My pregnant wife, contradicting lab results. Challenging to understand

[Zsolt]

Hello i need some advise for my wife,

She is pregnant and doctor prescribed to her T4 hormone, but i am concerned.

Her results are:

TSH 1,06 mIU/L 0.49-2.33 -> looks very good

FT4 10,16 pmol/L 10.30-18.11 -> this is low

FT3 5,33 pmol/L 3.80-5.81 ->looks normal

Tireoglobulin 16,83 μg/L 1,10 - 35,00 ->normal

Extra test were made to detect Auto Immunity for all parameters. Came back perfectly normal. Also we tested serum iodine, and that is low.

Iodine(serum) 42,0 ug/l 46,0 - 70,0

She is 165cm/55kg 8th week in pregnancy, not anyhow over weighted. however she is sleepy, cold always, and was always constipated, now with pregnancy extremely constipated(cannot go to toilet without Magnesium) so some symptoms of the Hypo is presented.

My questions:

a. How come her TSH and FT3 are normal, while T4 is so low? I cannot find any reference that is similar, i found her results really contradicting.

b. Does she can be really Hypo?

c. How much iodine is needed to get her back to normal? we started 150mcg now, and 3 times a week 225mcg

d. Does she need the T4 hormone?

Really appreciate any help that i get, even a clue might help!

Thank you!!

Zsolt

[Hidden]

Hi zsolt. It looks like you wife may have some form of thyroid resistance which leads to a low T4 as the body trys to convert as much as possible to the active thyroid hormone. People with thyroid resistance usually produce enough thyroid hormone but it does not get absorbed very well at a cellular level. She needs some NDT or preferably T3. The bad news is that her condition is very unlikely to be recognised with in NHS. There is a list of more helpful doctors available via the website and you also might want to consider self treatment.

[Poniesrfun]

The requirement for T4 is increased in pregnancy, as is iodine. The developing baby needs T4 for normal neural tube development, the fetus can not utilize T3 as it does not cross the placenta. Prenatal vitamins should supply adequate iodine and other trace minerals - they are usually more potent than every day supplements. Once the developing baby has its own thyroid, (I think around month 3 but don’t recall offhand) he/she will use iodine to create its own thyroid hormone.

Does Your wife still have a thyroid and does she normally take T4? In this case the ATA Guidelines call for increasing T4 immediately upon learning of pregnancy without waiting for lab work, then retesting every four weeks. The doc did the right thing in prescribing T4.

Patti in AZ

[Zsolt in reply to Poniesrfun]

That clears some things thank you! She has thyroid yes, never took hormone before. And she just got this tablets now, but they were aware of lower range t4 since 3 weeks!! Shit..

[SilverAvocado]

Were these results before she began any thyroxine?

In general, this is actually quite a common pattern. The thyroid produces mainly T4 and a little T3. T4 is a storage hormone and T3 the active hormone, so the body has to convert T4 into T3 for most of its needs.

When the thyroid very first starts to fail, this can be seen as low freeT4. But to combat this the body is able to ramp up the efficiency of its conversion to keep freeT3 in a good place.

This pattern pops up on the forum quite often. However I don't know anything about the specific pregnancy situation, it may be as one poster mentions that the baby hoovers up some of the T4 the mother produces and this puts extra pressure. But for non-pregnant people this pattern is common. The baby's thyroid is producing it's own thyroxine surprisingly early, I can't remember the exact time, but you can easily look it up.

It's also common that people with this pattern will start to feel symptoms even though the freeT3 remains at reasonable levels

The more difficult question is about adding thyroid replacement at this point. As you say, your partner's TSH and freeT3 both look good for a health person. TSH skews towards the bottom of the range, and hers is actually at the low end of normal (raised TSH means the body needs more hormone). The ranges for the frees are normal curves, so most people will be close to the centre.

On the contrary, once a person is on thyroid hormone, they will need a completely different pattern. In order to feel well most people will need freeT3 right at the top end of the range, and TSH suppressed below range. For many people, starting on 50mcg of T4, a common starting dose, will make them feel worse before they feel better.

I hope people will come along and suggest how to raise a dose to tune it in pregnancy. For a non-pregnant person you would go very slowly, and test and raise every 6 weeks, but when pregnant you want to get to a good dose as early as you can.

[Zsolt in reply to SilverAvocado]

Thank you! She got 25mcg Letrox. This results were measured 2 weeks ago, before any hormone. We talked thru and decided to take it, because of the baby only. Normally i would wait what would the increased iodine will effect, and retest. Because that alone can cause this i think. But about the dosage of iodine i am not sure.

She was taking 75mcg daily when the lab tests were done, now we raised to 180mcg daily.

That raise + T4 hormone can easily put her to the other side i am afraid.

[SilverAvocado in reply to Zsolt]

Zsolt, are you supplementing iodine? This is very controversial on the forum, and can be very bad for the thyroid. Unless you are outside the UK and in a country where iodine deficiency is common? These days it is very very rare to be deficient. Use the search box to look up iodine and see what people on the forum are saying about it.

25mcg is an absolutely tiny dose of Letrox. Usually people start on 50mcg, unless they have a heart condition or are otherwise at risk. It's very possible she will feel worse on even 50mcg, as low doses can disrupt our own thyroid, but not be high enough to actually add anything.

[Zsolt in reply to SilverAvocado]

Yes we supplement with iodine, because she is deficient on that. And we live outside UK, actually in place where iodine deficiency is more common. I have looked thru what she eats, and iodine deficiency is very justified.

I think she already feel worst on the 2nd day immediately. More fatigues, more nervous, depressed even. This is what the doctor said, and despite i don't really trust him, because of the baby, i am afraid this is a path that we cannot do otherwise right now. She need that extra T4.

[SilverAvocado in reply to Zsolt]

It's a difficult situation you are in

Hopefully she will get a dose increase as soon as possible. It's common to feel worse on a lower dose, so it might be reassuring to know it's not in her imagination!