Thyroxine in goiter, Helicobacter pylori infection, and chronic gastritis

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.

Thyroid Hormone Replacement Dosing after Bariatric Surgery in Patients with Primary Hypothyroidism And Severe Obesity: Tehran Obesity Treatment Study

Background: Obesity and hypothyroidism are common medical conditions that are associated with each other. Bariatric surgery (BS) is a common approach used to achieve substantial weight loss in obese patients. However, there is limited evidence regarding the need for postsurgery levothyroxine (LT4) dose adjustment in patients with hypothyroidism undergoing BS. Methods: This was a three-year prospective cohort study assessing postsurgery LT4 requirements with attention to body composition changes. The current study included 1030 patients with hypothyroidism, who underwent sleeve gastrectomy (SG) (n = 707, 88.3% women) or one anastomosis gastric bypass (OAGB) (n = 323, 92% women). Patients were followed for 36 months after surgery. A bioelectrical impedance analyzer was used for body composition assessment. LT4 requirements were assessed by generalized estimating equation (GEE) methods adjusted for weight as a time-varying covariate. Results: During the follow-up, TSH (mIU/L) and T4 (ng/dL) measurements did not significantly change in the OAGB group over time. However, in the SG group, TSH measurement decreased over time (ptrend = <0.001). In the third year of the follow-up, 56.1% and 33.3% of patients in the SG and OAGB groups experienced LT4 (μg/day) dose reduction, while 24.4% and 9.1% of the participants experienced LT4 dose increments, respectively. GEE analysis showed a significant increase in the LT4/fat mass (FM) (μg/kg) ratio after 36 months of follow-up compared with the baseline in both the SG [1.8 (1.5-2.2) to 2.7 (2.0-3.5), ptrend = 0.039)] and OAGB [1.7 (1.4-2.2) to 3.2 (2.7-4.8), ptrend = <0.001)] groups. Moreover, patients who underwent OAGB experienced greater LT4/FM (μg/kg) dose adjustments compared to those undergoing SG (pbetween = 0.060). In both groups, after the first year, the increase in LT4/FM (μg/kg) plateaued (pinteraction = 0.009). Conclusion: Most hypothyroid patients experienced either a reduction or no change in LT4 (μg/day) dosage after 36 months in both surgical groups. The LT4/FM (μg/kg) was significantly increased in patients undergoing either SG or OAGB with greater alterations in the latter. Further studies on larger populations and with longer duration of follow-up are needed to confirm our results.

Therapeutic efficacy and patient compliance of levothyroxine liquid and softgel formulations taken with meals: a systematic review

PURPOSE

Levothyroxine (L-T4) is the drug of choice for treating primary hypothyroidism. L-T4 tablets should be taken at least 30 min before breakfast. Several studies have suggested that serum thyroid profile is not affected by concomitant intake of liquid/softgel L-T4 with meals. Our aim is to review the evidence on therapeutic efficacy and patient compliance with the liquid and softgel formulation of L-T4 taken with meals, also compared with the standard tablet therapy regimen, in hypothyroid patients.

METHODS

We performed a systematic review of literature by searching PubMed, Embase, and Cochrane Library databases. PRISMA guidelines were applied, and the risk of bias of the included studies was assessed using the RoB 2 and ROBINS tools. The methodological quality was assessed following the GRADE criteria.

RESULTS

We included 13 studies, accounting for a total of 1697 patients. The timing of liquid L-T4 intake from breakfast did not affect the therapeutic efficacy of the treatment. No significant differences in the absorption of liquid L-T4 were found when administered together with different foods, beverages, drugs, or other supplements. TSH levels are not influenced by taking softgel L-T4 at breakfast; the efficacy of softgel and liquid formulation is similar when they are taken with a meal, but superior to that of tablet formulation. Shifting from L-T4 tablets taken 30 min before breakfast to liquid/softgel formulation taken with the meal improved medication adherence and perceived quality of life of patients.

CONCLUSION

Liquid and softgel formulation of L-T4 can be taken at breakfast or close to meals, without losing therapeutic efficacy. These formulations could also improve patient compliance and quality of life compared to L-T4 tablet therapy taken 30 min before breakfast.

Liquid L-T4 therapy in hypothyroid patients with gastric diseases, an observational study

Introduction

This is an observational and retrospective study, in which we have analyzed data from patients affected by gastric diseases (p) who have been treated with liquid L-T4 (L-LT4;84 p), or tablet L-T4 (T-LT4;120 p), for the replacement therapy of hypothyroidism. The aim of the study is to compare the stability of TSH [normal range, 0.3-3.5 μIU/ml] in these patients.

Methods

All p assumed L-T4 30 minutes before breakfast. The types of gastric disease were: a) T-LT4 group: 74 chronic gastritis (CG); 4 gastrectomy for gastric cancer (GTx); 42 gastro-plastics (GP); b) L-LT4 group: 60 CG; 3 GTx; 21 GP (p>0.05). 66% p in T-LT4 group were chronically treated with proton pump inhibitors (PPI), against 51% in L-LT4 group (p>0.05). The frequency of Helicobacter Pylori infection was 17% in both T-LT4 and L-LT4 groups. The gender distribution, mean age and body weight were similar in the 2 groups (p>0.05). The mean L-T4 dosage in T-LT4 group at the basal evaluation was 1.22+/-0.27 μg/kg/die, in the L-LT4 group 1.36+/-0.22 μg/kg/die (p>0.05).

Results

At the basal evaluation the prevalence of patients with a TSH>3.5 μIU/mL in T-LT4 group was 36%, in L-LT4 group 46% (p<0.05). After adjustment of the dosage of the LT-4 therapy, the p were re-evaluated in an interval range of 5-9 months, for 4 times, during an overall period ranging from 23 to 31 months. At the first re-evaluation, the prevalence of p with a TSH>3.5 μIU/mL was 13% in both groups. At the second re-evaluation, the prevalence of p with a TSH>3.5 μIU/mL in T-LT4 group was 26%, in L-LT4 group 13% (p>0.05). At the third re-evaluation, the prevalence of p with TSH<3.5 μIU/mL in T-LT4 group was 19%, in L-LT4 group 9% (p=0.05). At the fourth and last re-evaluation, the prevalence of patients with a TSH>3.5 μIU/mL in T-LT4 group was 18%, in L-LT4 group 5% (p<0.05). Mean FT4 and FT3 circulating levels were not significantly different in the two group at each visit.

Discussion

These data suggest that the liquid L-T4 formulation therapy can result in a more stable control of TSH levels in hypothyroid patients with gastric disorders in the long-term follow-up.

Proton Pump Inhibitors Do Not Affect the Bioavailability of a Novel Liquid Formulation of Levothyroxine

OBJECTIVE

This study evaluates the impact of a representative proton pump inhibitor (PPI) (omeprazole), administered simultaneously or staggered, on the pharmacokinetics of levothyroxine (LT4) solution (Tirosint-SOL).

METHODS

This was a randomized, 3-way crossover, comparative bioavailability study in 36 healthy adults under fasting conditions. Omeprazole 40 mg delayed-release capsule was administered once daily from Day 1 to 6 (mornings, Treatment-A; evenings, Treatment-B; none, Treatment-C) to increase and stabilize gastric pH. In the morning of Day 5, a single dose of LT4 solution 600 mcg was administered. Blood samples were collected 0 to 48 hours post-LT4 administration. Noncompartmental pharmacokinetic parameters were calculated for total serum thyroxine using baseline-corrected data. Maximum concentration (Cmax) and area under the concentration-time curve (AUC0-48) were included in an analysis of variance to obtain geometric mean ratios and 90% confidence intervals.

RESULTS

For both comparisons (A/C and B/C), geometric mean ratios and 90% confidence intervals for all parameters were within the equivalence boundaries (80%-125%), indicating bioequivalence: for A/C, AUC0-48 98.98% [94%-104%], and Cmax 91.68% [87%-97%]; for B/C, AUC0-48 98.94% [95%-103%], and Cmax 94.90% [90%-100%]. Median Tmax (time associated with Cmax) was similar across treatments.

CONCLUSION

This study demonstrated that Tirosint-SOL bioavailability is unaffected by coadministration of a representative PPI, given simultaneously or staggered by about 12 hours, compared to administration of LT4 solution alone. For hypothyroid patients on PPI therapy, administration of LT4 solution may reduce variations in thyroid stimulating hormone levels related to intermittent use of acid-reducing drugs and consequently the need for dose adjustments.

Increased Absorption of Thyroxine in a Murine Model of Hypothyroidism Using Water/CO2 Nanobubbles

Thyroxine (T4) is a drug extensively utilized for the treatment of hypothyroidism. However, the oral absorption of T4 presents certain limitations. This research investigates the efficacy of CO2 nanobubbles in water as a potential oral carrier for T4 administration to C57BL/6 hypothyroid mice. Following 18 h of fasting, the formulation was administered to the mice, demonstrating that the combination of CO2 nanobubbles and T4 enhanced the drug's absorption in blood serum by approximately 40%. To comprehend this observation at a molecular level, we explored the interaction mechanism through which T4 engages with the CO2 nanobubbles, employing molecular simulations, semi-empirical quantum mechanics, and PMF calculations. Our simulations revealed a high affinity of T4 for the water-gas interface, driven by additive interactions between the hydrophobic region of T4 and the gas phase and electrostatic interactions of the polar groups of T4 with water at the water-gas interface. Concurrently, we observed that at the water-gas interface, the cluster of T4 formed in the water region disassembles, contributing to the drug's bioavailability. Furthermore, we examined how the gas within the nanobubbles aids in facilitating the drug's translocation through cell membranes. This research contributes to a deeper understanding of the role of CO2 nanobubbles in drug absorption and subsequent release into the bloodstream. The findings suggest that utilizing CO2 nanobubbles could enhance T4 bioavailability and cell permeability, leading to more efficient transport into cells. Additional research opens the possibility of employing lower concentrations of this class of drugs, thereby potentially reducing the associated side effects due to poor absorption.

Thyroid disorders and gastrointestinal dysmotility: an old association

Gastrointestinal motility symptoms may be closely related to thyroid diseases. Sometimes, such symptoms are the only thyroid disease-related clue although the degree of the symptoms may vary. The exact mechanism of action of thyroid hormones on gastrointestinal motility is not completely understood, however, a clue lies in the fact that muscle cell receptors can be directly acted upon by thyroxines. Both hypo- and hyperthyroidism can cause impairment of gastrointestinal motility, modifying structure and function of pharynx and esophagus, and regulating esophageal peristalsis through neuro-humoral interaction. In hyperthyroid patients, alterations of postprandial and basic electric rhythms have been observed at gastro-duodenal level, often resulting in slower gastric emptying. Gastric emptying may also be delayed in hypothyroidism, but an unrelated gastric mucosa-affecting chronic modification may also cause such pattern. Hyperthyroidism commonly show malabsorption and diarrhoea, while hypothyroidism frequently show constipation. In summary, it can be stated that symptoms of gastrointestinal motility dysfunction can be related to thyroid diseases, affecting any of the gastrointestinal segment. Clinically, the typical thyroid disease manifestations may be missing, borderline, or concealed because of intercurrent sicknesses. Motility-linked gastrointestinal problems may easily conceal a misdetected, underlying dysthyroidism that should be carefully analyzed. Here, we aim to elaborate on the associations between thyroid disorders and GI dysmotility and the common clinical manifestations associated with GI dysmotility.

Lactose intolerance and levothyroxine malabsorption: a review of the literature and report of a series of patients treated with liquid L-T4 without lactose

In hypothyroid patients needing large doses of levothyroxine (L-T4) (>1.7-2 μg/kg/day) to reach euthyroidism, lactose intolerance (LI) needs to be excluded, owing to the high prevalence in the population. If LI is present, a lactose-free diet decreases the rate of L-T4 malabsorption. However, an increased requirement of L-T4 is described in patients with LI, which can be beneficially treated using lactose-free L-T4 formulation. The lactose-free liquid L-T4 formulation is able to circumvent LI malabsorption leading to the normalization of thyroid-stimulating hormone (TSH) in patients with subclinical hypothyroidism and long-term stable TSH levels.

Optimizing Thyroxine Dosage After Total Thyroidectomy: Understanding the Factors at Play

INTRODUCTION

Total thyroidectomy is evolving as the choice of treatment for non-malignant thyroid conditions. Therefore, an ideal method of thyroxine replacement is necessary to avoid the ill effects of under- and over-replacement in such patients.

AIM

To assess the correlation between optimal thyroxine dose and potential variables like lean body mass (LBM), body surface area (BSA), body mass index (BMI), body weight, age, and sex in patients who underwent total thyroidectomies for benign multinodular goiters in our institute.

MATERIALS AND METHODS

A longitudinal cohort study was undertaken at the Government Medical College Thrissur, a tertiary care provider in India, between October 2018 and September 2019. One hundred adult patients who underwent a total thyroidectomy for various benign thyroid conditions were included. They were initially given thyroxine 75 µg upon discharge and received follow-up doses every two months until they achieved euthyroid status on two consecutive visits. The variables evaluated at this stage included age, sex, actual body weight, lean body weight, BMI, and biochemical data (triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH)). Correlation, multiple step-wise regression, and variance were carried out using EPI INFO version 7.2.2.6.

RESULTS

The best predictors for optimum thyroxine dose were BSA (0.923, P < 0.01) and LBM (0.921, P < 0.01), compared with body weight (0.833, P < 0.01) and BMI (0.523, P < 0.01). In our study, the least significant factor was the age of the patient (r = 0.117, P < 0.01). There was no significant association between gender and thyroxine dose. The mean thyroxine dose was 1.87 µg/kg of the patient's body weight.

CONCLUSION

The optimum thyroxine replacement based on BSA or LBM is a more ideal method than based on BMI or body weight alone.

Helicobacter pylori Eradication Treatment in Older Patients

Helicobacter pylori is the main etiopathogenetic factor of chronic gastritis, peptic ulcer disease and gastric cancer. The world's population is shifting towards older people, who have the highest prevalence of H. pylori. Aging-related peculiarities could have an impact on the treatment of H. pylori and there is still a lack of research data in the older population. The aim of this review was to summarize the findings of the most recent information, publications and studies on the issues relating to H. pylori infection in older patients. H. pylori eradication offers gastrointestinal and extra gastrointestinal benefits in older patients. Based on the main guidelines, H. pylori should be eradicated independent of the patient's age, only reconsidering cases with terminal illness and low life expectancy. Proton pump inhibitors are generally safe and well tolerated. Some antibiotics require dose adjustment only in advanced renal insufficiency and the risk of hepatotoxicity is very low. Special precautions should be taken in patients with polypharmacy and those taking aspirin or non-steroidal anti-inflammatory drugs. In older patients, H. pylori eradication treatment frequently causes only mild and short-term adverse events; however, treatment compliance is usually still very good. H. pylori treatment in older patients does not increase the risk of Clostridium difficile infection. Optimal eradication effectiveness (> 90%) is mostly achieved with bismuth- and non-bismuth-based quadruple therapies. Susceptibility-guided treatment of H. pylori can contribute to increasing the effectiveness of eradication regimens in older adults. To achieve optimal H. pylori eradication effectiveness in older patients, the same guidelines, which are applied to adults, also apply to this population: avoiding repetitive treatment prescriptions, choosing quadruple therapies, prescribing longer treatment duration and administering high-dose proton pump inhibitors twice daily.

Levothyroxine personalized treatment: is it still a dream?

Levothyroxine is a milestone in the treatment of all causes of hypothyroidism. From 19th century till today, Levothyroxine experienced a great advancement, from hypodermic injections of an extract of the thyroid gland of a sheep to novel formulations, known to circumvent malabsorption issue. However, the rate of patients on suboptimal therapy is still high. Current Guidelines are clear, daily Levothyroxine dosage should be calculated based on body weight. However, we are still far away from the possibility to administer the right dosage to the right patient, for several reasons. We retrace the history of treatment with levothyroxine, pointing out strengths and weaknesses of different formulations, with particular attention to what keeps us away from tailored therapy. In the age of digitalization, the pharmaceutical industry has been giving rising importance to Digital therapeutics, that are known to be effective in reaching target therapies. By combining current knowledge of hypothyroidism therapy with cutting-edge technology, we also hypothesized what could be the future strategies to be developed in this field.

Efficacy of Levothyroxine Sodium Soft Gelatin Capsules in Thyroidectomized Patients Taking Proton Pump Inhibitors: An Open-Label Study

Background: Treatment with proton pump inhibitors (PPIs) and antacids affects the gastrointestinal absorption of levothyroxine sodium (LT4) tablets. Patients with hypothyroidism taking LT4 and PPIs or antacids, thus, require appropriate monitoring. The objective of this study was to determine whether a soft gelatin capsule of LT4 (Tirosint®) would obviate the effect of PPIs on LT4 absorption. The objective was achieved by assessing the effects of a switch from a conventional LT4 tablet form to the same dose as soft capsules in thyroidectomized patients on treatment with LT4 and PPIs. Methods: Patients with history of hypothyroidism due to total thyroidectomy on stable treatment with LT4 tablets, and with gastrointestinal disease treated with PPIs, were switched to a 12-week treatment with Tirosint at the same dose of the LT4 tablets, while maintaining treatment with PPIs. Serum thyrotropin (TSH) levels were the primary endpoint of the study. Secondary efficacy endpoints were: serum levels of free thyroxine (fT4), total thyroxine (TT4), free triiodothyronine (fT3), total triiodothyronine (TT3), creatine-phosphokinase (CPK), sex-hormone binding globulin, ferritin, angiotensin converting enzyme, and a lipid panel. Results: Forty-seven patients (36 females and 11 males, mean age 55.4 years) were enrolled and 45 of them completed the study (2 patients withdrew consent). During treatment with Tirosint, mean TSH levels demonstrated a statistically significant decrease (mean changes from baseline: -0.32 mIU/L at week 6 and -0.68 mIU/L at week 12) and concomitant increases in thyroid hormone (TH) levels from baseline to week 12, which were statistically significant for fT3 and TT3 (mean changes from baseline: 0.26 pmol/L and 0.10 nmol/L, respectively). Significant decreases of serum low-density lipoprotein, total cholesterol, and CPK levels were observed at week 12. No signs/symptoms arose during the study that could be specifically correlated to either hypo- or hyperthyroidism. Conclusions: In thyroidectomized patients taking PPIs and replacement LT4, a switch from conventional LT4 tablets to LT4 soft capsules at the same dose was associated with a significant decrease in TSH and increase in TH, indicating that LT4 absorption may be less affected by PPIs when given in the form of soft capsules. Clinical Trial Registration: NCT03094416.

Medications and Food Interfering with the Bioavailability of Levothyroxine: A Systematic Review

Purpose

Levothyroxine is a common prescribed drug. Many medications and food, however, can interfere with its bioavailability. The aim of this review was to summarize the medications, food and beverages that interact with levothyroxine and to assess their effects, mechanisms and treatments.

Methods

A systematic review on interfering substances that interact with levothyroxine was performed. Web of Science, Embase, PubMed, the Cochrane library, grey literature from other sources and the lists of references were searched for human studies comparing the levothyroxine efficacy with and without interfering substances. The patient characteristics, drug classes, effects and mechanism were extracted. The NHLBI study quality assessment tools and the JBI critical appraisal checklist were used to assess the quality of included studies.

Results

A total of 107 articles with 128 studies were included. Drugs interactions were revealed in calcium and iron supplements, proton pump inhibitors, bile acid sequestrants, phosphate binders, sex hormones, anticonvulsants and other drugs. Some food and beverage could also induce malabsorption. Proposed mechanisms included direct complexing, alkalization, alteration of serum thyroxine-binding globulin levels and acceleration of levothyroxine catabolism via deiodination. Dose adjustment, administration separation and discontinuation of interfering substances can eliminate the interactions. Liquid solutions and soft-gel capsules could eliminate the malabsorption due to chelation and alkalization. The qualities of most included studies were moderate.

Conclusion

Lots of medications and food can impair the bioavailability of levothyroxine. Clinicians, patients and pharmaceutical companies should be aware of the possible interactions. Further well-designed studies are needed to provide more solid evidence on treatment and mechanisms.

Effect of morning versus night-time administration of proton pump inhibitor (pantoprazole) on thyroid function test in levothyroxine-treated primary hypothyroidism: a prospective cross-over study

BACKGROUND

One of the common causes of suboptimal control of thyroid stimulating hormone (TSH) in levothyroxine-treated hypothyroidism is coadministration of proton pump inhibitors (PPIs). Morning administration of pantoprazole has been shown to suppress intragastric pH to a greater extent. We therefore aimed to determine the effect of pantoprazole at different time points of the day on thyroid function test (TFT) in levothyroxine-treated overt primary hypothyroidism.

METHODS

In this single centre, hospital based, prospective, two arm cross-over study (AB, BA), participants were randomized into 2 groups based on morning (6:00 am - 7:00 am simultaneously with the scheduled levothyroxine tablet) (group M) and evening (30 min before dinner) intake of 40 mg pantoprazole tablet (group N). After the initial 6 weeks (period 1), a washout period of 1 week for pantoprazole was given, and then both the groups crossed over for another 6 weeks (period 2). Patients were instructed to continue the same brand of levothyroxine tablet at empty stomach 1-hour before breakfast. Serum TSH was measured at baseline, week 6, and week 13.

RESULTS

Data from 30 patients, who completed the study with 100% compliance, were analysed. Mean TSH values of the study participants were significantly higher both at week 6 and week 13 compared to the baseline. Mean baseline serum TSH concentrations for groups M and N were 2.70 (± 1.36), and 2.20 (± 1.06) µlU/mL, respectively. Mean serum TSH concentrations at the end periods 1 and 2 for group M were 3.78 (± 4.29), and 3.76 (± 2.77) while the levels in group N were 3.30 (± 1.90), and 4.53 (± 4.590) µlU/mL, respectively. There was a significant rise in serum TSH concentration across periods 1 and 2 in both the groups (F_{2, 58} = 3.87, p = 0.03). Within group changes in TSH across periods 1 and 2 were not statistically significant. Similarly difference in TSH between the groups, either at 6 weeks or at 13 weeks, were also not statistically significant.

CONCLUSIONS

Concomitant use of pantoprazole, even for 6 weeks, leads to significant elevation in serum TSH in levothyroxine-treated patients who are biochemically euthyroid, irrespective of timing of pantoprazole intake. Early morning and night-time administration of pantoprazole have similar effect on TFT in these patients.

Validity of the Rapid Thyroxine Absorption Test for the Differentiation Between Levothyroxine Non-compliance and Malabsorption in Thyroid-Stimulating Hormone Refractory Hypothyroidism

Introduction Thyroid-stimulating hormone refractory hypothyroidism is a common problem. This is due to either non-compliance or malabsorption with levothyroxine (LT4). The study aimed to assess the validity of the rapid LT4 absorption test in the differentiation between LT4 malabsorption and non-compliance. Methods A cross-sectional study was done from January to October 2022 at Faiha Specialized Diabetes, Endocrine, and Metabolism Center, in Basrah, Southern Iraq. Twenty-two patients with thyroid-stimulating hormone (TSH) refractory hypothyroidism were evaluated by rapid LT4 absorption test with measurements of TSH before 1000 μg LT4 intake, and free thyroxine (pmol/l) and total thyroxine before (nmol/l) (baseline TT4 and baseline FT4) and two hours after (2-HR TT4 and 2-HR FT4). The findings were compared with the following four-week-long supervised LT4 absorption test results. Results In the rapid LT4 absorption test, patients with (2-HR FT4 minus baseline FT4 ≤1.28 pmol/l (0.1 ng/dl) or 2-HR FT4 minus baseline FT4 1.28-6.43 pmol/l (0.1-0.5 ng/dl) plus 2-HR TT4 minus baseline TT4<72.08 nmol/l (5.6 µg/dl)), eight out of 10 patients were correctly diagnosed with malabsorption. And in those with (2-HR FT4 minus baseline FT4 ≥6.43 (0.5 ng/dl) or 2-HR FT4 minus baseline FT4 1.28-6.43 (0.1-0.5 ng/dl) plus 2-HR TT4 minus baseline TT4≥72.08 (5.6 µg/dl)), 11 out of 12 patients were correctly diagnosed as non-compliant. This criterion showed 88.8% sensitivity, 15.4% specificity, 80% positive predictive value, and 91.6% negative predictive value for diagnosing LT4 malabsorption. Conclusion The rapid LT4 absorption test showed good diagnostic accuracy in differentiating non-compliance from malabsorption when (2-HR FT4 minus baseline FT4) and (2-HR TT4 minus baseline TT4) were used as criteria.

Levothyroxine Absorption Test - Results and Follow Up of Patients from a Single Center

Introduction

Treating primary hypothyroidism with appropriate weight-based dosing is usually straightforward. When supraphysiologic doses of thyroxine are required, it is important to know the reason behind the increased requirement. When compliance with medication is assured and when there are no drug interactions resulting in increased thyroxine requirements, a levothyroxine absorption test (LT4AT) could be performed to diagnose the coexistence of malabsorption.

Materials and Methods

This was a single-center, retrospective chart review. Patients who had undergone LT4AT between 2018 and 2020 with a complete evaluation and follow-up records were reviewed. LT4AT and further evaluation (if necessary) were standardized, and details until the last review were obtained.

Results

In all, 11 patients had complete records and follow-up details. The median age (range) of the cohort was 24 years (19 to 46), and the duration of hypothyroidism was 8 years (4 to 24). Seven had low absorption (<60%) in LT4AT of which two each had celiac disease and Helicobacter pylori infection; one had autoimmune gastritis, and in two the reasons of malabsorption was not known. The median follow-up duration was 13 months. Nine of 11 (81%) achieved euthyroid state with/without thyroxine dose reduction on follow-up.

Conclusion

A high proportion of patients requiring supraphysiological doses of levothyroxine had occult malabsorptive states, some of which were curable. Even in those with pseudo-malabsorption, LT4AT helped in reinforcing compliance and thereby thyroxine dose reduction.

Different FT3/TSH correlation in acquired and congenital hypothyroid patients reveals a different hypothalamic set-point

OBJECTIVE

To understand differences in thyroid hormone replacement therapy with levo-thyroxine (l-T4) between acquired and congenital hypothyroid (CH) patients.

DESIGN

We compared biochemical thyroid parameters between euthyroid subjects (EU) and both CH adult patients and thyroidectomized patients (TP) under replacement therapy.

PATIENTS AND MEASUREMENTS

A retrospective analysis was performed on a series of 98 consecutive adult CH patients (27 males and 71 females) with a median age of 24 years (range 18-58). Serum TSH, FT3, FT4, l-T4 dose and body weight were assessed. For comparison purposes, large series of 461 TP for thyroid cancer and 1852 EU followed at our Thyroid Clinic were used as control groups.

RESULTS

The daily weight-based l-T4 dose was significantly higher in CH than TP group (1.9 vs. 1.7 mcg/kg, p = .03). FT3/FT4 ratio was significantly higher in the EU group, intermediate in CH and lower in TP groups (0.32, 0.28 and 0.24, respectively). Linear regression analysis displayed an inverse correlation between FT4 and TSH in all the groups. An inverse correlation between FT3 and TSH was observed in the TP group, but not in the EU and CH group suggesting that CH patients, under replacement therapy, display biochemical thyroid parameters similar to EU subjects.

CONCLUSIONS

Adult CH patients require a higher daily l-T4 dose than adult TP. However, the different correlation of TSH and FT3 values between CH and TP patients suggests an adaptive and different hypothalamic-pituitary-thyroid axis regulation that may depend on the early timing of the onset of hypothyroidism in CH.

Seeking optimization of LT4 treatment in patients with differentiated thyroid cancer

Levothyroxine sodium (LT4) is the mainstay treatment to replace thyroid hormonal production in thyroidectomized patients, but, depending on the aggressiveness of the cancer and on the risk of recurrence, patients with differentiated thyroid cancer may also be treated in a TSH-suppressive or semi-suppressive mode. The pathophysiological rationale for this LT4 treatment stems from the role of TSH, considered to be a growth factor for follicular cells, potentially inducing initiation or progression of follicular cell-derived thyroid cancer. Therefore, accurate tailoring of treatment, taking into account both patient characteristics (age and comorbidities) and risk of persistent/recurrent disease, is highly recommended. Furthermore, adjustments to traditional LT4 treatment should be made in thyroidectomized patients due to the lack of thyroidal contribution to whole body triiodothyronine (T₃) concentration. Since LT4 exhibits a narrow therapeutic index and the side effects of over- and under-treatment could be deleterious, particularly in this category of patients, caution is required in dose individualization, in the mode of ingestion, and in potential pharmacological and other types of interference as well. Our aim was to analyze the current knowledge concerning LT4 dose requirements in patients with thyroid cancer according to different therapeutic approaches, taking into account a number of factors causing interference with LT4 efficacy. Specific mention is also made about the use of the novel LT4 formulations.

The Relationship between Gastrointestinal Health, Micronutrient Concentrations, and Autoimmunity: A Focus on the Thyroid

Currently, there is a lack of understanding of why many patients with thyroid dysfunction remain symptomatic despite being biochemically euthyroid. Gastrointestinal (GI) health is imperative for absorption of thyroid-specific nutrients as well as thyroid function directly. This comprehensive narrative review describes the impact of what the authors have conceptualized as the “nutrient–GI–thyroid axis”. Compelling evidence reveals how gastrointestinal health could be seen as the epicenter of thyroid-related care given that: (1) GI conditions can lower thyroid-specific nutrients; (2) GI care can improve status of thyroid-specific nutrients; (3) GI conditions are at least 45 times more common than hypothyroidism; (4) GI care can resolve symptoms thought to be from thyroid dysfunction; and (5) GI health can affect thyroid autoimmunity. A new appreciation for GI health could be the missing link to better nutrient status, thyroid status, and clinical care for those with thyroid dysfunction.

Levothyroxine-induced serum free thyroxine response following radioactive iodine administration in patients thyroidectomized for differentiated thyroid cancer: A randomized controlled trial

PURPOSE

Patients undergoing thyroidectomy for differentiated thyroid cancer (DTC) may require 131-radioactive iodine (RAI) administration for remnant ablation or disease treatment. After ingestion, RAI resides within the gastrointestinal tract potentially leading to mucosal damage and abnormalities in the absorption of levothyroxine (LT4). The aim of this study was to evaluate whether serum FT4 peak, induced by a LT4 challenge, changes according to the LT4 formulation (solid or liquid) in both RAI and non-RAI-treated DTC patients.

METHODS

This was a monocentric controlled clinical trial, with a parallel two-groups (1:1) randomization of sequence of LT4 formulation. Patients received 200 mcg LT4 orally administered at 08:00 h, in both solid and liquid formulation, at one-week interval, at baseline and after 1, 3, and 6 months from RAI administration. At each time-point, circulating FT4 was evaluated both before LT4 assumption as well as after 1 and 3 h. FT4 increments were evaluated as area under the curve response (AUC). Analogous protocol with the same time-intervals was followed for non-RAI patients.

RESULTS

The trial included 29 consecutive DTC patients, nineteen of whom were submitted to RAI. In RAI subjects, we observed an overall significant reduction in serum FT4 increments with the most relevant decrease at the 1-month time-point, (FT4 AUC: 4.46 ± 0.72 (M ± SD) vs 4.07 ± 0.63 in baseline vs 1-month, P = 0.001) without any difference between the two LT4 formulations. No difference in serum FT4 AUC was found in non-RAI subjects.

CONCLUSION

LT4-induced serum FT4 responses are reduced following RAI administration in thyroidectomized DTC patients.

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.

Levothyroxine treatment and gastric juice pH in humans: the proof of concept

PURPOSE

Despite the absorption of oral thyroxine (T4) occurs in the small bowel, several patients with gastric disorders show an increased need for T4. In vitro evidence suggested that medium pH variations interfere with T4 dissolution. This study was aimed at finding the proof of concept of a direct relationship between the minimal effective dose of T4 and the actual gastric juice pH.

PATIENTS AND METHODS

Among 311 consecutively thyroxine-treated patients, 61 bearing Hashimoto's thyroiditis (52 F/9 M; median age = 51 years) who complained persistent dyspepsia and/or upper abdominal symptoms following a noninvasive workup for gastrointestinal disorders, underwent EGDS with multiple biopsies and gastric juice pH measurement. All patients accepted to take thyroxine in fasting conditions, abstaining from eating or drinking for one hour.

RESULTS

Thyroxine requirement increased along with the rising gastric pH (ρ = 0.4229; p = 0.0007). A multivariate analysis revealed that gastric pH was, beside body mass index, the far more important independent variable in determining the effective dose of T4 (p = 0.001). The ROC curve revealed that the pH threshold for an increased thyroxine requirement was at 2.28, being the AUC by 78%. Subdividing patients by the histologic findings, it appeared a significant increase (p = 0.0025) along with the progressive damage of gastric mucosa.

CONCLUSION

The in vivo measurement of gastric pH highlighted its key role in determining the minimal effective dose of oral T4 and may explain the interference of food, of some drugs and gut disorders on levothyroxine treatment.

Pernicious Anemia: The Hematological Presentation of a Multifaceted Disorder Caused by Cobalamin Deficiency

Pernicious anemia is still a neglected disorder in many medical contexts and is underdiagnosed in many patients. Pernicious anemia is linked to but different from autoimmune gastritis. Pernicious anemia occurs in a later stage of autoimmune atrophic gastritis when gastric intrinsic factor deficiency and consequent vitamin B₁₂ deficiency may occur. The multifaceted nature of pernicious anemia is related to the important role of cobalamin, which, when deficient, may lead to several dysfunctions, and thus, the proteiform clinical presentations of pernicious anemia. Indeed, pernicious anemia may lead to potentially serious long-term complications related to micronutrient deficiencies and their consequences and the development of gastric cancer and type 1 gastric neuroendocrine tumors. When not recognized in a timely manner or when pernicious anemia is diagnosed with delay, these complications may be potentially life-threatening and sometimes irreversible. The current review aimed to focus on epidemiology, pathogenesis, and clinical presentations of pernicious anemia in an attempt to look beyond borders of medical specialties. It aimed to focus on micronutrient deficiencies besides the well-known vitamin B₁₂ deficiency, the diagnostic approach for pernicious anemia, its long-term complications and optimal clinical management, and endoscopic surveillance of patients with pernicious anemia.

An Unusual Cause of Refractory Hypothyroidism

Refractory hypothyroidism has been increasingly identified worldwide. Primary hypothyroidism is considered refractory when there is a persistent elevation of thyroid-stimulating hormone (TSH) above the upper limit of normal despite escalating doses of levothyroxine with or without the persistence of hypothyroid symptoms. Further escalation of levothyroxine to supratherapeutic doses could be associated with potential complications such as iatrogenic hyperthyroidism, cardiac failure, and other conditions. Therefore, physicians should rule out non-compliance and pursue a further evaluation to identify etiologies for increased requirements or decreased absorption of levothyroxine in patients not achieving therapeutic doses. Here, we present a 40-year-old Indian male with worsening refractory hypothyroidism that resolved following eradication of his Helicobacter pylori (H. pylori) infection. Herein, we highlight a unique and reversible cause of refractory hypothyroidism. With this case report, we hope to encourage physicians to include H. pylori testing in the evaluation of primary hypothyroidism refractory to treatment.

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.

An Overview on Different L-Thyroxine (l-T4) Formulations and Factors Potentially Influencing the Treatment of Congenital Hypothyroidism During the First 3 Years of Life

Congenital hypothyroidism (CH) is a relatively frequent congenital endocrine disorder, caused by defective production of thyroid hormones (THs) at birth. Because THs are essential for the development of normal neuronal networks, CH is also a common preventable cause of irreversible intellectual disability (ID) in children. Prolonged hypothyroidism, particularly during the THs-dependent processes of brain development in the first years of life, due to delays in diagnosis, inadequate timing and dosing of levothyroxine (l-thyroxine or l-T₄), the non-compliance of families, incorrect follow-up and the interference of foods, drugs and medications affecting the absorption of l-T₄, may be responsible for more severe ID. In this review we evaluate the main factors influencing levels of THs and the absorption of l-T₄ in order to provide a practical guide, based on the existing literature, to allow optimal follow-up for these patients.

Daily requirement of softgel thyroxine is independent from gastric juice pH

BACKGROUND

Softgel levothyroxine (LT4) preparation showed a better in vitro dissolution profile at increasing pH as compared to tablet LT4 preparation. Clinical studies suggested a better performance of softgel LT4 preparation in patients with gastric disorders but whether this finding is related to gastric juice pH variation in vivo is not known.

METHODS

Twenty-eight hypothyroid patients (24F/4M; median age=50 treated with tablet LT4 (median dose= 1.65 µg/kg/day) and with stable thyroid stimulating hormone (TSH) values on target (<0.8-2.5> mU/l) have been shifted to softgel LT4 preparation. The dose of softgel LT4 has been titrated to obtain a similar individual serum TSH value. All subjects followed a specific treatment schedule, taking LT4 in fasting condition and then abstaining from eating or drinking for at least 1 hour. Owing to the presence of long-lasting dyspepsia or of already known gastric disorders, all patients underwent endoscopy, upon informed consent. Gastric juice has been collected during endoscopy to measure gastric pH. Then we plotted the dose of LT4 with the gastric pH obtained in vivo, before and after the switch tablet/softgel preparation in all patients.

RESULTS

Upon the switch tablet/softgel preparation, the therapeutic LT4 dose was very slightly reduced (-6%) in the whole sample. However, the individual variations revealed the existence of two populations, one without any dose reduction (A) and the other showing a dose reduction >20% (B). Upon matching with the actual gastric pH, patients with normal pH (A: n=17; 14F/3M, median 1.52) no showed a lower softgel LT4 requirement. Instead, among patients with reduced gastric acid production (B: n=11; 10F/1M, median pH 5.02) the vast majority (10/11; 91%, p<0.0001) benefited from a lower dose of softgel LT4 (median = -23%, p<0.0001). Interestingly, the dose of LT4 in tablet correlated with pH value (Spearman's ρ =0.6409; p = 0.0002) while softgel dose was independent from gastric juice pH (Spearman's ρ =1.952; p = 0.3194).

CONCLUSIONS

These findings provide evidence that softgel LT4 preparation is independent from the actual gastric pH in humans and may represent a significant therapeutic option in patients with increased LT4 requirement, owed to disorders impairing the gastric acidic output.

Helicobacter pylori Infection Is Associated With Thyroid Dysfunction in Children With Congenital Hypothyroidism

Helicobacter pylori (H. pylori) infection leads to a systemic low-grade inflammatory state and has been associated causally with a diverse spectrum of extra-gastric disorders. Among them, the infection has been involved in the pathogenesis of autoimmune thyroid disease (ATD), but only one study had evaluated children. Therefore, a cross-sectional study was conducted in a cohort of 142 children and adolescents, randomly assessed among those followed up for thyroid diseases in a university pediatric endocrinology service: 106 with congenital hypothyroidism (CH) and 36 with ATD. All children were asymptomatic, under strict control on levothyroxine replacement, and reported no other diseases or use of drugs. Helicobacter pylori status was evaluated by the ¹³C-Urea Breath Test (¹³C-UBT). Antithyroid antibodies (ATPO, antiTg, and TRAb) and serum thyroid hormones (TSH, free T4, and T3) were assessed by standard assays. Data were analyzed in logistic models by the SPSS statistical software package, and a p-value ≤ 0.05 was considered statistically significant. The prevalence of H. pylori infection was 19.44% in children with ATD. Neither the gender nor the serum levels of thyroid hormones and antithyroid antibodies were associated with the H. pylori-positive status. Thirty-seven (34.90%) children with CH were infected with H. pylori. The mean T3 serum level (3.59 ± 0.84) was significantly lower (p = 0.001) in the infected children than in those free from the infection (3.95 ± 0.89), association that remained after adjustment for the other variables in the multivariate analysis. Because no difference was observed in the levels of TSH and T4, the results indicate that the infection may lead to impairment in the thyroid hormonal balance, but not in the hypothalamic-pituitary-thyroid axis function. In as much as H. pylori infection is highly widespread and the prevalence of CH is also not negligible, additional studies are required to confirm our results and to identify the involved mechanisms.

Liquid levothyroxine formulations in patients taking drugs interfering with L-T4 absorption

PURPOSE

To describe the current knowledge on thyroid hormonal profile in patients on liquid L-T4 therapy and drugs known to interfere with L-T4 absorption.

METHODS

A PubMed/MEDLINE, Web of Science, and Scopus research was performed. Case reports, case series, original studies and reviews written in English and published online up to 31 August 2022 were selected and reviewed. The final reference list was defined based on the relevance of each paper to the scope of this review.

RESULTS

The available data showed that novel levothyroxine formulations circumvent gastric pH impairment due to multiple interfering drugs such as proton pump inhibitors, calcium or iron supplements, sevelamer, aluminum/magnesium hydroxide and sodium alginate.

CONCLUSION

New formulations can be taken simultaneously with drugs interfering with L-T4 absorption, in particular liquid formulations. Softgel capsules need more studies to support these data.

Precision Medicine in Autoimmune Thyroiditis and Hypothyroidism

Autoimmune thyroid diseases (AITD) are T-cell-mediated organ specific autoimmune disorders, deriving from an altered response of the immune system that leads to the immune attack to the thyroid. Hashimoto’s thyroiditis (HT) and Graves’ disease (GD) are the two principal AITD clinical presentations. Hypothyroidism and thyrotoxicosis are, respectively, the clinical hallmarks of HT and GD. Patients with autoimmune thyroiditis are treated daily with synthetic L-thyroxine (L-T4) at the dose of 1.5–1.7 μg/kg. Various L-T4 formulations are commercially available (tablet, liquid solution, or soft gel capsule). L-T4 in tablets is generally prescribed to treat hypothyroidism, whereas the liquid formulation, or soft gel capsules, can be administered in hypothyroid patients in case of malabsorption or in patients in therapy with drugs interfering with L-T4 absorption. Furthermore, myoinositol has a crucial role in thyroid autoimmunity and function. Clinical studies reported a significant decline in TSH and antithyroid autoantibodies levels after treatment with myoinositol + selenium in patients with subclinical hypothyroidism and autoimmune thyroiditis. Moreover, thyroidectomy can be rarely recommended in patients with autoimmune thyroiditis, with cosmetic reasons for a goiter, or with important signs or symptoms of local compression, or nodular disease with a “suspicious” cytology for malignancy. Furthermore, a recent randomized trial suggested that total thyroidectomy can improve quality of life and fatigue, while medical therapy did not. In this review, we overview currently available evidence in personalized medicine in patients with autoimmune thyroiditis and hypothyroidism. Further research is needed in larger population to investigate the effect of these new treatments on quality of life.

Appropriate dose of levothyroxine replacement therapy for hypothyroid obese patients

Background

Athyreotic patients require a daily levothyroxine (LT4) doses of 1.6-1.8 mcg/kg of actual body weight (BW) to achieve normal thyroid stimulating hormone (TSH) levels. Lean body mass (LBM) calculation may be a more accurate determination of LT4 dose in obese patients. Previous studies were mainly investigated in Caucasians and LBM is markedly different between various ethnic groups. We aim to identify the optimal dose of LT4 replacement therapy in hypothyroid Thai patients including obese subjects.

Methods

We retrospectively reviewed the medical records of Thai adults with hypothyroidism at the thyroid clinic. Patients had been received LT4 (Brand: Euthyrox) at a stable dose ≥ 75 mcg/day for at least 1 year. Patients with thyroid cancer, pregnant, and lactating women were excluded. LBM was calculated by the Hume formula.

Results

Two hundred patients (80% females) with a mean age of 48.6 ± 14.8 years and a body mass index (BMI) of 24.5 ± 4.6 kg/m² were included. Daily LT4 dose/kg of actual BW according to BMI 18.5-24.9, 25-29.9, and ≥ 30 kg/m² were 1.67 ± 0.27, 1.51 ± 0.28 and 1.39 ± 0.34 mcg/kg, respectively. In contrast, LT4 dose/kg of LBM were 2.31 ± 0.39, 2.35 ± 0.45 and 2.36 ± 0.51 mcg/kg, respectively.

Conclusions

LBM is considered a better indicator for calculating an appropriate LT4 replacement dose than actual BW in hypothyroid obese Thai patients. The recommended daily dose of LT4 is 2.3 mcg/kg of LBM that could be applied for all ranges of BMI.

Concomitant Use of Levothyroxine and Proton Pump Inhibitors in Patients with Primary Hypothyroidism: a Systematic Review

BACKGROUND

The aim of this study was to assess the effect of concomitant use of levothyroxine (LT4) and proton pump inhibitors (PPIs) on thyroid-stimulating hormone (TSH) levels in patients with primary hypothyroidism.

METHODS

A systematic review of interventional and observational studies that compared the TSH levels before and after concomitant use of LT4 and PPI was performed. Articles published in English up to September 1, 2019, were included. PubMed, EMBASE, and Cochrane Library databases. Gray literature was also searched in repositories, websites OpenGrey and Google Scholar, and abstracts of major international congresses. Study quality was assessed with the Newcastle-Ottawa quality assessment scale for observational studies and the Risk Of Bias In Non-randomized Studies - of Interventions (ROBINS-I) tool was used.

RESULTS

Five thousand twelve discrete articles were identified. Following assessment and application of eligibility criteria, seven studies were included. There was a considerable heterogeneity among the included studies in design, sample size, inclusion and exclusion criteria, treatment regimen, and baseline demographics. Each of the included studies showed an increase in TSH levels following LT4 and PPI consumption, and in the majority of these, the increase was statistically significant.

DISCUSSION

The concomitant use of LT4 and PPI showed a significant increase in TSH concentration. However, given the small number of studies, further research is needed to clarify the interfering role of PPI on LT4 intestinal absorption.

PROSPERO REGISTRATION NUMBER

CRD42020047084.

Eradication of Helicobacter pylori and Gastric Cancer: A Controversial Relationship

Worldwide, gastric cancer (GC) represents the fifth cancer for incidence, and the third as cause of death in developed countries. Indeed, it resulted in more than 780,000 deaths in 2018. Helicobacter pylori appears to be responsible for the majority of these cancers. On the basis of recent studies, and either alone or combined with additional etiological factors, H. pylori is considered a "type I carcinogen." Over recent decades, new insights have been obtained into the strategies that have been adopted by H. pylori to survive the acidic conditions of the gastric environment, and to result in persistent infection, and dysregulation of host functions. The multistep processes involved in the development of GC are initiated by transition of the mucosa into chronic non-atrophic gastritis, which is primarily triggered by infection with H. pylori. This gastritis then progresses into atrophic gastritis and intestinal metaplasia, and then to dysplasia, and following Correa's cascade, to adenocarcinoma. The use of antibiotics for eradication of H. pylori can reduce the incidence of precancerous lesions only in the early stages of gastric carcinogenesis. Here, we first survey the etiology and risk factors of GC, and then we analyze the mechanisms underlying tumorigenesis induced by H. pylori, focusing attention on virulence factor CagA, inflammation, oxidative stress, and ErbB2 receptor tyrosine kinase. Moreover, we investigate the relationships between H. pylori eradication therapy and other diseases, considering not only cardia (upper stomach) cancers and Barrett's esophagus, but also asthma and allergies, through discussion of the "hygiene hypothesis. " This hypothesis suggests that improved hygiene and antibiotic use in early life reduces microbial exposure, such that the immune response does not become primed, and individuals are not protected against atopic disorders, asthma, and autoimmune diseases. Finally, we overview recent advances to uncover the complex interplay between H. pylori and the gut microbiota during gastric carcinogenesis, as characterized by reduced bacterial diversity and increased microbial dysbiosis. Indeed, it is of particular importance to identify the bacterial taxa of the stomach that might predict the outcome of gastric disease through the stages of Correa's cascade, to improve prevention and therapy of gastric carcinoma.

New Formulations of Levothyroxine in the Treatment of Hypothyroidism: Trick or Treat?

Background: Levothyroxine (LT4) as a medication is used by up to 5.3% of the adult population. For optimal efficacy, the traditional tablet formulation (LT4tab) requires that patients avoid concomitant ingestion with food, drinks, and certain medications, as well as excellent patient compliance. Some comorbidities influence bioavailability of LT4 and may mandate repeated dose adjustments. Summary: New LT4 formulations (soft gel [LT4soft] and liquid [LT4liq]) containing predissolved LT4 are claimed to improve bioavailability, presumably by facilitating absorption. Thus, these formulations may well be more suitable than LT4tab for patients whose daily requirements are subjected to variations in bioavailability. Here, we review the evidence and indications for use of new LT4 formulations and highlight areas of uncertainty that are worthy of further investigation. While bioequivalence is established for LT4soft and LT4liq administered to healthy volunteers compared with LT4tab in pharmacokinetic (PK) studies, therapeutic equivalence of the new formulations seems to be different in several clinical settings. Some evidence suggests that new formulations of LT4 may mitigate against the strict requirements relating to concomitant ingestion with food, drinks, and certain medications, which apply to traditional LT4 tablets. The principal indication is in selected patients with disease fluctuations and intermittent therapies with interfering medications, where the need for frequent dose adjustments and office visits may be diminished. Whether the use of LT4soft or LT4liq in patients with impaired gastric acid secretion results in better control of hypothyroidism than LT4tab remains unclear. Conclusions: The evidence in favor of using LT4soft and LT4liq in clinical practice over LT4tab is weak, and the underlying putative PK mechanisms unclear. Additional studies to investigate these potential benefits, define the cost-effectiveness, and understand the PK mechanisms involved with new LT4 formulations are needed.

The Stability of TSH, and Thyroid Hormones, in Patients Treated With Tablet, or Liquid Levo-Thyroxine

Approximately, 5% of the population is affected by hypothyroidism, mainly women and persons aged more than 60 years. After the diagnosis of hypothyroidism the usual therapy is tablet levothyroxine (L-T4), with a monitoring of the thyroid-stimulating hormone (TSH) level in primary hypothyroidism every 6-8 weeks and L-T4 is adjusted as necessary to reach an euthyroid state. Once TSH is stabilized in the normal range, it is recommended to conduct annual testing in the treated subjects to warrant suitable replacement. More recently advances regarding L-T4 treatment are the introduction of new oral formulations: the liquid solution, and soft gel capsule. The soft gel capsule permits a quick dissolution in the acid gastric pH. The liquid preparation does not require an acid gastric environment. Many pharmacokinetic studies demonstrated a more rapid absorption for the liquid L-T4, or capsule, than with tablet. Many studies have shown that the liquid, or capsule, formulations can overcome the interaction with foods, drugs or malabsorptive conditions, that are able to impair the tablet L-T4 absorption. Lately studies have suggested that liquid L-T4 can permit to maintain more efficiently normal TSH levels in hypothyroid patients in the long-term follow-up, than tablet L-T4, both in patients with malabsorptive states, and in those without malabsorption. Further large, prospective, longitudinal studies are needed to evaluate the stability of TSH, in hypothyroid patients treated with different L-T4 formulations.

L-T4 Therapy in Enteric Malabsorptive Disorders

Levothyroxine (L-T4) absorption can be impaired by various causes: a) L-T4 ingestion during breakfast, or with food; b) conditions of reduced gastric acidity; c) intestinal procedures and diseases such as bariatric surgery, lactose intolerance (LI), celiac disease (CD), inflammatory bowel disease; d) drugs that alter L-T4 absorption, increasing the gastric pH, or preventing the dissolution of tablets. The development of new oral formulations, i.e. the liquid preparation and the soft gel capsule, represents the most recent advance regarding L-T4 therapy. Treating hypothyroidism with L-T4 tablets can lead to an improper control of thyroid-stimulating hormone (TSH) in ~10%-15% of patients. The improperly elevated TSH is usually managed by increasing the L-T4 daily dose, and revaluating TSH upon 2-6 months. The increase of the L-T4 dosage may cause iatrogenic hyperthyroidism, especially when the underlying disorders are cured. Liquid L-T4 can be administered in patients unable to swallow capsules or tablets, and this is one of its major benefits. Liquid L-T4 can: 1- overcome food and beverages interference; 2- bypass the malabsorption associated with an increased gastric pH; 3- circumvent the issue of malabsorption in patients who underwent bariatric surgery; 4-maintain TSH values under control better than L-T4 tablets in hypothyroid patients with typical or atypical CD, or in patients with LI. Few clinical studies evaluated soft gel L-T4 with encouraging findings in patients with gastric- or coffee-related malabsorption, or hypothyroid patients without malabsorption. Additional research is necessary to investigate liquid L-T4, or soft gel capsule, in other conditions of altered L-T4 absorption.

L-T4 Therapy in the Presence of Pharmacological Interferents

Pharmacological interference on L-thyroxine (L-T4) therapy can be exerted at several levels, namely from the hypothalamus/pituitary through the intestine, where the absorption of exogenous L-T4 takes place. A number of medications interfere with L-T4 therapy, some of them also being the cause of hypothyroidism. The clinician should be aware that some medications simply affect thyroid function tests with no need of modifying the dose of L-T4 that the patient was taking prior to their prescription. Usually, the topic of pharmacological interference on L-T4 therapy addresses the patient with primary hypothyroidism, in whom periodic measurement of serum thyrotropin (TSH) is the biochemical target. However, this minireview also addresses the patient with central hypothyroidism, in whom the biochemical target is serum free thyroxine (FT4). This minireview also addresses two additional topics. One is the costs associated with frequent monitoring of the biochemical target when L-T4 is taken simultaneously with the interfering drug. The second topic is the issue of metabolic/cardiovascular complications associated with undertreated hypothyroidism.

Alternative routes of levothyroxine administration for hypothyroidism

PURPOSE OF REVIEW

The aim of the article is to present the basics of oral levothyroxine (LT4) absorption, reasons why patients may have persistently elevated serum thyroid stimulation hormone (TSH) levels, and alternative strategies for LT4 dosing.

RECENT FINDINGS

Although oral LT4 tablets are most commonly used for thyroid hormone replacement in patients with hypothyroidism, case studies report that liquid oral LT4, intravenous, intramuscular, and rectal administration of LT4 can successfully treat refractory hypothyroidism.

SUMMARY

Hypothyroidism is one of the most common endocrine disorders encountered by primary care physicians and endocrinologists. LT4 is one of the most widely prescribed medications in the world and it is the standard of care treatment for hypothyroidism. Generally, hypothyroid patients will be treated with LT4 tablets to be taken orally, and monitoring will occur with routine serum thyroid tests, including TSH concentrations. However, many patients fail to maintain serum TSH levels in the target range while managed on oral LT4 tablets. A subset of these patients would be considered to have poorly controlled hypothyroidism, sometimes termed refractory hypothyroidism. For these patients, optimization of ingestion routines and alternative formulations and routes of administration of LT4 can be considered, including oral liquid, intravenous, intramuscular, and even rectal formulations.

Potential proton pump inhibitor-related adverse effects

Proton pump inhibitors (PPIs) are one of the most common medications taken by patients worldwide. PPIs are used to treat acid-related disorders, including gastroesophageal reflux disease, peptic ulcer disease, Helicobacter pylori infection, and nonsteroidal anti-inflammatory drug/stress ulceration. For some of these diseases, long-term treatment is necessary. With such prolonged use, concern and investigation into potential adverse effects has increased. In addition, data are available regarding potential anticancer effects of PPIs, especially regarding solid tumors. The aim of this review is to assess the literature on PPIs with regard to common concerns, such as drug-drug interactions, the intestinal microbiome, dementia and central nervous system disease, and osteoporosis, as well as to highlight potential negative and positive impacts of the drug in cancer.

Effect of l-thyroxine administration before breakfast vs at bedtime on hypothyroidism: A meta-analysis

PURPOSE

To compare the effects of l-thyroxine (L-T4) administration before breakfast and administration at bedtime on hypothyroidism.

METHODS

The PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI) and Wanfang databases were searched to identify relevant articles. All prospective or randomized controlled studies (RCTs) comparing L-T4 administration before breakfast to the administration at bedtime in patients with hypothyroidism were included in the analysis.

RESULTS

Initially, 2884 articles were retrieved from the databases, and 10 articles were included in the quantitative analysis. The effect of L-T4 administration before breakfast compared with administration at bedtime had no statistically significant association with hormone thyrotropin (TSH) (Standardized mean differences [SMD] = 0.09, 95% confidence intervals (CI): -0.12, 0.30; P = .39), or free triiodothyronine (FT3) (SMD=-0.19, 95% CI: -0.53, 0.15; P = .28) in patients with hypothyroidism. However, the result of FT4 level was favourable for L-T4 bedtime administration group (SMD=-0.27, 95% CI: -0.52, -0.02; P = .03).

CONCLUSION

Our meta-analysis revealed that L-T4 administration at bedtime is as effective as administration before breakfast for patients with hypothyroidism. Taking L-T4 at bedtime may be an attractive option for patients with hypothyroidism.

Unraveling the toxic effects of neonicotinoid insecticides on the thyroid endocrine system of lizards

The widespread use of neonicotinoids has resulted in large residues in the soil, which has a major impact on the lizards that inhabit the soil. Thyroid hormones play an important role in the growth and development of lizards. In this report, we assessed the disrupting effects of thyroid system on lizards after 28 days of continuous exposure to dinotefuran, thiamethoxam, and imidacloprid, respectively. Neonicotinoid insecticides could seriously affect the concentration of T4 in lizard plasma and the conversion of T4 to T3 in the thyroid gland. Specifically, exposure to dinotefuran affected the intake and utilization of iodine in the thyroid gland, resulting in insufficient thyroid function, which in turn lead to thyroid epithelial hyperplasia and follicular volume enlargement by negative feedback. Exposure to thiamethoxam could activate thyroid function, significantly increasing plasma T3 and T4 concentrations and promoting the binding of T3 and thyroid hormone receptors. Imidacloprid exposure could inhibit the secretion of thyroid hormones, leading to down-regulation of thyroid hormone receptors and related phase II metabolic enzyme genes. This study verified that the continuous exposure of neonicotinoids could affect the lizard thyroid endocrine system. The harm of neonicotinoids to reptiles deserved more attention.

Prevalence of gastrointestinal disorders having an impact on tablet levothyroxine absorption: should this formulation still be considered as the first-line therapy?

PURPOSE

In patients with hypothyroidism, levothyroxine (LT4) is the treatment of choice, and tablets are the most commonly prescribed formulation. Despite multiple scenarios being reported in the literature with impaired tablet absorption and likely missed TSH targets, it is yet unclear what the implications are for clinical practice and the role of liquid solution (LS) and soft gel (SG) formulations. We have thus conducted a narrative review evaluating the prevalence within the general population of gastrointestinal disorders impacting tablet LT4 absorption.

METHODS

PubMed and Google Scholar were searched until December 2019 for systematic reviews and meta-analyses on the topic. If they could not be retrieved, other types of manuscripts were searched.

RESULTS

Lactose malabsorption and Helicobacter pylori infection represented the most common disorders, with a global prevalence of 68% and 48%, respectively. The prevalence of other conditions, including autoimmune gastritis, bariatric surgery, celiac disease, gastroparesis, giardiasis, liver cirrhosis, or ulcerative colitis, was lower than 20%. Data at regional and country levels were found to be heterogeneous, but at least one in five patients was diagnosed with one disorder.

CONCLUSIONS

The worldwide prevalence of gastrointestinal disorders associated with tablet LT4 malabsorption, including lactose malabsorption and Helicobacter pylori infection, is high. Interactions with drugs or food can further increase this risk. Considering that all studies investigating the impact of switching patients from tablet to LS or SG found an improved thyroid balance, the latter formulations should be considered as first-line therapy for managing hypothyroidism.

Levothyroxine Therapy in Gastric Malabsorptive Disorders

Oral levothyroxine sodium is absorbed in the small intestine, mainly in the jejunum and the ileum being lower the absorption rate at duodenal level. The time interval between the ingestion of oral thyroxine and its appearance in the plasma renders unlike a gastric absorption of the hormone. However, several evidence confirm the key role of the stomach as a prerequisite for an efficient absorption of oral levothyroxine. In the stomach, in fact, occur key steps leading to the dissolution of thyroxine from the solid form, the process bringing the active ingredient from the pharmaceutical preparation to the aqueous solution. In particular, gastric juice pH, volume, viscosity, as well as gastric emptying time seem to be the most important limiting factors. These hypotheses are confirmed by the detection of an increased need for levothyroxine in patients with Helicobacter pylori infection, chronic atrophic gastritis, gastroparesis, or in simultaneous treatment with drugs interfering with gastric acidic output. The aim of the present article is to focus on the knowledge of pathophysiologic events that determine the absorptive fate of traditional (tablet) and alternative thyroxine preparations (softgel capsule and liquid solution) in patients bearing gastric disorders.

Thyro-entero-gastric autoimmunity: Pathophysiology and implications for patient management

The association between autoimmune atrophic gastritis and thyroid disorders has been observed since the early 1960s and the expression "thyrogastric syndrome" was coined to indicate the presence of thyroid autoantibodies or autoimmune thyroid disease in patients with pernicious anemia, a late clinical stage of autoimmune atrophic gastritis. More recently, it was confirmed that autoimmune thyroid disorders, in particular Hashimoto's thyroiditis, may be frequently associated with other organ-specific, immune-mediated disorders, such as autoimmune atrophic gastritis or celiac disease. The association of Hashimoto's thyroiditis with autoimmune atrophic gastritis or celiac disease in adult patients is currently considered part of the polyglandular autoimmune syndromes which include several autoimmune disorders associated with an autoaggressive impairment of endocrine glands. From a clinical point of view, the thyro-entero-gastric autoimmunity may lead to potentially serious consequences like anemia, micronutrients deficiencies, and drugs malabsorption, as well as to an increased risk for malignancies. These alterations may frequently present in an underhand manner, with consequent diagnostic and treatment delays. Many aspects of the association between thyroid, gastric and intestinal autoimmune diseases still await clarification. The present review focuses on the embryological, genetic and pathophysiological aspects of thyro-entero-gastric autoimmunity. In particular, the current diagnostic criteria of autoimmune thyroid disease, autoimmune atrophic gastritis, and celiac disease are reviewed, along with the evidences for their association in poly-autoimmunity syndromes. The benefits of proactive screening of autoimmune thyroid disorders in patients with autoimmune gastritis or enteropathy and viceversa are also discussed.

Evaluation of evening versus morning levothyroxine intake in elderly (MONIALE)

Background

The aging population is associated with increased multimorbidity and polypharmacy. Older adults are at a higher risk of adverse events and reduced therapeutic response. This phenomenon is partially explained by drug interactions and treatment adherence. Most randomized clinical trials have found no significant differences between morning and evening levothyroxine (LT₄) administration in young adults, but there is little evidence regarding alternative LT₄ regimens in older populations. Thus, the MONIALE trial aims to test an alternative schedule for LT₄ administration in older adults.

Methods/design

This randomized crossover clinical trial will include participants aged 60 years or older with primary hypothyroidism. The trial groups will consist of morning LT₄ intake (60 min before breakfast) or evening LT₄ intake (60 min after supper). The primary outcome will be variation in serum thyrotropin (TSH) levels after 24 weeks of the LT₄ protocol. The secondary outcomes will be the prevalence of drugs that potentially interact with LT₄ and hypothyroidism control according to interaction status. The sample size was calculated to detect a minimum mean difference of 1 mUI/L in serum TSH level between the groups with 80% power and a 5% probability of type I error, resulting in 91 patients per group. The project was approved by the Hospital de Clínicas de Porto Alegre Ethics Committee.

Discussion

Considering the aging population, the increased prevalence of multimorbidity and polypharmacy, as well as potential drug interactions and treatment adherence difficulties, an alternative LT₄ protocol could be useful for hypothyroidism treatment in the elderly. Prior studies comparing alternative LT4 administration protocols have mainly included young adult populations and have not addressed potential drug interactions.

Trial registration

ClinicalTrials.gov, NCT03614988. Registered 30 July 2018.

The Levothyroxine Absorption Test: A Four-Year Experience (2015-2018) at The Mayo Clinic

Background: Levothyroxine (LT4) is the mainstay of therapy for hypothyroidism. Yet, despite physician efforts at dose titration, some patients remain hypothyroid on LT4 doses in excess of weight-based calculations, a condition known as refractory hypothyroidism. The LT4 absorption test (LT4AT) has been proposed to have utility in these patients by enabling distinction of LT4 malabsorption from pseudomalabsorption, a condition of intentional nonadherence. Given its rare use in clinical practice, we reviewed our institution's experience with the LT4AT to assess its impact on management of refractory hypothyroidism. Methods: We reviewed the charts of 16 patients diagnosed with refractory hypothyroidism and who had completed the LT4AT between January 2015 to January 2019. The primary aim was to determine the utility of this test in distinguishing LT4 malabsorption from pseudomalabsorption. Secondary aims were to determine whether the results of this test impacted physicians' management decisions, as well as to report on clinical outcomes at follow-up. Our LT4AT is a six-hour test wherein patients receive a weight-based dose of LT4 followed by serial measurements of total thyroxine (TT4) and thyrotropin (TSH). Percentage absorption is calculated using the following formula, with normal absorption being ≥60%: [Formula: see text] Results: Percentage absorption was calculated in 13 of 16 patients due to lack of TT4 data for 3 patients. Absorption was impaired in one patient (% absorbed = 0), who had known causes of malabsorption. The remaining 12 patients had normal absorption by hour 4 of the test (% absorption 60-158) in conjunction with upward TT4 trends. Clinical follow-up ranged from 1 to 32 months (median 6.5 months), with 11 patients having follow-up data. Six of these had normal or suppressed TSH values at most recent follow-up, and four had improved but persistent TSH elevations. The one said patient with malabsorption improved with intravenous LT4. Conclusions: The LT4AT can provide valuable information for distinguishing malabsorption from pseudomalabsorption. Our findings support the combined use of calculated percentage absorptions with TT4 trends for at least a four-hour time frame when making determinations regarding absorption.

Novel thyroxine formulations: a further step toward precision medicine

Levothyroxine (T4) is a critical-dose drug, because little variations in the blood concentration may cause treatment failure as well as iatrogenic thyrotoxicosis. Despite the dose response of this drug being more carefully titrated nowadays, several papers still report that a significant fraction of patients treated with levothyroxine demonstrate a TSH which is not on target. Moreover, some widespread gastrointestinal disorders as well as interfering drugs and foods may cause the "refractoriness" of a significant number of patients to an expected dose of thyroxine. The increasing awareness of the mechanisms interfering with the oral thyroid hormone bioavailability and the body of evidence regarding the complexity of treatment in certain classes of patients prompted pharmaceutical research to identify new hormonal formulations to optimize the performance of this drug. In this brief review, the progression of the scientific knowledge of novel T4 formulations use has been analyzed.