When thyroid hormone replacement is ineffective?

Hypothyroidism and metabolic cardiovascular disease

Cardiovascular disease (CVD) remains the leading cause of death worldwide, representing a major health issue of social and economic relevance. Both hyperthyroidism and hypothyroidism are very common in the adult population, and both disorders may contribute to the onset and progression of CVD. After a brief description of the role of thyroid hormones (THs) on the physiology of the cardiovascular system and the potential mechanism that links THs alterations with changes in cardiac function, blood pressure, endothelial function, and lipid levels, we review updated data about the clinical impact of overt hypothyroidism (OH) and subclinical hypothyroidism (SCH) on CV risk, CVD, and mortality. Furthermore, we summarize the current evidence for treating SCH with levothyroxine (L-T4). Several guidelines of distinguished endocrine societies recommend treatment for SCH with TSH higher than 10 mIU/L, where the benefit of L-T4 therapy is more evident for younger people, but still controversial in those aged over 65 years. Based on current knowledge, more research efforts are needed to better address the clinical management of CV risk and CVD in the elderly affected by SCH.

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.

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.

Hypothyroidism following Radiotherapy for Head and Neck Cancer: A Systematic Review of the Literature and Opportunities to Improve the Therapeutic Ratio

(1) Background: Radiotherapy (RT) is a central component for the treatment of many head and neck cancers. In this systematic review of the literature, we aimed to characterize and quantify the published evidence on RT-related hypothyroidism, including estimated incidence, clinical risk factors, and dosimetric parameters that may be used to guide clinical decision making. Furthermore, we aimed to identify potential areas of improvement in the prevention and clinical management of RT-induced hypothyroidism, including the role of modern advanced therapeutic techniques. (2) Methods: We conducted a systemic review of the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed and Google Scholar were searched to identify original research articles describing the incidence, mechanism, dosimetry, treatment, or prevention of radiation-related hypothyroidism for adults receiving RT for the treatment of head and neck cancers. The snowball method was used to identify additional articles. For identified articles, we tabulated several datapoints, including publication date, patient sample size, estimated hypothyroidism incidence, cancer site/type, follow-up period, radiation modality and technique, use of multimodality therapy, method of thyroid function evaluation, and proposed dosimetric predictors of hypothyroidism. (3) Results: One hundred and eleven articles met inclusion criteria, reflecting a range of head and neck cancer subtypes. There was a large variation in the estimated incidence of RT-related hypothyroidism, with a median estimate of 36% (range 3% to 79%). Reported incidence increased in later publication dates, which was likely related to improved screening and longer follow up. There were a wide variety of predictive metrics used to identify patients at high risk of hypothyroidism, the most common of which were volumetric and mean dosimetrics related to the thyroid gland (Vxx%, Dmean). More recently, there has been increasing evidence to suggest that the thyroid gland volume itself and the volume of the thyroid gland spared from high-dose radiation (VSxx) may better predict thyroid function after RT. There were no identified studies investigating the role of advanced radiotherapeutic techniques such as MRI-guided RT or particle therapy to decrease RT-related hypothyroidism. Conclusions: Hypothyroidism is a common toxicity resulting from therapeutic radiation for head and neck cancer with recent estimates suggesting 40-50% of patients may experience hypothyroidism after treatment. Dosimetric predictive models are increasingly able to accurately identify patients at risk of hypothyroidism, especially those utilizing thyroid VS metrics. Further investigation regarding the potential for advanced radiotherapeutic therapies to decrease RT-induced thyroid dysfunction is needed.

Engineering a functional thyroid as a potential therapeutic substitute for hypothyroidism treatment: A systematic review

Background

Hypothyroidism is a common hormone deficiency disorder. Although hormone supplemental therapy can be easily performed by daily levothyroxine administration, a proportion of patients suffer from persisting complaints due to unbalanced hormone levels, leaving room for new therapeutic strategies, such as tissue engineering and regenerative medicine.

Methods

Electronic searches of databases for studies of thyroid regeneration or thyroid organoids were performed. A systematic review including both in vitro and in vivo models of thyroid regenerative medicine was conducted.

Results

Sixty-six independent studies published between 1959 and May 1st, 2022 were included in the current systematic review. Among these 66 studies, the most commonly involved species was human (19 studies), followed by mouse (18 studies), swine (14 studies), rat (13 studies), calf/bovine (4 studies), sheep/lamb (4 studies) and chick (1 study). In addition, in these experiments, the most frequently utilized tissue source was adult thyroid tissue (46 studies), followed by embryonic stem cells (ESCs)/pluripotent stem cells (iPSCs) (10 studies), rat thyroid cell lines (7 studies), embryonic thyroid tissue (2 studies) and newborn or fetal thyroid tissue (2 studies). Sixty-three studies reported relevant thyroid follicular regeneration experiments in vitro, while 21 studies showed an in vivo experiment section that included transplanting engineered thyroid tissue into recipients. Together, 12 studies were carried out using 2D structures, while 50 studies constructed 3D structures.

Conclusions

Each aspect of thyroid regenerative medicine was comprehensively described in this review. The recovery of optimal hormonal equilibrium by the transplantation of an engineered functional thyroid holds great therapeutic promise.

Switching from the tablet to the powder formulation of levothyroxine corrects severe hypothyroidism in a patient with lactose intolerance

We describe a case of a 38-year-old woman who, after radioactive iodine therapy for Graves' disease, developed severe hypothyroidism despite receiving a high dose of levothyroxine (L-T4) tablet as replacement therapy. Her thyroid stimulating hormone (TSH) remained to be high despite the dose of L-T4 tablets to 400 μg/day after treatment for hypothyroidism, and the patient complained of general malaise and edema of the legs. Reduced intestinal absorption of L-T4 is the most common cause of failure to achieve the therapeutic target in hypothyroid patients receiving replacement therapy. She was admitted to our hospital for severe hypothyroidism due to resistance to treatment with L-T4 tablet. Our patient was found to have lactose intolerance (LI) by a detailed examination during hospitalization. Therefore, we assumed that LI was impairing intestinal absorption of L-T4 tablet in our patient, leading to severe hypothyroidism. The patient was switched to the powder formulation of L-T4 at the same daily dose, and serum levels of thyroid-stimulating hormone and thyroid hormones normalized. This is the case in which hypothyroidism due to reduced absorption of L-T4 tablet in a patient with LI was resolved by switching to L-T4 powder formulation.

Understanding treatment patterns and patient-reported outcomes associated with the use of authorized generics and corresponding independent generics across multiple therapeutic areas

OBJECTIVES

To assess patient characteristics, treatment patterns, and patient-reported outcomes (PROs) associated with authorized generics (AGs) and independent generics (IGs) use.

METHODS

Prescription claims and National Health and Wellness Survey (NHWS) data were linked. Adults with billable national drug code (AG or IG), NHWS completion from June 2015 to July 2019, AG or IG on-hand at NHWS completion, and continuous insurance eligibility in 12 months pre- and post-NHWS completion were included. To be included, all unique medication formulations had to have at least one AG and one IG observation. PRO index date was NHWS completion; claims index date was defined as the first prescription claim identified during the 180-day period prior to NHWS completion for the same active ingredient and formulation type that was on-hand at NHWS completion.

RESULTS

Patients (N = 20,229; 17.2% AG users) in six therapeutic areas (attention deficit-hyperactivity disorder [ADHD], antidepressants, beta blockers [BBs], calcium channel blockers [CCBs], statins, and thyroid) were included. Generally, AG (vs. IG) users were younger and differed in regional access and insurance type (all, p < .05). In multivariable analysis, significant differences were observed for presenteeism and overall work impairment (BBs), healthcare provider visits (BBs), and indirect costs (thyroid) (all, p < .05). AG and IG users differed in persistence (ADHD and statins; both, p < .05) and switch (BBs and CCBs; both, p < .01) rates.

CONCLUSIONS

PRO differences were often small in magnitude and varied by therapeutic area. The impact of switching should consider observed PRO differences, patient preferences, and market availability of AG and IG alternatives.

Tea consumption affects the absorption of levothyroxine

Levothyroxine (LT4) is a convenient treatment for hypothyroidism. Coffee, however, prevents the body from efficaciously absorbing LT4. It is unknown whether the intake of tea interferes with LT4 absorption. Thirty-seven hypothyroidism patients with the following types of consumption were recruited: 1) only tea, 2) tea and coffee, and 3) only coffee. The concentrations of thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) were recorded before and 3 months after changing the consumption. The patients had reductions in the concentration of TSH to varying degrees after 3 months (p < 0.001 or p < 0.05). The natural logarithms of the differences between the concentrations of TSH before and after the change in the consumption (Δln-TSH) of tea and coffee, only coffee, and only tea were 1.94, 2.00, and 2.18, respectively. Long-term consumption of tea, like coffee, interfered with the absorption of LT4. We believe that avoiding tea when taking LT4 will reduce malabsorption.

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.

Generation and Differentiation of Adult Tissue-Derived Human Thyroid Organoids

Total thyroidectomy as part of thyroid cancer treatment results in hypothyroidism requiring lifelong daily thyroid hormone replacement. Unbalanced hormone levels result in persistent complaints such as fatigue, constipation, and weight increase. Therefore, we aimed to investigate a patient-derived thyroid organoid model with the potential to regenerate the thyroid gland. Murine and human thyroid-derived cells were cultured as organoids capable of self-renewal and which expressed proliferation and putative stem cell and thyroid characteristics, without a change in the expression of thyroid tumor-related genes. These organoids formed thyroid-tissue-resembling structures in culture. (Xeno-)transplantation of 600,000 dispersed organoid cells underneath the kidney capsule of a hypothyroid mouse model resulted in the generation of hormone-producing thyroid-resembling follicles. This study provides evidence that thyroid-lineage-specific cells can form organoids that are able to self-renew and differentiate into functional thyroid tissue. Subsequent (xeno-)transplantation of these thyroid organoids demonstrates a proof of principle for functional miniature gland formation.

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.

Generic levothyroxine initiation and substitution among Medicare and Medicaid populations: a new user cohort study

PURPOSE

Generic levothyroxine has been approved and available since 2004 but its substitution remains controversial. Therefore, the objective was to examine patterns of and identify factors associated with initiation and substitution of generic levothyroxine treatment.

METHODS

This was a retrospective observational study, including new users of brand and generic levothyroxine in 2013-2015 Medicare (n = 15,877) or 2011-2012 Medicaid (n = 9390) administrative claim databases. The primary outcomes included (1) generic levothyroxine initiation, and (2) among brand-new users, generic levothyroxine substitution in 12 months. The factors associated with generic levothyroxine initiation and substitution were measured.

RESULTS

Among all levothyroxine new users, Medicare beneficiaries had a higher proportion of generic levothyroxine initiation than Medicaid beneficiaries (66.40% vs. 44.04%, respectively). Medicare beneficiaries' demographic factors, and health service utilizations were associated with generic levothyroxine initiation. Medicaid beneficiaries who were male and residing in the northeast region and rural areas were more likely to initiate generic levothyroxine. Among brand levothyroxine new users, the generic substitution rate was higher in the Medicare than the Medicaid cohort (18.26 vs. 3.88%). Medicare brand levothyroxine new users' demographic factors and health service utilizations were associated with generic levothyroxine substitution. Medicaid brand levothyroxine new users who were residing in the northeast region, with more prior hospitalization, and initiating a lower dosage of brand levothyroxine, had higher rates of generic substitution.

CONCLUSION

Patient demographic factors and health service utilizations are associated with generic levothyroxine initiation and substitution. Educational outreach programs targeted to increase generic levothyroxine use and prescription savings should be tailored based on different patient populations.

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.

Liquid and softgel capsules of l-thyroxine results lower serum thyrotropin levels more than tablet formulations in hypothyroid patients

Objective

Evidence indicates that L-T4 in liquid and softgel capsule are absorbed better than tablets in hypothyroid patients, even when patients are under medications that impair the intestinal absorption of L-T4. However, no study has evaluated all three L-T4 formulations in the same hypothyroid patients. This study aims to fill this gap. The outcome was the degree of TSH change in the liquid and softgel formulations, using tablet L-T4 as the reference, regardless of sequence of formulation and regardless of whether patients were co-ingesting with interfering medications.

Methods

We recorded serum TSH levels in two groups of L-T4 replaced patients with primary hypothyroidism (23 subjects who did not co-ingest interfering medications, and 20 subjects who did). Either group of patients took one formulation of L-T4 at a time with variable sequences. In the first group, the median durations of exposure to tablet, liquid or softgel L-T4 were 14, 9 and 10 months, respectively. In the second group the corresponding durations were 13, 11 and 10 months, during which patients co-ingested interfering medications.

Results

In the 23 patients, there were 78, 74 or 101 TSH determinations during liquid, softgel capsule or tablet L-T4 regimens. Serum TSH levels associated with liquid, capsule or tablet L-T4 were 1.62 ± 0.51, 1.77 ± 0.44 mU/L (P = 0.049 vs liquid) or 2.38 ± 0.69 mU/L (P < 0.0001 vs liquid or capsule). Rates of TSH ≤ 2.50 mU/L were 97.4% (liquid), 95.9% (softgel) or 64.4% (tablet, P < 0.0001 vs liquid or capsule). Rates of TSH ≤ 4.12 mU/L were 100%, 100% or 98.0%.

In the 20 patients, the corresponding TSH determinations were 56, 57 and 41, and corresponding TSH levels were 2.74 ± 0.98, 2.70 ± 0.79 or 7.53 ± 2.82 mU/L. Rates of TSH ≤ 2.50 mU/L were 51.8% (liquid), 47.4% (capsule, P = 0.64) or 2.4% (tablet, P < 0.0001 vs liquid or capsule). Rates of TSH ≤ 4.12 mU/L were 92.8% (liquid), 94.7% (capsule, P = 0.68) or 12.2% (tablet, P < 0.0001 vs liquid or capsule).

Conclusions

L-T4 ingested as liquid solution or softgel capsule is more bioavailable compared to L-T4 ingested as tablet, and it is slightly superior to capsule L-T4 only in the absence of co-ingestion of interfering medications.

In thyroxine-replaced hypothyroid postmenopausal women under simultaneous calcium supplementation, switch to oral liquid or softgel capsule L-thyroxine ensures lower serum TSH levels and favorable effects on blood pressure, total cholesterolemia and glycemia

PURPOSE

In postmenopausal women under L-T4 therapy, which was subsequently accompanied by calcium carbonate (CC) supplementation taken 6-8 h after tablet L-T4, TSH levels were greater than prior to adding CC. Total cholesterolemia [CHOL], fasting glycemia [FG], systolic and diastolic blood pressure [SBP, DBP] were also greater than baseline. Our aim was to explore the effects of either liquid or softgel capsule L-T4, while maintaining CC ingestion 6-8 h, later on TSH levels, CHOL, FG, SBP, and DBP.

METHODS

We proposed to 50 hypothyroid postmenopausal women under tablet L-T4 therapy, to switch to either liquid or softgel capsule L-T4 at the same daily dose while maintaining CC ingestion 6-8 h later. Sixteen women accepted [group I; liquid (n = 9), capsule (n = 7)], while 34 continued tablet L-T4 [group II, (n = 34)].

RESULTS

After 3 months, in group I, TSH decreased significantly (1.23 ± 0.49 vs. 1.80 ± 0.37 mU/L, P < 0.01), as did FG (80.7 ± 7.9 vs. 83.4 ± 6.3 mg/dL, P < 0.05); CHOL, SBP, and DBP decreased, though insignificantly. In contrast, in group II, TSH, FG, CHOL, SBP increased insignificantly, and DBP increased borderline significantly (69.7 ± 9 vs. 66.3 ± 6.5, P < 0.10). Compared to baseline (before adding CC), in group I, TSH was significantly lower (P < 0.01) and the other indices similar; in group II, TSH, FG, and SBP were significantly higher (P < 0.05), DBP borderline significantly higher (P < 0.10) and CHOL insignificantly higher. Performance of liquid L-T4 and capsule L-T4 was similar.

CONCLUSION

Delaying CC ingestion even by 6-8 h after taking tablet L-T4 is not entirely satisfactory, unlike liquid or softgel L-T4.

L-thyroxine malabsorption due to calcium carbonate impairs blood pressure, total cholesterolemia, and fasting glycemia

PURPOSE

Calcium carbonate was previously shown to interfere with L-thyroxine absorption. To estimate the magnitude of tablet L-thyroxine malabsorption caused by calcium carbonate, with resulting increase in serum thyrotropin (TSH), we performed a cohort study in a referral care center.

METHODS

Fifty postmenopausal hypothyroid L-thyroxine-treated women (age 71.7 ± 5.1 years) who added calcium supplementation (600-1000 mg/day) were considered. They were taking L-thyroxine 45-60 min before breakfast (setting 1). After 4.4 ± 2.0 years from initiation of L-thyroxine therapy, they took calcium supplemaentation within 2 h after L-thyroxine taking (setting 2) for 2.3 ± 1.1 years. Hence, we recommended postponing calcium intake 6-8 h after L-thyroxine (setting 3). We evaluated TSH levels, the prevalence of women with elevated TSH (>4.12 mU/L), total cholesterolemia, fasting glycemia, blood pressure, and the prevalence of hypercholesterolemia, hyperglycemia, and hypertension.

RESULTS

TSH levels were 3.33 ± 1.93 mU/L versus 1.93 ± 0.51 or 2.16 ± 0.54 comparing setting 2 with setting 1 or 3 (P < 0.001, both). In setting 2, 18% women had elevated TSH versus none in setting 1 or 3 (P < 0.01). Total cholesterolemia, fasting glycemia, systolic, and diastolic blood pressure were also significantly higher in setting 2 compared to settings 1 and 3. For every 1.0 mU/L increase within the TSH range of 0.85-6.9 mU/L, total cholesterolemia, glycemia, systolic, and diastolic blood pressure increased by 12.1, 3.12 mg/dL, 2.31, and 2.0 mmHg, respectively.

CONCLUSIONS

Monitoring of hypothyroid patients who ingest medications that decrease L-thyroxine absorption should not be restricted to solely measuring serum TSH.

A minimum of two years of undertreated primary hypothyroidism, as a result of drug-induced malabsorption of l-thyroxine, may have metabolic and cardiovascular consequences

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L-T4 malabsorption is frequently encountered in clinical practice.

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Drug induced L-T4 malabsorption has metabolic and cardiovascular consequences.

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Control of TSH is not enough when drug induced L-T4 malabsorption is suspected.

Objective

Cross-sectional studies have reported that TSH above or close to the upper normal limit correlates with unfavorable metabolic and cardiovascular outcomes. Certain medications impair intestinal absorption of levothyroxine (L-T4), resulting in undertreated hypothyroidism (viz. failure of serum TSH to reach target levels, if hypothyroidism is primary).

Further to evaluating the magnitude of sub-optimally treated primary hypothyroidism as a result of co-ingestion of those medications, we wished to ascertain whether the above complications would occur during a low number of years under polypharmacy.

Method

In this retrospective study in collaboration with 8 family physicians, we enrolled adults with primary hypothyroidism under L-T4 therapy that, for 2 years minimum, was not associated with those medications (non-exposure, baseline) and that, for another 2 years minimum, it was (exposure). Outcomes were serum levels and proportions of serum TSH levels >4.12 mU/L, and proportions of complications. Complications were aggravation of pre-existing or de novo onset of any of metabolic syndrome, impaired fasting glycemia (IFG), diabetes mellitus, dyslipidemia, hypertension, coronary heart disease (CHD), cerebrovascular disease (CVD).

Result

A total of 114 patients were enrolled. Duration of exposure to the interfering medication was 32.1 ± 6.9 months (median 31; range 24–55). Compared with non-exposure, the exposure period resulted in greater TSH levels (2.81 ± 3.62 [median 1.79] vs 1.27 ± 1.34 [median 0.93], P = 2.2 × 10⁻²⁰) and proportions of values >4.12 mU/L (18.5% vs 4.7%, P = 1.2 × 10⁻⁷). Seventy-six patients (67%) had complications, whose rates of TSH >4.12 mU/L were greater than in the 36 complication-free patients (22% vs 11%, P = 0.018).

Conclusion

During a median period of 31 months, there are relevant consequences for L-T4 treated adult hypothyroid patients resulting from hyperthyrotropinemia caused by medications impairing L-T4 absorption. This should be taken into account by future guidelines on hypothyroidism management.

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.

Ulcerative Colitis as a Novel Cause of Increased Need for Levothyroxine

Background: Thyroxine absorption takes place at the small intestine level and several disorders affecting this intestinal tract lead to thyroxine malabsorption. An increased need for thyroxine has also been observed in gastric disorders due to variations in drug dissolution and/or in its ionization status. Ulcerative colitis (UC) is an inflammatory bowel disease that has been postulated as a potential cause of the increased need for thyroxine, but there is a lack of evidence on this topic. This study is aimed at measuring the thyroxine requirement in hypothyroid patients with UC. Patients and Methods: Among 8,573 patients with thyroid disorders consecutively seen in our referral center from 2010 to 2017, we identified 34 patients with a definite diagnosis of UC. Thirteen of them were hypothyroid (12 F/1 M; median age = 53 years), bearing UC during the remission phase and in need for thyroxine treatment, thus representing the study group. The dose of T4 required by UC patients has been compared to the one observed in 51 similarly treated age- and weight-matched patients, compliant with treatment and clearly devoid of any gastrointestinal and /or pharmacological interference. Results: To reach the target serum TSH, the dose of thyroxine had to be increased in twelve out of thirteen (92%) hypothyroid patients with ulcerative colitis. The median thyroxine dose required by UC patients was 1.54 μg/kg weight/day, that is 26% higher than the control patients, to reach a similar TSH (1.23 μg/kg weight/day; p = 0.0002). Since half of our study group consisted of patients aged over 60 years old, we analyzed the effect of age on the subdivision in two classes. Six out of seven (86%) adult patients (<60 years) required more T4 than those in the respective control group (1.61 vs. 1.27 μg/kg weight/day; +27%; p < 0.0001). An increased dose (+17%; p = 0.0026) but to a lesser extent, was also observed in all patients over 60 years, as compared to the control group. Conclusions: In almost all hypothyroid patients with UC, the therapeutic dose of thyroxine is increased. Therefore, ulcerative colitis, even during clinical remission, should be included among the gastrointestinal causes of an increased need for oral thyroxine.

Interactions between hypothalamic pituitary thyroid axis and other pituitary dysfunctions

Central hypothyroidism is defined as low circulating free thyroxine (free T4) with inappropriately low circulating thyrotropin (TSH), in context of a hypothalamic pituitary pathology. Rare cases of idiopathic central hypothyroidism caused by a functional defect may occur, and the condition is often overlooked due to difficulty in achieving the correct diagnosis, sparse symptomatology of the condition and a high risk of misinterpretion of the biochemical changes in central hypothyroidism. Central hypothyroidism is mainly seen in patients with hypothalamic-pituitary pathology due to one of many possible aetiologies, where other hormone deficiencies often co-exist, and both the presence of other deficiencies and their replacement have a strong influence on the measurement of the thyroid-related hormones and thereby interpretation of the thyroid function variables in relation to the clinical impact of thyroid hormone substitution therapy. Conversely, lack of thyroid hormone has a similar strong influence on the interpretation of other pituitary hormone axes, as well as their replacement. Undertreating patients with central hypothyroidism may have serious metabolic consequences with a potentially increased risk of cardiovascular morbidity. The present review thus aims at describing central hypothyroidism, by an overview of interactions of hypothyroidism with other pituitary hormones, diagnosing/testing for central hypothyroidism, and focusing on consequences of undertreatment. Finally, it is mentioned how to deal with new diagnostic settings with lower a priori likelihood of hypopituitarism, particularly in view of the importance of stringent diagnostic testing in order to avoid overdiagnosing central hypothyroidism.

Shift from Levothyroxine Tablets to Liquid Formulation at Breakfast Improves Quality of Life of Hypothyroid Patients

Background: Until recently, treatment of hypothyroidism has been accomplished using monotherapy of synthetic L-thyroxine (L-T4) sodium tablets that should be taken 30-60 minutes before breakfast. Nowadays, a liquid preparation of levothyroxine is available and can effectively replace tablets without the need of waiting before having breakfast. Evidence of Quality of life (QoL) improvement when shifting from the former to the latter preparation, however, is still lacking.

Objective: The study aimed to assess changes in QoL of hypothyroid patients dissatisfied with their therapy with L-T4 sodium tablets who were switched from tablets taken 30-60 minutes before breakfast to liquid L-T4 at breakfast.

Methods: A total of 418 consecutive hypothyroid subjects treated by means of L-T4 tablets were asked about their satisfaction/dissatisfaction in order to take the medication 30-60 minutes before having breakfast. Overall, 110 patients (26.3%) complained of the timing of their L-T4 therapy (30-60 minutes before breakfast). A dedicated QoL questionnaire (ThyTSQ), taking just a few minutes to be filled in was then administered to these dissatisfied patients. They were therefore switched to L-T4 to be taken at breakfast. Aiming to avoid TSH elevation due to L-T4 tablets malabsorption caused by meal interference and gastric pH changes, patients were invited to take L-T4 liquid form, as this is claimed to be scarcely affected by the non-fasting state. The questionnaire (ThyTSQ) was administered again at the control visit 3 months later. TSH, FT4, FT3 serum concentrations and metabolic parameters were also recorded.

Results: An improved QoL, mainly due to an easier adherence to treatment, was reported by 66.6% of 102 patients who completed the study after shifting from taking medication 30-60 minutes before breakfast to at breakfast ingestion (P<0.01). An overall 10.7% of patients found the liquid formulation distasteful. Mean values of TSH, FT4, FT3, and of metabolic parameters did not significantly change but in eight patients (7.7%) who showed a TSH increase > 2mIU/L

Conclusion: In hypothyroid subjects dissatisfied with L-T4 tablets ingested 30-60 minutes before breakfast, the shift to the same dose of L-T4 in liquid form taken at breakfast improved QoL in the majority of patients, without affecting thyroid function.

Treatment with levothyroxin in subclinical hypothyroidism is associated with increased mortality in the elderly

INTRODUCTION

It is uncertain whether subclinical hypothyroidism should be treated with levothyroxine, particularly in the elderly. This study evaluated the association between levothyroxine treatment and mortality in individuals 65years or older with subclinical hypothyroidism and TSH values <10mIU/L.

METHODS

A case-control study in which patients 65years or older with TSH levels of 4.2-10mIU/L who died in the years 2012-2016 ('cases') were compared with matched individuals who did not die during this period ('controls'). Matching was based on gender, age, Charlson comorbidity index, date of TSH testing, duration of follow-up and TSH quartile. All cases of known thyroid disease or cases in which anti-thyroid medications or glucocorticoids were dispensed in the year preceding the TSH evaluation were excluded. Use of levothyroxine was compared between groups.

RESULTS

During the follow-up period, 419 individuals died and these were matched with 1558 individuals who did not. Factors found to be associated with mortality were age, senile dementia, congestive heart failure, chronic renal failure and a history of cerebrovascular disease. On multivariate analysis, treatment with levothyroxine was associated with significantly increased mortality (HR=1.19 CI 1.03-1.38). Femoral fractures and atrial fibrillation following initiation of levothyroxine therapy were not more prevalent in individuals who died during the follow-up period.

CONCLUSIONS

Treatment with levothyroxine is associated with significantly increased mortality in individuals 65years or older with subclinical hypothyroidism and TSH<10.

Circulating thyrotropin is upregulated by estradiol

After encountering two women with serum thyrotropin (TSH) levels greater in periovulatory phase than in other days of the menstrual cycle, we hypothesized that TSH levels could be sensitive to changes in circulating estrogens in women.

The objective of this study was to evaluate whether serum TSH increases after an induced acute increase of serum estradiol, and compare serum TSH increase with that of prolactin (PRL) which is a classic estradiol-upregulated pituitary hormone.

In this retrospective study, we resorted to stored frozen sera from 55 women who had undergone the GnRH agonist (buserelin)-acute stimulation test of ovarian steroidogenesis. This test, that is preceded by dexamethasone administration to suppress adrenal steroidogenesis, had been performed to show an increased buserelin-stimulated response of 17-hydroxyprogesterone, a response that is frequent in polycystic ovary syndrome. Fifty-five women had enough serum volume at pertinent times (first observation early in the follicular phase and all times of the test) to permit assay of serum estradiol, TSH and PRL.

Before dexamethasone administration, estradiol averaged 26.4 ± 15.5 pg/ml (reference range 23–139, follicular phase), TSH 1.78 ± 0.86 mU/L (reference range 0.3–4.2) and PRL 409.4 ± 356 mU/L (reference range 70.8–556) (mean ± SD).

Serum estradiol, TSH and PRL averaged 47.2 ± 27 pg/ml, 0.77 ± 0.48 mU/L and 246.4 ± 206.8 mU/L just prior to the buserelin injection, but they peaked at 253.4 ± 113.5 pg/ml (nv 83–495, midcycle), 3.30 ± 1.65 mU/L and 540.3 ± 695.2 mU/L after injection. The responses to buserelin of estradiol, TSH and PRL were of wide magnitude. There was a significant correlation between TSH peak and serum estradiol peak, betweeen AUC0-24 h-TSH and AUC0-24 h-estradiol, or between PRL peak and estradiol peak and AUC0-24 h -PRL and AUC0-24 h-estradiol in only a subgroup of women.

Therefore, women with estradiol-dependent increase in serum TSH do exist. Reference bands of serum TSH dependent on the phases of the menstrual cycle should be available.

Increased Requirement of Replacement Doses of Levothyroxine Caused by Liver Cirrhosis

BACKGROUND

Since hypothyroidism is a fairly common dysfunction, levothyroxine (L-T4) is one of the most prescribed medications. Approximately 70% of the administered L-T4 dose is absorbed. The absorption process takes place in the small intestine. Some disorders of the digestive system and some medicines, supplements, and drinks cause L-T4 malabsorption, resulting in failure of serum TSH to be normal. Only rarely liver cirrhosis is mentioned as causing L-T4 malabsorption.

CASE REPORT

In this study, we report increased requirement of daily doses of l-thyroxine in two patients with the atrophic variant of Hashimoto's thyroiditis and liver cirrhosis. In one patient, this increased requirement could have been contributed by the increased serum levels of the estrogen-dependent thyroxine-binding globulin (TBG), which is the major plasma carrier of thyroid hormones. In the other patient, we switched from tablet L-T4 to liquid L-T4 at the same daily dose. Normalization of TSH levels was achieved, but TSH increased again when she returned to tablet L-T4.

CONCLUSION

Liver cirrhosis can cause increased L-T4 requirements. In addition to impaired bile secretion, the mechanism could be increased serum TBG. A similar increased requirement of L-T4 is observed in other situations characterized by elevation of serum TBG. Because of better intestinal absorption, L-T4 oral liquid formulation is able to circumvent the increased need of L-T4 in these patients.

Adherence to Levothyroxine Treatment Among Patients With Hypothyroidism: A Northeastern Italian Survey

Background: A significant number of patients show sub-optimal adherence to levothyroxine (LT4) therapy, mainly because they have to postpone their breakfast by at least 30 min. The aim of this observational cross-sectional study was to assess the therapeutic compliance of patients on LT4 treatment and to verify the preference of a lifetime treatment in tablet or liquid form. Patients and Methods: Ambulatory care patients aged 18 years or older, affected by hypothyroidism and on LT4 treatment (in tablet or liquid form) were administered the eight-item Morisky Medication Adherence Scale (MMAS-8). The MMAS-8 questionnaire was supplemented with 3 further items to specifically evaluate preference between tablet and liquid forms of LT4 for lifetime treatment. Results: A total of 320 patients (272 female), median age 47.9 ± 15.6 years (range, 20-78 years), completed the MMAS-8 questionnaire. Eighty-seven percent of the participants were adhering to their treatment for both tablet and liquid LT4 formulations, although significant differences emerged. Patients on LT4 tablets forgot to take their medication more frequently (p < 0.001), felt hassled about sticking to their treatment plan (p < 0.001), and had difficulty remembering to take all their medication(s) (p < 0.001) than those on liquid LT4 treatment. Conclusions: Adherence to LT4 treatment was high for both tablet and liquid formulations. Taking LT4 at breakfast was the most convenient option for most patients.

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.

Non-Autoimmune Subclinical and Overt Hypothyroidism in Idiopathic Steroid-resistant Nephrotic Syndrome in Children

OBJECTIVE

To evaluate the frequency of non-autoimmune subclinical and overt hypothyroidism in children with idiopathic steroid-resistant nephrotic syndrome (SRNS).

METHODS

This cross-sectional study recruited 30 children (age 1-18 y) with idiopathic SRNS; and 30 healthy controls. Serum T3, T4 and TSH were performed in cases as well as controls. Anti-thyroid peroxidase and anti-thyroglobulin antibody tests were performed in all cases.

RESULTS

Non-autoimmune subclinical or overt hypothyroidism was detected in 10 out of 30 children with idiopathic SRNS; 2 had overt hypothyroidism, while 8 patients had subclinical hypothyroidism. Children with SRNS had a mean (SD) TSH value 4.55 (4.64) mIU/L that was higher as compared to controls (1.88 (1.04) mIU/L) (P<0.01). Focal segmental glomerulosclerosis (FSGS) was the commonest histopathological condition, seen in 13 (43.3%). Children with overt hypothyroidism (2 cases) and grade III subclinical hypothyroidism (1 case) were subsequently started on levothyroxine therapy.

CONCLUSION

The prevalence of subclinical and overt hypothyroidism seems to be high in idiopathic SRNS, with almost one-third of children having overt or subclinical non-autoimmune hypothyroidism.

Treatment pattern and frequency of serum TSH measurement in users of different levothyroxine formulations: a population-based study during the years 2009-2015

BACKGROUND

Several conditions can modify the intestinal absorption of levothyroxine tablets, with potential consequences on their therapeutic effect. Pre-dosed ampoules and oral drops have been recently made available to overcome this limitation.

AIMS

To describe the pattern of use of different formulations of levothyroxine in a general population of Southern Italy and to perform an exploratory analysis investigating the effect of switching from levothyroxine tablets to oral liquid formulations.

METHODS

Data were extracted from the Caserta Local Health Unit database. All patients receiving at least one levothyroxine prescription during the years 2009-2015 were identified. 1-year incidence of use of formulation-specific levothyroxine was calculated. Switchers between levothyroxine tablets and oral liquid formulations were identified and the frequency of thyroid-stimulating hormone measurement within 2 years prior and after the switch date was explored.

RESULTS

Overall, 56,354 levothyroxine users were included in the study. Of these, 55,147 patients received at least one prescription for tablets (97.9%), 1867 pre-dosed ampoules (3.3%) and 1550 oral drops (2.8%). The proportion of levothyroxine users receiving oral liquid formulations slightly increased over time. Patients switching from tablets to oral liquid formulations showed a statistically significant reduction in the number of thyroid-stimulating hormone measurements after switching from tablets, especially in presence of drugs interacting with levothyroxine potentially altering its absorption.

CONCLUSIONS

Use of levothyroxine oral liquid formulations is increasing over time even though their use is still limited in a general population of Southern Italy. Our exploratory analysis showed that the frequency of thyroid-stimulating hormone measurement was reduced in patients switching from levothyroxine tablet to new formulations.

Serum Thyrotropin and Phase of the Menstrual Cycle

About one-fifth of patients treated with levothyroxine have serum thyrotropin (TSH) above target concentrations but, in approximately 15% of them, the cause of this TSH insufficient normalization remains unknown. We report the cases of two regularly menstruating women with known thyroid disease who had TSH levels consistently >3 mU/L (and sometimes above target levels) during mid-cycle, but consistently lower serum levels during the follicular and luteal phases of menstrual cycle. A major TSH release by the thyrotrophs in response to high circulating levels of estradiol (E2) at mid-cycle may increase levels of TSH compared to other phases of the cycle. The increased TSH can be misinterpreted as refractory hypothyroidism if the woman is under L-T4 replacement therapy or as subclinical hypothyroidism if the woman is not. Our findings might have important implications for diagnosis and management of thyroid disease, suggesting to request serum TSH measurements outside of the periovulatory days.

Serum Thyroid Hormone Antibodies Are Frequent in Patients with Polyglandular Autoimmune Syndrome Type 3, Particularly in Those Who Require Thyroxine Treatment

Polyglandular autoimmune syndrome (PAS) type 3 consists of autoimmune thyroid disease (AITD) coexisting with ≥1 non-thyroidal autoimmune disease (NTAID) other than Addison's disease and hypoparathyroidism. We evaluated the prevalence and repertoire of thyroid hormones antibodies (THAb) in PAS-3 patients. Using a radioimmunoprecipation technique, we measured THAb (T3IgM, T3IgG, T4IgM, and T4IgG) in 107 PAS-3 patients and 88 controls (patients with AITD without any NTAID). Based on the selective coexistence of AITD with one NTAID (chronic autoimmune gastritis, non-segmental vitiligo or celiac disease), patients were divided into group 1 (chronic autoimmune gastritis positive, n = 64), group 2 (non-segmental vitiligo positive, n = 24), and group 3 (celiac disease positive, n = 15). At least one of the four THAb was detected in 45 PAS-3 patients (42.1%) and 28 controls (31.8%, P = 0.14), with similar rates in the three PAS-3 groups. The rates of T3Ab, T4Ab, and T3 + T4Ab were similar in groups 1 and 2, while in group 3, T3Ab was undetected (P = 0.02). In PAS-3 patients, the rate of levothyroxine treatment was greater in THAb-positive patients compared to THAb-negative patients (76.7 vs. 56.1%, P = 0.03, RR = 1.4, 95% CI 1.03-1.81). Not unexpectedly, levothyroxine daily dose was significantly higher in group 1 and group 3, namely in patients with gastrointestinal disorders, compared to group 2 (1.9 ± 0.4 and 1.8 ± 0.3 vs. 1.5 ± 0.2 μg/kg body weight, P = 0.0005 and P = 0.004). Almost half of PAS-3 patients have THAb, whose repertoire is similar if chronic autoimmune gastritis or celiac disease is present. A prospective study would confirm whether THAb positivity predicts greater likelihood of requiring levothyroxine treatment.

Undertreated hypothyroidism due to calcium or iron supplementation corrected by oral liquid levothyroxine

PURPOSE

The aim of this study was to assess whether oral liquid levothyroxine would correct tablet levothyroxine malabsorption induced by calcium or iron, two sequestrants of levothyroxine.

METHODS

Nineteen adult hypothyroid patients with tablet levothyroxine malabsorption caused by calcium and/or iron supplements were switched from tablet to liquid levothyroxine at the same dose. Primary outcomes were: (1) significantly lower mean serum thyroid-stimulating hormone with the liquid compared with the tablet formulation, and (2) significantly greater rate of serum thyroid-stimulating hormone less than or equal to 4.12 or 2.5 mU/L.The mean follow-up was 25.2 ± 16.5 weeks.

RESULTS

TSH was lower with liquid levothyroxine compared with tablet levothyroxine (7.48 ± 5.8 vs. 1.95 ± 1.3 mU/L, P < 0.001), both in the calcium group (8.74 ± 7.2 vs. 2.15 ± 1.4, P < 0.001) and iron group (8.74 ± 7.2 vs. 1.68 ± 0.9, P < 0.001). Thyroid-stimulating hormone levels ≤4.12 mU/L in all patients, calcium group and iron group were more frequent post-switch (95, 87 and 100%) compared to pre-switch (26, 22 and 29%, P < 0.001), and so were thyroid-stimulating hormone levels ≤2.50 mU/L (66, 59 and 76% compared to 5, 9 and 0%, P < 0.001). The pattern held comparing the first liquid levothyroxine thyroid-stimulating hormone levels and the first tablet levothyroxine thyroid-stimulating hormone levels or the corresponding rates of thyroid-stimulating hormone levels below the target.

CONCLUSIONS

Liquid levothyroxine is resistant to the sequestration by calcium or iron. The high rate of thyroid-stimulating hormone normalization already at the first check (6-8 weeks) should avoid frequent adjustments in levothyroxine doses and assays of thyroid-stimulating hormone, with consequent financial savings.

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.

New levothyroxine formulation meeting 95-105% specification over the whole shelf-life: results from two pharmacokinetic trials

OBJECTIVE

Small levothyroxine (L-T4) dose changes can lead to significant clinical effects. To ensure thyroid hormone levels are safely maintained, authorities are increasingly adopting stricter potency specifications for L-T4, the most stringent of these being 95-105% of the labeled dose over the whole shelf-life. Levothyroxine sodium (Euthyrox, Eutirox, Lévothyrox ) has been reformulated, and two studies performed, to ensure bioequivalence to the currently marketed formulation and dosage form proportionality of the new formulation.

METHODS

The bioequivalence study was an open-label, randomized, single-dose, two-period, two-sequence crossover comparing the highest dosage strengths of the currently marketed and the new L-T4 formulation at a total dose of 600 μg. The dosage form proportionality study was an open-label, randomized, three-period, six-sequence crossover, comparing 50 μg, 100 μg, and 200 μg L-T4 tablets, at a total dose of 600 μg. Blood samples were taken at predefined time intervals. Primary outcomes were area under the curve (AUC) and maximum concentration (C_max) of thyroxine (T4) in plasma.

RESULTS

In the bioequivalence study, comparing the T4 profiles for the new and current formulation of L-T4, the geometric least square mean ratio of the baseline-adjusted AUC_0-72,adj was 99.3% (90% confidence interval [CI]: 95.6-103.2) and the C_max,adj was 101.7% (90% CI: 98.8-104.6). Bioequivalence was established if the 90% CI lay within the predefined 0.9-1.11 limits. In the dosage form proportionality study, pairwise comparisons ranged from 99.3% to 104.8%, and all 95% CIs were within the predefined CI range (0.8-1.25): the three dose strengths were dosage form proportional.

CONCLUSIONS

The new formulation of L-T4 meets the most stringent potency specification guidelines, and has been demonstrated to be bioequivalent to the current formulation and to show dosage form proportionality. The new formulation will enable patients to receive a dose fine tuned to their medical needs, contributing to improved safety in the use of L-T4.

Factors Affecting Gastrointestinal Absorption of Levothyroxine: A Review

PURPOSE

Levothyroxine (LT4) is a drug with a narrow therapeutic index, applied in small amounts (micrograms), which makes interactions in the absorption phase clinically significant. The main aim of this article was to review and present the latest information on factors that affect the gastrointestinal absorption of this drug.

METHODS

Relevant data were collected by using the MEDLINE, PubMed, EMBASE, Web of Science, Science Direct, and Scopus databases with the key words levothyroxine and absorption. Searches were not limited to specific publication types, study designs, dates, or languages. The reports were highly variable in the amount of information provided regarding study design and methods. Because of the heterogeneity of studies, no statistical analysis was performed.

FINDINGS

Many gastrointestinal disorders, such as celiac disease, atrophic gastritis, lactose intolerance, and Helicobacter pylori infection, may impede the absorption of levothyroxine. During treatment of these disorders, it is necessary to monitor serum thyroid-stimulating hormone and free T4 values to reduce the risk of developing iatrogenic hyperthyroidism. Soybeans and coffee have the greatest impact on the reduction of absorption, whereas vitamin C has the ability to increase it. Conversely, the effect of dietary fiber on the absorption of LT4 is not yet fully understood; further research is needed on this topic. A decrease in the absorption of LT4 is established and clinically significant when administered concomitantly with cholestyramine, colesevelam, lanthanum, calcium carbonate, calcium citrate, calcium acetate, iron sulfate, ciprofloxacin, aluminum hydroxide, sevelamer, or proton pump inhibitors. This effect should be taken into consideration when prescribing these drugs concomitantly with LT4. The effects of Giardia lamblia infection and the influence of orlistat, polystyrene sulfonate, raloxifene, and simethicone on absorption of LT4 have been poorly documented. For bariatric surgery, sucralfate and H₂-antagonist interactions are not well founded or contradictory evidence is available regarding their existence; additional research should be conducted.

IMPLICATIONS

The majority of the interactions are clinically significant. They are based on the LT4 adsorption on interfering substances in the digestive tract, as well as a consequently reduced amount of the drug available for absorption. These interactions can be avoided by separating the administration of LT4 and the interfering substance.

Out-of-Reference Range Thyroid-Stimulating Hormone Levels in Levothyroxine-Treated Primary Hypothyroid Patients: A Multicenter Observational Study

OBJECTIVE

Although levothyroxine (LT4) replacement therapy for hypothyroidism has been established as safe, inexpensive and effective, many studies from different countries reported out-of-reference range thyroid-stimulating hormone (TSH) values for the hypothyroid patients under LT4 treatment. The aim of this study was to determine TSH levels of primary hypothyroid patients under LT4 treatment and to assess self-reported compliance with daily LT4 intake in tertiary care centers in Turkey.

DESIGN

In this cross-sectional, observational study, adult patients with primary hypothyroidism, receiving LT4 treatment for at least 6 months, were included. The patients were from 12 tertiary care centers in 9 cities of Turkey. TSH and free T4 levels were recorded from patient files and self-reported compliance with daily LT4 intake was assessed by interviewing the subjects at the last visit.

RESULTS

A total of 1,755 subjects (46 ± 13 years; F/M: 89.9/10.1%) with primary hypothyroidism were enrolled. Of the hypothyroid subjects, 44.8% had out-of-reference range serum TSH levels. TSH values were over the reference range (TSH > 4 mIU/L) in 26.2% and were under the reference range (TSH < 0.5 mIU/L) in 18.6% of the patients. Total duration of LT4 treatment was 5.9 ± 4.7 years and mean dose was 1.2 ± 0.6 μg/kg/day. Non-compliant patients (31.1%) had higher TSH levels (6.9 ± 16 vs 3.8 ± 0.9 mIU/L, P = 0.01) compared to compliant patients.

CONCLUSION

The results of this study revealed that nearly half of the hypothyroid patients had out-of-reference range serum TSH values, despite under LT4 treatment. Compliance with LT4 treatment seems to be one of the major determinants to reach the target TSH levels in hypothyroid patients.

l-Thyroxine in an Oral Liquid or Softgel Formulation Ensures More Normal Serum Levels of Free T4 in Patients with Central Hypothyroidism

CONTEXT

l-Thyroxine (l-T4) therapy of central hypothyroidism (CH) is guided by measurements of serum free thyroxine (FT4), which should be above the midnormal range value (MNRV). In some countries, novel formulations of oral l-T4 (liquid or softgel) are available further to the classic tablets. The intestinal absorption of either novel formulation is greater than tablets in patients with primary hypothyroidism.

OBJECTIVE

To evaluate whether new oral formulations of l-T4 could be considered optimal in patients with CH who do not reach the FT4 target using tablet l-T4.

DESIGN

Our observation of six patients with isolated CH and serum FT4 below MNRV under stable adequate doses of tablet l-T4 (median 1.51 μg/kg bw/day), prompted us to switch them to liquid (n = 4) or softgel (n = 3) l-T4 at the same dose, and verify whether FT4 increased above MNRV. A seventh patient with FT4 above MNRV was enrolled because she wanted a "more modern formulation." Postswitch FT4 was measured at least twice with the same kit as preswitch FT4.

RESULTS

In the first six patients, postswitch FT4 averaged 13.0 ± 1.6 pg/ml compared to 10.4 ± 1.8 preswitch FT4 (P = 0.00026), with 11/13 (85%) measurements above MNRV compared to 0/20. In the liquid or softgel l-T4 group, postswitch FT4 averaged 13.1 ± 1.6 vs. 10.6 ± 0.9 pg/ml preswitch (P = 0.0004) or 12.9 ± 2.1 vs. 10.3 ± 2.4 (P = 0.048), respectively. In the seventh patient (switched to liquid l-T4), averages were 18.3 vs. 15.2 pg/ml, and proportions 4/4 vs. 2/2.

CONCLUSION

In CH patients, oral liquid or softgel l-T4 administered at the same doses as tablet l-T4 ensures target serum FT4 levels above MNRV that tablet l-T4 may miss. In turn, this performance suggests the more favorable pharmacokinetics profile of either novel formulation compared with the tablet formulation.

Refractory Hypothyroidism Due to Improper Storage of Levothyroxine Tablets

CONTEXT

A not negligible part of hypothyroid patients on levothyroxine therapy do not normalize serum thyrotropin (TSH) concentrations. "Refractory hypothyroidism," i.e., a condition characterized by persistently abnormal serum TSH levels despite adequate titration of l-T4 substitution therapy, requires biochemical and instrumental investigation, but no definite etiology is found in up to 15% of cases.

OBJECTIVE

To report patients presenting with refractory hypothyroidism with proven improper storage of levothyroxine tablets.

DESIGN

Patients on l-T4 substitution therapy referred to three Italian outpatient Clinics of Endocrinology between January 2013 and December 2015 for refractory hypothyroidism were investigated for levothyroxine tablet exposure to humidity, light, and high temperature.

RESULTS

We report eight patients, accounting for approximately 1% of all hypothyroid patients and 5% of those with refractory hypothyroidism in our series. Careful anamnesis disclosed that these patients stored levothyroxine tablets inappropriately. Normalization of serum TSH concentrations was obtained in all cases by simply recommending to store the new levothyroxine tablets away from heat, light, and humidity.

CONCLUSION

Refractory hypothyroidism linked to improper storage of l-T4 tablets does exist and might be an underrecognized entity. In addition to proper modalities of ingestion of l-T4 tablets, patients need to be instructed on proper modalities of storage, as well.

Severe Hypothyroidism due to the Loss of Therapeutic Efficacy of l-Thyroxine in a Patient with Esophageal Complication Associated with Systemic Sclerosis

BACKGROUND

Thyroid function abnormalities and thyroid autoantibodies have been frequently described in patients with systemic autoimmune diseases as systemic sclerosis (SSc). Serum TSH levels are higher in SSc patients with more severe skin diseases and a worse modified Rodnan skin score. Asymptomatic esophageal involvement due to SSc has never been described as a cause of severe hypothyroidism due to l-thyroxine (l-T4) malabsorption in patients with Hashimoto's thyroiditis (HT) and SSc.

CASE REPORT

Here, we report a case of a 56-year-old female affected by both SSc and HT who developed severe hypothyroidism due to the loss of therapeutic efficacy of l-T4. Therapeutic failure resulted from the altered l-T4 absorption because of SSc esophageal complications. Clinical findings improved after the administration of oral liquid l-T4. Thyroid function completely normalized with a full clinical recovery, the disappearance of the pericardial effusion and the improvement of the pulmonary pressure.

CONCLUSION

A recognition of a poor absorption is crucial in patients with hypothyroidism and SSc to reduce the risk of the subsequent adverse events. This case suggests the importance of clinical and laboratory surveillance in patients with SSc and HT because the systemic complications of these dysfunctions may worsen the prognosis of hypothyroid SSc/HT patients.

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

Background

The CONTROL Surveillance Project was a comprehensive patient-based survey conducted among hypothyroid patients undergoing treatment. The primary objective of the study was to specifically quantify the prevalence of factors adversely affecting levothyroxine therapy.

Methods

Participants were selected from a large proprietary database. Those eligible for the study completed a 21-question survey.

Results

Of the eligible hypothyroid patients, 925 (92.5 %) were being treated with levothyroxine monotherapy. The mean age was 60.4 years; 755 (81.6 %) were female and 168 (18.2 %) were male. Almost half of those receiving levothyroxine (435, 47.0 %) had at least one comorbid condition that could adversely affect its absorption: gastroesophageal reflux disease (33.8 % of patients), irritable bowel syndrome (9.7 %), lactose intolerance (7.8 %), or a history of gastric bypass surgery or bowel resection (3.0 %). Other factors reported by many patients that could adversely affect levothyroxine absorption included use of prescription medications (20.6 %) and over-the-counter medications (34.3 %) used to treat comorbid gastrointestinal (GI) conditions; use of dietary supplements (51.8 %, primarily calcium and iron); and intake of foods/beverages high in fiber, iodine, or soy (68.0 %). Of the 13.4 % who reported difficulty controlling their hypothyroid symptoms, significantly more patients with comorbid GI conditions reported such difficulty (7.8 versus 5.6 %, P < 0.01). Frequent changes in levothyroxine dosing (two or more dose changes in the past year) were reported by 8.0 % of survey participants. Those with GI comorbidities were nearly twice as likely to have such changes (5.0 versus 3.0 %, P < 0.01).

Conclusion

Better initial workup of patients, including identification of relevant GI comorbidities and allergies, may help in the early detection of factors that may affect the performance of levothyroxine.

Liquid and softgel levothyroxine use in clinical practice: state of the art

Levothyroxine is recognized as the treatment of choice for hypothyroidism. So far, the tablet levothyroxine has been the formulation almost exclusively used, even though an optimal daily dose of levothyroxine has been unsuccessfully sought and a consensus not achieved. Due to progressive use of a more individually tailored levothyroxine dose, increasing evidence has instead displayed that many gastrointestinal disorders, polypharmacy, and food interference may raise the daily levothyroxine requirement. In recent years, alternative levothyroxine formulations have become available and have rapidly gained attention because of their pharmacokinetic properties. This study aims to provide an overview regarding the use of softgel capsule and/or liquid levothyroxine solution while performing a review of published studies about such topic. A comprehensive computer literature search of the PubMed/MEDLINE, Scopus, and Google Scholar databases has been conducted to find published articles on this topic. The search algorithm was based on the combinations of the following terms: "oral solution" or "soft gel" or "liquid", and "levothyroxine". The computer search resulted in 75 articles; through a critical review of such titles and abstracts and a screening of their references lists, the review included 18 original articles relating to 800 patients treated with alternative formulations. Despite some limits, the results obtained using softgel and liquid levothyroxine were consistent with each other. In selected categories of levothyroxine-treated patients (pediatric, suffering from hypo-achlorhydria, polypharmacy, undergone bariatric surgery, fed through enteric tube) these new formulations have shown promising attributes in improving a treatment that needs to be individually tailored.

Oral L-thyroxine liquid versus tablet in patients with hypothyroidism without malabsorption: a prospective study

No consistent data are present in literature about the effectiveness of levothyroxine (L-T4) liquid formulation in patients without malabsorption. The aim of this study is to compare the effectiveness of L-T4 liquid formulation, with L-T4 tablets, in hypothyroid patients without malabsorption or drug interference. One hundred and fifty two patients were recruited. Patients were switched from the L-T4 therapy in tablets, to liquid L-T4 at the same dosage, 30 min before breakfast. Serum thyrotropic hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were re-evaluated after 1-3 months (first control) and 5-7 months (second control) from the switch. TSH values significantly declined with respect to the basal value after the switch to liquid L-T4 both at the first control (P < 0.05) and at the second control (P < 0.01); FT4 and FT3 levels were not significantly changed. We show that liquid L-T4 is more effective than L-T4 tablet in controlling TSH levels in hypothyroid patients without malabsorption, gastric disorders, or drug interference.

Do Not Forget Nephrotic Syndrome as a Cause of Increased Requirement of Levothyroxine Replacement Therapy

Nephrotic syndrome increases L-thyroxine requirements because of urinary loss of free and protein-bound thyroid hormones. We report 2 hypothyroid patients referred to us because of high serum TSH, even though the L-thyroxine daily dose was maintained at appropriate levels or was increased. The cause of nephrotic syndrome was multiple myeloma in one patient and diabetic glomerulosclerosis in the other patient. As part of the periodic controls for diabetes, urinalysis was requested only in the second patient so that proteinuria could be detected. However, as in the first patient, facial puffiness and body weight increase were initially attributed to hypothyroidism, which was poorly compensated by L-thyroxine therapy. In the first patient, the pitting nature of the pedal edema was missed at the initial examination. An endocrinologist consulted over the phone by the practitioner hypothesized some causes of intestinal malabsorption of L-thyroxine. This diagnosis would have been accepted had the patient continued taking a known sequestrant of L-thyroxine, i.e. calcium carbonate. The diagnostic workup of patients with increasing requirements of L-thyroxine replacement therapy should not be concentrated on the digestive system alone. Careful history taking and physical examination need to be thorough. Endocrinologists should not forget nephrotic syndrome that, in turn, can be secondary to serious diseases.

An examination of myth: a favorable cardiovascular risk-benefit analysis of high-dose thyroid for affective disorders

INTRODUCTION

High dose thyroid (HDT) is included in major treatment guidelines for the treatment of bipolar disorders. Yet it is seldom used partly based on perceived cardiovascular risks. The cardiovascular risks of HDT are examined.

METHODS

A literature search was conducted for the cardiovascular risks of HDT and for comparisons sake psychiatric medications. Case reports of atrial fibrillation (afib) associated with HDT are reported.

RESULTS

While hyperthyroidism is a significant cardiovascular risk factor causing a 20% premature death rate, HDT treatment does not appear to be of significant cardiovascular risk. HDT differs from hyperthyroidism in significant ways. The sequela of hyperthyroidism are increasingly tied to autoimmune complications which are absent with HDT. Equating hyperthyroidism with HDT is incorrect. The five case reports of HDT treatment associated with afib were potentially caused by other factors. If HDT increases the risks of afib, monitoring for afib would minimizes the risk. Even in overt hyperthyroidism the risk of other arrhythmias are minimal. When compared to many psychiatric medications HDT is as safe or safer.

LIMITATIONS

There are no direct studies of cardiovascular risks of HDT for affective patients. High tolerance of a medication does not necessarily imply lack of risk. The five case reports were spontaneous, other cases may not have been reported.

CONCLUSION

The cardiovascular risks of HDT appear to be low. HDT is at least as safe as or safer than many psychiatric medications. It is effective and well tolerated.