7 things you should know if you take thyroxine (T4)

Today I booked myself another blood test to check whether the thyroxine (levothyroxine, T4) dose I am on is keeping my other thyroid-related hormones within normal range. I have Hashimoto’s Thyroiditis – a chronic autoimmune condition that, if left untreated, can be a serious problem.

Each time I collect my thyroxine from the chemist he tells me not to have it with milk. I then tell him that I’m dairy intolerant so it’s not an issue. Recently I started wondering what it was about the milk that was a problem. And, are there other things we should be aware of that we aren’t routinely told?

Whether you have Hashimoto’s thyroiditis or another form of hypothyroidism, you need your thyroxine to be working so you feel your best and stay healthy long-term. This is important stuff!

This week I went back to the original scientific literature to check a few things out. Here are some of the things you need to know if you take thyroxine:

  1. Most people on thyroxine have Hashimoto’s Thyroiditis (Davis et al, 2015) – an autoimmune disease that will not go away. It seems that many people on thyroxine don’t really know why they are on it. If that’s you, don’t panic, just book an appointment with your doctor to check it out. Your doctor will explain the medical reasons behind you taking thyroxine and whether or not it is an autoimmune condition, and together you can take control of your health from there.
  2. Thyroxine (T4) is the hormone our thyroid is struggling to produce when we are hypothyroid. It comes in several different forms, but the most common (especially in the UK) is tablet form of synthetic T4, commonly known as Levothyroxine.
  3. Many things affect how well Levothyroxine works in replacing your natural T4 supply.  For example, whether the dose is right, if we take it regularly and whether it interacts with other things that may stop it being absorbed properly into our body.
  4. Levothyroxine guidelines recommend taking on an empty stomach first thing in the morning. This is supported by Bach-Huynh et al. (2009), who also recommend fasting for 1 hour afterwards, and highlight that it can take up to 4 hours for levothyroxine to be absorbed. The idea behind fasting is to maximise the chance of it being absorbed without something we eat interfering.  Do you wait an hour to eat after taking thyroxine? 
  5. Common “morning” foods and habits that can reduce your thyroxine absorption include coffee, soy, grapefruit juice, high fibre foods (e.g. bran, granola and wholemeal bread) and multivitamins that contain calcium and iron (Andrade 2013).
  6. Levothyroxine needs high stomach acidity to be properly absorbed (Centanni et al. 2006) – something people with Hashimoto’s Thyroiditis usually lack!
  7. Levothyroxine can lead to dairy intolerance as it inhibits lactase production (the enzyme needed to breakdown milk sugar). Unsurprisingly therefore, 79% of people with Hashimoto’s in one study were found to be lactose intolerant (Asik et al. 2014). Lactose is often used to “fill” thyroxine tablets, so if you’re concerned about this talk to your doctor about possible alternatives. I’m not sure if this was what my chemist was referring to – I haven’t come across any other milk-related problems with taking levothyroxine, apart from maybe that calcium reduces absorption, have you?

How do you know if your thyroxine is working?

If you keep going back to the doctor and get a higher dose of thyroxine, you may be doing something that is stopping it from working properly, and perhaps you should discuss this with your doctor on your next visit.  Otherwise, try a few things. 1)  do a Symptom check (I am a BIG advocate of this and use it regularly with my clients – it reminds us that we are experts of our own body and only we know how we feel). If you’re having the tell-tale hypothyroid symptoms of fatigue, aches and pains, brain fog etc, then it’s likely you need to review your thyroxine dose or the way you take it. 2) get a blood test and discuss with your doctor whether your hormone levels are within normal range.

Other factors can affect the dose of thyroxine you need, like life-stage and weight, so  make sure you get checked periodically. Also, be aware that you can be within “normal” range and still feel rubbish – that is where point 1 comes in and you will probably need to consider dietary and lifestyle changes to reduce your symptoms. Give me a shout HERE if that’s you!

Do you have a “must-know” fact about thyroxine (preferably backed up by science)?  Let us all know by commenting below.

Remember, if you have ANY concerns about your health or questions about why you are on thyroxine, please discuss this with your doctor (not google).

Don’t forget to share and like this post especially if you know someone who could benefit!

Be well!

Caroline x

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