How long does Thyroxine take to start showing s... - Thyroid UK

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How long does Thyroxine take to start showing signs of improving symptoms?

DaveT81 profile image

Hi, I've made a huge post already, so just wanted to ask a shorter question - how long does thyroxine take to start improving symptoms?

I had originally been prescribed 25mg but that didn't seem to do much for me, other than what seemed an initially boost for a couple of days. So I've been prescribed 50mg for 4 weeks.

4 Replies
shaws profile image

Your initial dose was too low, unless you have a heart disease. 50mcg is a starting dose with 25mcg increments every six weeks. It is a slow process as hormones have to be gradually increased.

Unfortunately it is not as quick-acting as a headache pill would be and we all vary on what an optimum level would be (i.e. feel well with no clinical symptoms). 'Feeling Well' means that all symptoms are relieved and TSH around 1 or lower with FT4 and FT3 in the upper part of the ranges, but the last two are rarely tested. We can, however, get a private test if necessary but you might not need them if your symptoms are gradually being relieved.

DaveT81 profile image
DaveT81 in reply to shaws

Hi, my initial blood tests showed TSH and T4 in normal range, with T3 pretty high (but still in normal range) and the private GP I'm seeing mentioned something about 'conversion' being an issue for me. Having seen him again this week, he's upped my dose to 50mg. He's convinced thay all of my symptoms point toward hypo and wants to see how I respond to this. Posted the medicheck bloods I had done prior to starting.

SeasideSusie profile image
SeasideSusieAdministrator in reply to DaveT81


the private GP I'm seeing mentioned something about 'conversion' being an issue for me

Is he saying you're a poor converter? Not so. The results you have posted here show your conversion is excellent, if I have the numbers right, they are very feint:

FT4: 17.5 = 55% through range

FT3: 5.63 = 68% through range

FT4:FT3 ratio is 3.1 : 1 and good conversion takes place when the ration is between 3:1 and 4:1

I felt an improvement after 3 weeks or so initially with a TSH of over 100 😱 but it has taken me a year to notice that I feel completely better after years of generally feeling quite rubbish - hair has grown back, have lost a stone but have also cut out gluten, take iron, zinc and selenium.

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