Thyroid UK

After dosage reduction, how long for blood results to change?

For the first year after being diagnosed with an under active thyroid I felt very unwell. My GP eventually referred me to a wonderful consultant who has allowed me to select my own dose of thyroxine judging by how I have felt instead of blood test results.

However, after two years I have now been passed onto another consultant who insists I must reduce my dose as all previous blood results are consistent with over-treatment. I have been told the aim is to normalize my free T4 & T3 and to avoid TSH suppression.

I have quite a stash of thyroxine and obviously want to stay on my present dose as long as possible.

My question is how long before my next blood test should I think about reducing my dose? Is this something that takes months or could I reduce literally the week before in order to get a lower result reading?

5 Replies

I would advise not reducing your dose if you are feeling well. Why should you only because the Consultant you are now seeing is going only by your blood test results and not your wellbeing.

An excerpt - go to date November 24, 2001:-

In deciding what dose of thyroid hormone is safe and effective for a patient, urine levels of T3 and T4 are as useless as blood levels of the TSH, T3, and T4. (Elsewhere, I've give my view on the use of free T3 and free T4 serum levels to adjusting thyroid hormone dosage.) The response to a particular dose of thyroid hormone varies in different tissues in the same patient, and the response varies in the same tissues in different patients. The typical patient wants more than most anything else to overcome her symptoms and recover her health. To achieve this, variable tissue responsiveness dictates that she use a thyroid hormone dose that produces desirable tissue responses—regardless of what the dose does to her blood or urine T3 and T4 levels.

Another Extract of Dr Lowe's reply:-

I don't believe that measuring the free T4, free T3, or any other circulating hormone level, is the most effective approach to adjusting patients’ thyroid hormone dosages. My belief is based partly on the studies of Escobar-Morreale and colleagues in Spain.[1][2] Those who advocate the use of free T3 and free T4 levels to adjust patients' dosages imply that these levels reliably predict T3 concentrations in cells. However, Escobar-Morreale’s studies make one thing clear—circulating free T3 and T4 levels don't allow us to accurately predict T3 concentrations in the cells of most tissues. His studies show that there’s simply too much variation in cell T3 concentrations in different tissues in the same patient. Moreover, there's too much variation between the tissues of different patients. This makes predicting the physiological and clinical effects of different dosages, and of different circulating free T3 and T4 blood levels, unreliable. Again, there's simply too much variation between patients to allow accurate predictions from blood hormone levels.

"Dr. Broda Barnes was right when, long ago, he wrote that circulating levels of hormones don't measure what's most important. What’s most important is (1) how the patient's tissues are responding to a dosage of thyroid hormone, and (2) the physiological and clinical effects on the patient of that dosage.


Hello shaws. I hear what you say and will fight to stay on my present dose no matter what.

I have felt so well for over two years and do not suffer any over treatment symptoms whatsoever. Thank for your reply.

1 like

You can just refuse to see the new consultant and refuse them any blood. Why did you see him if you were feeling ok on the dose you had?

If you are as over treated as the consultant says, then you would have signs and symptoms. If you go back to him ( why?). Then you could ask him what the long term consequences of over treatment are. He will say osteoporosis... Volunteer for a dexa scan. Then he will say heart problems.... Volunteer for an echocardiogram... Do you have a tremor? Heat intolerance? Weight loss? In fact do you have any signs of over treatment? Tell him you will continue on your present dose and will inform him of any of the previously listed signs appear and will reduce your dose accordingly.

Been there done that.. :-).

Xx. G

1 like

Thank you galathea. I do not have any over treatment symptoms and am feeling great. The new consultant shattered me, immediately bringing back all that desperation of feeling so unwell when I was first diagnosed. He only wants to reduce my dose of Levothyroxine by 10mg a day but I know my magic number is 137.5mg a day (given by 125mg one day and 150mg the next). I have previously played around with these doses and know that any increase gives me loads of ezra energy but at the cost of extra heart beats and sleepless nights. Any less in dosage and I suffer all the usual... lethargy, buzzing in my ears, internal tremors, loss of confidence, slow healing, etc.

You are so right... and I will stay on my magic dose and prepare my defence in plenty of time so I don't go worrying about it.

Thank you for your kind and sensible reply.

1 like

Currently mine are on the NHS but nothing is ever guaranteed in the world of thyroid so it might be I will have to order again from them on a regular basis in the future....... Thanks :)



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