Factors that can affect levothyroxine absorption
Many food items people don't usually give a second thought to can impact the way levothyroxine is absorbed when it reaches the gut. For this reason, many doctors often advise people to take the hormone while hungry, about an hour prior to a meal. A fasting state helps the body to absorb around 80 percent of levothyroxine taken orally, and also prevents malabsorption of the drug. When it comes to other forms of levothyroxine intake, they are associated with elevated and irregular concentrations of thyroid-simulating hormone.
Many people with underactive thyroid find taking levothyroxine as soon as they wake up to be a solution to this problem. Besides time of the day, certain drugs, herbal remedies, as well as several gastrointestinal conditions can be the cause of erratic absorption of levothyroxine.
The right moment to ingest levothyroxine: before or after a meal?
Although benefits of early consumption of the thyroid medication are indisputable, there's actual research suggesting that levothyroxine taken around sleep time increases the levels of thyroid hormones thyroxine and triiodothyronine, and decreases the levels of thyrotropin.
Many patients have started taking their levothyroxine late at night and doctors should consider suggesting this practice to patients as the plasma lipid levels and overall quality of life showed no major change with morning or evening application.
What types of foods influence Levothyroxine uptake?
It's not only the timing of the meal that affects the levels of thyroid-stimulating hormone. Certain foods don't mix well with levothyroxine as they can cause its malabsorption, as well as fluctuations in the levels of TSH. It's recommended to wait at least half an hour, preferably an hour after levothyroxine dosage before eating again. Certain nutrients can still interfere with proper absorption even if you follow all the “rules” and take levothyroxine as recommended by your doctor. These foods include:
- Most dairy products such as cow's milk, cheese, yogurt, ice cream... They might be rich in calcium and considered good for your general health, but it's possible that they're going to affect the absorption of levothyroxine, so it's best to consume them at some other part of the day, apart from your hypothyroidism drugs.
- Research has found that fiber from food sources elevates the levels of TSH. Most patients will need higher doses of levothyroxine if the hormone is ingested close to a meal that contains soluble fiber such as fiber-fortified bread.
- Espresso coffee is another thing that can elevate TSH levels and cause levothyroxine malabsorption, according to the same research mentioned above. If you love your cup of coffee, make sure to consume it at least a couple of hours apart from your thyroid medications.
Levothyroxine and other medications
Many medications can cause malabsorption of levothyroxine in the body. The reason is still not quite clear, but it probably occurs because certain drugs bind with levothyroxine in the gut, making it impossible for the body to properly absorb the thyroid hormone.
Of all medications that have been reported to interact with levothyroxine, around 70 percent are proton pump inhibitors (PPIs). Reportedly, they increase the gastric pH, which prevents your thyroid medication from dissolving properly in the stomach.
Antacids that contain aluminum are another bad choice to combine with levothyroxine because of the aluminum that binds with levothyroxine in a way that it limits its intestinal absorption.
Levothyroxine absorption and its bioavailability are often affected by phosphate binders including lanthanum carbonate and sevelamer, as well as calcium carbonate.
If levothyroxine is ingested in combination with ferrous sulphate, as a consequence you'll have increased levels of the thyroid-simulating hormone.
Orlistat — a drug commonly used to treat obesity — is reported to cause malabsorption of levothyroxine due to its ability to interfere with gastritic lipases. The ability to break down lipases is quite useful when it comes to losing weight, but it negatively affects many known medications such as amiodarone, warfarin, and cyclosporine.
Colesevela and cholestyramine — bile acid sequestrants — are also to be blamed for levothyroxine malabsorption.
When taken with sucralfate, the absorption of levothyroxine is notably reduced.
If you have a condition that requires treatment with medications listed above, make sure to be careful and try to:
Take levothyroxine couple of hours before or after the other medication, and make this routine a habit
Make sure that you observe your TSH levels often and closely, and search for any evidence of levothyroxine malabsorption
Do not disregard even the slightest deviations from your usual TSH levels.
A link between levothyroxine malabsorption and other health issues
Certain gastrointestinal issues such as celiac disease, lactose intolerance, as well as conditions characterized by increased stomach acidity such as gastritis and Heliobacter pylori are proven to impact levothyroxine absorption.
If celiac disease – the condition that is frequent in people who suffer from underactive thyroid – is undiagnosed and therefore not treated, this autoimmune disorder can cause levothyroxine malabsorption, but it gets better if the condition is treated properly.
If a person is unable to digest lactose — a sugar found in dairy products — this can make them resistant to levothyroxine ingested orally. This occurs quite often.
Having Heliobacter pylori is a common reason for levothyroxine malabsorption. The condition reduces the production of gastric acid, thus making it hard for the body to properly absorb levothyroxine ingested orally.