The Effect of Coffee on the Absorption of Thyroid Hormone in Patients With Thyroid Carcinoma

Study Overview
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Brief Summary
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The purpose of this study is to evaluate whether taking thyroid hormone medication with beverages other than water, decreases absorption of the medication by the intestine. Specifically we are interested in whether coffee, coffee with milk, or black tea affects how thyroid medication is absorbed by the body. Previous studies have suggested that taking thyroid hormone with coffee may interfere with the ability to absorb thyroid medicine. Given that many patients take their thyroid medicine with beverages other than water, and specifically with coffee or tea, understanding whether and how much coffee or tea may decrease thyroid hormone absorption is important for clinical practice. This study will help determine the safest and most effective way for adults to take their thyroid medication and will guide medical practitioners in how to counsel their patients when they prescribe thyroid hormone.

Detailed Description
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Previous studies have suggested that taking thyroid replacement therapy with coffee potentially hinders its absorption. We already know that food especially a fiber-rich diet, cholestyramine resin, aluminum containing antacids, activated charcoal, and certain herbal remedies among others interfere with the ability to absorb thyroid medicine. These findings have prompted providers to advise patients to take their levothyroxine on an empty stomach in the morning. However, many patients take their thyroid medicine with their morning cup of coffee prior to eating breakfast. A small study has shown that Italian espresso coffee can decrease the absorption of levothyroxine, but the effect of American style coffee is not known. Given that the intestinal absorption of levothyroxine can be hindered by multiple substances and coffee is the most commonly consumed beverage worldwide, it is important to investigate what effect coffee may have on thyroid hormone absorption and thyroid function tests. Using methods similar to those used in previous studies, this study will measure thyroid function tests in approximately 10-20 subjects (18-60 years of age) over a 6 hour period of time after taking their thyroid medication with the specified study beverage for a 6 week period. Subjects will be randomized to water, black coffee, coffee with milk, and black tea as four specified study beverages, with water serving as the control beverage. Each subject will be recruited to participate with each study beverage for a 6 week period of time in a total of four consecutive 6 week periods. Blood draws will occur at the end of each 6 week period on test days 1, 2, 3, and 4. The coffee will represent the most common household coffee brand, Folgers. Thyroid function tests with each beverage will be compared to thyroid function tests with water to determine if thyroid medication absorption is impaired by coffee, coffee with milk, or tea. This study will help determine the safest and most efficacious way for adults to take their thyroid medication and will guide medical practitioners in how to counsel their patients when they prescribe thyroid replacement therapy.

Official Title
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The Effect of Coffee Consumption on the Intestinal Absorption of Levothyroxine Thyroid Hormone Replacement in Patients With Thyroid Carcinoma

Conditions
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Thyroid Carcinoma, Hypothyroidism

Intervention / Treatment
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* Other: Black Coffee
* Other: Coffee with Milk
* Other: Black Tea
* Other: Water


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - patients with thyroid carcinoma after standard care of treatment on stable dose of Synthroid with a detectable baseline TSH Exclusion Criteria: Pregnancy Undetectable baseline TSH Not willing to drink coffee, coffee with milk, or black tea Age less than 18 or greater than 60 years old Taking generic thyroid hormone (levothyroxine) and not brand-name Synthroid Dose of thyroid medication has been recently changed (less than 3 months ago) Currently receiving treatment for gastroesophageal reflux disease, gastritis, stomach or intestinal cancer, inflammatory bowel disease, or H. pylori Taking cholestyramine resin, colestipol hydrochloride, sucralfate, iron sulphate, aluminum containing antacids, activated charcoal, raloxifene, and herbal remedies History of previous gastric or small intestine surgery Diagnosis of kidney or liver disease, congestive heart failure, anemia, biliary disease, pancreatitis

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Black coffee<br>Synthroid will be administered with 12 ounces of black coffee for a period of 6 weeks. | Other: Black Coffee<br>* Taking Synthroid with 12 ounces of black coffee for 6 weeks.<br>|
| Active Comparator: Coffee with Milk<br>Synthroid will be administered with 12 ounces of coffee and 2 ounces of 2% milk for a period of 6 weeks. | Other: Coffee with Milk<br>* Taking Synthroid with 12 ounces of black coffee and 2 ounces of 2% milk for a period of 6 weeks.<br>|
| Active Comparator: Black Tea<br>Synthroid will be administered with 12 ounces of black Lipton tea for a period of 6 weeks. | Other: Black Tea<br>* Taking Synthroid with 12 ounces of black tea for a period of 6 weeks.<br>|
| Placebo Comparator: Water<br>Synthroid will be administered with 12 ounces of water for a period of 6 weeks. | Other: Water<br>* Taking Synthroid with water for a period of 6 weeks.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in TSH (thyrotropin-stimulating-hormone) with each beverage type | change in TSH over 6 hours peak change in TSH over 6 hours | 6 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in TSH with various beverages | To determine if taking Synthroid for 6 weeks with each of the prescribed study beverages results in a different baseline TSH, reflecting altered absorption of levothyroxine with each particular beverage. | 6 weeks | 
| Change in total T4 with each beverage type | Change in total T4 over 6 hours Peak change in total T4 over 6 hours area under the curve (AUC) for total T4 | 6 hours | 
| Change in free T4 with each beverage type | Change in free T4 over 6 hours Peak change in free T4 over 6 hours area under the curve (AUC) for free T4 | 6 hours | 
| Change in total T3 with each beverage type | Change in total T3 over 6 hours Peak change in total T3 over 6 hours area under the curve (AUC) for total T3 | 6 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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levothyroxine, synthroid, coffee, absorption, tea, thyroid carcinoma