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Hypothyroid Medications & Factors that Influence Absorption

How does one typically treat hypothyroidism or Hashimoto’s disease? Thyroid medications, which typically come in several different types available on the market. Today, we will dive a bit deeper into these medications, their different types, and the kinds of effects they can have on your body. From synthetic to natural desiccated thyroid, let’s discuss!

Thyroid Medications: Defined & Explained

The most mainstream way of treating hypothyroidism is using a synthetic medication, Levothyroxine, even though natural thyroid medication was primarily the medicine of choice up until the 1950’s (McAninch & Bianco, 2016).

There are several ways to administer thyroid medication, such as:

  • Tablets
  • Capsules
  • Liquid solutions
  • Intravenous (IV) or intramuscular (IM) injections

The most prevalent way is in a tablet form. The question is what form allows for better absorption and will yield the best outcome of an optimal TSH? TSH is known as thyroid stimulating hormone, and this is the hormone released from your pituitary that communicates with your thyroid gland to release thyroid hormone (1).

In patients with hypothyroidism and Hashimoto’s, they tend to have elevated TSH levels and low free thyroid hormone, hence the need for thyroid hormone replacement. The following are types of thyroid hormone replacement options.

Tablet Forms

Synthroid

The name brand of levothyroxine contains sodium and a number of excipients in each tablet such as confectioner’s sugar, corn starch, lactose monohydrate, magnesium stearate, povidone and talc.

NatureThroid

A form of natural desiccated thyroid, contains Lactose, Colloidal Silicon Dioxide, Dicalcium Phosphate, Magnesium Stearate, Microcrystalline Cellulose, Croscarmellose Sodium, Stearic Acid, Opadry II 85F19316 Clear – tablet coating.

Key Insight: Lactose is found in levothyroxine and also in NDT tablets, but it is not found in capsules or in liquid forms. Keep in mind that in NDT, this is a part of the raw material that is present to make tablets and not added ingredient. RLC labs, the manufacturer of NatureThroid, actually discloses the amount present, whereas other manufacturers may not disclose this information.

Capsule Form

Another name brand of levothyroxine, Tirosint, contains Gelatin, glycerine, purified water.

Liquid Form

Eltroxin, name brand of levothyroxine, is an oral solution that contains glycerine, citric acid monohydrate, sodium methyl parahydroxybenzoate (E219), sodium hydroxide, purified water.

This form of T4 comes as a liquid drop. T4 is usually best dissolved with fats. This form also contains ethanol as a preservative, which then comes with monitoring treatment with caution. A 1mL solution contains 243mg of ethanol.

IV and IM forms

These are non-conventional ways to treat hypothyroidism and are usually reserved for refractory hypothyroidism and in the myxedematous coma and administered in hospital settings.

How Does Thyroid Medication Absorption Work?

To understand absorption, we need to have a better understanding of the exact ingredients and if and how any excipients that are added are affecting thyroid hormone absorption.

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As listed above, different manufacturers add different excipients to thyroid hormone medications.

The capsule form of T4, such as in Tirosint, is resistant to pH changes and resistant to binding to molecules such as coffee in the intestinal tract (Vita, Fallahi, Antonelli, & Benvenga, 2014).

Invitro, the capsule of T4 had the least amount of chance of being affected by pH. This was shown by adding in anti-acid medication, a PPI, known as esomeprazole with a T4 capsule.

Furthermore, the capsule showed that it does not bind as much to food or molecules in the gut, including coffee as much and this can be contributed to the gelatin shell it comes in which acts as a protection barrier (Vita et al., 2014).

Perhaps the capsule form may have a better absorption advantage in patients with digestive concerns such as celiac disease and bariatric surgery.

Since absorption times can vary from person to person, a better method to determine if thyroid medication will be available is how quickly it disintegrates with stomach pH.

If a person has a condition known as hypochlorhydria (low stomach acid), this can also be a factor in how well they will absorb thyroid medication. NDT such as NatureThroid has an expected disintegration time of 15 minutes, usually mostly achieved in 5 to 7 minutes after taking it.

Bottom Line: For patients that are taking tablet thyroid medications and are seeing changes in their TSH levels, a suggestion would be to have them chew the tablet and see if this can help speed up the disintegration process by the stomach and allow for better and faster absorption of the medication.

When is it Best to Take Thyroid Medication?

The timing of taking thyroid medication has been known for over 10 years and numerous studies have demonstrated that optimal intestinal absorption of T4 has been in fasting patients (Bach-Huynh, Nayak, Loh, Soldin, & Jonklaas, 2009).

Other factors that can affect thyroid levels in the blood are consistency with taking medication (compliance), medical conditions such as:

  • Celiac disease
  • Lactose intolerance
  • Gastritis
  • Impaired gastric acid secretion (Bach-Huynh et al., 2009)

Key Insight: Medications can also impair T4 absorption including iron, calcium, cholestyramine, antacids, and excipients added to them.

Diet can also affect thyroid medication absorption, including:

  • Fiber (2)
  • Soy
  • Coffee (Bach-Huynh et al., 2009)

A crossover study from 2009 tested TSH levels on 3 groups of people whose timing of thyroid medication differed. One group took thyroid medication after an overnight fast and 1 hour before breakfast, the second group took thyroid medication 2 hours after dinner and before bedtime, and the third group took thyroid medication 20 mins after breakfast.

The differences in TSH levels were tested and the outcomes suggested that when thyroid medication was taken with breakfast, higher TSH levels were clearly seen. The fasting state was associated with the best TSH outcomes (Bach-Huynh et al., 2009).

If fasting is not an option for patients, thyroid medication should be taken at least 2 hours away from a meal with 8 oz of water and then need to wait at least one hour to eat food or drink caffeine.

Another big factor that can affect thyroid hormone absorption is coffee. A study from 2008 suggested that, when coffee was taken with thyroid medication, TSH hormones varied as much as 25% among different patients that were studied.

Key Insight: It is generally recommended that thyroid medication is taken at least 1 hour prior to coffee or tea consumption to allow for maximum absorption.

A pharmacokinetic study from 2011 showed that when synthetic T4 medication, levothyroxine, was taken along with a calcium supplement, there was a 20-25% reduction in absorption of T4 levels (Zamfirescu & Carlson, n.d.). Any calcium or iron supplement should be taken at least four hours away from thyroid medication.

Bottom Line: Other factors that can affect the absorption of thyroid medication include supplements such as iron and calcium (3).

Heal Your Thyroid Today

Interested in learning more about what you can do about your thyroid health? Take the time to reach out to Integrative Health today to schedule a time to meet one of our doctors to discuss your health – and how you can optimize it.

1. Bach-Huynh, T.-G., Nayak, B., Loh, J., Soldin, S., & Jonklaas, J. (2009). Timing of levothyroxine administration affects serum thyrotropin concentration. The Journal of Clinical Endocrinology and Metabolism, 94(10), 3905–3912. https://doi.org/10.1210/jc.2009-0860
2. McAninch, E. A., & Bianco, A. C. (2016). The History and Future of Treatment of Hypothyroidism. Annals of Internal Medicine, 164(1), 50–56. https://doi.org/10.7326/M15-1799
3. Vita, R., Fallahi, P., Antonelli, A., & Benvenga, S. (2014). The administration of l -thyroxine as soft gel capsule or liquid solution. Expert Opinion on Drug Delivery, 11(7), 1103–1111. https://doi.org/10.1517/17425247.2014.918101
4. Zamfirescu, I., & Carlson, H. E. (n.d.). Absorption of Levothyroxine When Coadministered with Various Calcium Formulations. https://doi.org/10.1089/thy.2010.0296
5. Salvatore Benvenga,1–3 Luigi Bartolone,1 Maria Angela Pappalardo,1 Antonia Russo,1 Daniela Lapa,1 Grazia Giorgianni,4 Giovanna Saraceno,1 and Francesco Trimarchi1THYROID Volume 18, Number 3, 2008 ª Mary Ann Liebert, Inc. DOI: 10.1089=thy.2007.0222

Written by Dr. Linda Khoshaba of Integrative Health. Dr. Linda Khoshaba has been practicing as an Associate Physician at Integrative health for 5 years. She specializes in treating Hashimoto’s and Graves thyroid disease, Adrenal Dysfunction and Hormone imbalance in both men and women.

Learn more about Dr. Khoshaba here.