Comorbidities, Concomitant Medications, and Diet as Factors Affecting Levothyroxine Therapy: Results of the CONTROL Surveillance Project

Breakfast Habits in Patients Using Levothyroxine: Patient Experiences and Preferences

Background

Levothyroxine (LT4) is recommended to be ingested in a fasting state, 30-60 minutes before breakfast to avoid interactions with food and drugs. In clinical practice, we noticed that this instruction may be inconvenient for patients. Therefore, we aimed to evaluate patient experiences and preferences concerning the recommended fasting administration of LT4.

Methods

Patients using LT4 were invited to complete a questionnaire. Regression analyses were performed to identify patient characteristics associated with taking LT4 close to or together with food and/or interfering drugs, feeling burdened with postponing breakfast, and preferring nonfasting LT4 ingestion.

Results

Of 463 invited patients, 410 completed the questionnaire (88.6%). Of these, 76.8% was female and median age was 57 years (interquartile range: 43-67). Nearly all patients (97.3%) reported to have received instruction on fasting LT4 ingestion, but only 30% adhered to this. Nonfasting LT4 intake was associated with use of co-medication (odds ratio [OR], 2.82; 95% CI, 1.77-4.47), treatment duration >1 year (OR, 1.76; 95% CI, 1.02-3.04), and male sex (OR, 1.67; 95% CI, 1.03-2.70). Approximately half of the patients reported being burdened with postponing breakfast and the majority (60.5%) expressed their preference for nonfasting LT4 ingestion. Interestingly, 25% omitted breakfast and 13.4% forgot their medication because of the fasting requirement. Furthermore, the majority (68.2%) of patients that used interfering drugs stated not to be instructed to separate these drugs from LT4.

Conclusion

This study highlights the burden associated with fasting LT4 ingestion, leading to nonadherence, irregular LT4 intake, and omitting breakfast. Given the clear preferences towards nonfasting LT4 ingestion, further research into alternative nonfasting administration methods is warranted.

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 function status in patients with hypothyroidism on thyroxine replacement and associated factors: a retrospective cohort study in primary care

BACKGROUND

Long-term management of patients with hypothyroidism on thyroxine replacement requires thyroid function test (TFT) monitoring once every six-12 months as recommended by clinical practice guidelines. This study determined their thyroid function status during two-year follow-up visits in primary care, and the factors influencing their thyroid status, and assessed the optimal interval for TFTs.

METHODS

A retrospective cohort study was conducted on adults with a clinical diagnosis code for hypothyroidism in their electronic health records taken from a group of polyclinics in Singapore between July 2017 and June 2020. The follow-up thyroid status was categorized as under-replacement (TSH ≥ 3.70mIU/L), over-replacement (TSH ≤ 0.65mIU/L) or euthyroid (TSH 0.65-3.70mIU/L). The patients' demographic, clinical and TFT data were analyzed using appropriate statistical tests during the two-year follow-up. Stepwise logistic regression analysis identified the factors associated with suboptimal thyroid control. Kaplan-Meier analysis was used to compare their thyroid function status in association with the interval between TFT monitoring.

RESULTS

Data from 5,749 eligible subjects (mean age 62.1 ± 13.29 years; 79% female; 79.7% Chinese) were analyzed. After a two-year follow-up, 61.9% (n = 3558) of all subjects were euthyroid, with 29.5% (n = 1694) being under-replaced and 8.6% (n = 497) over-replaced. However, thyroid status did not differ significantly with the various dose regimen (daily, segmented, or alternate days) (p = 0.193). Stepwise logistic regression showed that thyroxine under-replacement was significantly associated with the male gender (AOR = 1.25,95%CI = 1.03-1.51,p = 0.02) and obesity (AOR = 1.34,95%CI = 1.08-1.66,p = 0.008). Every unit (μg/kg body weight) increase in the mean daily thyroxine dose was associated with 2.72 times greater odds of over-replacement. When comparing thyroid function monitoring at intervals of 13-24 months, monitoring at shorter intervals (≤ 12 months) was less likely to detect thyroxine under-replacement (AOR = 0.57,95%CI = 0.44-0.74,p < 0.001) and over-replacement (AOR = 0.62,95%CI = 0.41-0.97,p = 0.033). Among the 3,312 adults who were euthyroid at baseline, 22.2%, 41.7% and 59.6% had suboptimal thyroid control at 6, 12 and 24 months respectively (Kaplan-Meier analysis).

CONCLUSION

Around six in ten patients were euthyroid with thyroxine replacement for hypothyroidism in primary care over two years. Thyroxine under-replacement was associated with male gender and obesity. The proportion of euthyroid patients developing abnormal thyroid function doubled with TFTs at six, 12 and 24-month intervals.

Liquid Thyroxine Improves Outcomes in Hypothyroid Patients With Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome

OBJECTIVE

Malabsorption of levothyroxine (LT4) is often seen in patients with hypothyroidism and gastrointestinal (GI) conditions. Our study was designed to establish the prevalence of small intestinal bacterial overgrowth (SIBO) in patients with hypothyroidism and irritable bowel syndrome (IBS), and to demonstrate that liquid LT4 is more consistently absorbed vs tablet, leading to improvement in thyroid and GI symptoms.

METHODS

This was a single-center, open label, prospective cohort study of liquid LT4 in 75 adult patients with hypothyroidism and IBS. Patients were transitioned from LT4 tablets to solution at equivalent dosing. Patients returned at 6 and 12 weeks for repeat thyroid levels and completion of validated questionnaires. A standard 2-hour SIBO breath test was administered at Week 6. Patients recorded daily stool appearance and frequency.

RESULTS

Prevalence of SIBO was 65.3%. Liquid LT4 normalized thyroid stimulating hormone (TSH) in a higher percentage of patients vs tablet (77.55% vs 57.14%); significantly decreased TSH in subjects with SIBO; improved hypothyroid symptoms, IBS symptoms, stool appearance in all groups, and significantly altered bowel frequency among those with SIBO.

CONCLUSION

Small intestinal bacterial overgrowth (SIBO) is common in patients with hypothyroidism and IBS. Among SIBO patients, LT4 tablets were inefficiently absorbed, leading to suboptimal thyroid control; however, transitioning from LT4 tablets to solution normalized TSH and improved hypothyroid symptoms. Liquid LT4 also significantly improved GI symptoms in all patients with hypothyroidism and IBS, regardless of SIBO status. Additionally, 1 in 5 patients had complete resolution of IBS symptoms after switching from LT4 tablets to solution, independent of changes in TSH.

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.

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.

Refractory Hypothyroidism: Unraveling the Complexities of Diagnosis and Management

INTRODUCTION

Refractory hypothyroidism (RH) represents a challenge in the diagnosis and treatment within the field of thyroidology. It is defined as the inability to achieve disease control despite using levothyroxine (LT4) doses of 1.9 μg/kg/d or higher.

METHODS

A comprehensive review, encompassing 103 articles, was conducted using the Scielo, Scopus, and EMBASE databases, providing an approach to evaluation and diagnosis of this condition.

RESULTS

LT4 disintegrates and dissolves within an acidic gastric environment before being absorbed in the jejunum and ileum. It then extensively binds to serum transporter proteins and undergoes deiodination to yield tri-iodothyronine, the biologically active hormone. There are various nonpathological causes of RH, such as noncompliance with treatment, changes in the brand of LT4, food and drug interferences, as well as pregnancy. Pathological causes include lactose intolerance, Helicobacter pylori infection, giardiasis, among others. The diagnosis of RH involves conducting a thorough medical history and requesting relevant laboratory tests to rule out causes of treatment resistance. The LT4 absorption test allows for the identification of cases of malabsorption. The treatment of RH involves identifying and addressing the underlying causes of noncompliance or malabsorption. In cases of pseudomalabsorption, supervised and weekly administration of LT4 may be considered.

DISCUSSION

Early recognition of RH and correction of its underlying cause are of utmost importance, as this avoids the use of excessive doses of LT4 and prevents cardiovascular and bone complications associated with this condition.

Demographic, Healthcare Access, and Dietary Factors Associated With Thyroid Hormone Treatments for Hypothyroidism

CONTEXT

Clinical guidelines have recommended a trial of liothyronine (LT3) with levothyroxine (LT4) in select patients with hypothyroidism. However, little is known about the real-world use of LT3 and desiccated thyroid extract (DTE) and the characteristics of patients treated with LT3 and DTE.

OBJECTIVES

(1) Determine national trends of new LT4, LT3, and DTE prescriptions in the United States; (2) determine whether sociodemographic, healthcare access, and dietary factors are associated with different thyroid hormone (TH) therapies.

METHODS

Parallel cross-sectional studies were conducted using 2 datasets: (1) a national patient claims dataset (2010-2020) and (2) the National Health and Nutrition Examination Study (NHANES) dataset (1999-2016). Included participants had a diagnosis of primary or subclinical hypothyroidism. Study outcomes included the impact of demographics and healthcare access on differences in the proportion of TH therapies consisting of LT4, LT3, and DTE (patient claims) and differences in dietary behaviors between DTE-treated participants and LT4-treated matched controls (NHANES).

RESULTS

On an average annual basis, 47 711 adults received at least 1 new TH prescription, with 88.3% receiving LT4 monotherapy, 2.0% receiving LT3 therapy, and 9.4% receiving DTE therapy. The proportion receiving DTE therapy increased from 5.4% in 2010 to 10.2% in 2020. In the analysis between states, high primary care and endocrinology physician densities were associated with increased use of LT4 monotherapy (odds ratio 2.51, P < .001 and odds ratio 2.71, P < .001). DTE-treated NHANES participants (n = 73) consumed more dietary supplements compared to LT4-treated participants (n = 146) (4.7 vs 2.1, P < .001).

CONCLUSIONS

The proportion of new TH therapies containing DTE for hypothyroidism doubled since 2010 while LT3 therapies remained stable. DTE treatment was associated with decreased physician density and increased dietary supplement use.

Interference or Noninterference Between Soy and Levothyroxine: That Is the Question. A Narrative Review of Literature

OBJECTIVE

To evaluate the effect of soy intake on levothyroxine (L-T4) absorption among different L-T4 formulations.

METHODS

A PubMed/MEDLINE, Web of Science, and Scopus research was performed. Case reports, case series, and original studies written in English and published online up to November 30, 2022, were selected and reviewed. The final reference list was defined based on the relevance of each study to the scope of this review.

RESULTS

Few data, mainly case reports, seemed to suggest a possible interference of soy products on L-T4 tablets absorption. However, the only prospective randomized cross-over study showed no differences in L-T4 absorption when L-T4 and soy isoflavones were assumed concomitantly. The very little data available on liquid L-T4 formulations did not allow for any conclusions to be made, even if a double-blind placebo-controlled trial showed no impaired L-T4 absorption.

CONCLUSION

The inference of soy products on L-T4 absorption, if present, seems to have little clinical impact. Considering this fact, the Hamlet-like question whether soy milk interferes with L-T4 absorption remains unanswered.

Unusual causes of hyperthyrotropinemia and differential diagnosis of primary hypothyroidism: a revised diagnostic flowchart

The clinical consequences of primary hypothyroidism include cardiovascular morbidity, increased mortality, and poor quality of life; therefore guidelines endorsed by several Scientific Societies recommend measuring circulating thyroid-stimulating hormone (TSH) in patients at risk. The assessment of serum TSH levels is also deemed to be the most robust and accurate biomarker during the management of replacement therapy in patients with a previous diagnosis of primary hypothyroidism. In line with a reflex TSH laboratory strategy, free thyroxine is measured only if the TSH falls outside specific cutoffs, in order to streamline investigations and save unjustified costs. This serum TSH-based approach to both diagnosis and monitoring has been widely accepted by several national and local health services; nevertheless, false-negative or -positive testing may occur, leading to inappropriate management or treatment. This review aims to describe several infrequent causes of increased circulating TSH, including analytical interferences, resistance to TSH, consumptive hypothyroidism, and refractoriness to levothyroxine replacement treatment. We propose a clinical flowchart to aid correct recognition of these various conditions, which represent important potential pitfalls in the diagnosis and treatment of primary hypothyroidism.

Levothyroxine Timing during Ramadan: A Randomized Clinical Trial

INTRODUCTION

Hypothyroidism requires lifelong thyroid hormone replacement with levothyroxine. For most hypothyroid patients fasting during Ramadan, compliance with the administration procedure is a challenge. This study aimed to determine the impact of different administration times of levothyroxine on thyroid-stimulating hormone (TSH) and free T4 (FT4) levels before and after the holy month of Ramadan. Materials and Methodology. Hypothyroid patients taking levothyroxine were randomized to 3 groups during Ramadan: group 1, 30 minutes before the iftar meal; group 2, 3-4 hours after the iftar meal, with no food taken for at least 1 hour after the meal; group 3, they were not given specific instructions for taking levothyroxine during Ramadan. Thyroid function tests were performed within 2 weeks before Ramadan and within 2 weeks after Ramadan. Pre- and post-Ramadan TSH and free T4 levels were compared. Mixed-effects analyzes were performed to identify factors associated with changes in TSH and FT4 levels.

RESULTS

Compliance was lower in patients taking levothyroxine 3-4 hours after iftar. In addition, the majority of patients who had not received a specific recommendation took levothyroxine 30 minutes before iftar. There was a statistically significant increase in TSH (P=0.006) and FT4 (P=0.044) levels after Ramadan. In multivariate analysis, the cause of hypothyroidism (Hashimoto's; postthyroidectomy; compared to postradioactive iodine) and levothyroxine dose significantly affected FT4 levels. In contrast, no variable was significantly associated with TSH level. The timing of levothyroxine intake during Ramadan did not significantly affect TSH or FT4 levels.

CONCLUSION

TSH and FT4 significantly increased after Ramadan. However, the timing of levothyroxine intake per se had no influence on TSH or free T4 levels. Therefore, hypothyroid patients might take levothyroxine either 30 minutes or 3-4 hours after iftar with no meal for 1 hour, depending on preference.

SIMULTANEOUS INTAKE OF LIQUID L-T4 FORMULATION AND IRON SALT: FACT OR FICTION?

Context

Hypothyroidism and iron deficiency are among the most common pathologies in population. Therefore, there are a lot of patients assuming both iron salt supplements and levothyroxine therapy.

Objective

To evaluate the effect of iron salt intake on L-T4 absorption among different L-T4 formulations.

Materials and methods

A PubMed/MEDLINE, Web of Science, and Scopus research was performed. Original studies and reviews written in English and published online up to 21 December 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 data show an impaired absorption of L-T4 in tablets formulation when taken concomitantly with iron salt supplements. These phenomena seem to be circumvented by new L-T4 formulations.

Conclusion

Liquid L-T4 formulations can be ingested with iron salts, with no impairment of absorption. More studies are necessary to confirm these data for soft-gel capsules L-T4.

A Novel Levothyroxine Solution Results in Similar Bioavailability Whether Taken 30 or Just 15 Minutes Before a High-Fat High-Calorie Meal

Background: Levothyroxine (LT4) sodium is a standard treatment for hypothyroidism. Its absorption and bioavailability when taken as a tablet have been shown to be significantly decreased with concomitant food ingestion. Therefore, LT4 formulations are recommended to be taken on an empty stomach, at least 30, ideally 60, minutes before breakfast, potentially affecting adherence to therapy. A novel LT4 solution (Tirosint^®-SOL) has been shown to result in a faster absorption process than tablets or soft-gel capsule formulations. The objective of this trial was to evaluate the bioavailability of this preparation taken 15 minutes before a high-fat high-calorie meal in comparison with the minimally recommended 30-minute interval. Methods: Thirty-six (33 completers, 24 males and 9 females) healthy volunteers participating in the randomized study took 600 mcg of LT4 oral solution, single doses after a 10-hour fast, 15 or 30 minutes before a high-fat, high-calorie, FDA-approved standardized meal in a controlled research setting. We measured serum total thyroxine using Liquid Chromatography with Tandem Mass Spectrometry at baseline and multiple time points up to 72 hours after LT4 administration. The predefined equivalence boundaries for the extent of exposure reflected by the area under the curve (AUC) were 80-125%. The washout period was at least 35 days. Results: The geometric mean ratios and confidence intervals (CIs) for the baseline-adjusted extent of exposure represented by AUCs truncated at both 48 and 72 hours after dosing (AUC_0-48: 90% [90% CI 86-94]; and AUC_0-72: 92% [90% CI 87-97]) were within the prespecified equivalence boundaries. The baseline-adjusted peak concentration was also clinically similar (C_max: 85% [90% CI 80-90]). The median t_max was 1.5 hours in each group. The rate of adverse events was similar between groups. Conclusions: We observed no significant difference in the pharmacokinetic properties of a novel LT4 solution administered 15 and 30 minutes before a high-fat high-calorie meal in normal subjects. Further research is needed to evaluate (a) the differences in overall bioavailability at other time points (including immediately premeal) and (b) the real-world effectiveness of this preparation in newly proposed administration conditions to optimize treatment outcomes in hypothyroid patients.

SEVERE REFRACTORY HYPOTHYROIDISM IN A 48-YEAR-OLD FEMALE: ROLE OF LOW-DOSE THYROXINE ABSORPTION TEST IN ESTABLISHING DIAGNOSIS OF NONCOMPLIANCE

A 48-year-old female presented with severe chronic hypothyroidism despite progressively increasing doses of levothyroxine. Poor adherence was suspected based on previous laboratory investigations. A low dose thyroxine absorption test using 400 µg of levothyroxine taken orally was performed. FT4 increased by 4.7 pmol/L at 3 hours and 6.6 pmol/L at 5 hours, following ingestion, effectively ruling out malabsorption. Her cardiac hemodynamic profile, measured noninvasively, also improved following levothyroxine intake, further supporting our diagnosis. Poor adherence was successfully managed by implementing twice weekly visits by a registered nurse and an improvement in both thyroid function tests and cardiac parameters was seen at the one-month follow-up visit. We suggest using a lower dose thyroxine absorption test, owing to its efficacy in establishing diagnosis and a safer alternative compared to higher doses in particular in high-risk cardiac patients.

Pharmacokinetics and Clinical Implications of Two Non-Tablet Oral Formulations of L-Thyroxine in Patients with Hypothyroidism

BACKGROUND

Increased knowledge of the pharmacokinetic characteristics of orally administered levothyroxine (L-T₄) has improved individualization of dosing regimens. However, up to 40-45% of patients, depending on the leading cause of hypothyroidism, are still over- or, more often, undertreated. Unintentional non-adherence to L-T₄ replacement therapy includes all situations of unintended drug-drug and drug-food interactions as well as fasting conditions that are not necessarily respected by patients.

RESULTS

In this specific context, the overall information concerning those factors with the potential to affect L-T₄ absorption refers only to tablet formulation. Indeed, this is the reason why new non-tablet formulations of L-T₄ were introduced some years ago. In this regard, the current literature review was designed to summarize pharmacokinetic, drug and food interactions and clinical data focusing on two new oral L-T₄ formulations, i.e., liquid and soft-gel capsule in healthy volunteers and patients with primary hypothyroidism. The non-tablet L-T₄ soft-gel capsules and solution have proven bioequivalence with the usual L-T₄ tablet Princeps and generic formulations. Clinical studies have suggested higher performance of non-tablet formulations than tablet in those patients with suboptimal adherence. The impact of gastrointestinal conditions and variation of gastric pH was lower with either soft gel/solution than with tablets. In addition, the extent of drug-drug and drug-food interactions remains low and of uncertain clinical relevance.

CONCLUSIONS

Pending further studies allowing one to extend the use of soft-gel/solution preparations in unselected patients, non-tablet L-T₄ formulations should be considered as a first-line choice, especially in those patients with moderate-to-high potential of suboptimal tablet performance.

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.

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.

Levothyroxine Sodium Oral Solution Normalizes Thyroid Function in a Patient with Hashimoto's Disease, Gastritis, Diabetic Gastroparesis, and Small Intestinal Bacterial Overgrowth (SIBO)

BACKGROUND

Levothyroxine (L-T4) is used as a standard-of-care treatment in patients with hypothyroidism. L-T4 is absorbed throughout the small intestine, and consistent drug absorption is required for successful treatment. Patients with Hashimoto's disease (autoimmune thyroiditis) often have food and medication sensitivities, as well as comorbid gastrointestinal (GI) disorders detrimental to L-T4 absorption.

CASE PRESENTATION

This case report describes a 51-year-old female patient with long-standing Hashimoto's disease and multiple sensitivities to food chemicals and medications. The patient suffered from GI symptoms and poor thyroid-stimulating hormone (TSH) control. She was switched to compounded thyroxine/triiodothyronine medication due to her multiple allergies, with only mild improvement in thyroid function and no symptom resolution. She was subsequently diagnosed with gastroparesis and small intestinal bacterial overgrowth (SIBO). Because of further worsening of her GI symptoms and weight loss, she was switched to levothyroxine sodium oral solution (Tirosint®-SOL), which contains only three ingredients-levothyroxine, water, and glycerol-which was well tolerated and led to normalization of TSH levels.

CONCLUSION

Malabsorption of L-T4 is often seen in patients with Hashimoto's disease-related hypothyroidism and comorbid GI conditions, such as gastroparesis and SIBO. L-T4 tablets and a compounded oral suspension were inefficiently absorbed, leading to suboptimal TSH control. Switching to levothyroxine sodium oral solution resulted in sustained TSH control with subsequent resolution of symptoms. No side effects or reactions to the medication were observed, despite the patient's multiple allergies and sensitivities to food chemicals and medications.

Levothyroxine sodium oral solution to control thyroid function in a patient with hypothyroidism and celiac disease

Implementing a gluten-free diet and switching to the levothyroxine oral solution significantly improved malabsorptive and hypothyroid symptoms in a patient with hypothyroidism, Addison's disease, and celiac disease without the need to increase levothyroxine dosage.

Preference, Adherence, and Maintenance of Euthyroidism Using 3 Different Regimens of Levothyroxine Intake during the Fasting Month of Ramadan

<b><i>Introduction:</i></b> Millions of Muslim hypothyroid patients fast during Ramadan. Limited data are available on the effect of fasting during Ramadan and different levothyroxine (L-T4) timings on thyroid status. The present study aimed to report preference, adherence, and maintenance of euthyroidism using 3 different regimens of L-T4 intake during Ramadan. <b><i>Methods:</i></b> This is a prospective study including Muslim hypothyroid patients fasting during Ramadan between 2018 and 2019. Patients freely chose between 3 regimens, regimen 1: to take L-T4 at sunset and postpone food and beverages for 60 min; regimen 2: to have iftar (first meal) at sunset, stop food and beverages for 3–4 h, have L-T4, and wait for 60 min before suhor (last meal); regimen 3: have suhor at midnight, stop food and beverages for 3–4 h, and have L-T4 before next fast. Thyroid status was assessed before and within 6 weeks after Ramadan. <b><i>Results:</i></b> 393 patients were included. The first 2 regimens or a combination of both was the most preferred by patients 40.5, 36.7, and 17%, respectively. 323/393 patients were adherent to L-T4 regimens (82.2%). 273/393 patients were euthyroid after Ramadan (69.5%). TSH pre- and post-Ramadan were 4.35 ± 12.30 mIU/L and 2.73 ± 3.37 mIU/L, respectively, with no statistically significant change (<i>p</i> = 0.225). Adherence was predicted post-Ramadan euthyroidism (odds ratio [OR] 2.8 in univariate and OR 2.96 in multivariate models). <b><i>Conclusions:</i></b> The first and second regimens or a combination of both was preferred by most patients. High rates of adherence and post-Ramadan euthyroidism were observed. Adherence to the preferred regimen is the main determinant of post-Ramadan euthyroidism.

Levothyroxine Interactions with Food and Dietary Supplements-A Systematic Review

Levothyroxine (l-thyroxine, l-T4) is a drug of choice for treating congenital and primary hypothyroidism. Although clinically significant interactions between l-T4 and food can alter the safety and efficacy of the treatment, they still seem to be generally underestimated by patients, physicians and pharmacists. This review aimed to investigate the effects of meals, beverages, and dietary supplements consumption on l-T4 pharmacokinetics and pharmacodynamics, to identify the most evident interactions, and to perform the recommendations for safe co-administering of l-T4 and food. A total of 121 studies were identified following a systematic literature search adhering to PRISMA guidelines. After full-text evaluation, 63 studies were included. The results proved that l-T4 ingestion in the morning and at bedtime are equally effective, and also that the co-administration of l-T4 with food depends on the drug formulation. We found limited evidence for l-T4 interactions with coffee, soy products, fiber, calcium or iron supplements, and enteral nutrition but interestingly they all resulted in decreased l-T4 absorption. The altered l-T4 efficacy when ingested with milk, juices, papaya, aluminium-containing preparations, and chromium supplements, as well as observed enhancement effect of vitamin C on l-T4 absorption, shall be further investigated in larger, well-designed studies. Novel formulations are likely to solve the problem of coffee, calcium and iron induced malabsorption of l-T4. Maintaining a proper time interval between l-T4 and food intake, especially for coffee and calcium, or iron supplements, provides another effective method of eliminating such interactions.

Patient satisfaction and quality of life in hypothyroidism: An online survey by the british thyroid foundation

OBJECTIVE

Dissatisfaction with treatment and impaired quality of life (QOL) are reported among people with treated hypothyroidism. We aimed to gain insight into this.

DESIGN AND PATIENTS

We conducted an online survey of individuals with self-reported hypothyroidism.

RESULTS

Nine hundred sixty-nine responses were analysed. Dissatisfaction with treatment was common (77.6%), and overall QOL scores were low. Patient satisfaction did not correlate with type of thyroid hormone treatment, but treatment with combination levothyroxine (L-T4) and liothyronine (L-T3) or with desiccated thyroid extract (DTE) was associated with significantly better reported QOL than L-T4 or L-T3 monotherapies (P < .001); however, multivariate analysis inclusive of other clinical parameters failed to confirm an association between type of thyroid hormone treatment and QOL or satisfaction. Multivariate analysis showed positive correlations between satisfaction and age (P = .026), male gender (P = .011), being under the care of a thyroid specialist (P < .001), family doctor (GP) prescribing DTE or L-T4 + L-T3 or L-T3 (P < .001) and being well informed about hypothyroidism (P < .001); negative correlations were observed between satisfaction and negative experiences with L-T4 (P < .001) and expectations for more support from the GP (P < .001), for L-T4 to resolve all symptoms (P = .004), and to be referred to a thyroid specialist (P < .001). For QOL, positive correlations were with male gender (P = .011) and duration of hypothyroidism (P = .002); negative correlations were with age (P = .027), visiting the GP more than 3 times before diagnosis (P < .001), sourcing DTE or L-T3 independently (P = .014), negative experiences with L-T4 (P = .013), having expectations for L-T4 to resolve all symptoms (P < .001) and of more support from the GP (P = .006).

CONCLUSIONS

Multiple parameters including prior healthcare experiences and expectations influence satisfaction with hypothyroidism treatment and QOL. Focusing on enhancing the patient experience and clarifying expectations at diagnosis may improve satisfaction and QOL.

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 activities of drug inactive ingredients on biological targets

Excipients, considered "inactive ingredients," are a major component of formulated drugs and play key roles in their pharmacokinetics. Despite their pervasiveness, whether they are active on any targets has not been systematically explored. We computed the likelihood that approved excipients would bind to molecular targets. Testing in vitro revealed 25 excipient activities, ranging from low-nanomolar to high-micromolar concentration. Another 109 activities were identified by testing against clinical safety targets. In cellular models, five excipients had fingerprints predictive of system-level toxicity. Exposures of seven excipients were investigated, and in certain populations, two of these may reach levels of in vitro target potency, including brain and gut exposure of thimerosal and its major metabolite, which had dopamine D3 receptor dissociation constant K _d values of 320 and 210 nM, respectively. Although most excipients deserve their status as inert, many approved excipients may directly modulate physiologically relevant targets.

Hypothyroidism: current state of the problem

The article presents the issues of epidemiology, classification, and clinic of hypothyroidism. The frequency of hypothyroidism increases significantly with age. The most common form is primary hypothyroidism, caused by a pathological process in the thyroid gland itself. Secondary hypothyroidism or tertiary hypothyroidism is caused by insufficient secretion of thyroid- stimulating hormone (TSH), or thyrotropin-releasing hormone. The article deals with the main causes of primary and secondary hypothyroidism. The most common cause of primary hypothyroidism is autoimmune thyroiditis, which can develop both separately and simultaneously with other autoimmune diseases, as part of polyglandular syndrome. Special attention should be paid to the change of thyroid status as a result of adverse side reactions when using a range of drugs. The questions about the mechanisms of thyroid insufficiency development as a result of unfavorable side reactions when using a number of drugs (lithium preparations, iodine-containing compounds, tyrosine kinase inhibitors, etc.) have been raised. Undiagnosed hypothyroidism is a risk factor for the progression of already existing cardiovascular diseases. The severity of clinical manifestations is determined by the severity of thyroid hormone deficiency. There are no significant clinical differences between the pronounced forms of primary and secondary hypothyroidism. Depending on the degree of lesion, secondary hypothyroidism may be complicated by other manifestations of hypothalamic-pituitary disorders, as well as the latter may include a decrease in the secretion of antidiuretic hormone at a certain stage of their development. Diagnostic difficulties are discussed, as hypothyroidism disrupts the functioning of most organs and systems of the body (musculoskeletal, cardiovascular, urinary, gastrointestinal, central and peripheral nervous systems) and can be masked by various diseases. The final diagnosis of hypothyroidism is clarified by a number of laboratory and instrumental studies. Substitution therapy with levothyroxine is used to treat hypothyroidism of any etiology.

Comparison of Levothyroxine Dosing in Patients with and without Heart Failure

Background: Evidence has shown that low thyroid hormone levels may lead to worse prognosis including a higher mortality rate in patients with heart failure (HF). Thyroid replacement increases cardiac output and exercise performance without causing significant adverse events. The purpose of this study is to compare levothyroxine doses in patients with and without HF.Methods: This single center, retrospective cohort study compared levothyroxine doses in ambulatory hypothyroid patients with a history of HF to those without a history of HF. Patients were stratified into three groups: no HF, HF with reduced ejection fraction (HFrEF, EF<40%), and other types of HF. The primary endpoint of average levothyroxine dose was analyzed using multivariable linear regression with variables determined a priori.Results: Three hundred patients were included in the study with 100 patients in each arm. Average levothyroxine doses (mcg/kg) were 1.5 ± 0.7, 1.6 ± 0.8, and 1.6 ± 0.9 for no HF, other types of HF, HFrEF, respectively (p= .61). Factors found to be significantly related to levothyroxine dosing included gender, drug-drug interactions, and the timing of clinic visit to lab draw. No differences were found in secondary outcomes including TSH levels, free T₄, T₃, and percentage of patients with elevated thyroid-stimulating hormone (TSH) among HFrEF, other types of HF, and no HF patients. Among HF patients, average ejection fractions were also similar comparing patients with elevated TSH, normal TSH, and low TSH.Conclusion: The dose of levothyroxine was not significantly different in HF patients compared to patients without HF.

Thyroid hormone therapy for hypothyroidism

The purpose of this article will be to review the basics of thyroid hormone therapy, including various thyroid hormone formulations, the institution and monitoring of thyroid hormone therapy, adverse effects of overtreatment, the management of patients with persistent symptoms despite normal thyroid function tests, and potential new innovations in thyroid hormone therapy. The conclusions support the necessity to personalize thyroid hormone replacement therapy in hypothyroid patients.

Challenges in Interpreting Thyroid Stimulating Hormone Results in the Diagnosis of Thyroid Dysfunction

The pituitary hormone, thyrotropin (TSH), is regarded as the primary biomarker for evaluating thyroid function and is useful in guiding treatment with levothyroxine for patients with hypothyroidism. The amplified response of TSH to slight changes in thyroid hormone levels provides a large and easily measured signal in the routine care setting. Laboratories provide reference ranges with upper and lower cutoffs for TSH to define normal thyroid function. The upper limit of the range, used to diagnose subclinical (mild) hypothyroidism, is itself a matter for debate, with authoritative guidelines recommending treatment to within the lower half of the range. Concomitant diseases, medications, supplements, age, gender, ethnicity, iodine status, time of day, time of year, autoantibodies, heterophilic antibodies, smoking, and other factors influence the level of TSH, or the performance of current TSH assays. The long-term prognostic implications of small deviations of TSH from the reference range are unclear. Correction of TSH to within the reference range does not always bring thyroid and other biomarkers into range and will not always resolve the patient's symptoms. Overt hypothyroidism requires intervention with levothyroxine. It remains important that physicians managing a patient with symptoms suggestive of thyroid disease consider all of the patient's relevant disease, lifestyle, and other factors before intervening on the basis of a marginally raised TSH level alone. Finally, these limitations of TSH testing mitigate against screening the population for the undoubtedly substantial prevalence of undiagnosed thyroid disease, until appropriately designed randomised trials have quantified the benefits and harms from this approach.

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

Levothyroxine is the standard therapy for patients with hypothyroidism, a condition that affects up to 5% of people worldwide. While levothyroxine therapy has substantially improved the lives of millions of hypothyroid patients since its introduction in 1949, the complexity of maintaining biochemical and clinical euthyroidism in patients undergoing treatment with levothyroxine cannot be underestimated. Initial dosing of levothyroxine can vary greatly and may be based on the amount of residual thyroid function retained by the patient, the body weight or lean body mass of the patient, and thyroid-stimulating hormone levels. As levothyroxine is usually administered over a patient's lifetime, physiological changes throughout life will affect the dose of levothyroxine required to maintain euthyroidism. Furthermore, dose adjustments may need to be made in patients with concomitant medical conditions, in patients taking certain medications, as well as in elderly patients. Patients who have undergone any weight or hormonal changes may require dose adjustments, and the majority of pregnant women require increased doses of levothyroxine. Optimal treatment of hypothyroidism requires a partnership between patient and physician. The physician is tasked with vigilant appraisal of the patient's status based on a thorough clinical and laboratory assessment and appropriate adjustment of their levothyroxine therapy. The patient in turn is tasked with medication adherence and reporting of symptomatology and any changes in their medical situation. The goal is consistent maintenance of euthyroidism, without the patient experiencing the adverse events and negative health consequences of under- or overtreatment.Funding Merck.Plain Language Summary Plain language summary available for this article.

Gastrointestinal Malabsorption of Thyroxine

Levothyroxine, a largely prescribed drug with a narrow therapeutic index, is often a lifelong treatment. The therapeutic efficacy of T4 may be marred by behavioral, pharmacologic, and pathologic issues acting as interfering factors. Despite a continuous search for an optimal T4 treatment, a significant number of patients fail to show a complete chemical and/or clinical response to this reference dose of T4. Gastrointestinal malabsorption of oral T4 represents an emerging cause of refractory hypothyroidism and may be more frequent than previously reputed. In this review, we examine the pharmacologic features of T4 preparations and their linkage with the intestinal absorption of the hormone. We have stressed the major biochemical and pharmacologic characteristics of T4 and its interaction with the putative transporter at the intestinal level. We have examined the interfering role of nutrients, foods, and drugs on T4 absorption at the gastric and intestinal levels. The impact of gastrointestinal disorders on T4 treatment efficacy has been also analyzed, in keeping with the site of action and the interfering mechanisms. Based on the evidence obtained from the literature, we also propose a schematic diagnostic workup for the most frequent and often hidden gastrointestinal diseases impairing T4 absorption.

Concurrent Milk Ingestion Decreases Absorption of Levothyroxine

BACKGROUND

Levothyroxine is the most commonly prescribed medication in the United States. Many foods and medications, including calcium supplements, can interfere with levothyroxine absorption. No studies have investigated the effect of cow's milk, a common breakfast staple, on the absorption of oral levothyroxine. Cow's milk contains approximately 450 mg of elemental calcium per 12 oz (355 mL) serving.

METHODS

A pharmacokinetic study was conducted in healthy euthyroid subjects to assess levothyroxine absorption with and without concurrent cow's milk consumption. Following an overnight fast, serum total thyroxine (TT4) concentrations were measured at baseline and at one, two, four, and six hours after ingestion of 1000 μg of oral levothyroxine alone or when co-administered with 12 oz (355 mL) of 2% milk. There was a four-week washout period between the two assessments in each subject.

RESULTS

Ten subjects (M_age ± SD = 33.7 ± 10.2 years; 60% male) completed the study. The area under the curve (AUC) of TT4 concentrations was significantly lower when levothyroxine was ingested along with 12 oz (355 mL) of 2% cow's milk (M ± SD = 67.3 ± 12.1) compared to that with levothyroxine alone (73.5 ± 17.0; p = 0.02). Also, peak serum TT4 concentrations were significantly lower when cow's milk was co-administered with levothyroxine (M ± SD = 14.1 ± 0.8 μg/dL) than with levothyroxine alone (13.0 ± 0.9 μg/dL; p = 0.04).

CONCLUSIONS

This is the first study to demonstrate that concurrent cow's milk ingestion reduces oral levothyroxine absorption. The findings support previous literature showing the interference of elemental calcium and food with thyroid hormone absorption. Patients managed with thyroid hormone should be advised to avoid taking their levothyroxine simultaneously with cow's milk.

Diagnosis and management of treatment-refractory hypothyroidism: an expert consensus report

There is a frequently encountered subset of hypothyroid patients who are refractory to standard thyroid hormone replacement treatment and require unexpectedly high doses of levothyroxine. In addition to clinical situations where hypothyroid patients are non-compliant, or where there is the possibility of excipient-induced disease exacerbation (gluten/celiac disease), therapeutic failure may be due to impaired absorption of the administered drug. The common approach to managing patients with unusual thyroxine needs is to escalate the dose of levothyroxine until targeted TSH levels are achieved. This approach can increase the risk for prolonged exposure to supratherapeutic doses of levothyroxine, which increase the chances of adverse outcomes. Repeated adjustments of levothyroxine can also escalate the costs of treatment, as frequent office visits and laboratory tests are required to determine and maintain the desired dose. Clinicians should take a systematic approach to managing patients whom they suspect of having treatment-refractory hypothyroidism. This may include searching for, and adjusting, occult medical conditions and/or other factors that may affect the absorption of levothyroxine, before up-titrating the dose of traditional levothyroxine therapy. Depending on the underlying pathology, another approach that may be considered is to try alternative formulations of levothyroxine that are less susceptible to intolerance issues related to excipients, or, in some cases, to malabsorption. The early discovery of these factors via a thoughtful patient work-up may avoid unnecessary thyroid medication adjustments and their consequences for both patients and clinicians.

Retrospective Study of Patients Switched from Tablet Formulations to a Gel Cap Formulation of Levothyroxine: Results of the CONTROL Switch Study

INTRODUCTION

Medication changes involving levothyroxine-either dose titrations or switching formulations-occur frequently in patients with erratic thyroid-stimulating hormone (TSH) levels and persistent hypothyroid symptoms. We investigated whether switching patients from levothyroxine tablets to a gel cap formulation of levothyroxine might reduce dose adjustments and improve tolerability and efficacy outcomes.

OBJECTIVES

Primary study objectives included quantifying the percentage of patients achieving TSH levels within a pre-specified range, median dose changes experienced, and the percentage of patients with improved hypothyroid symptom control after switching from levothyroxine tablets to levothyroxine gel caps.

METHODS

A retrospective medical chart review was conducted among 99 randomly selected hypothyroid patients who were switched from a tablet to a gel cap formulation of levothyroxine. Patients were required to have been on levothyroxine monotherapy for ≥1 year prior to the medication switch. Data was collected for 6 months pre-switch and up to 6 months post-switch.

RESULTS

Of the 99 patients studied, the majority (51.5%) experienced no documented change in TSH status after the switch (P < 0.0001). However, there was a decrease in the mean number of dose changes experienced (1.61 ± 0.96 vs. 0.73 ± 0.96; P < 0.0001). Improved hypothyroid symptom control was reported among 61.6% of patients (61 of 99; P < 0.0001).

CONCLUSION

The results of CONTROL Switch support a strategy of switching patients who may experience tolerability or efficacy problems with standard levothyroxine tablets to the levothyroxine gel cap formulation.

The Economic Impact of Levothyroxine Dose Adjustments: the CONTROL HE Study

Background

In general, hypothyroidism can be adequately treated with a consistent daily dose of levothyroxine. However, the need for levothyroxine dose adjustments is frequent in clinical practice. The extent to which levothyroxine dose adjustments increase the utilization of healthcare resources has not previously been described in the clinical literature.

Objective

The primary objective of our study was to measure the effect of levothyroxine dose adjustments in terms of their utilization of healthcare resources including direct and indirect costs. A secondary goal was to identify any differences in patient characteristics that may be responsible for levothyroxine dose adjustments.

Methods

A retrospective medical chart review was conducted among patients of selected healthcare providers in the USA. Patients who were recently started on levothyroxine therapy (<6 months) were excluded to avoid situations that were more likely attributable to treatment initiation than inadequate therapeutic effect. Trained nurses extracted data from patient charts and electronic medical record systems for review. We analyzed the cost of resources consumed by the frequency of levothyroxine dose changes over 24 months: 0 dose changes (no dose adjustment group); one dose change, two dose changes, three or more dose changes (≥1 dose adjustment group).

Results

The study included 454 patients. Overall estimated resource utilization was higher per patient in the ≥1 dose adjustment group (US$5824) vs. the no dose adjustment group (US$3166) during the 24-month study period. When direct and indirect costs were combined, overall costs of care were greatest in patients requiring three or more dose adjustments (US$8220/patient). Patients in this cohort incurred 2.5-fold greater total costs compared with patients requiring no dose adjustments (US$8220 vs. US$3166). Among the 58 patients in the group requiring three or more dose adjustments, mean direct medical costs were significantly higher than in the patients requiring no dose adjustments (US$6387 vs. US$2182). Patients with at least one dose adjustment experienced a 40.3% increase in lost productivity vs. patients who had no dose adjustments (US$1381 vs. US$984). Loss of productivity was highest among patients with three or more levothyroxine dose adjustments. Among this cohort, there was an 86.4% increase in lost productivity vs. patients who had no levothyroxine dose adjustments (US$1833 vs. US$984).

Conclusions

Patients experiencing multiple levothyroxine dose adjustments were shown to consume more healthcare resources, resulting in higher costs than those who required no dose adjustments. Each care episode contributed to lost time and wages with total estimated lost productivity escalating with increasing levothyroxine dose adjustments over a 24-month period.

Electronic supplementary material

The online version of this article (doi:10.1007/s40261-016-0462-3) contains supplementary material, which is available to authorized users.

The Thyroid Registry: Clinical and Hormonal Characteristics of Adult Indian Patients with Hypothyroidism

OBJECTIVES

Appropriate treatment of hypothyroidism requires accurate diagnosis. This registry aimed to study the disease profile and treatment paradigm in hypothyroid patients in India.

MATERIALS AND METHODS

We registered 1500 newly diagnosed, treatment-naïve, adult hypothyroid males and nonpregnant females across 33 centers and collected relevant data from medical records. The first analysis report on baseline data is presented here.

RESULTS

The mean age of the study population was 41.1 ± 14.01 years with a female to male ratio of 7:3. The most frequently reported symptoms and signs were fatigue (60.17%) and weight gain with poor appetite (36.22%). Menstrual abnormalities were reported in all women (n = 730) who had not attained menopause. Grades 1 and 2 goiter (as per the WHO) were observed in 15.41% and 3.27% patients, respectively. Comorbidities were reported in 545 patients (36.36%), type 2 diabetes mellitus being the most prevalent (13.54%) followed by hypertension (11.34%). Total serum thyroxine (T4) and thyroid-stimulating hormone (TSH) levels were assessed in 291 (19.47%) patients only. In majority of patients (81%), treatment was based on serum TSH levels alone. The dose of levothyroxine ranged from 12.5 to 375 mcg.

CONCLUSIONS

Guidelines suggest a diagnosis of hypothyroidism based on TSH and T4 levels. However, most of the patients as observed in this registry received treatment with levothyroxine based on TSH levels alone, thus highlighting the need for awareness and scientific education among clinicians in India. The use of standard doses (100, 75, and 25 mcg) of levothyroxine may point toward empirical management practices.

Resistance to levothyroxine in a bariatric surgery patient: an indication for liquid formulation?

We report the case of a 49-year-old female patient with hypothyroidism who underwent bariatric surgery and developed severe hypothyroidism despite high doses of oral levothyroxine (L-T4) tablets. Initially, a high-dose L-T4 tablets absorption test was performed to exclude pseudo-malabsorption. In view of a modest increase in serum T4 levels, L-T4 liquid formulation absorption test was performed, and showed faster and more efficient absorption of thyroid hormones. We discuss the issue of distinguishing malabsorption from pseudo-malabsorption, review the literature concerning the benefits of liquid L-T4 in cases of impaired absorption such as bariatric surgery and consider the socio-economic implications of different liquid formulations.