Occurrence of overt celiac disease in the elderly following total thyroidectomy

TSH-Suppressive Therapy: A Thorny Issue

Thyroid stimulating hormone (TSH)-suppressive therapy with levothyroxine is a cornerstone of thyroid carcinoma follow-up therapy, but the achievement of therapeutic goals must be balanced against L-T4 side effects. We describe the case of a 64-year-old cardiopathic patient with papillary thyroid carcinoma and autoimmune thyroiditis, whose cardiac condition worsened during TSH-suppressive therapy. TSH concentrations also fluctuated widely because of changing intestinal absorption due to coeliac disease.

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.

Advancements in the treatment of hypothyroidism with L-T4 liquid formulation or soft gel capsule: an update

INTRODUCTION

The most recent advance concerning levothyroxine (L-T4) therapy is the development of novel oral formulations: the liquid preparation, and the soft gel capsule. Areas covered: This review evaluates the most recent clinical studies about these new formulations. The liquid formulation has been shown to overcome: the food and beverages intereference with L-T4 tablets absorption, caused by food or coffee at breakfast; malabsorption induced by the increased gastric pH, resulting from atrophic gastritis, or due to proton-pump inhibitors; and malabsorption after bariatric surgery. The use of liquid L-T4 has been studied also in pregnancy, newborns and infants, suggesting a better bioequivalence than tablets. Finally, liquid L-T4 is more active than tablets in the control of thyroid-stimulating hormone (TSH) in hypothyroid patients without malabsorption, drug interference, or gastric disorders, leading to a hypothesized higher absorption of liquid L-T4 also in these patients. Few studies have evaluated soft gel L-T4 with promising results in patients with malabsorption related to coffee or gastritis. Expert opinion: Liquid L-T4 (and soft gel capsules) are more active than the tablet L-T4 in the control of TSH in hypothyroid patients with gastric disorders, malabsorption, or drug interference, but also in patients without absorption disorders.

Celiac disease detection in hypothyroid patients requiring elevated thyroid supplementation: A prospective cohort study

BACKGROUND

Celiac disease (CD) is associated with hypothyroidism, but the disease prevalence is not thought to be great enough to warrant testing all hypothyroid patients. We hypothesized that hypothyroid patients with concomitant CD would require elevated doses of levothyroxine, and there is a threshold daily dose, above which, hypothyroid patients should be tested for CD.

METHODS

Hypothyroid patients presenting to the endoscopy or endocrinology clinics at the University of Vermont Medical Center were included. Patients were categorized by whether or not they required ≥125mcg/day of levothyroxine. A serum tissue transglutaminase (tTG) was performed on enrolled patients. Patients with an elevated serum tTG underwent endoscopy with duodenal biopsies. Symptoms were assessed by the Gastrointestinal Symptom Rating Scale.

RESULTS

Overall, 500 patients were enrolled and 29% (144 patients) required ≥125mcg/day of levothyroxine. CD was detected in 9 patients. The prevalence of CD ranged from 1.8% in our entire cohort to 12.5% in patients requiring ≥200mcg/day of levothyroxine. Eight patients with CD (89%) required ≥125mcg/day of levothyroxine. Patients who required ≥125mcg/day of levothyroxine had a significantly increased risk of CD (p<0.001). CD was detected in 5.6% of patients requiring ≥125mcg/day of levothyroxine.

CONCLUSIONS

Hypothyroid patients requiring elevated daily doses of levothyroxine are more likely to have CD. Hypothyroid patients requiring ≥125mcg/day of levothyroxine should undergo serologic testing for CD.

Surgical Aspects of Celiac Disease

Celiac disease, characterized by intestinal inflammation and malabsorption, occurs in 1 per cent of the population and is often undiagnosed. These patients are at increased risk for surgical procedures resulting from symptoms, associated intestinal disorders, and malignancy. Our aim was to determine the incidence and outcome of abdominal operations in patients with celiac disease. Records of 512 adult patients with celiac disease evaluated over a 22-year period were reviewed. Operations were classified as related or unrelated to celiac disease. One hundred eighty-eight (36%) of 512 patients underwent abdominal operations. One hundred twenty-seven (68%) of the 188 patients had unrelated procedures. Sixty-one (32%) had operations considered related to celiac disease. Twenty-six (43%) of 61 with related procedures were diagnosed preoperatively. Procedures were performed for pain, obstruction, motility disorders, and malignancy. Six patients had recurrent pancreatitis. Seven patients underwent liver transplantation. Thirty-five (57%) related procedures led to the diagnosis of celiac disease including “unmasking” (n = 25) and diagnostic findings (n = 10). One-third of patients with celiac disease undergo abdominal operations of which one-third are related to celiac disease. Operations are related to complications of celiac disease and often lead to the initial diagnosis.

Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement

BACKGROUND

A number of recent advances in our understanding of thyroid physiology may shed light on why some patients feel unwell while taking levothyroxine monotherapy. The purpose of this task force was to review the goals of levothyroxine therapy, the optimal prescription of conventional levothyroxine therapy, the sources of dissatisfaction with levothyroxine therapy, the evidence on treatment alternatives, and the relevant knowledge gaps. We wished to determine whether there are sufficient new data generated by well-designed studies to provide reason to pursue such therapies and change the current standard of care. This document is intended to inform clinical decision-making on thyroid hormone replacement therapy; it is not a replacement for individualized clinical judgment.

METHODS

Task force members identified 24 questions relevant to the treatment of hypothyroidism. The clinical literature relating to each question was then reviewed. Clinical reviews were supplemented, when relevant, with related mechanistic and bench research literature reviews, performed by our team of translational scientists. Ethics reviews were provided, when relevant, by a bioethicist. The responses to questions were formatted, when possible, in the form of a formal clinical recommendation statement. When responses were not suitable for a formal clinical recommendation, a summary response statement without a formal clinical recommendation was developed. For clinical recommendations, the supporting evidence was appraised, and the strength of each clinical recommendation was assessed, using the American College of Physicians system. The final document was organized so that each topic is introduced with a question, followed by a formal clinical recommendation. Stakeholder input was received at a national meeting, with some subsequent refinement of the clinical questions addressed in the document. Consensus was achieved for all recommendations by the task force.

RESULTS

We reviewed the following therapeutic categories: (i) levothyroxine therapy, (ii) non-levothyroxine-based thyroid hormone therapies, and (iii) use of thyroid hormone analogs. The second category included thyroid extracts, synthetic combination therapy, triiodothyronine therapy, and compounded thyroid hormones.

CONCLUSIONS

We concluded that levothyroxine should remain the standard of care for treating hypothyroidism. We found no consistently strong evidence for the superiority of alternative preparations (e.g., levothyroxine-liothyronine combination therapy, or thyroid extract therapy, or others) over monotherapy with levothyroxine, in improving health outcomes. Some examples of future research needs include the development of superior biomarkers of euthyroidism to supplement thyrotropin measurements, mechanistic research on serum triiodothyronine levels (including effects of age and disease status, relationship with tissue concentrations, as well as potential therapeutic targeting), and long-term outcome clinical trials testing combination therapy or thyroid extracts (including subgroup effects). Additional research is also needed to develop thyroid hormone analogs with a favorable benefit to risk profile.

Celiac disease and hypothyroidism

BACKGROUND

Celiac disease is more common in patients with hypothyroidism. Malabsorption of levothyroxine has not been studied in this population. We sought to determine if levothyroxine dosing was influenced by the presence and treatment of celiac disease.

METHODS

This retrospective study was conducted at an academic medical center. Cases had hypothyroidism and celiac disease. Controls had hypothyroidism alone and were selected randomly through the endocrinology clinic records. Celiac disease was defined as representative pathology with positive serology. Age, sex, height, weight, body mass index, creatinine, and medical comorbidity were assessed for cases and controls. The levothyroxine dose and weight-based levothyroxine dose necessary to maintain a euthyroid state was evaluated for controls, and before and after celiac disease therapy for cases.

RESULTS

Celiac disease was identified in 152 patients, and 22 patients had concomitant hypothyroidism (14.5%). Seven cases met inclusion criteria. Overall, 200 control patients were identified. The mean celiac disease pretreatment levothyroxine dose and weight-based levothyroxine dose needed to maintain a euthyroid state were higher in cases than in controls (154 μg vs 106 μg, P=.007, and 2.6 μg/kg vs 1.3 μg/kg, P <.001). Doses decreased significantly after treatment of celiac disease (154 μg vs 111 μg, P=.03; and 2.64 μg/kg vs 1.89 μg/kg, P=.04). All cases required at least 125 μg of levothyroxine initially to maintain a euthyroid state.

CONCLUSIONS

Levothyroxine malabsorption likely occurs with hypothyroidism and untreated celiac disease. Absorption may improve after celiac disease treatment. Screening for celiac disease in patients with hypothyroidism requiring elevated levothyroxine doses warrants further investigation.

Atypical celiac disease as cause of increased need for thyroxine: a systematic study

OBJECTIVE

Replacement T4 dose in hypothyroid patients bearing both chronic autoimmune thyroiditis and atypical celiac disease (CD) has been analyzed.

DESIGN

Replacement T4 dose has been analyzed in 35 hypothyroid patients with Hashimoto's thyroiditis (HT) and atypical CD, as defined by the American Gastroenterological Association. We have evaluated the ability of the same dose of T4 to reach target TSH in 21 patients before and during gluten-free diet (GFD). In the remaining 14 patients, noncompliant with GFD, we analyzed replacement T4 dose and compared it with that in a similar group consisting of 68 patients with hypothyroid HT but no evidence of celiac sprue or other conditions interfering with T4 absorption.

RESULTS

In patients with isolated HT, the desired serum TSH (median=1.02 mU/liter) was reached in all patients after 5±2 months of treatment at a median T4 dose of 1.31 μg/kg·d. After a similar period and dose of T4, higher levels of TSH (median=4.20 mU/liter) were observed in patients with HT and CD. In 21 CD patients, target TSH (median TSH=1.25 mU/liter) has been attained after 11±3 months of GFD without increasing T4 dose (1.32 μg/kg·d). In the remaining 14 patients, who were noncompliant with GFD, target TSH has also been achieved but at a higher T4 dose (median=1.96 μg/kg·d; +49%; P=0.0002) than in hypothyroid patients without CD.

CONCLUSIONS

Atypical CD increases the need for T4. The effect was reversed by GFD or by increasing T4 dose. Malabsorption of T4 may provide the opportunity to detect CD that was overlooked until the patients were put under T4 therapy.

Conditions and drugs interfering with thyroxine absorption

Food, dietary fibre and espresso coffee interfere with the absorption of levothyroxine. Malabsorptive disorders reported to affect the absorption of levothyroxine include coeliac disease, inflammatory bowel disease, lactose intolerance as well as Helicobacter pylori (H. pylori) infection and atrophic gastritis. Many commonly used drugs, such as bile acid sequestrants, ferrous sulphate, sucralfate, calcium carbonate, aluminium-containing antacids, phosphate binders, raloxifene and proton-pump inhibitors, have also been shown to interfere with the absorption of levothyroxine.