Over the last 50 years, the use of levothyroxine has rapidly increased and it is now one of the top 10 medications prescribed Worldwide. It has become the second most common prescribed drug in the USA and third most commonly prescribed drug in the UK. But where did it all begin?
History:
During the late 19th Century, doctors experimented by injecting thyroid extract from a sheep’s thyroid into their patients to treat thyroid disorders. Sheep extracts were later charged to porcine (pig) extracts as this was considered immunologically safer, and the treatment became known as Natural Desiccated Thyroid (NDT).
Tablets made using NDT extracts from either pigs or cows, and containing both thyroxine (T4) and triiodothyronine (T3) were then used as the primary therapy to treat hypothyroidism up until the 1970’s. These thyroid hormone formulations were problematic though as they tended to vary from batch to batch making it difficult for clinicians to maintain stable TSH levels in their patients. Some patients didn’t respond to the treatment at all, others developed hyperthyroidism and the product was found to have a limited shelf life. For this reason, most authoritative associations eventually warned against the use of NDT.
Back in 1927 British pharmacists Charles Robert Harrington and George Barger were aware of this issue and so created and brought to market an alternative solution to NDT called thyroxine, a synthetic form of thyroid hormone, taken in tablet form. Early versions of the tablet had limited oral absorption, but by 1949 a sodium salt of thyroxine had been introduced which improved absorption. It was also discovered that the body was capable of producing T3 itself, as long as it had sufficient amounts of T4, thus further validating the use of T4 alone. Preparations were slowly made available for clinical use, but were introduced worldwide, without ever going through any kind of formal randomised controlled trials to test their effectiveness and safety first.
To this day, guidelines state that using synthetic T4 as a standalone monotherapy is the most favourable pharmaceutical treatment for those with a thyroid condition, and that each person’s levothyroxine dosage should be calculated based on their body weight, age and gender. However, finding the right dosage for each person is still problematic and a GP or endocrinologists’ solution is to often increase the dose when symptoms don’t improve, leaving patients frustrated and confused.
How does it work:
3 hours after consumption, between 60-90% of levothyroxine is absorbed in the small intestine, and absorption has been found most effective on an empty stomach. The presence of food has been found to decrease its absorption which is why levothyroxine is recommended to be taken in the morning, 30-60 minutes before breakfast.
Once absorbed, T4 is converted into T3 (this conversion happens mostly in the liver), and T3 is then taken up by the cells of the body. Levothyroxine’s half-life (the time it takes for the amount of a drug’s active substance in the body to reduce by half), is around 6-7 days.
Stomach acid pH levels also play a role in absorption (acidity increases absorption), and so stomach acid alkalising medications like proton pump inhibitors (omeprazole) or calcium carbonate can reduce the absorption and therefore effectiveness of the drug.
It can be very common for people on thyroid medication to still experience symptoms and there could be a number of reasons why this is happening. Some patients may have difficulty converting synthetic T4 in to active T3 if they are deficient in certain nutrients such as selenium, which is required by enzymes known as deiodinases to convert T4 into T3. There may be other underlying factors which also need addressing such as viral load, deficiencies, heavy metals, toxins, a sluggish liver or various stressors.
Getting to the root cause:
An alternative route to overcoming a thyroid disorder is to get to the root cause of what’s driving it in the first place. Both NDT and levothyroxine, whilst providing some kind of temporary relief, only mask the problem at hand. But exploring other healing modalities like diet, lifestyle, acupuncture, homeopathy or herbal remedies can have far more long-term benefit bringing the body back in to balance, rather than simply flooding it with a cocktail of synthetic hormones.
A thyroid diagnosis doesn’t have to mean a lifetime of medication. If you are looking for an alternative, natural solution please feel free to drop me a line and book in a free 15-minute discovery call to see if nutritional therapy could benefit you instead.
References:
Cappelli, C. Gatta, E and Ippolito, S. (2023) ‘Levothyroxine personalized treatment: is it still a dream?’ Frontiers in Endocrinology. 14 Available at: https://www.ncbi.nlm.nih.gov/pmc/articles
Cristelle, R. Mateo, I. and Hennessey, J.V. (2019) ‘Thyroxine and treatment of hypothyroidism: seven decades of experience’ Endocrine. 66(1): 10–17. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6794242/
Eghtedari, B and Corre, R. (2023) ‘Levothyroxine’ StatPearls Publishing. Available at: https://www.ncbi.nlm.nih.gov/books/NBK539808/?report=classic
Harington, C.C. and Barger, G. (1927) ‘Chemistry of Thyroxine: Constitution and Synthesis of Thyroxine’ The Biochemical Journal. 21(1): 169–183. Available at: https://portlandpress.com
https://www.medicinenet.com/what_are_the_top_10_most_prescribed_drugs/article.htm
https://thyroiduk.org/if-you-are-hypothyroid/natural-desiccated-thyroid/https://www.btf-thyroid.org/new-levothyroxine-prescribing-guidance
