Log in
Thyroid UK
93,531 members107,580 posts

Question about retesting timing (TSH+ ft4)

So my doctor wants to test my thyroid function once more as TSH 3.5 (0.4-4.0) and ft4 10 (10-25) is not good, but not bad enough for start trial of levo. I do understand its the ground rules and my doctor cannot prescribe based on my previous levels that was tested in different hospital. (TSH slowly increasing since last August and ft4 rock bottom, not budging at all)

So I was tested two weeks ago (27th Feb) and she said that I can book lab when I feel doing so four to six weeks from now. She said that she wants to have that certain gap between testing so we could see TSH would rise above 4 which is the limit for her to safely prescribe levo regardless of rock bottom ft4 and symptoms.

Ofc I am keen to have it tested four weeks from now meaning 6 weeks between testing. Is it enough if we assume TSH would continue increasing? I had myself tested privately 5 weeks before 27th Feb when TSH was 3 and ft4 10.

My other concern is that as I was put on high vit D and iron to improve D and optimize iron , does it have impact on thyroid levels? My ferritin and iron were slightly low, not anemic and nothing dramatic, but low enough to get ferritin (and vitamin D) retested end of May.

It concerns me as the doctor has their hands tied and cannot go just by low ft4 even though I am symptomatic. I know I have to take vit D and iron and cannot skip them just to see what happens to my thyroid levels.

If I am not making sense, I am sorry I am ridiculously sleepy, it was awful weather to drive and it was very consuming.

10 Replies

Hi Justina. Vit d and iron need to be at optimum levels for thyroid to function properly.

TSH is highest first thing in the morning, so I wondered what time of day you had bloods, and did you eat or drink (other than water) beforehand?

I've had quick glance at your previous posts, and I note that you feel the cold. I also was cold (especially when tired) when others weren't, and TAT. Now for last 6 months I've been working on boosting iron levels, and do feel much better and warmer (a first for me!!).

My GP was also reluctant to prescribe levo, as my T4 was "normal" (but low), albeit TSH was above 4. I argued that given the symptoms, and lack of anything constructive from that GP, she eventually agreed to a trial. I only discovered the low iron when I switched GP.

Most using this forum will tell you that unless TSH is below 2, they have symptoms. Suggest you try different GP for 2nd opinion if nothing else; and argue case based on symptoms as they're not supposed to rely just on lab results.

Hope you feel better sooon. It's awful being cold and tired.


Yeah I hate being cold! Needed three blankets this winter even though it was not as cold as usual. Worst times it can be -35 for a week! So popping out during times like that is torture! :D

But i have been intolerant to cold for several years so low iron isn't the only possible cause. But ofc I hope improving iron level helps with some symptoms.

I am glad this doctor monitors my iron even though it's mildly low. My sister in law was severely anemic with ridiculously low ferritin and iron because of ovarian fibroid size of big orange. She had iron transfusion and hysterectomy and nothing but haemoglobin tested since!

I agree I will find another doctor if my current doctor can't help. I have been so tired ever since my ft4 started dropping and cant continue this way.

Last time I was tested at 8 am and had fasted.

Over here in finland at most places they won't test you after 10 nor if you have eaten. They ask that before testing and reschedule if you haven't fasted.



There's not likely to be much increase in TSH in under 6 weeks. Book the test as early as possible in the morning when TSH is highest and fast (water only) because TSH drops after eating and drinking.

Good levels of vitD aid T4 to T3 conversion but if your T4 is low there won't be much to convert.

1 like

Thanks. My doctor said it's upto me when I want to get retested based on how I feel as my sleepiness has worsened

I can take three hours nap after bucketful of coffee. All other tests were clear so no infection or illness that would explain my symptoms.

Fortunately she is willing to monitor me!


Has gp tested antibodies? A positive antibody result is evidence that you have Hashi's and along w your low t4 you might get somewhere.

Tsh can fluctuate so just because you're leaving six wks between tests is no guarantee your tsh will be higher then than previous test. It is said that the earlier the blood draw the higher the tsh will be, and that the test should be fasting. Some (bad? good?) luck is involved.

In my layperson's opinion there's no reason why you can't skip the iron and vit d for a short period. If they hadn't been tested you'd be none the wiser and wouldn't be supplementing. I do not know if this will have any effect on your tsh though.

Truth be told if they know you have antibodies and your t4 is *that low* it's a bit cruel to leave you hanging like this but I understand your doc is better than most if you'll get treatment when you tsh hits 4.

1 like

Unfortunately I have been gluten, dairy and sugar free for years before I had my antibodies tested. Last summer I had elevated TPOAB twice, but now low again. That time different doctor didn't want to treat as TSH was just 2.5 and ft4 10.

My current doctor tested antibodies but negative this time. Last summer my antibodies were elevated after I tried to reintroduce dairy and that other doctor did agree that dairy could indeed be the trigger as some doctors have noticed that if patient has casein antibodies they most likely have elevated TPOAB.

Tho i have had high thyroglobulin few times which is considered normal leakage and ignored as i don't have thyroglobulin antibodies.

My current doctor is very nice and I get along with her very well. She isn't denying hypothyroidism she just can't help before TSH is 4. As my symptoms worsened when my ft4 dropped down to 10 it's clear indicator for her, but the rule is to follow TSH. Which is unfortunate for us patients, but no can do :(

She said I can try to find another doctor. I said at this point it's pointless as new doctor will want to test me as well and I still have to wait until I can get tested. So I will wait until I get tested as it's in public hospital it's free and then find another doctor.


Yes, I do understand your doc sounds good, certainly much better than many. If she is interested in your well-being that's half the battle. Good luck. :-)

1 like

Just in case, this link might be helpful in informing GP as well as you :)


1 like

That's informative chart! Thanks :)

I noticed it consider TT4 as valid value too. My TT4 is 2.5 (5-10.8) and I have tried to explain it cannot be considered nowhere near normal as it is consistent with my dropping ft4. I would understand if tt4 as single value would be ignored as you can still have normal ft4.


I would put this question onto a fresh post as those who are more knowledgeable will respond. It is an interesting question. It's a pity doctors are so unknowledgeable where hypo is concerned.

1 like

You may also like...