optimal ft3 and ft4? : I’ve had a test recently... - Thyroid UK

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optimal ft3 and ft4?

HoneyBee2 profile image
26 Replies

I’ve had a test recently and my results are

Tsh 2.34 mu/L (range 0.27-4.2 mu/L)

Ft4 19 pmol/L (range 12-22 pmol/L)

Ft3 4.8 pmol/L (range 3.1- 6.8 pmol/L)

Tpo antibodies 72 IU/mL

Can anyone help me interpret this? I’m on 25mcg Levothyroxin and I did the blood test early in the morning before I took my levothyroxine.

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HoneyBee2 profile image
HoneyBee2
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26 Replies
greygoose profile image
greygoose

They could hardly be optimal with such a high TSH. Your FT4 is high but it can't be optimal by itself. It needs to correspond to your FT3, but that's low because you're a poor converter.

Why you're a poor converter is anybody's guess. Could be low nutrients, but it could be a lot of other things, too. Could just be because you have Hashi's, and there's nothing anyone can do about that.

So, the only solution - after having optimised your nutrients - is to obtain some T3, and that's not easy. You would need to be referred to a T3-friendly endo and hope he's willing to prescribe.

Sorry to be the bearer of bad tidings, but it's best to know exactly where you are.

HoneyBee2 profile image
HoneyBee2 in reply to greygoose

thank you for replying, you’ve confirmed what I was thinking, it just sucks that the gp won’t refer me and doesn’t care about ‘optimal’ levels as long as I’m not clinically hypo

I got this private test as the first step before seeking help from a private endo who I know prescribes t3, I was unsure about going private but it does seem to be the only way forwards

greygoose profile image
greygoose in reply to HoneyBee2

It often is the only way forward, yes. So, I hope he does prescribe you T3. :)

SmallBlueThing profile image
SmallBlueThing

The late, great Diogenes advised that poor conversion is indicated when fT4/fT3 is 4.5 or higher. Yours is still below 4: your fT3 would need to be 4.2 or lower with your current fT4 for there to be poor conversion, according to this rule.

With older patients, GPs often want to keep TSH within the upper part of the range, supposedly to avoid cardiac complications. That shouldn't be a factor against you asking for an increased dose.

I don't think requesting "optimal" values to some high degree of precision is a reasonable expectation. We're not world-beating athletes with access to frequent testing, and just about everything in the real world works within allowable tolerance ranges.

Noelnoel profile image
Noelnoel in reply to SmallBlueThing

The late, great Diogenes advised that poor conversion is indicated when fT4/fT3 is 4.5 or higher

FT4 or(???) is 4.5 or higher. What does that mean?

SmallBlueThing profile image
SmallBlueThing in reply to Noelnoel

It's fT4 divided by fT3, using SI units (pmol/L, as used by the NHS in the UK).

helvella profile image
helvellaAdministratorThyroid UK in reply to Noelnoel

helvella - T4:T3 Ratios

Some notes and links about calculating T4:T3 ratios and what they mean.

helvella.blogspot.com/p/hel...

inthedoldrums

Noelnoel profile image
Noelnoel in reply to helvella

Thank you

inthedoldrums profile image
inthedoldrums in reply to SmallBlueThing

Me too, I would like to understand because I have the faulty gene for conversion and would like to have a deeper understanding of my test results. Best wishes.

HoneyBee2 profile image
HoneyBee2 in reply to SmallBlueThing

So you think I should be happy sticking with the 25mcg?

SmallBlueThing profile image
SmallBlueThing in reply to HoneyBee2

No, your fT3 is 46% through the range, and a dose increase should take it over halfway through the range, which was one of the recommendations from diogenes and his colleagues. As you are young, that's one obstacle removed from many GPs' reluctance about having TSH in the lower part of the range. If you're on a restrictive diet there could be a negative impact on your nutritional status, which could affect your conversion of fT4 to fT3. Liver, including liver pâté, for example, for iron and vitamins B12 and A, but too much wouldn't be good for you.

An interesting reply from the author (an endocrinologist) to a comment at: hormonesdemystified.com/t3-...

"The first citation is a nice summary of the relationship between iron status and the thyroid, but it doesn’t support the assertion that subtle decreases of iron within the normal range will cause clinically meaningful changes to thyroid hormone metabolism. I think that’s important to note, given the propensity of alt med practitioners to recommend a host of vitamins, minerals, and nutraceuticals to “optimize” levels that don’t need optimizing. Now, if one has a tendency to develop iron deficiency anemia for some reason, I am all for eating iron rich foods to be proactive. But if one has a normal hemoglobin and hematocrit, with no history of anemia, and low-normal iron levels, I would say it is highly unlikely that boosting iron levels would cause a clinically meaningful improvement in thyroid levels."

Incidentally, I found the link above just now, after suggesting to you that seeking some idea of optimal values is unreasonable.

SlowDragon profile image
SlowDragonAdministrator

How long have you been on 25mcg

Which brand

Next step retest again in another 6 weeks INCLUDING vitamin levels

HoneyBee2 profile image
HoneyBee2 in reply to SlowDragon

I’ve been on them for 12 weeks, and have had two test in that time, including vitamins which they say are adequate

SlowDragon profile image
SlowDragonAdministrator in reply to HoneyBee2

Can you add actual vitamin results

Adequate means “Within range” which is not the same as optimal

HoneyBee2 profile image
HoneyBee2 in reply to SlowDragon

The didn’t give me any information, just all the vitamins they tested were ‘normal’

This is why I’m so frustrated, the gp gives me next to no information

SlowDragon profile image
SlowDragonAdministrator in reply to HoneyBee2

You are legally entitled to printed copies of your blood test results and ranges.

The best way to get access to current and historic blood test results is to register for online access to your medical record and blood test results

UK GP practices are supposed to offer everyone online access for blood test results. Ring and ask if this is available and apply to do so if possible, if it is you may need "enhanced access" to see blood results.

Link re access

patients-association.org.uk...

healthunlocked.com/thyroidu...

In reality some GP surgeries still do not have blood test results online yet

Alternatively ring receptionist and request printed copies of results. Allow couple of days and then go and pick up.

Bloods should be retested 6-8 weeks after each dose change or brand change in levothyroxine

For full Thyroid evaluation you need TSH, FT4 and FT3 tested

Also both TPO and TG thyroid antibodies tested at least once to see if your hypothyroidism is autoimmune

Very important to test vitamin D, folate, ferritin and B12 at least once year minimum

Low vitamin levels are extremely common when hypothyroid, especially with autoimmune thyroid disease

Optimal vitamin levels

Vitamin D at least over 80nmol minimum

Serum B12 at least over 500

Folate at least over 20

Ferritin at least over 70

Likely many are scraping along bottom of range

Come back with new post once you get results

HoneyBee2 profile image
HoneyBee2 in reply to SlowDragon

My gp is not going to test all that just because I request it, they do not listen to me, constantly gaslight me and just overall don’t really care/ think I’m making a big deal over nothing

SlowDragon profile image
SlowDragonAdministrator in reply to HoneyBee2

That’s why thousands of U.K. patients test privately to make progress

(Myself included…..only made progress after 25 years left inadequately treated on NHS - more on my profile)

SlowDragon profile image
SlowDragonAdministrator in reply to HoneyBee2

High Ft4 suggests possible Hashimoto’s flare

Early stage hashimoto’s levels can go up and down quite a lot until on or near full replacement dose Levo

That’s why many hashimoto’s patients feel best with TSH below 1 as this will stop your own variable thyroid output

Tanglewooddream profile image
Tanglewooddream

You’re on a very low dose of levo, how long have you been on 25mcg?

HoneyBee2 profile image
HoneyBee2 in reply to Tanglewooddream

Yeah the doctors refuse to increase, they said it will cause more harm than good

SlowDragon profile image
SlowDragonAdministrator in reply to HoneyBee2

Levothyroxine doesn’t “top up” failing thyroid, it replaces it.

Even if we frequently start on only 50mcg, most people need to increase levothyroxine dose slowly upwards in 25mcg steps (retesting 6-8 weeks after each increase) until eventually on, or near full replacement dose

pathlabs.rlbuht.nhs.uk/tft_...

Guiding Treatment with Thyroxine:

In the majority of patients 50-100 μg thyroxine can be used as the starting dose. Alterations in dose are achieved by using 25-50 μg increments and adequacy of the new dose can be confirmed by repeat measurement of TSH after 2-3 months.

The majority of patients will be clinically euthyroid with a ‘normal’ TSH and having thyroxine replacement in the range 75-150 μg/day (1.6ug/Kg on average).

The recommended approach is to titrate thyroxine therapy against the TSH concentration whilst assessing clinical well-being. The target is a serum TSH within the reference range.

……The primary target of thyroxine replacement therapy is to make the patient feel well and to achieve a serum TSH that is within the reference range. The corresponding FT4 will be within or slightly above its reference range.

The minimum period to achieve stable concentrations after a change in dose of thyroxine is two months and thyroid function tests should not normally be requested before this period has elapsed.

TSH should be under 2 as an absolute maximum when on levothyroxine

gponline.com/endocrinology-...

Graph showing median TSH in healthy population is 1-1.5

web.archive.org/web/2004060...

Comprehensive list of references for needing LOW TSH on levothyroxine

healthunlocked.com/thyroidu....

onlinelibrary.wiley.com/doi...

If symptoms of hypothyroidism persist despite normalisation of TSH, the dose of levothyroxine can be titrated further to place the TSH in the lower part of the reference range or even slightly below (i.e., TSH: 0.1–2.0 mU/L), but avoiding TSH < 0.1 mU/L. Use of alternate day dosing of different levothyroxine strengths may be needed to achieve this (e.g., 100 mcg for 4 days; 125 mcg for 3 days weekly).

HoneyBee2 profile image
HoneyBee2 in reply to SlowDragon

I know this but if my doctor refuses to prescribe what can I do?

SlowDragon profile image
SlowDragonAdministrator in reply to HoneyBee2

Get hold of vitamin test results as first step

How long ago were vitamin levels tested?

Are you vegetarian or vegan?

which brand of levothyroxine are you taking

Approximately how much do you weigh in kilo

Has GP done coeliac blood test yet ….if not get tested

nice.org.uk/guidance/ng20/c...

1.1 Recognition of coeliac disease

1.1.1 Offer serological testing for coeliac disease to:

people with any of the following:

persistent unexplained abdominal or gastrointestinal symptoms

faltering growth

prolonged fatigue

unexpected weight loss

severe or persistent mouth ulcers

unexplained iron, vitamin B12 or folate deficiency

type 1 diabetes, at diagnosis

autoimmune thyroid disease, at diagnosis

irritable bowel syndrome (in adults)

first‑degree relatives of people with coeliac disease.

DippyDame profile image
DippyDame in reply to HoneyBee2

Try to see another doctor! This one is a disaster!!

Complain to your Practice Manager that despite your lab results showing that your T4 to T3 conversion is impaired and despite having symptoms of hypothyroidism your GP insists on keeping you on 25mcg levo which is less than the usual starter dose of 50mcg....and is not resolving your symptoms or improving your health.

You need T3....but they fear it because of their lack of knowledge. This one is obviously afraid of T4 too!!

Increasing your levo will absolutely not do more harm than good...that would only be a possibility if your FT3 were over range. But they won't know that because they cling to TSH which research proves is not a reliable marker

Your conversion isn't at rock bottom so Initially increasing your T4 dose might provide some extra needed T3 . You have room to increase to 50mcg....maybe more. Testing will show the way forward

It's a start....but ultimately you are likely to need exogenous T3

The ignorance and lack of empathy showed by this GP is astounding....accept it and suffer or complain and try to achieve appropriate treatment.....or look elsewhere!

How many other patients is s/he failing to treat correctly....it's a scandal

HoneyBee2 profile image
HoneyBee2 in reply to DippyDame

It really is! And they ‘consulted’ with another gp and called me back, saying they both decided it’s too much of a risk to increase the dose, I don’t understand what they think is going to happen

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