Levothyroxine Dose Adjustment to Optimise Therapy Throughout a Patient's Lifetime

Bioinspired Long-Acting Mucoadhesive Gastric Patch for Levothyroxine Delivery

The delivery of long-acting therapeutic dosage forms through the oral route is a challenge. A bioinspired mucoadhesive gastric patch was developed as a platform technology for the long-acting delivery of levothyroxine sodium (LT). The mucoadhesive patch was designed to have a three-layer composition, including a core, mucoadhesive, and backing layer. The water contact angle on the mucoadhesive and backing layer sides of the patch was found to be 68 ± 1.4° and 121 ± 0.4°, respectively. The adhesive strength of the mucoadhesive layer, made of a 4-carboxyphenylboronic acid-chitosan conjugate, was found to be 25 ± 1.1 kPa when adhered to the rat stomach mucosa. The LT-containing patch was found to remain adhered to the body region of the rat stomach after 30 days of oral administration. A single dose of the mucoadhesive gastric patch containing 15.8 μg/kg/day of LT was able to provide a constant plasma concentration (87-126 ng/mL) of LT for 38 days in rats. There was no significant (P < 0.05) difference in the concentration of inflammatory markers including tumor necrosis factor-α (TNF-α), interleukins 1β (IL-1 β) and 6 (IL-6), with and without long-acting patch administration. The patches were found to be stable when stored at 5 ± 3 °C for 6 months. Taken together, the bioinspired mucoadhesive gastric patch can be developed for the long-acting delivery of LT through the oral route.

Subject-Specific Dosage Estimation for Primary Hypothyroidism Using Sparse Data

Subject-specific dosage estimation for primary hypothyroidism using subject-specific parameters of the thyrotropic regulation system is presented in this work. The data needed for such personalized modeling are usually sparse. This is addressed by utilizing available data along with domain knowledge for estimation of model parameters but with some uncertainty. Optimization-based dosage estimation approaches may not be applicable in the presence of such uncertainty. In this work, the optimal drug dosage range based on estimated parameter ranges for primary hypothyroid condition is estimated using the mathematical model through satisfiability modulo theory (SMT)-based analysis. The salient features of this work are as follows: (1) estimation of subject-specific model parameters with uncertainty using subject-specific pre-treatment and post-treatment observations, (2) modeling periodic drug administration as part of the ordinary differential equation model of thyrotropic regulation pathway through Fourier series approximation, (3) application of SMT-based analysis for determining optimal dosage range using this model and estimated parameter ranges, and (4) an initial dosage estimation method using the regression model. Results have been obtained to support the working of the developed computational procedures.

Association Between Serum Thyrotropin and Cancer Recurrence in Differentiated Thyroid Cancer: A Population-Based Retrospective Cohort Study

Background: Levothyroxine to suppress thyrotropin (TSH) to <0.5 mIU/L following thyroidectomy in differentiated thyroid cancer (DTC) may reduce recurrence in higher-risk DTC. However, there is limited evidence to support guideline recommendations to maintain TSH in the low-normal range of 0.5-2 mIU/L to reduce recurrence in patients with lower risk DTC. The primary objective was to assess the association between exposure to high normal serum TSH (2-4 mIU/L) as compared with low normal TSH (0.5-2 mIU/L) target ranges and cancer recurrence in patients with DTC after thyroidectomy. Methods: This population-based retrospective cohort study used linked, administrative health care databases from Ontario, Canada, to follow patients with DTC post-thyroidectomy from 2007 to 2018. The exposure was time updated, serum TSH, treated as a cumulative and instantaneous exposure. Multivariable cause-specific proportional hazard regression analyses were performed to determine time to DTC recurrence from index date, defined as a composite of repeat neck surgery, radioactive iodine (RAI) treatment, and/or DTC-specific death. Results were also stratified by initial treatment as a marker of baseline recurrence risk in a sensitivity analysis. Results: This cohort of 26,336 individuals (78% female) with DTC and a median age of 50 years were followed for a median of 5.9 (interquartile range 3.6-8.6) years; 40.9% were initially treated with a hemi-thyroidectomy only and 38.2% received a total thyroidectomy and RAI. Compared with exposure to TSH 0.5 to ≤2 mIU/L, DTC recurrence rate was similar for each additional 3 months of exposure to TSH >2 to ≤4 mIU/L (adjusted cause specific [cs] hazard ratio [HR] 0.99 [confidence interval or CI 0.97-1.02]) but was significantly increased with each additional 3 months of exposure to TSH >4 mIU/L (adjusted csHR 1.07 [CI 1.04-1.09]). Results were similar across baseline treatment groups. Conclusion: There was no difference in clinically significant recurrence in those with low-risk DTC maintained with a TSH of 0.5-2 mIU/L compared with 2-4 mIU/L. Guidelines should consider liberalizing target TSH level post thyroidectomy in low-risk cohorts. These results cannot be applied to patients with high-risk DTC.

Refractory hypothyroidism in children: an overview

Refractory hypothyroidism (RF) defined as raised serum levels of thyroid stimulating hormone (TSH) above upper limit of the reference range with or without the persistence of hypothyroid symptoms following a 6-week interval after the dosage was last increased to upper limits of dose per age. The most common cause of RH is inadequate compliance. In addition, diet, concomitant medication interactions, and gastrointestinal diseases can all result in l-thyroxine (LT4) malabsorption, which can cause RH. Moreover, weight gain, switching brands of LT4, poor storage of LT4, chronic liver disorders, cystic fibrosis, nephrotic syndrome, consumptive hypothyroidism, Addison's disease are significant contributors to RF in children. RH in children is frequently asymptomatic, when symptoms do occur, they are typically minor and resemble those of hypothyroidism. It is essential to identify RH early and treat its underlying cause in order to avoid overusing LT4, which can lead to cardiac and bone problems. Endocrinologists should handle children who they suspect of having RH methodically after making sure there is enough compliance. Searching for undiagnosed illnesses and/or other factors that can affect LT4 absorption could be part of this. We present this review after an extensive literature search and long-standing clinical experience. This review's objective is to shed light on the causes, clinical manifestations, investigations, and treatment of RH in children.

One sip of water with LT-4 supplementation-a key to euthyroidism in Hashimoto's thyroiditis

PURPOSE

Recommended pharmacotherapy for hypothyroidism in Hashimoto's thyroiditis (HT) is oral supplementation with levothyroxine (LT-4). However, serum thyrotropin (TSH) levels within normal range are not consistently achieved with LT-4 medication.

PATIENTS AND METHODS

We report on 35 HT patients with LT-4 therapy in this retrospective evaluation. In general, we recommend that a maximum of two sips of water, which would then amount to < 50 mL, be ingested at the same time as LT-4. We report on follow up examinations measuring TSH and antibodies against thyroid peroxidase (TPOAb) after 6 months to five years.

RESULTS

After median time of 643 days (range 98-1825) we found in 35 HT patients a statistical significant reduction of serum TSH (p < 0.001) and TPOAb (p = 0.006). The patients median body weight was 71 kg (range 48-98) and a daily LT-4 dosage was used with median 69.1 µg (range 25-150). This results in a daily LT-4 dose of median 1.01 µg/kg bodyweight (range 0.3-2.3).

CONCLUSIONS

The reduction of water ingestion to a maximum of two sips, which is <50 mL, combined with LT-4 supplementation helps to achieve euthyroidism in HT. In addition, it reduces the L-T4 medication dosage needed to lower TSH serum levels and decreases TPO antibodies in HT.

Genetically predicted hypothyroidism, thyroid hormone treatment, and the risk of cardiovascular diseases: a mendelian randomization study

BACKGROUND

In this study, we explored the impact of hypothyroidism and thyroid hormone replacement therapy on the risk of developing cardiovascular diseases, including myocardial infarction, heart failure, and cardiac death, via Mendelian randomization analysis.

METHODS

Genetic instrumental variables related to hypothyroidism, levothyroxine treatment (refer to Participants were taking the medication levothyroxine sodium) and adverse cardiovascular events were obtained from a large publicly available genome-wide association study. Two-sample Mendelian randomization analysis was performed via inverse-variance weighting as the primary method. To ensure the reliability of our findings, we performed MR‒Egger regression, Cochran's Q statistic, and leave-one-out analysis. Additionally, multivariable Mendelian randomization was employed to regulate confounding factors, including systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), diabetes, cholesterol, low-density lipoprotein (LDL), triglycerides and metformin. A mediation analysis was conducted to assess the mediating effects on the association between exposure and outcome by treating atrial fibrillation and stroke as mediator variables of levothyroxine treatment and bradycardia as mediator variables of hypothyroidism.

RESULTS

Genetically predicted hypothyroidism and levothyroxine treatment were significantly associated with the risk of experiencing myocardial infarction [levothyroxine: odds ratio (OR) 3.75, 95% confidence interval (CI): 1.80-7.80; hypothyroidism: OR: 15.11, 95% CI: 2.93-77.88]. Levothyroxine treatment was also significantly related to the risk of experiencing heart failure (OR: 2.16, 95% CI: 1.21-3.88). However, no associations were detected between hypothyroidism and the risk of experiencing heart failure or between hypothyroidism or levothyroxine treatment and the risk of experiencing cardiac death. After adjusting for confounding factors, the results remained stable. Additionally, mediation analysis indicated that atrial fibrillation and stroke may serve as potential mediators in the relationships between levothyroxine treatment and the risk of experiencing heart failure or myocardial infarction.

CONCLUSION

The results of our study suggest a positive association between hypothyroidism and myocardial infarction and highlight the potential effects of levothyroxine treatment, the main thyroid hormone replacement therapy approach, on increasing the risk of experiencing myocardial infarction and heart failure.

Importance of right communication with healthcare providers and patients about the new levothyroxine formulation: an expert opinion from Asia Pacific Thyroid Advisory Board

Levothyroxine (LT4), being "narrow therapeutic index" drug, may lead to significant fluctuations in thyroid stimulating hormone (TSH) levels. Such fluctuations can result in clinically noteworthy disruptions in thyroid function and give rise to adverse clinical consequences. Consequently, regulatory standards for LT4 potency have been tightened, with the most stringent specifications requiring maintenance of potency within the range of 95-105% of the labeled dose throughout the entire shelf-life of the product. The LT4 new formulation with tightened specification adheres to these rigorous standards, demonstrating established bioequivalence to its older formulation while upholding an equivalent standard of safety and efficacy. Furthermore, the novel formulation exhibits enhanced stability and an extended shelf-life. Of paramount significance is its capacity to provide patients with accurate and consistent dosing, thereby effectively catering to their medical requirements. The primary objective of the Asia-Pacific advisory board meeting (held in June 2022 with endocrinologists, experts from India, Indonesia, Philippines, Thailand, Malaysia and Singapore) was to establish the importance of appropriate communication to HCPs, patients and other stakeholders regarding the LT4 new formulation. The aim of this brief review is to highlight the importance of communication with healthcare professionals that should focus on providing accurate information on the LT4 new formulation, emphasizing efficacy, safety, and bioequivalence with clear guidance and ensure that patients and clinicians are fully informed about any changes to medications such as LT4 to reduce the risk of unrelated adverse events being incorrectly attributed to the newer formulation.

Color Doppler ultrasound and real-time elastography in patients with hypothyroidism for the prediction of levothyroxine replacement: a cross-sectional study of 338 patients

AIMS

While hormonal assays are commonly used for thyroid function assessment, Doppler sonography provides valuable information on vascularization and blood flow. This study aimed to examine the potential associations between Doppler parameters and clinical characteristics of hypothyroid patients, such as the autoimmune nature of the disease and adequacy of LT4 replacement.

METHODS

A total of 338 patients with hypothyroidism, primarily caused by autoimmune thyroiditis (AT), were enrolled in this study. Exclusion criteria comprised specific medical conditions, medication history, and nodular abnormalities of the thyroid gland. Patient demographics (age, sex, BMI), treatment parameters (LT4 daily dose), and thyroid hormone levels (TSH, fT4) were recorded.

RESULTS

Among the enrolled patients, 85.2% had autoimmune thyroiditis. Suboptimal levothyroxine (LT4) replacement was observed in 20.1% of patients at the time of enrollment. Patients with autoimmune thyroiditis had increased elastography ratios compared to those without autoimmune disease and present a positive association of elastography ratios with vascularity. In patients without autoimmune thyroiditis, those with suboptimal LT4 replacement had lower total thyroid volume. Patients with suboptimal LT4 replacement had higher peak systolic velocity (PSV) and end-diastolic velocity (EDV) in the inferior thyroid artery and lower resistive index (RI). The severity of hypothyroidism, as indicated by LT4 dose/body mass index (BMI), was negatively correlated with thyroid volume and EDV values of superior and inferior thyroid arteries. PSV of the inferior thyroid artery can predict suboptimal LT4 replacement (sensitivity 81.8%, specificity 42%).

CONCLUSIONS

In situations where obtaining blood tests may be challenging, utilizing color Doppler ultrasound can serve as an alternative method to assess treatment responses and identify patients who require further hormonal examinations.

Cryopreserved Thyroid Tissue Autotransplant in Pediatric Age Patients: A Feasibility Study and Literature Review

BACKGROUND AND AIMS

This paper aims to study an alternative solution to hormonal replacement therapy in specific groups of patients who underwent thyroidectomy during childhood or adulthood. After cryopreservation, thyroid autotransplantation could be an alternative solution which would allow us to use the ability of the thyroid tissue of producing hormones according to the physiological needs of the body.

MATERIALS AND METHODS

A feasibility study about the effects of the most modern cryopreservation techniques on the structural and functional integrity of the follicular cells of the thyroid tissue has been carried out. Patients who could benefit from the treatment have been found for both autotransplant techniques. Additionally, a literature review has been conducted.

RESULTS

The histological analysis has shown that cryopreservation does not alter the original architecture, and the culture examination that cell viability is successfully preserved. Moreover, both thyroid autotransplantation studies on animals and those on humans that were found in the literature have shown good results regarding the viability and functionality of the transplant.

CONCLUSIONS

The viability of cryopreserved thyroid tissue found in this study is encouraging. Further studies to evaluate the levels of FT3, FT4 and thyroglobulin in thyroid tissue after cryopreservation are needed to verify that the secretory properties of the thyrocytes have been maintained intact. Furthermore, autotransplanted cases found in the literature do not have a long-term follow-up.

Association of pharmacogenomic, clinical and behavioural factors with oral levothyroxine (LT-4) dose of hypothyroid patients in Sri Lanka: a matched case control study

BACKGROUND

Hypothyroidism is a common endocrine disorder that exerts a substantial influence on people all over the world. Levothyroxine (LT-4) is the drug of choice for the treatment of hypothyroidism and the starting oral dose is typically ranging from 1.5 to 1.7 µg/kg/day. The target is to achieve an optimum serum TSH level of 0.4-4.0 mIU/L; hence, the dose is titrated accordingly. Once the LT-4 dose is adjusted to obtain the target TSH level, it usually remains stable for a long period of time in most cases. However, some of the patients require frequent dose adjustments and some of them require unusually high doses. Therefore, the aim of this study is to determine the association of pharmacogenomic, clinical and behavioural factors with the oral levothyroxine (LT-4) dose requirement of hypothyroid patients in Sri Lanka.

METHOD

This study will be conducted as a matched case-control study and will involve primary hypothyroid patients who visit the diabetes and endocrinology clinic at the National Hospital, Kandy, Sri Lanka. We will recruit a total of 292 cases and select 292 controls from the clinic who are matched in terms of age, sex and Body Mass Index (BMI). An interviewer-administered questionnaire will be used to collect data from the participants (n = 584). Of the 584 patients, blood samples will be collected from a sub-sample (n = 150) for DNA extraction. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) will be performed for single nucleotide polymorphisms (SNP) analysis.

DISCUSSION

Frequent dose adjustments of levothyroxine cause a serious economic burden to the healthcare system. By identifying the root causes of the variations in LT-4 dosage, a more comprehensive comprehension of hypothyroidism and its management can be attained in Sri Lanka. Furthermore, upon identification of a positive association/correlation between genetic polymorphisms and the LT-4 dose, SNP profiles can be used as a possible genetic marker for dose adjustment determination in future patients.

Analysis of dose-TSH response effect of levothyroxine soft-gel formulation

Background

Hypothyroidism is treated with daily levothyroxine (LT4). In recent years, soft gel caps of LT4 (LT4-C) have been commercialized, and their performance has been optimized. Since guidelines recommend dose LT4 according to the tablet preparation efficacy, the present study was undertaken to obtain data about the daily requirement, normalized per body weight, of LT4-C.

Methods

Patients undergoing LT4-C after total thyroidectomy and radioiodine treatment for differentiated thyroid carcinoma were selected. There was no specific indication of suppression of TSH (i.e., <0.5 or <0.1 mIU/L). Patients were required to maintain a stable LT4 dose during the study period. Patients with interfering factors were excluded from this study.

Results

Thirty patients were enrolled (18 females and 12 males; median age, 50 years; median body weight, 71 kg; median LT4-C dose, 1.71 µg/kg/day). The analysis of patient age did not reveal any differences. The LT4-C dose correlated with free-T4 p = 0.03), but not with TSH (p = 0.42) and free-T3 (p = 0.13). TSH was <1.0 mIU/L in 90% of the cases. The LT4-C dose-TSH response effect was analysed by probit regression model: the probability to achieve TSH <1.0 mIU/l was 99% with a dose of 1.84 (95%CI 1.57-2.12) µg/kg/day, 75% with a dose of 1.38 µg/kg/day (95%CI 1.17-1.59), and 50% with a dose of 1.20 (95%CI 0.96-1.43). At ROC curve analysis, the most accurate cut-off of LT4-C dose to achieve TSH <1.0 mIU/l was 1.53 ug/kg/day with 70% sensitivity and 100% specificity.

Conclusions

Athyreotic patients can be initially treated with an LT4-C dose lower than previously stated. Therefore, further prospective studies are warranted.

Association of Thyroid Hormone Medication Adherence With Risk of Dementia

CONTEXT

Recent studies suggest that hypothyroidism is a risk factor for dementia. Based on existing literature, it is unclear if treatment or compliance to treatment is associated with decreased dementia risk in hypothyroidism patients.

OBJECTIVE

To determine the association between thyroid hormone medication adherence and risk of dementia.

METHODS

A population-based cohort study following patients with newly diagnosed hypothyroidism until incidence of dementia, death, or December 31, 2020, whichever came earliest. The study comprised 41 554 older adults age 50 and above with newly diagnosed hypothyroidism between 2004 and 2008 who underwent health screening. Risk of dementia was evaluated using multivariable-adjusted Cox proportional hazards regression.

RESULTS

Among 5188 men (12.5%) and 36 366 (87.5%) women, 2120 cases of incident dementia were identified. After stratification of the participants according to the interquartile range of the medication possession ratio (MPR), the fourth quartile (highest adherence) showed a 14% lower risk of overall dementia compared with the first quartile (lowest adherence) (adjusted hazard ratio 0.86; 95% CI 0.76-0.97). No consistent association was observed between thyroid hormone medication adherence and vascular dementia. After a dichotomous stratification of the MPR, higher MPR (≥0.8) showed a lower risk of Alzheimer disease (adjusted hazard ratio 0.91; 95% CI 0.84-0.99) than lower MPR (<0.8).

CONCLUSION

Better adherence to thyroid hormone medication may be beneficial in preventing incident dementia, especially Alzheimer disease, in older adults with newly diagnosed hypothyroidism. Along with the resolution of hypothyroid symptoms and the reduction of cardiovascular risk factors, the reduction of dementia risk may be another potential benefit of thyroid hormone medication.

Pharmacist-Mediated Thyroid-Stimulating Hormone (TSH) Test Guideline Monitoring Program- Outcomes of a Retrospective Study In Patients On Levothyroxine

Thirty to sixty percent of individuals taking levothyroxine were either under or overtreated, which leads to organ damage and excess mortality. This study aims to assess the gaps in the "thyroid-stimulating hormone (TSH) test guideline compliance rate" and validate the scope of ambulatory care pharmacist-mediated practice in patients on levothyroxine. At the study site, pharmacists offered patient-centered telephonic counseling to patients on levothyroxine who had been non-compliant with TSH tests for more than a year. A two-month quantitative retrospective analysis of this practice was conducted to assess its impact on TSH lab test adherence and dose modification outcomes. 415 patients met the study's inclusion criteria who received pharmacist counseling with documented intervention. Pharmacists bridged the significant gap in practice by creating new TSH lab requests with counseling in 81.2% (n = 337) of the study population who did not have TSH lab requests prior to the program. The non-compliance rate population dropped from 79.27% (n = 329) to 17.59% (n = 73) in the study population who had been non-compliant with the TSH test for 13 and 24 months. 74.5% (n = 309) were found to have performed their TSH test after the pharmacist's intervention. Among 100, 66% (n = 66) patients with abnormal TSH values consulted their physician for advice, of which 60.6% (n=40) had their levothyroxine dose adjusted (χ2=82.702, P < 0.01. The study suggests that pharmacists can significantly mediate between patients and physicians to enhance TSH test compliance and essential dose adjustment in patients prescribed levothyroxine.

Deiodinase Type 3 Polymorphism (rs1190716) Affects Therapeutic Response to Levothyroxine

Objectives

Levothyroxine (LT4) is a commonly used treatment for hypothyroidism. Deiodinase enzymes control the metabolism and homeostasis of thyroid hormones (THs). Deiodinase type 3 gene (DIO3) encodes deiodinase type 3 enzyme (D3), and the genetic polymorphisms of this gene could affect the levels of THs and the response to LT4 treatment. This study aimed to investigate the single-nucleotide polymorphism (SNP), rs1190716; C > T, of DIO3 as a candidate genetic variant that might affect the clinical response to LT4 treatment.

Materials and Methods

Two hundred Iraqi hypothyroid female patients aged 40 years were enrolled in this cross-sectional study. All of them were already on the LT4 treatment for at least 4 months. THs [thyroxin (T4), triiodothyronine (T3), reverse triiodothyronine (rT3), and diiodothyronine (T2)] were estimated. An allele-specific polymerase chain reaction technique was performed to detect the rs1190716; C > T SNP.

Results

The genotypes distribution of rs1190716; C > T SNP was 10 (4.5%) for the wild type (CC), 50 (22.7%) for the heterozygous mutant type (TC), and 160 (72.7%) for the homozygous mutant type (TT). The patients were divided into three groups according to their genotypes. Significant differences were found in the T4, T3, and T2 levels among the patients (p=0.019, p=0.039, p=0.032, respectively).

Conclusion

The rs1190716; C > T SNP could affect the activity of the D3 enzyme and the metabolic homeostasis of the THs; therefore rs1190716; C > T SNP could have an impact on the therapeutic response to LT4 in Iraqi female patients with primary hypothyroidism. Regarding DIO3 gene, this is a novel finding; hence, further studies are needed to confirm it.

Use of thyroid hormones in hypothyroid and euthyroid patients: a 2022 THESIS questionnaire survey of members of the Latin American Thyroid Society (LATS)

PURPOSE

Inconsistencies in the medical management of hypothyroidism have been reported between endocrinologists in different countries. This study aimed to identify the attitudes of Latin America thyroid specialists towards the use of thyroid hormones.

METHODS

Online survey of members of the Latin America Thyroid Society.

RESULTS

81/446 (18.2%) completed the questionnaire. Levothyroxine (LT4) was the initial treatment of choice for all respondents. 56.8% would consider LT4 use in biochemically euthyroid patients: infertile women with elevated anti-thyroid antibodies (46.9%), resistant depression (17.3%) and growing goiter (12%). Most respondents preferred tablets (39.5%) over liquid formulations (21.0%) or soft gel capsules (22.2%) and would not consider switching formulations in patients with persistent symptoms. 39.5% would never use LT4 + liothyronine (LT3) combination therapy in symptomatic euthyroid patients, due to low quality evidence for benefit. 60.5% reported that persistence of symptoms despite normal TSH is rare (below 5% of patients) and its prevalence has been stable over the last five years. Psychosocial factors (84.0%), comorbidities (86.4%) and the patient unrealistic expectation (72.8%) were considered the top three explanations for this phenomenon.

CONCLUSION

LT4 tablets is the treatment of choice for hypothyroidism. A significant proportion of respondents would use LT4 in some groups of euthyroid individuals, contrasting the recommendations of the major clinical practice guideline indications. LT4 + LT3 combination treatment in euthyroid symptomatic patients was considered by nearly 50%. Practices based on weak or absent evidence included use of thyroid hormones for euthyroid subjects by 56.8% of respondents and use of LT4 + LT3 treatment by 60.5% of respondents for patients with persistent symptoms. In contrast to many European countries, LATS respondents report a low and unchanged proportion of dissatisfied patients over the last five years.

Concomitant use of levothyroxine and interacting medications in U.S. ambulatory care visits

BACKGROUND

Levothyroxine (LT4) is the third most commonly prescribed medication in the United States. It is a narrow therapeutic index medication, and thus can be impacted by drug-drug interactions, which are primarily available over-the-counter. The prevalence and associated factors with concomitant interacting drugs with LT4 is limited since over-the-counter products are not routinely captured in many drug databases.

OBJECTIVE

This study aimed to characterize the concomitant use of LT4 with interacting drugs at ambulatory care visits in the United States.

DESIGN

A cross-sectional analysis of the National Ambulatory Medical Care Survey (NAMCS) from 2006 to 2018 was completed.

SETTING AND PARTICIPANTS

Ambulatory care visits in the United States involving adult patients with a LT4 prescription were included in the analysis.

OUTCOME MEASURES

The primary outcome was initiation or continuation of a selected concomitant interacting drug which impacts LT4 absorption (e.g., proton pump inhibitor) in a patient visit in conjunction with LT4.

RESULTS

The authors analyzed 372,942,000 visits (weighted from a sample of 14,880) with a reported LT4 prescription. Concomitant use of interacting drugs with LT4 occurred in 24.4% of visits in which 80% of interacting drugs were proton pump inhibitors. Ages 35-49 years (adjusted odds ratio [aOR], 1.59), 50-64 years (aOR, 2.27), and ≥65 years (aOR, 2.87) compared to 18-34 years, female (aOR 1.37) versus males, and visits in 2014 or later (aOR, 1.27) versus 2006-2009 were associated with increased odds of concomitant interacting drug use in multivariable analysis.

CONCLUSION

At ambulatory care visits between 2006 and 2018, concomitant use of LT4 and interacting drugs impacted one-quarter of patient visits. Increased age, females, and visits later in the study period were associated with increased odds for concomitant interacting drugs. Additional work is needed to identify downstream consequences of concomitant use.

Levothyroxine Treatment Adequacy and Formulation Changes in Patients with Hypothyroidism: A Retrospective Study of Real-World Data from the United States

Background: The prevalence of hypothyroidism (HT) has increased over time. To assess the effectiveness of treatment, we (1) studied thyrotropin (TSH) levels among patients receiving levothyroxine (LT4) and (2) determined the percentages of patients switching among LT4 formulations. Methods: Data on patients with HT receiving LT4 from the Optum™ Clinical and Claims Database were analyzed from March 2013 through February 2020. Eligible adult patients had ≥1 medical claim with an HT diagnosis and all patients were observed for ≥12 months. Patients included in Objective 1 were indexed on a randomly selected TSH result and had ≥2 results for TSH 1-15 months apart. Patients included in Objective 2 were indexed on a randomly selected LT4 pharmacy claim and had ≥2 LT4 claims ≥1 month apart and ≥1 claim during follow-up. Outcomes were the proportion of patients with low, normal, or high (<0.45, 0.45-4.5, or >4.5 mIU/L, respectively) TSH levels and the proportion of patients switching LT4 formulations, respectively. Data were stratified by age group, sex, and insurance type. All data reported were analyzed using descriptive statistics. Results: Of patients who were in the indexed TSH group, 81.1% [confidence intervals: 80.4-81.8; n/N = 9130/11,259] achieved normal TSH values. When stratified by age group, sex, and insurance type, ≥70% of patients in each of these subgroups exhibited normal mean TSH values at follow-up. For Objective 2 (N = 25,076), 24.9% (N = 6238) of the LT4-indexed group had ≥1 formulation switch in 12 months, of which 67.3% only switched once, and 41.4% (N = 10,370) had ≥1 formulation switch in up to 24 months. A significantly higher proportion of Medicare vs. commercially insured patients had switched formulations (26.2% vs. 23.1%, p < 0.001). Conclusions: Most LT4-treated patients maintain normal TSH levels, which is an improvement vs. previous reports. Continued physician engagement and patient education are advised to further reduce the number of patients who maintain off-target TSH levels. Contrary to clinical recommendations, about 25% of patients receiving LT4 switched formulations within 1 year, with >40% switching within 2 years; among patients who switched, most only switched once.

The Use of Levothyroxine Absorption Tests in Clinical Practice

Although levothyroxine (LT4) is a widely prescribed drug, more than 30% of LT4-treated patients fail to achieve the recommended serum level of thyrotropin with a body weight-based dose of LT4. An LT4 absorption test (LT4AT) is part of the workup for confirming normal LT4 absorption or diagnosing malabsorption. We searched PubMed with the terms levothyrox*, L-T4, LT4, TT4, FT4, FT3, TT3, test, loading, uptake, absorp*, "absorb*, bioavailab*, bioequiv* malabsorb*, and pseudomalabsorb*. A total of 43 full-text publications were analyzed. The published procedures for LT4AT differ markedly in the test dose, formulation, test duration, frequency of blood collection, analyte (total thyroxine [TT4] or free thyroxine [FT4]), metric (absolute or relative peak or increment, or area under the curve) and the threshold for normal absorption. In a standardized LT4AT for routine use, the physician could advise the patient to not consume food, beverages, or medications the morning of the test; administer 1000 µg of LT4 in the patient's usual formulation as the test dose; ensure that the patient is supervised throughout the LT4AT; perform a 4-hour test, with hourly blood samples; assay FT4; and consider that normal LT4 absorption corresponds to an FT4 increment of more than 0.40 ng/dL (5.14 pmol/L) or a TT4 increment of more than 6 μg/dL (77.23 nmol/L) for a test dose of at least 300 µg, or a percentage TT4 absorption of more than 60%. If the test indicates abnormal LT4 absorption, the physician can increase the LT4 dose, change the formulation or administration route, and/or refer the patient to a gastroenterologist.

Fast Track Treatment of Hypothyroidism with Levothyroxine: Reaching Homeostasis within Four Weeks

With the current clinical method for the treatment of hypothyroidism the target for the optimum individual values for free thyroxine concentrations [FT4] and thyrotropine concentrations [TSH] of the specific patient are unknown. This situation leads to unnecessary long experimental medication administration that can take a period of sometimes one year. In this article a method will be described where hypothyroid patients are characterized with weekly measured FT4 and TSH concentrations during the first three weeks of synthetic thyroxine or levothyroxine (L-T4) treatment to predict their optimum [FT4] and belonging [TSH] endpoint for a euthyroid homeostatic state. The treatment with levothyroxine will start for all patients with a reference dose of 100 µg, which can be adjusted by the treating physician to a more safe and appropriate dose for the individual which is monitored with weekly thyroid function tests to observe the progress. After three weeks all characteristics of the patient can be inferred from the measured data. The final titration target together with the individual thyroxine half life can be calculated. With the known characteristics and the L-T4 titration target the clinician or treating physician has an instrument to reduce the experimental treatment burden for the patient from one year to a maximum of four weeks.

Comparative Bioavailability of a Novel Solution and a Tablet Formulation of Levothyroxine

Levothyroxine (LT4) is the standard of care for treating hypothyroidism. Despite the established efficacy of LT4, 50% of treated patients fail to achieve normal thyrotropin levels. Oral formulations of LT4 that bypass the gastric phase of dissolution may offset some of the therapeutic shortcomings observed with tablets. An oral solution of LT4 can be administered to patients who are unable to swallow tablets; allows flexibility to individualize dosing; and may mitigate interference with LT4 absorption caused by food, coffee, increased gastric pH from atrophic gastritis, and malabsorption from bariatric surgery. The bioavailability of a novel LT4 oral solution and a reference LT4 tablet were compared in a randomized, laboratory-blinded, single-dose, 2-period, 2-sequence, crossover study in healthy euthyroid subjects. A single 600-μg oral dose of LT4 solution (30 mL × 100 μg/5 mL) or tablet (2 × 300-μg tablet) was administered under fasting conditions in each study period, and total thyroxine concentrations were measured for 72 hours after administration. The ratio of geometric least-squares means and 90% confidence intervals for area under the concentration-time curve from time 0 to 72 hours and maximum plasma concentration were calculated. Among 42 subjects in the pharmacokinetic population, the geometric least-squares mean ratio of area under the concentration-time curve from time 0 to 72 hours and maximum plasma concentration for baseline-adjusted thyroxine was 109.1% and 107.9%, respectively, meeting Food and Drug Administration bioequivalence criteria. Adverse events (AEs) were similar between treatment groups with no serious AEs or discontinuations for AEs. Comparable bioavailability was observed between the LT4 oral solution and reference tablet after a single oral 600-μg dose under fasting conditions.

Getting the levothyroxine (LT4) dose right for adults with hypothyroidism: opportunities and challenges in the use of modern LT4 preparations

Lifelong treatment with levothyroxine (LT4) is the mainstay of management for individuals with hypothyroidism. Many hypothyroid patients start LT4 treatment at a low dose (e.g. 25-50 µg), especially the elderly, those with residual thyroid function, those with low body weight, and those with significant (especially cardiac) comorbidities. Almost half of patients on LT4 replacement therapy demonstrate either under- or over-treatment. Many LT4 preparations have relatively large intervals between tablet strengths at the lower end of their dose ranges (providing 25 µg, 50 µg, and 75 µg tablets), which may represent a barrier to achieving the optimum maintenance treatment for some patients. The availability of intermediate tablet strengths of LT4 in the 25-75 µg range may facilitate precise and effective dose titration of LT4 and may also enable convenient maintenance regimens based on a single LT4 tablet daily, to support adherence to therapy.

Towards De-Implementation of low-value thyroid care in older adults

PURPOSE OF REVIEW

This review discusses the current literature regarding low-value thyroid care in older adults, summarizing recent findings pertaining to screening for thyroid dysfunction and management of hypothyroidism, thyroid nodules and low-risk differentiated thyroid cancer.

RECENT FINDINGS

Despite a shift to a "less is more" paradigm for clinical thyroid care in older adults in recent years, current studies demonstrate that low-value care practices are still prevalent. Ineffective and potentially harmful services, such as routine treatment of subclinical hypothyroidism which can lead to overtreatment with thyroid hormone, inappropriate use of thyroid ultrasound, blanket fine needle aspiration biopsies of thyroid nodules, and more aggressive approaches to low-risk differentiated thyroid cancers, have been shown to contribute to adverse effects, particularly in comorbid older adults.

SUMMARY

Low-value thyroid care is common in older adults and can trigger a cascade of overdiagnosis and overtreatment leading to patient harm and increased healthcare costs, highlighting the urgent need for de-implementation efforts.

Suboptimal Thyroid Hormone Replacement Is Associated With Worse Hospital Outcomes

CONTEXT

Many patients with hypothyroidism receive suboptimal treatment that may affect hospital outcomes.

OBJECTIVE

This work aimed to identify differences in hospital outcomes between patients with and without hypothyroidism.

METHODS

A retrospective cohort study, using the propensity score-based fine stratification method to balance covariates, was conducted using a large, US-based, commercial claims database from January 1, 2008 to December 31, 2015. Participants included patients aged 64 years and younger who had a thyrotropin (TSH) level collected before a hospital admission. Covariates included age, sex, US region, type of admission, year of admission, and comorbidities. Exposure included clinical hypothyroidism, which was divided into 4 subgroups based on prehospitalization TSH level: low (TSH < 0.40 mIU/L), normal (TSH 0.40-4.50 mIU/L), intermediate (TSH 4.51-10.00 mIU/L), and high (TSH > 10.00 mIU/L).

MAIN OUTCOME MEASURES INCLUDED

length of stay (LOS), in-hospital mortality, and readmission outcomes.

RESULTS

A total of 43 478 patients were included in the final study population, of whom 8873 had a diagnosis of hypothyroidism. Those with a high prehospitalization TSH level had an LOS that was 1.2 days longer (95% CI, 1.1-1.3; P = .003), a 49% higher risk of 30-day readmission (relative risk [RR] 1.49; 95% CI, 1.20-1.85; P < .001), and a 43% higher rate of 90-day readmission (RR 1.43; 95% CI, 1.21-1.67; P < .001) compared to balanced controls. Patients with normal TSH levels exhibited decreased risk of in-hospital mortality (RR 0.46; 95% CI, 0.27-0.79; P = .004) and 90-day readmission (RR 0.92; 95% CI, 0.85-0.99; P = .02).

CONCLUSION

The results suggest suboptimal treatment of hypothyroidism is associated with worse hospital outcomes, including longer LOS and higher rate of readmission.

Factors influencing the levothyroxine dose in the hormone replacement therapy of primary hypothyroidism in adults

Levothyroxine (LT4) is a safe, effective means of hormone replacement therapy for hypothyroidism. Here, we review the pharmaceutical, pathophysiological and behavioural factors influencing the absorption, distribution, metabolism and excretion of LT4. Any factor that alters the state of the epithelium in the stomach or small intestine will reduce and/or slow absorption of LT4; these include ulcerative colitis, coeliac disease, bariatric surgery, Helicobacter pylori infection, food intolerance, gastritis, mineral supplements, dietary fibre, resins, and various drugs. Once in the circulation, LT4 is almost fully bound to plasma proteins. Although free T4 (FT4) and liothyronine concentrations are extensively buffered, it is possible that drug- or disorder-induced changes in plasma proteins levels can modify free hormone levels. The data on the clinical significance of genetic variants in deiodinase genes are contradictory, and wide-scale genotyping of hypothyroid patients is not currently justified. We developed a decision tree for the physician faced with an abnormally high thyroid-stimulating hormone (TSH) level in a patient reporting adequate compliance with the recommended LT4 dose. The physician should review medications, the medical history and the serum FT4 level and check for acute adrenal insufficiency, heterophilic anti-TSH antibodies, antibodies against gastric and intestinal components (gastric parietal cells, endomysium, and tissue transglutaminase 2), and Helicobacter pylori infection. The next step is an LT4 pharmacodynamic absorption test; poor LT4 absorption should prompt a consultation with a gastroenterologist and (depending on the findings) an increase in the LT4 dose level. An in-depth etiological investigation can reveal visceral disorders and, especially, digestive tract disorders.

Optimal Thyroid Hormone Replacement

Hypothyroidism is a common endocrinopathy, and levothyroxine is frequently prescribed. Despite the basic tenets of initiating and adjusting levothyroxine being agreed on, there are many nuances and complexities to consistently maintaining euthyroidism. Understanding the impact of patient weight and residual thyroid function on initial levothyroxine dosage and consideration of age, comorbidities, thyrotropin goal, life stage, and quality of life as levothyroxine is adjusted can be challenging and continually evolving. Because levothyroxine is a lifelong medication, it is important to avoid risks from periods of overtreatment or undertreatment. For the subset of patients not restored to baseline health with levothyroxine, causes arising from all aspects of the patient's life (coexistent medical conditions, stressors, lifestyle, psychosocial factors) should be broadly considered. If such factors do not appear to be contributing, and biochemical euthyroidism has been successfully maintained, there may be benefit to a trial of combination therapy with levothyroxine and liothyronine. This is not supported by the majority of randomized clinical trials, but may be supported by other studies providing lower-quality evidence and by animal studies. Given this discrepancy, it is important that any trial of combination therapy be continued only as long as a patient benefit is being enjoyed. Monitoring for adverse effects, particularly in older or frail individuals, is necessary and combination therapy should not be used during pregnancy. A sustained-release liothyronine preparation has completed phase 1 testing and may soon be available for better designed and powered studies assessing whether combination therapy provides superior therapy for hypothyroidism.

Levothyroxine dosages during pregnancy among hypothyroid women. An experience from a tertiary care center of Karachi, Pakistan, based on data from Maternal Hypothyroidism on Pregnancy Outcomes Study (MHPO-5)

Objectives

The dosage of levothyroxine (LT4) during pregnancy differs among different ethnic groups worldwide. These differences are due to variations in geographical iodine distribution, autoimmunity, and variations in thyrotropin (TSH) targets for pregnancy. To the best of our knowledge, we report the levothyroxine dosage prescribed during pregnancy in hypothyroid women, for the first time from Pakistan.

Results

Levothyroxine dosage of 280 hypothyroid women during pregnancy were reviewed. The median LT4 dosages prescribed before conception was 85.7 mcg per day which increased by 14.3 mcg per day in the first trimester (P 0.001). A significant difference in dosage was observed between controlled and uncontrolled TSH groups in the first trimester (P 0.05). Lower LT4 dosage was prescribed for subclinical hypothyroid women as compared to overt hypothyroid cases, whereas dosages did not differ according to autoimmune status in the latter part of gestation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-05984-7.

Increased Risk of Type 2 Diabetes in Patients With Thyroid Cancer After Thyroidectomy: A Nationwide Cohort Study

CONTEXT

Abnormal thyroid function after thyroidectomy and subsequent thyroid-stimulating hormone suppression can have detrimental effects on glucose homeostasis in patients with thyroid cancer.

OBJECTIVE

To investigate whether thyroidectomy increases the risk of type 2 diabetes in patients with thyroid cancer and to explore the association between levothyroxine dosage and type 2 diabetes risk.

METHODS

A retrospective population-based cohort study using the Korean National Health Insurance database. We included 36 377 thyroid cancer patients without known diabetes who underwent thyroidectomy between 2004 and 2013. Matched subjects with nonthyroid cancer were selected using 1:1 propensity score matching. The main outcome measure was newly developed type 2 diabetes mellitus.

RESULTS

Patients with thyroid cancer who underwent thyroidectomy had a higher risk of developing type 2 diabetes mellitus than the matched controls (hazard ratio [HR] 1.43, 95% CI 1.39-1.47). Among patients with thyroid cancer, when the second quartile group (in terms of the mean levothyroxine dosage; 101-127 μg/day) was considered the reference group, the risk of type 2 diabetes mellitus increased in the first quartile (<101 μg/day; HR 1.45, 95% CI 1.36-1.54) and fourth quartile groups (≥150 μg/day; HR 1.37, 95% CI 1.29-1.45); meanwhile, the risk decreased in the third quartile group (128-149 μg/day; HR 0.91, 95% CI 0.85-0.97).

CONCLUSION

Patients with thyroid cancer who underwent thyroidectomy were more likely to develop type 2 diabetes mellitus than the matched controls. There was a U-shaped dose-dependent relationship between the levothyroxine dosage and type 2 diabetes mellitus risk.

Role of pharmacists in management of patients with thyroid disorders

Thyroid dysfunction is one of the most prevalent endocrine disorders, especially common in female patients. If patients are not diagnosed in time or adequately treated, the patients' quality of life can be significantly impaired and additional health problems may occur, considering the key roles of thyroid hormones in the body. Therefore, it is necessary to raise awareness about the importance of recognition of symptoms that may indicate a potential problem with the thyroid gland and help to identify possible causes. For patients who are already being treated with levothyroxine (hypothyroidism), or thiamazole, carbimazole or propylthiouracil (hyperthyroidism), it is necessary to point out the necessity of proper, regular use of the drugs and implementation of accompanying nonpharmacological measures, as well as the potential for the occurrence of adverse reactions and interactions with other drugs or food. A significant role in the mentioned activities should be played by the pharmacist, as the most accessible member of the health team, who can, if necessary, refer the patient to a doctor for diagnosis, monitor the effectiveness and safety of the therapy, and provide appropriate patient counseling.

Prunella vulgaris can improve the pregnancy outcomes of experimental autoimmune thyroiditis rats by inhibiting Th1/Th17 immune responses

Autoimmune thyroiditis (AIT), one of the most common autoimmune diseases among women of reproductive age, is closely associated with reproductive failure and other obstetric complications. However, effective clinical strategies for the management of pregnant women with AIT are limited. It has been shown that Prunella vulgaris (PV), a traditional herbal medicine, can ameliorate AIT and other common thyroid disorders. Therefore, using an experimental autoimmune thyroiditis (EAT) rat model, we investigated the potential effects of PV on AIT-related pregnancy outcomes. According to the administered dose of PV, EAT rats were randomly divided into the untreated EAT and PV-treated EAT groups. We found that thyroid peroxidase antibody and thyroglobulin antibody serum levels and the inflammatory infiltration of the thyroid were reduced in all PV-treated groups. Increased splenic Tgfb1 mRNA levels and Treg cell proportions were associated with decreased Th1/Th17 cell proportions, and Ifng mRNA levels were reduced in rats that received low and medium doses of PV. Moreover, in the low-dose PV group, fetal development retardation and placental injuries were reversed. Overall, our findings indicated that PV could alleviate AIT and improve pregnancy outcomes in EAT rats by downregulating Th1/Th17 immune responses and inducing Treg cell proliferation.

Levothyroxine Treatment and the Risk of Cardiac Arrhythmias - Focus on the Patient Submitted to Thyroid Surgery

Levothyroxine (LT4) is used to treat frequently encountered endocrinopathies such as thyroid diseases. It is regularly used in clinical (overt) hypothyroidism cases and subclinical (latent) hypothyroidism cases in the last decade. Suppressive LT4 therapy is also part of the medical regimen used to manage thyroid malignancies after a thyroidectomy. LT4 treatment possesses dual effects: substituting new-onset thyroid hormone deficiency and suppressing the local and distant malignancy spreading in cancer. It is the practice to administer LT4 in less-than-high suppressive doses for growth control of thyroid nodules and goiter, even in patients with preserved thyroid function. Despite its approved safety for clinical use, LT4 can sometimes induce side-effects, more often recorded with patients under treatment with LT4 suppressive doses than in unintentionally LT4-overdosed patients. Cardiac arrhythmias and the deterioration of osteoporosis are the most frequently documented side-effects of LT4 therapy. It also lowers the threshold for the onset or aggravation of cardiac arrhythmias for patients with pre-existing heart diseases. To improve the quality of life in LT4-substituted patients, clinicians often prescribe higher doses of LT4 to reach low normal TSH levels to achieve cellular euthyroidism. In such circumstances, the risk of cardiac arrhythmias, particularly atrial fibrillation, increases, and the combined use of LT4 and triiodothyronine further complicates such risk. This review summarizes the relevant available data related to LT4 suppressive treatment and the associated risk of cardiac arrhythmia.

Physical Activity in Women With Hypothyroidism on Thyroid Hormone Therapy: Associated Factors and Perceived Barriers and Benefits

BACKGROUND

The purpose of this study was to analyze factors associated with physical activity (PA) and to identify perceived barriers and benefits of PA among patients with hypothyroidism on thyroid hormone therapy.

METHODS

This survey-based cross-sectional study was conducted among members of the Dutch thyroid patient organization. Self-reported data on respondents' PA levels and demographic, clinical, and physical health variables were collected. Moreover, perceived barriers and benefits to PA were identified. Respondents were categorized as physically active when meeting the recommended Dutch PA guidelines and physically inactive otherwise. To compare physically active and inactive respondents, potential confounders were entered into univariate analyses. Factors showing significant correlations (P < .20) were added to a multivariate model to determine the associated factors of PA.

RESULTS

About 1724 female respondents (mean age 53.0 [11.6] y) were included; 16.1% reported meeting the PA recommendations. Multivariate analysis showed that factors associated with PA included levothyroxine/liothyronine therapy, comorbidities, self-perceived physical fitness, and diminished physical endurance. Overall, physically related barriers to PA were rated highest.

CONCLUSIONS

The vast majority of treated hypothyroid respondents are physically inactive and experience long-term exercise intolerance. Considering the health implications of physical inactivity, promotion of regular PA is of key importance in this population.

Biochemical and developmental effects of thyroid and anti-thyroid drugs on different early life stages of Xenopus laevis

The effects of two drugs containing the synthetic thyroid hormone levothyroxine (LEV) and an anti-thyroid drug containing propylthiouracil (PTU) on the three early life stages of Xenopus laevis were evaluated with the Frog Embryo Teratogenesis Assay-Xenopus, Tadpole Toxicity Test, and Amphibian Metamorphosis Assay using biochemical and morphological markers. Tested drugs caused more effective growth retardation in stage 8 embryos than stage 46 tadpoles. Significant inhibition of biomarker enzymes has been identified in stage 46 tadpoles for both drugs. AMA test results showed that LEV-I caused progression in the developmental stage and an increase in thyroxine level in 7 days exposure and growth retardation in 21 days exposure in stage 51 tadpoles. On the other hand, increases in lactate dehydrogenase activity for both drugs in the AMA test may be due to impacted energy metabolism during sub-chronic exposure. These results also show that the sensitivity and responses of Xenopus laevis at different early developmental stages may be different when exposed to drugs.

What should patients do if they miss a dose of medication? A theoretical approach

Medication adherence is a major problem for patients with chronic diseases that require long term pharmacotherapy. Many unanswered questions surround adherence, including how adherence rates translate into treatment efficacy and how missed doses of medication should be handled. To address these questions, we formulate and analyze a mathematical model of the drug concentration in a patient with imperfect adherence. We find exact formulas for drug concentration statistics, including the mean, the coefficient of variation, and the deviation from perfect adherence. We determine how adherence rates translate into drug concentrations, and how this depends on the drug half-life, the dosing interval, and how missed doses are handled. While clinical recommendations require extensive validation and should depend on drug and patient specifics, as a general principle our theory suggests that nonadherence is best mitigated by taking double doses following missed doses if the drug has a long half-life. This conclusion contradicts some existing recommendations that cite long drug half-lives as the reason to avoid a double dose after a missed dose. Furthermore, we show that a patient who takes double doses after missed doses can have at most only slightly more drug in their body than a perfectly adherent patient if the drug half-life is long. We also investigate other ways of handling missed doses, including taking an extra fractional dose following a missed dose. We discuss our results in the context of hypothyroid patients taking levothyroxine.

Understanding Worry About Risks Associated With Thyroid Hormone Therapy: A National Survey of Endocrinologists, Family Physicians, and Geriatricians

OBJECTIVE

Thyroid hormone use is widespread, and prior studies have shown that over- and undertreatment with thyroid hormone are common. Our objective was to understand physician worry regarding risks associated with thyroid hormone therapy, specifically overtreatment or undertreatment.

METHODS

A nationwide survey was administered to physician members of the Endocrine Society, the American Academy of Family Practice, and the American Geriatrics Society. Participants were asked how often they were worried about various risks that may be associated with thyroid hormone over- or undertreatment, that is, cardiovascular complications, bone complications, and poor quality of life due to overtreatment or undertreatment with thyroid hormone. Multivariable regression analyses were conducted to determine physician characteristics associated with each worry.

RESULTS

The response rate was 63% (359 of 566); of those who responded, 128 (36%) were primary care physicians, 114 (32%) were endocrinologists, and 113 (32%) were geriatricians. Overall, 74 (21%) physicians reported that they frequently or always worried about cardiovascular complications, 74 (21%) about bone complications, 111 (31%) about the poor quality of life due to symptoms from undertreatment with thyroid hormone, and 87 (24%) about the poor quality of life due to symptoms from overtreatment with thyroid hormone. Endocrinologists were more likely to frequently or always worry about the patients' poor quality of life due to symptoms from overtreatment (odds ratio, 2.05; 95% confidence interval, 1.09-3.93) compared with primary care physicians.

CONCLUSION

Up to one third of the physicians frequently or always worried about risks resulting from the thyroid hormone overtreatment or undertreatment. More research is needed across specialties to understand physician perceptions of how thyroid hormone therapy impacts the patients' quality of life.

Sociodemographic Disparities in the Treatment of Hypothyroidism: NHANES 2007-2012

PURPOSE

Both undertreatment and overtreatment of hypothyroidism with thyroid hormone are associated with adverse clinical outcomes. Disparities in the treatment of hypothyroidism may lead to a higher risk of adverse outcomes for certain sociodemographic groups. Our objectives were to identify sociodemographic disparities between those with treated and untreated hypothyroidism, and between those who were adequately and inadequately treated.

METHODS

This is a cross-sectional study of a representative sample of US adults aged 20 years and older with hypothyroidism (n = 698). The main measures were age, gender, race/ethnicity, education, income, and health care access differences among those with treated and untreated hypothyroidism.

RESULTS

Of those with hypothyroidism, women were more likely than men to be taking thyroid hormone (odds ratio [OR] 2.66 [95% confidence interval (CI) 1.42-4.99]), as were older participants (45-69 years old vs 20-44 years old: OR 7.25 [95% CI 4.15-12.67]; 70 years of age and older: OR 11.00 [95% CI 5.30-22.79]). Health care access was strongly associated with thyroid hormone use (OR 14.32, 95% CI 3.63-56.58). Hispanic race/ethnicity was associated with inadequate treatment compared with non-Hispanic whites (OR 2.42, 95% CI: 1.14-5.14).

MAIN CONCLUSIONS

Male gender, younger age, and lack of health care access were associated with untreated hypothyroidism, and Hispanic race was associated with inadequate treatment of hypothyroidism. Clinicians should be aware of these sociodemographic disparities in the hypothyroid population and consider strategies to improve treatment of hypothyroidism in men, younger adults, Hispanics, and those without routine health care access.

HPLC method for levothyroxine quantification in long-acting drug delivery systems. Validation and evaluation of bovine serum albumin as levothyroxine stabilizer

Deficiency of thyroid hormones (hypothyroidism) is treated with oral levothyroxine (LEVO). However, the effectiveness of oral administration is highly dependent on the co-administration of food and other drugs. This factor, in combination with the chronic nature of this condition, mean that there are concerns with patient compliance. Development of long acting formulations to treat hypothyroidism could potentially solve this problem. However, LEVO instability in solution could be problematic. In order to develop long acting LEVO delivery systems in vitro drug release experiments should be carried out. However, short term LEVO stability in aqueous solution will prevent this. BSA was used as a stabiliser for LEVO; extending the stability of the drug in aqueous solutions from a few hours to 2 weeks. In order to achieve this, the required concentration of the protein was 0.1% w/v. Subsequently, an HPLC method capable of separating LEVO from the protein was developed and validated following ICH guidelines. The analysis was carried out using a reverse phase HPLC method on an Agilent 1220 Infinity II LC system. The column used to achieve separation was a Zorbax Eclipse plus C18 (95 Å pore size, 250 mm length x 4.6 mm internal diameter; 5 μm particle size). The mobile phase used was composed of acetonitrile and 0.1% trifluoroacetic acid at a ratio of 50:50% v/v. UV detection of LEVO sodium was carried out at 225 nm. The retention time for the drug was 6.6 minutes. The method showed a limit of detection of 0.03 μg/mL and a limit of quantification of 0.09 μg/mL. Finally, this method was used to evaluate the release from implants containing 20% w/w of LEVO. These devices were prepared using a solvent casting method with poly(caprolactone) and LEVO. These devices showed an initial burst release over the first 3 days. Subsequently, they were capable of providing a linear release rate over the following 25 days.

Weight and Body Mass Index for Predicting Thyroxine Dose in Primary Hypothyroidism

Background

The treatment of primary hypothyroidism with thyroxine is weight-based or body mass index (BMI)-based. However, significant variation in the dose and the consequent delay in achieving euthyroid state is observed along the spectrum of patient body weights.

Objectives

To determine the weight and BMI-based dosing of thyroxine in primary hypothyroidism to achieve euthyroidism.

Material and methods

It was a retrospective review of the patient records conducted in the department of endocrinology, Shifa International Hospital, Islamabad, from July 1, 2014, to June 30, 2019 (five-year period). Patients with clinical and biochemical hypothyroidism were enrolled and initiated on thyroxine replacement to achieve euthyroid status. A total of 504 patients were included in the study.

Results

The mean age was 44.5 ±13.6 standard deviation. Females were 83.5%. The mean dose of thyroxine to achieve euthyroid status was 107.7 ± 39.3 mean standard deviation mcg/day, i.e. 1.4 (0.5) mcg/kg/day. Euthyroid status was achieved in 264 (52.4%) of patients at three months. The mean TSH level after treatment was 2.09 (1.2) mU/L. The linear regression model showed that BMI and weight are independent predictors of the required thyroxine dose (R and Rsquare values are .274 and 0.075 for BMI and .319 and .102 for weight, respectively (P-value <.0001). There was no impact of age, gender, height, and duration of disease on achieving euthyroid at six months after treatment (P values: .85, .394, .827, and .105, respectively).

Conclusion

The optimum dose in primary hyperthyroidism can be determined with body weight and BMI-based calculations.

Physiological Role and Use of Thyroid Hormone Metabolites - Potential Utility in COVID-19 Patients

Thyroxine and triiodothyronine (T3) are classical thyroid hormones and with relatively well-understood actions. In contrast, the physiological role of thyroid hormone metabolites, also circulating in the blood, is less well characterized. These molecules, namely, reverse triiodothyronine, 3,5-diiodothyronine, 3-iodothyronamine, tetraiodoacetic acid and triiodoacetic acid, mediate both agonistic (thyromimetic) and antagonistic actions additional to the effects of the classical thyroid hormones. Here, we provide an overview of the main factors influencing thyroid hormone action, and then go on to describe the main effects of the metabolites and their potential use in medicine. One section addresses thyroid hormone levels in corona virus disease 19 (COVID-19). It appears that i) the more potently-acting molecules T3 and triiodoacetic acid have shorter half-lives than the less potent antagonists 3-iodothyronamine and tetraiodoacetic acid; ii) reverse T3 and 3,5-diiodothyronine may serve as indicators for metabolic dysregulation and disease, and iii) Nanotetrac may be a promising candidate for treating cancer, and resmetirom and VK2809 for steatohepatitis. Further, the use of L-T3 in the treatment of severely ill COVID-19 patients is critically discussed.

Development and Prospective Validation of the Levothyroxine Dose Prediction Model in Primary Hypothyroidism

Multiple visits are needed to achieve euthyroidism on levothyroxine in newly detected primary hypothyroidism. We aimed to develop a levothyroxine dose estimation algorithm for primary hypothyroidism. Adults with newly diagnosed hypothyroidism were enrolled prospectively, first in the training cohort, followed by the validation cohort separated by time and person. We developed a predictive algorithm from Training Cohort and validated the model in Validation Cohort. Training Cohort: In this cohort, 358 subjects (259 women and 99 men) were enrolled. The median duration needed to achieve euthyroidism was 4±0.5 months. The mean levothyroxine daily dose was 60.5±34.1 μg. Data of euthyroid subjects within 6 months of treatment initiation and age range 18-65 years were used for algorithm development. In the multivariable linear regression algorithm, pretreatment serum thyrotropin level, and sex formed the best-fit predictive model (adjusted R² 0.73, p-value <0.001). Validation Cohort: Eighty-four subjects (61 women and 23 men) were enrolled and started on an estimated levothyroxine dose derived from the developed prediction model. On the first follow-up on treatment, 34/50 participants achieved euthyroidism (68%) at 1.5 months. In conclusion, the proposed prediction model for levothyroxine dose estimation effectively achieves early euthyroidism in two-third subjects in the age range of 18-65 years.

Reinterpreting patterns of variation in human thyroid function: An evolutionary ecology perspective

Two hundred million people worldwide experience some form of thyroid disorder, with women being especially at risk. However, why human thyroid function varies between populations, individuals, and across the lifespan has attracted little research to date. This limits our ability to evaluate the conditions under which patterns of variation in thyroid function are best understood as 'normal' or 'pathological'. In this review, we aim to spark interest in research aimed at understanding the causes of variation in thyroid phenotypes. We start by assessing the biomedical literature on thyroid imbalance to discuss the validity of existing reference intervals for diagnosis and treatment across individuals and populations. We then propose an evolutionary ecological framework for understanding the phylogenetic, genetic, ecological, developmental, and physiological causes of normal variation in thyroid function. We build on this approach to suggest testable predictions for how environmental challenges interact with individual circumstances to influence the onset of thyroid disorders. We propose that dietary changes, ecological disruptions of co-evolutionary processes during pregnancy and with pathogens, emerging infections, and exacerbated stress responses can contribute to explaining the onset of thyroid diseases. For patients to receive the best personalized care, research into the causes of thyroid variation at multiple levels is needed.

Children with Hashimoto’s Thyroiditis Have Increased Intestinal Permeability: Results of a Pilot Study

Increased intestinal permeability (IIP) precedes several autoimmune disorders. Although Hashimoto’s thyroiditis (HT) is the most common autoimmune disorder, the role of IIP in its pathogenesis had received little attention. Zonulin plays a critical role in IIP by modulating intracellular tight junctions. Rise of serum zonulin levels were shown to indicate IIP in human subjects. In this case-control study, we examined the hypothesis that patients with HT have IIP. We studied 30 children and adolescents with HT, and 30 patients with congenital hypothyroidism (CH) matched for age, gender and body mass index (BMI). Serum zonulin levels, free thyroxine (fT4), thyroid stimulating hormone (TSH), anti-thyroglobulin antibody and anti-thyroid peroxidase antibody were measured. Zonulin levels were significantly higher in patients with HT than patients with CH (59.1±22.9 ng/mL vs. 43.3±32.9 ng/mL, p=0.035). In patients with HT, zonulin levels were positively correlated with weight (r=0.406, p=0.03), BMI (r=0.486, p=0.006) and levothyroxine dose (r=0.463, p=0.02). In patients with CH, zonulin levels were positively correlated with age (r=0.475, p=0.008), weight (r=0.707, p<0.001), BMI (r=0.872, p<0.001) and levothyroxine dose (r=0.485, p=0.007). After adjusting for age, weight, TSH and fT4 levels, serum zonulin was only associated with levothyroxine dose in patients with HT (R²=0.36, p=0.05). In patients with CH, only weight was associated with zonulin levels (R²=0.62, p<0.001). In conclusion, higher zonulin levels in children and adolescents with HT suggested IIP in these patients. Additionally, the association between zonulin levels and levothyroxine dose might imply a relationship between serum zonulin and disease severity.