For Synthroid Users, Pinpointing the Correct Dosage is Key

For Synthroid users finding the correct dosage is key.

Finding the correct dosage of this thyroid hormone isn’t always easy: Take too little Synthroid and your symptoms of weight gain, fatigue and depression won’t go away. Take too much and you’re at risk for weak bones, insomnia, breathlessness and even heart problems.

My own experience with Synthroid began a few years ago when I started feeling more tired than usual. I chalked it up to stress, my endless to-do list and the lack of sleep. A blood test, however, revealed that I had hypothyroidism. That meant my thyroid wasn’t churning out enough thyroid hormone. So I became a member of what my friend MJ calls the Synthroid Society and began taking a small dosage of levothyroxine, the generic version of Synthroid and a synthetic form of thyroid hormone.

According to the National Institutes of Health, nearly 5% of Americans age 12 and over suffer from hypothyroidism. Because the symptoms mimic those of other conditions, experts believe many people are undiagnosed. In fact, the American Thyroid Association estimates that including mild cases, hypothyroidism actually affects up to 15% of Americans. 

How the Thyroid Gland Works

Think of the thyroid as your body’s internal thermostat. This small bow-tie shaped gland is a power player in the body, one that has the potential to inflict a lot of chaos and confusion. It regulates your heart rate, metabolism, gastrointestinal function, menstrual cycle, mood, respiration and virtually every other function in the body. 

When your body doesn’t make enough thyroid hormone, everything slows down, and you develop hypothyroidism. Symptoms vary. Some people gain weight, suffer depression or develop dry skin and nails. Others experience constipation, a foggy brain and chronic fatigue. Women may notice that their periods are heavier and more frequent, and that it may be difficult to get pregnant.

Too much thyroid hormone causes hyperthyroidism and has the opposite effect. This condition makes you anxious and irritated, and you may lose weight, have trouble sleeping and suffer diarrhea. It can also cause heart palpitations and weak bones. Hyperthyroidism is much less common than hypothyroidism and affects only about 1% of the population.

When the Thyroid Slows

Hypothyroidism is caused by several different disorders. For most people, it’s the result of an autoimmune disease called Hashimoto’s disease, which causes thyroiditis, or inflammation of the thyroid gland. Others develop hypothyroidism when they suffer thyroiditis due to the use of certain medications such as interferon or amiodarone, or when they undergo the surgical removal of the thyroid due to problems such as thyroid cancer.  Some people simply develop hypothyroidism with age.

Women are much more likely than men to develop hypothyroidism. The condition is more common after age 50, but can occur in children as well. It is also more common in people who have autoimmune diseases and is a certain result of thyroid cancer or any other condition that requires the surgical removal of your thyroid.

Hypothyroidism often goes undiagnosed because the symptoms resemble those of other problems.  If you’re tired, you might blame your late nights at the office. Gaining weight? Could be those late night snacks. Depression? Chalk that up to your volatile marriage. But in reality, any of these symptoms could be hypothyroidism.

Treating Hypothyroidism

Detecting hypothyroidism is fairly simple. All you need is a blood test that measures levels of thyroid stimulating hormone (TSH), which is what your pituitary gland produces when your thyroid isn’t making enough thyroid hormone. High TSH levels means your pituitary is signaling your thyroid to secrete more, once prescribed, thyroid hormone. Treatithe rest of your ng hypothyroidism requires you to replace the thyroid hormone your body normally makes. Synthroid is what experts call true hormone replacement therapy because you are using medicine to replace what your body no longer makes but should be making. Synthroid is generally taken for life.

Before taking Synthroid or the generic levothyroxine, you should notify your doctor about any medical conditions you have, such as heart disease or diabetes, and any medications you take. It used to be thought that certain medications such as anticoagulants (warfarin) can become more potent in the presence of Synthroid, however  recent research has shown that there is no interaction between Synthroid and warfarin. Insulin or sulfonylureas for diabetes may become more or less effective. Antacids that contain aluminum, magnesium, simethicone or calcium,  such as Gaviscon, Maalox, Mylanta, Gas-X or Rolaids, can make Synthroid less effective. The same is true of sucralfate (Carafate), which is prescribed for peptic ulcers. Iron can also interfere with the absorption of Synthroid. If you need to take these medications or supplements, take them four hours before or after you take Synthroid. You should also point out to your doctor if you are trying to get pregnant or are breastfeeding.

A significant number of Synthroid users find they have to ask their doctors to adjust their dosage. It’s important, therefore, that those on this thyroid hormone monitor whether they are having any side effects from the medicine and whether their original symptoms are abating. Luckily for me, my initial dosage has worked well. A follow-up blood test six weeks after I started Synthroid showed my TSH levels were back to normal.

Many people aren’t so lucky. Consider my friend MJ who spent years trying to figure out why she felt so anxious and tired. Doctors eventually determined she was taking too much Levoxyl, another synthetic thyroid hormone treatment, and it was making her jumpy and wearing her out. Reducing the dosage helped, but she’s worried how the extra Levoxyl all those years may have affected her bones.

And it turns out that for those with the early signs of underactive thyroid, or subclinical hypothyroidism, taking thyroid hormone medication doesn’t help to treat symptoms or improve quality of life. According to a study reported in JAMA, researchers conducted a meta-analysis of 21 clinical trials that enrolled 2,200 people with subclinical hypothyroidism. In those trials, participants received either a thyroid hormone drug (levothyroxine in most of the trials), a placebo or no treatment at all. Hormone treatment was not associated with a benefit in terms of improved quality of life or a reduction in hypothyroid symptoms. Thyroid hormone drugs also did not lead to improvement in terms of depressive symptoms, cognitive functions, muscle strength and blood pressure. The study authors also note that “thyroid hormone therapy is associated with adverse effects when overtreatment occurs.” Overtreatment caused MJ to feel jumpy and worn out, and other adverse effects can include fast heart rate, excessive sweating and weight loss. 

Meanwhile, my friend Cheryl spent years trying to figure out why her TSH levels are so high when she’s already taking a relatively high dose of Synthroid. Should she instead take Armour, which is a thyroid hormone extracted from pig thyroids? Ultimately, what worked for her was taking levothyroxine with aqueous selenium and liquid iodine. Last year, she began taking the selenium and iodine every other day. Iodine is essential to the production of thyroid hormone, while selenium helps the body convert T4, the inactive form of thyroid hormone into T3, the active form.

Be Smart With Synthroid

If you have hypothyroidism, taking Synthroid needs to become a part of your daily routine. To keep blood levels on an even keel, you should also take it at the same time every day.

Ideally, you should take Synthroid on an empty stomach since food can delay absorption. Me? I take it in the middle of the night, when I know I won’t be eating anything. In fact, it’s best to wait an hour after taking your pill before eating. Certain foods can inhibit absorption of Synthroid, too. A diet rich in fiber for instance, may decrease the amount your body absorbs.

Foods such as soy and grapefruit juice, and supplements like calcium and iron can also interfere with absorption. If you must eat these foods or take these supplements, make sure to wait at least four hours after taking your medication before doing so.

The good news is that Synthroid doesn’t usually cause serious side effects or stress on the kidneys or liver. Although some hair loss can be a side effect in the first few months of treatment, most of the time Synthroid improves hair growth. Any side effects are usually the result of overdosage. In 2011, I coauthored the book The Everything Guide to Thyroid Disease with Theodore C. Friedman, MD, PhD, an endocrinologist and chief of endocrinology, molecular medicine and metabolism at Charles R. Drew University of Medicine and Science  in Los Angeles. According to Dr. Friedman, “Too much thyroid medication can lead to heart problems, weight loss, osteoporosis and symptoms of hyperthyroidism including palpitations and nervousness.” Too much thyroid hormone in the blood can put a person at risk for having a bone fracture or a heart arrhythmia. If someone has heart problems, it can also lead to a heart attack. For these reasons, you should never take a higher dosage of thyroid hormone for the purpose of losing weight.

Knowing whether you need to adjust your dosage is a matter of being vigilant about how you feel. It’s important to note whether you’re gaining weight for no good reason, feeling more tired than usual or are suddenly inexplicably depressed. If you notice these or any new symptoms, you should talk to your doctor about adjusting your dosage.

Buying Synthroid

Most people, including me, get their Synthroid from their local drugstore or a mail-order pharmacy. But if you want to buy Synthroid online, make sure to get a prescription from your doctor and use a licensed pharmacy, which means you’ll have access to a licensed pharmacist in case you have questions. Dr. Friedman echoes this advice and encourages patients to read the site’s privacy and security policies to ensure their information is kept private. In addition, he recommends that you always ask for Synthroid and not its generic version, levothyroxine.

Other Options

While levothyroxine, the generic of Synthroid is the drug of choice for people with hypothyroidism, patients do have other treatment options. Many alternative doctors prescribe Armour because it comes from the thyroids of pigs and is believed by some to be more natural and more similar to human thyroid hormone. But many traditional doctors favor Synthroid, believing that synthetic is best, says Dr. Friedman. Since some patients may do better on Armour, however, Dr. Friedman recommends talking to your doctor about trying Armour if you are not feeling well on Synthroid.

Although most patients do just fine taking Synthroid, some do better if they also take T3, the active form of thyroid hormone. Synthroid is comprised of thyroxine, or T4, which is converted into T3 in the body. About 5% to 10% of people taking T4 still have bothersome hypothyroid symptoms. For these patients, adding T3 or Cytomel, to their treatment regimen may help.

For more than 60 years, levothyroxine has been used by millions of Americans. In fact, according to the IQVIA Institute for Human Data Science, 96 million prescriptions were written for generic Synthroid in 2018.

The key to successful use of Synthroid seems to be in the monitoring of the dosage you receive. Keeping close tabs on any changes in how you feel on Synthroid and working with your doctor to make sure your dosage is correct can go a long way in using this ubiquitous thyroid medication successfully.

Winnie Yu is a nationally known writer and author, and coauthor of The Everything Guide to Thyroid Disease.


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