [4.1%; 95% CI, 3.4%-5.0%] vs 88 [3.9%; 95% CI, 3.1%-4.7%]; P = .65). Among 1034 propensity score-matched patients who achieved a normal thyrotropin value within 3 months of initiation of levothyroxine, the proportion maintaining subsequent normal thyrotropin levels during the next 3 months was similar for patients receiving generic vs brand-name levothyroxine (427 [82.6%] vs 433 [83.8%]; P = .62).Conclusions and relevanceInitiation of generic vs brand-name levothyroxine formulations was associated with similar rates of normal and stable thyrotropin levels. These results suggest that generic levothyroxine as initial therapy for mild thyroid dysfunction is as effective as brand-name levothyroxine.

Dataset Information

Is a Normal TSH Synonymous With "Euthyroidism" in Levothyroxine Monotherapy?

Context

Objective

Design

Participants

Results

Conclusions

Publications

Is a Normal TSH Synonymous With "Euthyroidism" in Levothyroxine Monotherapy?

Similar Datasets

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