10 Surprising Facts about Levothyroxine, the Hypothyroidism Drug

a doctor's prescription pad
Dr. Sharon Orrange
Dr. Orrange is an Associate Professor of Clinical Medicine in the Division of Geriatric, Hospitalist and General Internal Medicine at the Keck School of Medicine of USC.
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Levothyroxine is the current standard treatment for hypothyroidism, but many patients are hesitant about a drug they may have to take for their lifetime. I get that. From when to take it and what it does to your body to different options in medications, it can be scary. So, here are some lesser known facts about levothyroxine that may help seal your commitment.

First, levothyroxine is a synthetic hormone used to treat hypothyroidism and the most frequently prescribed medication in many states. Treatment aims to restore well-being by getting the body’s serum thyroid-stimulating hormone (TSH) levels to reference range and the patient to normal thyroid function, or euthyroidism.

How to take levothyroxine

1) Not just for the morning

Because levothyroxine absorption is better on an empty stomach, the standard recommendation is that levothyroxine be taken one half to one hour prior to breakfast. But sticking with that recommendation is a problem for people with unpredictable or variable schedules.

Taking levothyroxine at night is another option. Studies show taking levothyroxine before bedtime is just as effective as one hour before breakfast.

2) Foods to avoid

Know this: foods high in dietary fibers (e.g. beans, nuts, seeds, whole grains), grapes, soybeans, papaya and coffee reduce the absorption of levothyroxine.

3) With T3 liothyronine or without?

This has been a source of ongoing debate for years in folks taking levothyroxine alone. What’s the issue? The thyroid gland secretes both T3 and T4 hormones (levothyroxine is synthetic T4), so studies have focused on whether or not to also replace low T3 levels in hypothyroidism with synthetic T3, liothyronine (generic Cytomel). In other words, should people with hypothyroidism take levothyroxine plus liothyronine?

Clinical trials in humans have not shown clear advantages of this approach over taking levothyroxine alone. Current guidelines suggest that until clear advantages of levothyroxine plus liothyronine are demonstrated, levothyroxine alone should remain the treatment of choice for hypothyroidism.

Health benefits of levothyroxine

4) A levothyroxine a day keeps the doctor away.

Take notice here. A recent study showed that patients who remembered to take their levothyroxine more than 80% of the time were significantly less likely to be diagnosed with bipolar disorder, chronic kidney disease, depression, migraine, obesity, type 1 diabetes or type 2 diabetes compared to those who didn’t stick to taking their levothyroxine.

5) Levothyroxine and Alzheimer’s Disease

This could be very exciting. A recent study on rats with Alzheimer’s Disease showed that injections of levothyroxine alleviated memory deficits and improved levels of Brain Derived Neurotrophic Factor (BDNF), a protein that acts like fertilizer for the brain. While it’s way too early to get excited, these results demonstrated that low-dose levothyroxine improved deficits in learning and memory in those rats. Hmmm, is low dose levothyroxine a place researchers will look next for AD treatment?

6) Levothyroxine and the risk of death

Hypothyroidism in folks over the age of 65 is associated with an increased risk of death. However, a very recent study showed that patients who had replacement therapy with levothyroxine had a lower risk of death compared to those who did not.

7) What happens when you don’t stick to taking it?

Replacement therapy with a thyroid hormone is generally a lifetime commitment, yet after five years of levothyroxine therapy, approximately 22% of patients have abnormal TSH levels anyway because of poor “medication adherence” — aka. not taking their meds on a regular schedule.

Alternatives to levothyroxine tablets

8) Liquid levothyroxine

Levothyroxine oral solution (Tirosint-SOL) theoretically should eliminate the need to take levothyroxine on an empty stomach since the liquid form does not need to be dissolved like tablets do. But even if you had a meal — in particular breakfast, it wouldn’t influence liquid levothyroxine’s bioavailability (or how well it’s absorbed by the human body). However, levothyroxine solution is expensive and hard to find. Additionally, while Tirosint capsules have a relative bioavailability of 103% compared to levothyroxine, they still probably aren’t worth the money.

9) Unithroid or Tirosint

Statistically speaking, you are less likely to stick to Unithroid or Tirosint over time compared to generic levothyroxine. One study showed that taking Unithroid or Tirosint was associated with substantially reduced odds of taking the medication 80% of the time or more compared to taking generic levothyroxine. One explanation for these results may be that Unithroid and Tirosint are more expensive brand-name medications, though the next point throws a wrench into that explanation.

10) Synthroid  

Research shows that you are more likely to still be taking Synthroid at six and 12 months compared to if you started with generic levothyroxine. However, Synthroid is more expensive, so why folks are more adherent with this regimen is unknown. But if you are paying for Synthroid and sticking with it, carry on.

Dr O.

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