Without enough thyroid hormone circulating in your body, you may feel low energy and generally wiped out. To make things more complicated, an underactive thyroid can also affect other health conditions. For example, hypothyroidism can contribute to high cholesterol levels, so people being evaluated for high cholesterol and heart disease may also need thyroid blood tests. Rarely, If the underactive thyroid is left untreated, you can develop a myxedema coma.
Hyperthyroidism usually develops as an autoimmune disease. The immune system produces antibodies that stimulate the thyroid to make more thyroid hormone than it should. The treatment for hyperthyroidism is to remove or inactivate the overactive thyroid. This can be accomplished with surgery, radioactive iodine, or antithyroid medications like methimazole or propylthiouracil NIDDK, Levothyroxine is the most common synthetic thyroid hormone used to treat an underactive thyroid, according to the American Association of Clinical Endocrinologists and the American Thyroid Association Garber, Also sold under the brand names Synthroid, Levoxyl, and Tirosint, levothyroxine is a synthetic version of the T4 thyroid hormone.
Your treatment of hypothyroidism entails restoring your thyroid hormone levels to normal. It may take several weeks, as the peak effect of levothyroxine can take weeks to achieve DailyMed, Levothyroxine replaces the primary hormone produced by the thyroid gland that it can no longer make for itself.
For example, you might be instructed to take the same dose daily or different amounts on different days of the week. Your healthcare provider will check your thyroid-stimulating hormone TSH levels with blood tests to see if your thyroid hormones are in balance; a high TSH means that you need more thyroid hormone and vice versa.
Your healthcare provider will estimate what dosage of thyroid replacement medicine to give you based on things like your age, weight, why you have low thyroid hormone levels and other factors.
The dosage might also be influenced by other medicines you take—be sure to tell your provider about any other drugs you take, including prescriptions, over-the-counter medications, and dietary supplements. Levothyroxine is most effective if you take it on an empty stomach, minutes before eating DailyMed, Also, to maximize effectiveness, do not take calcium carbonate like in over-the-counter antacids or iron supplements, as they can prevent levothyroxine from being absorbed.
Proton pump inhibitors like omeprazole brand name Prilosec and other antacids brand names Maalox, Mylanta, etc. You may need to adjust your dosage over time. Often, healthcare providers start people on a low dose to get people used to the hormone replacement medicine and prevent symptoms of hyperthyroidism.
Thyroxine is slow-acting, and it can take time for levels of this hormone to rise to the target level. In a typical scenario, your healthcare provider will test your TSH level after weeks to see how you have responded Garber, The mean SD plasma thyrotropin level significantly decreased from 5.
The circadian pattern of thyrotropin rhythm remained intact, which was important regarding the time of blood sampling for thyrotropin levels to monitor levothyroxine therapy. Accordingly, we conducted a randomized double-blind crossover trial to confirm whether levothyroxine taken at bedtime leads to lower thyrotropin and higher FT 4 and T 3 levels.
Hypothyroidism can have major effects on health and quality of life QOL , as it is associated with fatigue, weight gain, cold intolerance, depression, neuromuscular symptoms, diastolic dysfunction, and impairment of renal function.
The primary objective of this study was to determine whether a change occurred in thyrotropin and thyroid hormone levels when levothyroxine was taken at bedtime vs in the morning. We further investigated whether a bedtime regimen would affect creatinine and lipid levels, body mass index, heart rate, and QOL. A randomized double-blind crossover trial was performed among consecutive patients with primary hypothyroidism who visited our clinics.
The patients had to be 18 years or older and have been on a stable levothyroxine regimen for at least 6 months. Patients with a gastrointestinal tract disorder, those with thyroid carcinoma, and those who were pregnant were excluded from the study.
Also excluded were patients who were taking medication known to interfere with the uptake of levothyroxine. After informed consent had been obtained, patients were randomized to start the study period with 1 capsule of levothyroxine in the morning and 1 capsule of placebo at bedtime or with 1 capsule of levothyroxine at bedtime and 1 capsule of placebo in the morning.
After 3 months, patients were switched from levothyroxine in the morning to placebo and vice versa for another 3 months. Double-blind study medication was provided by the hospital pharmacy, which performed the randomization. Commercial levothyroxine sodium tablets Thyrax Duotab, 0.
Every patient received study capsules containing a similar dose of levothyroxine as before entry into the trial. Placebo and levothyroxine capsules were visually identical.
Patients were instructed by a research nurse to take the morning capsule on an empty stomach half an hour before breakfast and the bedtime capsule at night just before going to bed.
At baseline and every 6 weeks, patients were seen in our clinics by a research nurse. At these visits, blood samples were obtained to determine plasma thyrotropin, FT 4 , T 3 , creatinine, and lipid levels, and blood pressure, heart rate, and body weight were measured.
The remaining capsules in the containers were counted to check for compliance. Quality-of-life questionnaires were completed by patients at baseline, at 3 months, and at the end of the study. Blood samples were drawn on the morning of the planned visit to the research nurse. Capsules were not withheld on the day of blood sampling. Serum thyrotropin levels reference range, 0. Levels of FT 4 reference range, Three QOL questionnaires Item Short Form Health Survey, Hospital Anxiety and Depression Scale, and Item Multidimensional Fatigue Inventory and a specific questionnaire about symptoms of hypothyroidism and hyperthyroidism were completed by patients at baseline, at 3 months, and at the end of the study.
Patients completed the questionnaires under the supervision of a research nurse. After the trial ended, patients were free to choose at what time of day they preferred to continue taking levothyroxine, in the morning or at bedtime.
One year after the trial, we asked every patient at what time he or she was taking the levothyroxine tablet. The primary end point was a change in thyroid hormone variables thyrotropin, FT 4 , and total T 3 [TT 3 ] levels between 12 weeks of morning levothyroxine intake and 12 weeks of bedtime levothyroxine intake.
Secondary end points were changes in QOL measured by 3 questionnaires , thyroid symptom score, body mass index, heart rate, and serum lipid and creatinine levels. The direct treatment effect among all variables was measured by performing an independent-samples t test between the differences of week 12 and week 24 in the first group started with morning levothyroxine and the second group started with bedtime levothyroxine.
All P values were 2-sided and were not adjusted for multiple testing. All calculations were performed using commercially available statistical software SPSS To calculate the sample size, we assumed that a difference in thyrotropin level of 1.
From previous results in a pilot study, we calculated that the standard deviation of the difference between morning and bedtime administration would be between 2. Between April 1, , and November 30, , a total of consecutive patients with primary hypothyroidism were assessed for study eligibility.
Ultimately, patients met the inclusion criteria and gave written informed consent. Fifteen randomized patients withdrew their consent shortly after enrollment in the trial and had baseline data only. The baseline characteristics of these patients did not differ from those of patients who completed the trial. Baseline characteristics of the 2 groups are given in Table 1.
There were differences between the 2 groups in the proportions of male patients, levothyroxine dosages, and thyrotropin levels. On average, patients missed a mean SD of 1. Because there were no severe symptoms related to hypothyroidism or hyperthyroidism, no patient required a change in levothyroxine dosage during the trial. Results of the primary outcomes are summarized in Table 2 and in Figure 2. Among the group that received morning levothyroxine first, the mean SD thyrotropin level decreased from 2.
In contrast, among the group that received bedtime levothyroxine first, the mean SD thyrotropin level increased from 2. When overall changes were compared between the 2 groups, bedtime levothyroxine intake was found to have a direct treatment effect, with a decrease in thyrotropin level of 1.
The mean SD FT 4 level in the group that received morning levothyroxine first increased from 1. In the group that received bedtime levothyroxine first, the mean SD FT 4 level decreased from 1.
Therefore, bedtime levothyroxine intake resulted in a direct treatment effect, with an increase in FT 4 level of 0. Changes in TT 3 levels were similar to changes in FT 4 levels. In the group that received morning levothyroxine first, the mean SD TT 3 level increased from In the group that received bedtime levothyroxine first, the mean SD TT 3 level decreased from In this case, the direct treatment effect of bedtime levothyroxine was an increase in TT 3 level of 6.
No first-order carryover effect was found for thyrotropin, FT 4 , or TT 3 levels. There were no differences between the 2 study groups in serum creatinine or lipid levels, blood pressure, body mass index, or heart rate. These results are summarized in Table 2. Hypothyroidism symptoms were unchanged between the 2 periods, despite improved thyroid hormone profiles, nor was there a difference in hyperthyroidism symptoms.
When asked at the end of the trial before the randomization code was broken , 34 of 90 patients said that they felt better during the period of morning intake of levothyroxine, 31 patients preferred the period of bedtime intake, and 25 patients indicated no preference. At 1 year after completion of the trial, more than half of the patients still preferred bedtime intake of levothyroxine. We performed this large, randomized, double-blind crossover trial among 90 patients to address whether levothyroxine taken at bedtime instead of in the morning improves thyroid hormone levels.
The primary outcomes show a decrease in thyrotropin level of 1. Despite the change in thyroid hormone levels, the patient QOL did not differ. Bedtime levothyroxine intake could be more convenient for patients, as they do not have to postpone breakfast. After our study was completed, more than half of the patients decided to continue with bedtime intake of levothyroxine.
How can the bioavailability effects of levothyroxine be explained? An interval of 30 minutes between taking levothyroxine and eating breakfast may be too short to prevent interference with gastrointestinal absorption of levothyroxine. Moreover, many patients drink coffee in the morning, often instead of eating breakfast, 6 or may take other medications that interfere with levothyroxine absorption.
In contrast, most patients in our study stated that they had eaten no food or snacks for several hours before bedtime, this being their usual routine. Bowel motility is slower at night, resulting in more prolonged exposure of levothyroxine to the intestinal wall and, consequently, in better bioavailability.
The American Thyroid Association recommends that adults, particularly women, have a blood test to detect thyroid problems every 5 years starting at age While rare, hypothyroidism can also be caused by too much or too little intake of dietary iodine or by abnormalities of the pituitary gland.
Certain factors may increase your chance of developing thyroid disorders. You may require more regular testing if you have 2,3 :. Hypothyroidism rarely causes symptoms in the early stages, but if left untreated over time it can cause a number of medical problems such as infertility, obesity, heart problems, and joint pain. The symptoms associated with hypothyroidism can vary from patient to patient. The most common symptoms associated with hypothyroidism include:.
Myxedema coma is referred to as the most severe form of hypothyroidism, and rarely occurs. The symptoms and signs associated with myxedema coma include below normal temperature, shallow breathing, low blood pressure, and blood glucose, as well as unresponsiveness. If your doctor suspects that you have hypothyroidism, he or she will obtain a blood sample and test your levels of thyroid hormone. If you have been diagnosed with hypothyroidism your doctor will prescribe a synthetic form of the thyroid hormone.
Levothyroxine, a synthetic thyroid hormone product, is the standard treatment for managing hypothyroidism and is available under various brand names eg, Levothroid, Synthroid. The good news is that hypothyroidism can almost always be completely controlled with the use of synthetic levothyroxine, as long as the recommended dose is taken daily as instructed.
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