Your Thyroid: How Effective is Thyroxine?

 Issue # 144 October 17, 2013

 

Welcome to KnowYourThyroid.

 

I hope everyone is having a great week.  I love fall and all the activities that come with the season, so far I have made apple crisp 3 times. The apples this year are wonderful!

 

Today, Louise O’Connor is going to explain how thyroxine works and why it may not be the correct prescription for you.

 

Enjoy!

 

Corri

 

 How Effective is Thyroxine Medication?

By Louise O’Connor

Levothyroxine is a synthetic form of the thyroid hormone thyroxine (T4). It is the drug of choice to treat hypothyroidism. It is also the standard medical treatment for goitre, or an enlarged thyroid.

Levothyroxine hormone replacement therapy is only available with a doctor’s prescription. Brand names of synthetic preparations of levothyroxine include; Eutroxsig(r), Oroxine(r), Synthroid(r) and Levothroid(r). This thyroid medication can range in strength from 50 to 200 micrograms.

Levothyroxine dosage + side effects

Levothyroxine is normally first prescribed using a dose at the lower end of the dosing range. Thyroid blood tests are routinely performed to check that the dose is adequate to meet individual requirements. Adjustments to the dose are done gradually until the level of thyroid stimulating hormone (TSH) drops down to the lower end of the standard reference range.

Changes to the dose are minor to reduce the risk of side effects. Too much levothyroxine is associated with an increased risk of atrial fibrillation, a fast and irregular heartbeat. This is a side effect you would expect if your thyroid became overactive.

Levothyroxine has a full therapeutic effect three to four weeks after starting treatment and will continue to have effects for one to three weeks if treatment is stopped. The half-life of this thyroid medication is six to seven days. This means it takes at least six to seven days to clear exactly one half of this thyroid drug from your system. Given that levothyroxine stays in the body for a considerable length of time, the general recommendation for doctors is that the small adjustments to the dose are done at three to four week intervals.

For pregnant women or women considering having a baby their levothyroxine dose is closely monitored by their medical practitioner. The dose is often increased during pregnancy as healthy thyroid hormone activity is particularly crucial at this time. A maternal thyroid deficiency during pregnancy can impair healthy development of the baby’s brain and nervous system.

How effective is levothyroxine?

For many individuals they fail to experience improvements in thyroid symptoms after taking leveothyroxine for months, or even years. They continue to suffer with the frustrating symptoms of an underactive thyroid. Looking at the role of the different thyroid hormones it becomes clearer why a single prescription for levothyroxine may be inadequate.

The thyroid normally manufactures and releases two key hormones: thyroxine (T4) and triiodothyronine (T3). While T4 does have some effect, it is considered the ‘storage’ thyroid hormone. T4 is converted to T3 by the body when a greater thyroid response is required. This means T4 needs to be converted through to T3 to be the most effective.

When conversion of T4 to the more potent T3 takes place its usual to notice improvements in low thyroid symptoms. T3 helps stimulate metabolism which has far reaching effects in the body including sparking energy production, weight loss and firing up brain activity to improve memory and concentration. This scenario also applies to prescribed levothyroxine; the effects are more noticeable when the body can convert this synthetic form of T4 to T3.

There are two nutrients necessary to support ongoing conversion of T4 to T3 and they are zinc and selenium. Less conversion of T4 to T3 occurs when there is a deficiency of these two minerals. Lowered conversion of T4 to T3 also occurs in response to dieting, stress and toxicity.

Many thyroid health experts advocate the use of T4/T3 medications. Using a combination of the two key hormones can compensate for the body’s reduced ability to effectively convert T4 to T3. An example of this is Armour Thyroid medication. This alternative thyroid medication contains both T4 and T3.

A Naturopathic viewpoint

From a Naturopathic viewpoint there is a broad range of factors that influence thyroid health. To see real improvements in thyroid health it is important to identify and address the underlying causes. Stress, an unhealthy diet, specific nutrient deficiencies, food sensitivities and environmental toxins really take a toll on thyroid health.

A nutritional product that provides a comprehensive range of nutrients to assist healthy thyroid hormone activity is recommended. A good quality product features at the very least iodine, zinc and selenium.

Note: Leveothyroxine medication is typically advocated for life and requires ongoing monitoring. Do not discontinue or change your medication without the informed consent of your prescribing medical practitioner.

Click here to check out Louise’s 4 week plan to living well: The Natural Thyroid Diet

References

Cornelli U, Belcaro G, Recchia M, Finco A. Levothyroxine and lung cancer in females: the importance of oxidative stress. Reprod Biol Endocrinol. 2013 Aug 8;11(1):75.

Khandelwal D, Tandon N. Overt and subclinical hypothyroidism: who to treat and how. Drugs. 2012 Jan 1;72(1):17-33.

Roberts, GW. Australian Prescriber. Taking care of thyroxine. June 2004. Available from: http://www.australianprescriber.com/magazine/27/3/75/6.

Mandel SJ, Larsen PR, Seely EW, et al: Increased need for thyroxine during pregnancy in women with primary hypothyroidism. N Engl J Med 1990; 323:91-96

Medline Plus. Bethesda (MD): National Library of Medicine (US). Drug Information for Levothyroxine. Page updated: 25 July 2013. Available from: http://www.nlm.nih.gov/medlineplus/druginfo/meds/a682461.html.

myDr, MIMS Australia. Medicines Health Centre. http://www.mydr.com.au/medicines.

Villar HC, Saconato H, Valente O, et al. Thyroid hormone replacement for subclinical hypothyroidism. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD003419.

Walsh JP, Stuckey BG. What is the optimal treatment for hypothyroidism? Med J Aust. 2001 Feb 5;174(3):141-3.