I was diagnosed with hypothyroidism about 4 years ago after some very unpleasant illnesses which pretty much curtailed my training. I've been on levothyroxine ever since with blood tests every 6 months. Last September I completed my first marathon for 10 years. Since then I have cut back my training to pre marathon levels, and continued with my 3 weekly hard core aerobics classes, My speeds have gone up and I'm feeling great. BUT, I've been losing a lot of weight, my hair is falling out, and I'm not sleeping well. I've got another blood test booked in a couple of weeks, but I wondered if anyone had an opinion on whether my exrecise level is making me need a lower dose of levothyroxine. Has anyone tried varying their dosage to take into account their increased/decreased activity level?



  • MartenkayMartenkay ✭✭✭

    Say you need a blood test now for the reasons you have given. Say you want it fast-tracked with an early appointment with your G.P. to discuss blood results and your general health.

    Do not adjust your dosage of levothyroxine (up or down) without your doctor's instruction. I cannot believe you have even thought about it  "after some very unpleasant illnesses".

  • Thanks for your comments, Martenkay. Actually it was a doctor who suggested varying the dosage according to activity level. I wasn't planning on going ahead without consulting a doctor, I am just interested if anyone else has experienced the same symptoms as this. There is anecdotal evidence that more exercise = more naturally produced thyroxine, but I haven't seen anything from runners, as yet. I like to be as well informed as possible before I see my doctor. After all he/she isn't a runner......

  • I've never heard of anyone varying their dosage depending on activity level, and I can't begin to think how it might work - levothyroxine has a half life of about a week, and it takes several weeks after commencing a dose for plasma levels to settle. So to think that day to day activity should require a variable dose just makes no sense to me.

  • I know that when I'm in hard training my TSH is suppressed - but I don't vary my thyroxine levels as it usually goes back up within a couple of weeks of easing back - and I've never been (possibly) symptomatic of being hyper.

    If you think you can or you think you can't you're probably right.
  • SteadyCJSteadyCJ ✭✭✭

    I have been right on the borderline of dosage, they could not get exact dosage due to tablet sizes, but GP said to take the higher dose for at least a month, if any symptoms to cut back and speak to him again then monitor it for another 3 months. As it was I stayed on the higher dose with no side effects.

    I have never heard of varying the amount required due to increase in actrivity, if your thyroid is not producing enough stuff naturally no amount of exercise is going to increase what it produces.

    I even asked about taking the pills late at night to not interfere with a really early start time for a race, emphatic answer was NO. Take it in the morning 30 minutes before food and mug of tea. So I woke up at 3.15am to take tablets.

    Edited for spelling errors.

  • I managed to get a blood test today and an appointment with the doc on Tuesday. I'll update this thread some time next week.

  • Hi cjbv how did you get on at the doctors? Hope you got sorted.

  • Blood test done and visit to Doctor over. The results were as expected - my dose ws too high and all these symptoms were related to that. I'm expecting to lose the overdose symptoms in about 3 weeks and go back for another blood test after 6 weeks.

    I  chose a doctor with a particular interest in thyroid problems and she told me that my exercise level will definitely be affecting my thyroid levels.I didn't ask her about varying the dose according to exercise levels, but I'm going to keep a record of symptom chjanges and see if I can spot a relationship myself. I guess that is going to take quite some time!

    Thanks for everyone's comments and I hope this discussion is useful to many people. 

  • Glad to hear you're sorted. I wouldn't vary the dose according to exercise as that would be very difficult to judge on a week to week basis but I would be aware that if you enter a period of hard training and your TSH is already on the low side that may push you into being hyper, the lowest I've been tested at is 0.1 - but as I wasn't symptomatic we just left the dose as was, retested about two weeks after my race and found that it had returned to closer to 2 - so no need to change the meds at all.

    Steady - given the half life of thyroxine I think your doctor was being a little pedantic saying that you couldn't take your dose the night before - in fact there's some research supporting taking it before bed rather than in the morning


    If you think you can or you think you can't you're probably right.
  • MartenkayMartenkay ✭✭✭

    Good to see that your doctor quickly identified your problem. Your symptoms were typical of too high a dose. You might have saved your eyebrows! What you will probably soon find is that your weight will go back to normal and you will begin to sleep better and generally feel better..

    Obviously I know nothing of your running but it is likely that you will also see some falling away of speed or having to work much harder to maintain levels reached. Yes, you've been having some assistance! image

  • Just want to join this thread. My annual follow up has indicated I might have hypothyroidism. They're tracking me for a bunch of illnesses that are common following radiotherapy and chemotherapy.

    My haematologist has suggested a retest. I have to talk to my doctor on Monday. Would marathon training/overtraining cause false readings. 

    My blood test was done 3 days after a half marathon PB on a hot day and a hard course.

    Obviously I'll go for a retest but am now training for a September marathon.

    My only symptoms are tiredness and sore skin, which on their own I heven't taken much notice of. 

  • SteadyCJSteadyCJ ✭✭✭

    TimR, I only had 3 symptoms - extreme tiredness, dry skin and my periods went haywire, so it is possible.
    You are sensible in having a retest, so long as you are not overtraining at the moment for your marathon I would have thought the next blood test would be more representative of the hormone levels.

    Thanks for the link Little Miss Happy, it was the pharmacist who made the comment, I will not worry next time I have such an early race start.

  • Hi Tim, I wouldn't expect marathon training alone to make much of a difference to your TSH or T4 readings but there is little research on the subject. I have to be training consistently around 12 - 15 hours a week for it to affect my results.

    Glad to be of help Steady - it's bad enough without inconveniences like that!

    If you think you can or you think you can't you're probably right.
  • Thanks for your input. I ran 14miles this morning and struggled. It was hot but I've had no energy this afternoon at all. I'll report back soon. 

  • Soonish then. Marathon completed on Sunday and went to see doc this morning. Second test confirms hypothyroidism. Now have a prescription so let's see how I go from here.

    Any tips?

  • Just keep taking the tablets.image

  • As above!

    And just to add in - I always take my tablets in the evening and my bloods have been stable for years image

  • You may need to pace yourself for a while - I found working to HR helped me as it stopped me beating myself up over being slower and also meant that I could keep the distances up easier. Once you have your meds sorted though there's no excuses - I've PBd at all distances and do IM triathlons with reasonable success image

    If you think you can or you think you can't you're probably right.
  • Will I slow down when I start taking them or just stay the same and notice an improvement in 3-4 weeks? 

    I generally run to HR on 13mile plus runs anyway. 

    I have a 10mile race in October and planning a PB half marathon in November. 


  • I see no reason you should slow. Like Bookie I take my meds at night - no hassle with when you drink your coffee or pre-race etc.

    If you think you can or you think you can't you're probably right.
  • Ok, just wondered why you said you were beating yourself up over being slow. Did you just mean slower than other people who appeared to be training as hard and were apparently as fit?

  • Thanks for raising this thread again. I may decide to swap to taking my meds at night, it will just mean taking the calcium and Vit D tablets in the morning and lunch time rather than lunch and dinner as there needs to be a 4 hour gap to the Thyroid meds.

  • I was quite ill before being diagnosed Tim - could barely manage to walk and breath at the same time - so it took me a while to get my running back whereas you've been able to carry on so should be fine. When my meds have needed adjusting as the TSH has risen I haven't noticed a difference in my running.

    Steady - taking them at night makes life much easier and as I linked to before there's some good evidence that it actually aids absorption.

    If you think you can or you think you can't you're probably right.
  • Resurrecting the thread a bit. 

    I was prescribed 25mcg to start with and waited until my 10mile race was done before starting. 

    10days in. I'm feeling quite a bit better already which I'm guessing is because I'm only very slightly hypo. For the first few days up to last weekend I was getting quite bad sudden headaches that disappeared quickly but they seem to have gone now.


  • Pleased to hear it Tim - strangely enough I was wondering how you were getting on only this morning whilst out on my run.

    If you think you can or you think you can't you're probably right.
  • That's weird. image

    but also happens to me quite often. Think of someone and the phone rings...

  • I've only just come across this very interesting thread. I was diagnosed as diabetic in 2007, had some trouble adjusting, but have finally found various ways of coping with training, racing and blood sugar levels going up and down - only to be diagnosed this year, like a lot of diabetics, with hypothyroidism. My symptoms weren't major - a bit of weight gain, some tiredness, but mainly slower times for just about every race I went in for after years of getting better. In a lot of cases I suffered catastrophic loss of energy about halfway through most things. Since my blood is tested pretty regularly, they soon discovered low readings and I've been put on levothyroxi. My impression after a few months of this is that it's a much more difficult condition to prescribe for. With diabetes, if you are insulin-dependent, you more or less work out how much insulin you need for every 10g of carbohydrate you take in and bob's your uncle. It seems to me it's not that simple with thyroxin - there's no simple way of working out what you need or when. Which means that despite those months of meds, my running shows little sign of picking up. That might just be age - I'm over 50 now - or lack of fitness, but I don't know. I'm sure further tests will help me out, but is this what others have experienced or are experiencing? I've been told that over-50s should beware taking anything higher than the prescribed dose, but I'll admit it's tempting nearer a long race or run to do so. Does anyone do this and does it help or hinder? Didn't realise it was all so widespread, but now I've found a home!image

  • Peter - taking the odd extra dose won't really help you as levothyroxine has quite a long half life. If your TSH and T4 are now normal I wouldn't expect you to still be experiencing symptoms to the extent that you describe, I presume you've been tested for pernicious anaemia too?

    If you think you can or you think you can't you're probably right.
  • I think I've probably been tested for everything under the sun, but I shall ask next time I see a doc. I haven't actually been tested yet since I've been taking the tabs, so I must sort that out...

  • Monday I finally got the results from my latest blood test and now have a lower dose to take, which will be easier as it is only one tablet now and I have switched to taking it at night. So far I have only felt slightly colder but that is probably the weather.

    Next blood test in 3 months.

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