can i take thyroid medication before colonoscopy

Medication can be taken 4 hours before examination with little sips of water. They also noted that a high-fat, large American-style breakfast may impact absorption of the drug. 2014;18(4):451-6. doi:10.1016/j.clinthera.2017.01.005, Rajput R, Chatterjee S, Rajput M. Can levothyroxine be taken as evening dose? Aspirin Medications to Avoid. However, it will take four to eight weeks for your TSH blood levels to improve. What foods can interfere with thyroid medication? Arthrotec, Voltaren), ibuprofen (e.g. This means it takes longer for your medication to go through your intestines. You need to take Tapazole and PTU consistently. For aspirin (81 or 325 mg daily) used to prevent heart problems, this is usually safe to stop for seven (7) days prior to any procedure. Saravanan P, Siddique H, Simmons D, Greenwood R, Dayan C. Twenty-four Hour Hormone Profiles of TSH, Free T3 and Free T4 in Hypothyroid Patients on Combined T3/T4 Therapy. For example, maybe you take your thyroid medication first thing every morning but forgot until lunchtime. My first six week test results showed my TSH jumping from .861 to 3.840. Coumadin (Warfarin) How many days BEFORE your surgery to stop taking this drug. Eur Rev Med Pharmacol Sci. Abnormal thyroid function test results in patients taking salsalate. Well, it's a pretty risky business. Drugs that interact with levothyroxine: an observational study from the Thyroid Epidemiology, Audit and Research Study (TEARS). Step 2: Tweak Your Diet. What would that indicate to you? I ask because my doctor has reduced my dose of Nature-throid several times over this last year, trying to bring my TSH into the normal range. Aleve, Anaprox, Naprosyn, Vimovo) it is usually okay to continue taking these medicines. April 4, 2022. The answer is yes, based on a 2007 study in Experimental and Clinical Endocrinology & Diabetes, we know what blood levels do after taking medication. There is some research, though, that suggests it may be better to take your dose at bedtime. This medication releases slowly and steadily resulting in a relatively stable hormone level in your body. The information here can help guide your conversation. You can take any meds expect blood thinners. Any input would be helpful. My goodness that is a conundrum - I'm sorry if this seems obvious, but does your endo have an opinion about what to do or is the doctor you refer to in your post your endo already? Can You Eat Soy If You Have a Thyroid Condition? However, good quality scientific studies have shown that even slightly elevated TSH and mildly slow thyroid functioning is associated with higher risks of decline in both . This precaution is not agreed upon by all doctors. 2. Other medications that can cause blood-thinning may cause complications during or after a colonoscopy as well. Im just miserable with myself! I just had a colonoscopy and I did change anything. Get our printable guide for your next healthcare provider's appointment to help you ask the right questions. Over the counter: aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. For me,TSH is a start, but it does not give me the whole picture. Six hours before your appointment: Drink the second dose of the prep. A pharmacy can make substitutions without your healthcare provider's knowledge unless they write "dispense as written/no substitutions" on your prescription. If you get pregnant or suspect you are while taking Tapazole (methimazole or MMI), stop your medication and contact your healthcare provider immediately. Ferritin went up some 26.90 ng/mL. If you develop agranulocytosis, it's important to avoid exposure to people who are sick. Otun, J., Sahebkar, A., stlundh, L. et al. Apparently they were going to prescribe Magnesium Citrate and then the Miralax, but I'm already taking lots of magnesium so that one got tabled. Methimazole. It proves important to comply with these drug restrictions, and if not, it proves crucial for people to tell their doctor they took a drug on the must-stop list. Thyroxine is also called T4. No surprise. Ive been taking Synthroid for 23 years. Drugs.com. The camera sends images to an external monitor so that the doctor can study the inside of your colon. Many dietary supplements can interfere with the absorption or action of thyroid hormones and may affect thyroid test results. T4 levels should be between 0.82-1.77.mine is 0.77. Yes Can you take synthroid with Ibuprofen? Please contact the Gastroenterology office. You will continue these medicines after the test. These questions must be answered by the doctor that will be doing your colonoscopy. A Matter of Choice Drugs.com. This is a little scary to me. Irving SA, Vadiveloo T, Leese GP. Taking it on an empty stomach helps your body absorb the full dosage. And t4 is 5..93 do do i need increase or decrease. Get your FREE gift Dr. Accessed June 10, 2021. Trifiro G, Parrino F, Sultana J, et al. Low adrenal output is common with low thyroid and visa versa. If necessary, polyps or other types of abnormal tissue can be removed through the scope during a colonoscopy. Certain drugs and supplements, and some medical conditions can make you absorb more or less of the drug. Levothyroxine. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Clopidogrel ( e.g. Plavix), ticagrelor (Brilinta) : Usually these medications are continued. Step 4: The Purge. Also, be sure to stay up-to-date on immunizations. No other blood test values other than calcium. 3) Don't take your medicine within 4 hours of taking iron-, aluminum-, or calcium-containing supplements or antacids Depending on the size and number of polyps, you may need to follow a more rigorous surveillance schedule in the future to look for more polyps. Oct. 10, 2017, at 9:32 a.m. What to Do About Pre-Colonoscopy Anxiety. 4-Way Cold Tabs. Synthroid builds up in your body, so missing a day will not be an issue. When you visit the site, Dotdash Meredith and its partners may store or retrieve information on your browser, mostly in the form of cookies. She is the author of "The Thyroid Diet Revolution.". You should also be able to take on your prep day. This field is for validation purposes and should be left unchanged. Im afraid I may end up a mess. Furthermore, The adrenal glands need thyroid hormone to function and with low thyroid hormone as well as greater pressure due to body stress the adrenal glands cannot cope and suffer fatigue. Once the adrenals receive appropriate support you will tolerate better the thyroid hormone and the anxiety will improve. Acetaminophen (e.g. Chon DA, Reisman T, Weinreb JE, et al. TSH levels should be between 0.450-4.500.. mine is 13.230!! AskMayoExpert. A friend just had a colonoscopy, and she was surprised at how little of the "stuff" she had to drink on the morning of the procedure. I think the prep you need really depends on how sensitive you are to the magnesium and calcium issues. 1998-2023 Mayo Foundation for Medical Education and Research (MFMER). What about absorption? You should have expectations by rights to feel the best you can . Sodium salicylate and synthroid interactions. Anacin products. Stop taking ALL natural products, herbal medicines, vitamins, and other supplements 7 days before . Its half-life is 9 days, meaning that if you do not take any more medication, it takes 9 days to clear half of it from your body. https://www.drugs.com/drug-interactions/lemon-with-synthroid-2993-0-1463-869.html. Thyroid hormonal medications come in pill form and are easy to take. I like to testwhat the clinicians in the study used: free T3 and free T4 in addition to TSH. I can't NOT take the calcium, magnesium, D3, plus my Thyroid, so they prescribed a solution to drink for the prep that would tolerate the other meds. In the end, the key is to be consistent. Khanna S (expert opinion). Levothyroxine absorption in health and disease, and new therapeutic perspectives. They don't want to wait an hour before eating or drinking coffee. The24 hour study followed 44 people diagnosed ashypothyroid and treated with medication, taking 12 blood samples to measure TSH, free T3, and free T4. Tylenol): Continue taking this as you usually do. I am taking T4 meds. The colonoscopy was completed as planned, and apparently the diet prep eliminated the need to chug-a-lug nasty powerful laxatives the day before. As many things in life, the answer is: it depends. Mayo Clinic; 2021. Thank you, {{form.email}}, for signing up. Thyroid medication, when used correctly, has a beneficial impact on quality of life. This gives some information to interpret the TSH value, but it is not complete. It's considered safe to take your hypothyroid treatment while breastfeeding. If you take a combination T3/T4 therapy or desiccated thyroid, it might keep you awake. A colonoscopy is considered negative if the doctor doesn't find any abnormalities in the colon. Free T4 drooped 0.64 ng/dL Free Triiodothyronine pg/dL 4.6. Contact a colonoscopy specialist if you need help with antibiotics or other medications before your colonoscopy procedure. This may be because it's easier for your body to absorb thyroid hormone overnight. Thank you, {{form.email}}, for signing up. Before a colonoscopy, you'll need to clean out (empty) your colon. "Mayo," "Mayo Clinic," "MayoClinic.org," "Mayo Clinic Healthy Living," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research. Check with your provider any time you change your medication or supplement regimen. Any use of this site constitutes your agreement to the Terms and Conditions and Privacy Policy linked below. Switching Brands Switching brands of levothyroxine or changing to a generic may affect your symptoms or side effects. Clin Endocrinol. Bowel preparation before colonoscopy in adults. How medications affect thyroid function. Consult your doctor if you continue to pass blood or blood clots or if you have persistent abdominal pain or a fever. I am allergic to the Dulcolax tablets so we know they are OUT but the dr. has been equivocal about which prep to use. Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. Figure out ways to remind yourself so you can be consistent. Blood pressure medicines: Be sure to still use these medications while preparing for the test. What drugs can interact with hyperthyroid drugs? If you stop taking your thyroid medication, you can expect your hypothyroid symptoms to return. American Thyroid Association. Post your colon health question and get information from healthcare providers. On the day of your test, take these medications with water at least 2 hours before your test. I recently was told by a different physician that if my thyroid was out I do not have hashimoto anymore. Coumadin), apixaban (Eliquis), dabigatran (Pradaxa), or rivaroxaban (Xarelto): Please check with your doctor about how to take them. Review/update the Your symptomsfatigue, constipation, dry skin, brittle nails, and so forthshould get better within a few days. My question is when your scheduled for colonoscopy are med (NDT +T4) dosing go on as usual ? Thyroid. Cooper JG, Harboe K, Frost SK, Skadberg . Ciprofloxacin interacts with thyroid replacement therapy. TSH is the hormone that tells your body to make thyroid hormones. The most common thyroid hormone replacement medication is levothyroxine. Some recent research supports taking thyroidmedication at bedtime to maximize absorption. Diarrhea. https://thyroidpharmacist.com/articles/which-thyroid-medication-is-best, https://thyroidpharmacist.com/articles/top-11-things-you-need-to-know-about-thyroid-medications, https://thyroidpharmacist.com/articles/where-do-i-start-with-hashimotos, https://thyroidpharmacist.com/articles/overcoming-hashimotos-in-the-new-year, https://thyroidpharmacist.com/articles/functional-medicine-approach-to-the-thyroid, http://www.thyroidpharmacistconsulting.com/clinician-database.html, https://thyroidpharmacist.com/articles/the-dose-of-your-thyroid-medication-can-uncover-your-root-cause, https://thyroidpharmacist.com/articles/autoimmune-thyroid-disease-and-anxiety, https://thyroidpharmacist.com/articles/are-you-going-crazy-or-is-it-just-your-thyroid, https://thyroidpharmacist.com/articles/are-your-adrenals-sabotaging-your-health, https://thyroidpharmacist.com/articles/what-type-of-doctor-should-you-see-if-you-have-hashimotos, https://thyroidpharmacist.com/articles/10-things-i-wish-my-endocrinologist-would-have-told-me, https://www.functionalmedicine.org/practitioner_search.aspx?id=117, https://thyroidpharmacist.com/articles/top-10-tips-for-overcoming-hashimotos-fatigue, https://thyroidpharmacist.com/articles/thiamine-and-thyroid-fatigue, https://thyroidpharmacist.com/articles/hair-loss-and-thyroid, https://thyroidpharmacist.com/articles/10-most-helpful-diy-interventions-for-hashimotosaccording-to-my-clients, https://thyroidpharmacist.com/articles/how-to-get-accurate-lab-tests-when-taking-thyroid-medications, https://thyroidpharmacist.com/articles/how-to-get-accurate-lab-tests-when-taking-thyroid-medications/, https://thyroidpharmacist.com/articles/are-you-doing-everything-for-your-thyroid-but-not-yet-well/, https://thyroidpharmacist.com/articles/do-you-have-hypothyroidism-or-hashimotos-or-both/, https://thyroidpharmacist.com/articles/top-6-thyroid-tests/, https://thyroidpharmacist.com/articles/top-6-thyroid-tests, https://thyroidpharmacist.com/checkout/?product_id=4702, https://thyroidpharmacist.com/articles/which-thyroid-medication-is-best/, https://thyroidpharmacist.com/articles/top-11-things-you-need-to-know-about-thyroid-medications/, https://thyroidpharmacist.com/articles/the-dose-of-your-thyroid-medication-can-uncover-your-root-cause/, https://www.amazon.com/Hashimotos-Protocol-Reversing-Thyroid-Symptoms-ebook/dp/B01HXK6GVQ/ref=sr_1_1?ie=UTF8&qid=1505933035&sr=8-1&keywords=hashimotos+protocol+izabella+wentz, https://www.thyroidpharmacistconsulting.com/collections/labs/products/hpa-stress-profile-201a, https://thyroidpharmacist.com/articles/iodine-hashimotos/, https://thyroidpharmacist.com/articles/my-challenges-and-finding-dr-right/, https://www.amazon.com/gp/product/0615825796?ie=UTF8&camp=1789&creativeASIN=0615825796&linkCode=xm2&tag=thyroipharma-20, https://thyroidpharmacist.com/articles/controversy-coffee-bad-thyroid-myths-truths/, https://www.thyroidpharmacistconsulting.com/clinician-database.html, https://thyroidpharmacist.com/articles/what-to-do-if-your-tsh-is-normal-and-you-are-anything-but/, https://thyroidpharmacist.com/database-recommended-clinicians/, https://thyroidpharmacist.com/database-recommended-compounding-pharmacies/, https://thyroidpharmacist.com/articles/the-many-faces-of-hashimotos/, https://thyroidpharmacist.com/articles/need-know-thyroid-disease/, https://thyroidpharmacist.com/articles/5-stages-hashimotos-thyroiditis, 8 Benefits of the Infrared Sauna That Can Reduce Symptoms of Hashimotos and Hypothyroidism. Is she correct? I can't NOT take the calcium, magnesium, D3, plus my Thyroid, so they prescribed a solution to drink for the prep that would tolerate the other meds. If you were to take your thyroid medication within 5 hours of getting your thyroid function tests done, your lab results may show that you are overdosed, even when you may be accurately dosed, or they may show your labs to be within normal limits, when you may actually be under-dosed. Anesthesia. Therefore, it is important not to take the medication with meals, other medicines, or supplements. ThyCa: Thyroid Cancer Survivors' Association, Inc. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Reverse T3 10.5. A colonoscopic examination involves gently inserting a fiber-optic colonoscope into your rectum and large intestine to view your lower gastrointestinal tract. Diabetes medications: Use of these medications often needs to be changed around the time of the colonoscopy. Talk to your doctor about when to take your thyroid medication. The choice is really just a matter of what suits your lifestyle best. Make a donation. Vomiting. I have had T3, T4, and TSH tested by my endocrinologist. Why Your Thyroid Hormone Levels May Be Fluctuating, Medications Used to Treat Thyroid Disease. This problem happens to many of us with low thyroid hormone physical, emotional and psychological stress including illness will impact the Adrenal glands. If you experience nausea or vomiting rinse your . I was just wondering why I get anxiety so bad when I take levothyroxine. What drugs are used to treat hypothyroidism? Is There a Best Time to Take Your Thyroid Medication? There usually arent any side effects, but it is, American Society for Gastrointestinal Endoscopy, Bipolar Disorder: How Genetics Plays a Role. The binding of the hormone is a complex deal that is affected by other circulating hormones, such as estrogen. Don't drive or make important decisions or go back to work for the rest of the day. Ana Maria Kausel, MD, is a double board-certified endocrinologist affiliated with Mount Sinai St. Luke's/Mount Sinai West in New York City. The amount of time it takes to treat hyperthyroidism can change depending on what caused it. The peak is about 4 hours after taking the medication. You can take your MVM any time you'd like. Measuring the free levels of hormone in your blood means we are measuring how much is available to work on the cellular level. Thyroid hormones help tissues develop, control muscle growth and maintain your brain function among other things. During a colonoscopy, a long, flexible tube (colonoscope) is inserted into the rectum. 2020;92(5):475-81. doi:10.1111/cen.14172, Ianiro G, Mangiola F, Di Rienzo TA, et al. Disclaimer: No Physician-Patient Relationship Most of the rest of the day, the T4 levels will be stable. Are thyroid replacement hormones taken with or without food? Certain psychiatric and weight loss medicationscan cause potentially harmful interactions with anesthetic medications. Mayo Clinic does not endorse companies or products. Yes, depressed too. Your doctor may recommend a colonoscopy to: There is a problem with I have been diagnosed and taking 88mcg Levothyroxine for 30 days. Clark CD, Bassett B, Burge MR. Iron containing medications like ferrous fumarate, ferrous gluconate, ferrous sulphate, multivitamins with iron. I would like to know your opinion, as well. You may feel bloated or pass gas for a few hours after the exam, as you clear the air from your colon. Whether you're just starting it or picking up a refill, check the label to make sure you're getting: Also, check for substitutions. Thanks, Hadassah-1. Other patients who should consult their gastroenterologists (GI doctors) about antibiotics include people with liver disorders, people who have had intensive surgery in the past for conditions such as heart failure and aneurysm and people who have artificial joints in place. Dairy products and coffee have both been found to reduce the absorption of levothyroxine. Thanks for replying though and good to know that others have survived this ordeal. GREAT TOPIC . If we combine this information with your protected Then avoid food and drink, including coffee, for at least an hour. And that is GREAT . Prostate Cancer Screening: Should You or Shouldn't You? My t3 is 1.93. Our website is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Ive researched for hours. 2017;39(2):378-403. doi:10.1016/j.clinthera.2017.01.005, Pirola I, Formenti AM, Gandossi E, et al. Take the medication in the morning. If you are experiencing health issues that need personal attention, I invite you to reach out for a chat to discuss how I can help you enjoy life again! I'm always on the low for calcium even with 2000 mg per day and my thyroid is on the high side (.18). The scope which is long enough to reach the entire length of your colon contains a light and a tube (channel) that allows the doctor to pump air, carbon dioxide or water into your colon. Koulouri O, Moran C, Halsall D, Chatterjee K, Gurnell M. Pitfalls in the measurement and interpretation of thyroid function tests. Typically, you're told to take your medication with water and wait at least an hour before breakfast or coffee. I have been on Synthroid for a year. However, that information will still be included in details such as numbers of replies. Im just starting gluten free and dairy free. In fact, my latest ultra-sound this spring showed they were completely gone. I just got that confirmed from the dr.s office today (the gastroenterologist). For hyperthyroidism treatments, make sure you don't double up on natural T3 drugs. Thus, it is usually best to postpone your combination medication until after you get your lab test done. The following are guidelines only more specific questions can be handled by your doctor or health care provider. That can change how fast it dissolves and how it's absorbed in your intestines. There is hope! Both Tapazole (methimazole) and propylthiouracil (PTU) can be taken with or without food. Effect of High-dose Biotin on Thyroid Function Tests: Case Report and Literature Review. Reasons may include: There is some evidence that taking your medication at night may help your body absorb it. But the prep has to be changed to accommodate my medicines.calcium, magnesium, D3, thyroid. Read our, Taking Your Medication for Hyperthyroidism. Polyps removed during colonoscopy are sent to a laboratory for analysis to determine whether they are cancerous, precancerous or noncancerous. Adprin-B products. The problem is she is ignoring symptoms in pursuit of this number. The authors found that patients who took their medication at bedtime had a significant increase in their levels of free T4. Root Causes of Depression and Hashimotos, Top 9 Takeaways From 2232 People With Hashimotos. Learn more from our experts abou, If a polyp is discovered during a colonoscopy, the physician will most likely take a tissue sample o, What are the possible side effects of colonoscopy? Go over your possible interactions and what to do about them with your healthcare provider and pharmacist whenever you start a new medication. According to one study, one reason for this could be because coffee stimulates the colon, so there is less time for the medication to be absorbed. Often the person is under conscious-sedation and thus not real. But a detailed discussion will show you how the thyroid blood tests are affected, and which ones are affected the most. You owe it to YOURSELF AND FAMILY AND FREINDS . other information we have about you. Missing even a day or two of thyroid medication can cause symptoms. Due to biopsy of abnormal cells I had a total thyroidectomy. With natural desiccated thyroid medications, debate exists over whether taking it, Acacia, which can cause allergies in some people with tree or grass allergies, Lactose, which can be a problem for those with lactose intolerance, Cornstarch, which can affect those with a corn allergy and possibly some people with gluten sensitivity, Beta-blockers, such as Tenormin (atenolol). Im interested in your thoughts on taking Nature-Throid at night, as well. 1. 2013;23(9):14931496. Don't expose them to moisture or heat, and it's best to not keep them in the bathroom. GOOD LUCK . De Luca F, Arrigo T, Pandullo E, Siracusano MF, Benvenga S, Trimarchi F. Changes in thyroid function tests induced by 2 month carbamazepine treatment in L-thyroxine-substituted hypothyroid children. Are Flame Retardant Toxins Contributing to Your Thyroid Condition? Colon cancer screening: At what age can you stop? Dong BJ. The thyroid is like the engine of your body. Hypothyroidism (underactive thyroid). And how do I know what to tell you? I need to find an endocrinologist but I have no idea who to go see either. During a colonoscopy, the doctor inserts a colonoscope into your rectum to check for abnormalities in your entire colon. National Institute of Diabetes and Digestive and Kidney Diseases. Warfarin (Coumadin) is usually stopped 5-7 days before your colonoscopy. For most people, it doesn't really matter if you take your thyroid medicine in the morning or just before bed. This hormone is also called T3. Experts also recommend waiting three or four hours before taking other medications or supplements. I already take magnesium to the tune of 450 mg a day. Therefore patients taking aspirin should consult their doctors before stopping medication. This may include calcium, iron, and high-fiber foods. Lovenox is usually stopped about 12 hours before colonoscopy. Too much would be a problem, according to the gastroenterologist. Im so confused. Colonoscopy. Look up Adrenal Fatigue..a book Adrenal Fatigue A Desk Reference by Dr Salmaan Dalvi is an excellent resource providing detail about the necessary vitamins and minerals, herbs etc. In fact, heavy iodine intake can actually worsen hypothyroidism. Post your colon health question and get information from healthcare providers. Experts have long recommended taking thyroid medication like levothyroxine first thing in the morning. This helps make sure your thyroid medication is absorbed by your body. Tissue samples (biopsies) can be taken during a colonoscopy as well. Any ideas?? Reviewed 12/14/2011 by David M. Nolan, M.D.Diplomate of the American Board of Internal Medicine, 2011Currently a Fellow of Gastroenterology, at UCI 2011-2014. DIO2 affects how your body converts T4 into T3, which is the active form of the hormone. There is hope . March 25, 2016. She is the author of "The Thyroid Diet Revolution. Mayo Clinic Healthcare expert: Artificial intelligence improves colonoscopy accuracy, Mayo Clinic Q and A: Advances in screening for colon cancer, Mayo Clinic Minute: The importance of cancer screenings for LGBTQ community, Ask the Mayo Mom: How and why endoscopy is used in children, Mayo Clinic Q and A: Polyps are possible culprits in colon cancer, AI reduces miss rate of precancerous polyps in colorectal cancer screening, Consumer Health: Colon polyps and colon cancer screening, Mayo Clinic Minute: What to know when colorectal cancer runs in the family, Mayo Clinic Minute: Breaking down colorectal cancer, Mayo Clinic Minute: How COVID-19 has affected cancer care, Mayo Clinic Minute: How to be healthier in 2022, Primary care clinicians adjust recommendations for colorectal cancer screening to accommodate patient needs and preferences, study finds, Mayo Clinic Minute: Prepare for colon cancer screening with confidence, Bowel cancer: Mayo Clinic Healthcare expert describes role hard-to-see polyps play in cancer risk, Mayo Clinic Q and A: Colorectal cancer screening remains important, Colorectal cancer cases rising in younger adults, screenings are down, Sharing Mayo Clinic: Celebrating 5 years cancer-free after colon cancer, Updated screening guidelines for colorectal cancer. Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement. Effects of kelp supplementation on thyroid function in euthyroid subjects. My T3 and T4 are also improved to normal range per my doctor, but I need to ask for exact values for my own records still.

Robert Gentry Obituary, Malaysian Lamb Curry Slow Cooker, Is Dr Teals Sleep Bath Safe For Babies, Disney Worldwide Services Payroll Phone Number, Articles C

can i take thyroid medication before colonoscopy