Why a different threshold for pregnancy? - Thyroid UK

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Why a different threshold for pregnancy?

Cooper27 profile image
10 Replies

I'm thinking out loud and interested in thoughts.

It's occurred to me that a woman trying to conceive is told that TSH needs to be below 2.5, while non pregnant/TTC, the threshold is 4.something or even 10.

If a woman's body is under extreme stress, their reproductive system tends to shut down because it knows "now is not a good time to add a baby to the mix".

On that basis, I'm thinking our bodies can recognise that it's in a poor way when TSH is over 2.5, so I have to wonder if there's an argument for the threshold to be 2.5 for all?

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Cooper27 profile image
Cooper27
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10 Replies
nightingale-56 profile image
nightingale-56

Makes perfect sense Cooper27 and I think a lot of us would agree with you. Pity most of the Endos do not.

helvella profile image
helvellaAdministrator

My first TSH test, when I already had symptoms, returned 2.1.

It took several more tests and rising on each one to get diagnosed.

I do appreciate the need to avoid jumping in and treating what could be a brief, transient slightly low level of thyroid hormone.

It emphasises the desirability of having test results from when we were well.

The 2.5 for pregnancy issue is a reaction to being sued for malpractice if they didn't do that and the offspring suffered. There is no logic that, in the years following a pregnancy, women might be allowed to have their TSH rise to 5, to 10 or higher.

Cooper27 profile image
Cooper27 in reply tohelvella

I wasn't aware of the lawsuits issue! It really does seem crazy.

I wonder if a woman who had a TSH of 3 pre-pregnancy would be taken off levo after giving birth and only put on again if TSH later went up to 5? Or would they let her stay on for life?

helvella profile image
helvellaAdministrator in reply toCooper27

Sorry - I didn't mean that there had actually been lawsuits (I would have to check), but obstetrics has some of the highest malpractice insurance costs. So they have become increasingly risk-averse - otherwise they couldn't afford to continue in practice.

Given the impact of pregnancy on their bodies, thyroid hormone levels can change significantly in the time after giving birth. Therefore, test results can appear to imply that supplementation is no longer required. After that, yes, I do think letting TSH rise to 5 or 10 is quite possible.

SlowDragon profile image
SlowDragonAdministrator

Mean and mode TSH are under 2 on healthy population

Likely anyone with a TSH over 2.5 has suspect thyroid issue

Median TSH graph

healthunlocked.com/thyroidu...

Plus important when you test TSH ....

researchgate.net/publicatio...

“According to the current TSH reference interval, hypothyroidism was not diagnosed in about 50% of the cases in the afternoon.”

“Further analysis demonstrated inadequate compensation of hypothyroidism, which was defined in 45.5% of the morning samples and in 9% of the afternoon samples”

ncbi.nlm.nih.gov/pubmed/252...

TSH levels showed a statistically significant decline postprandially in comparison to fasting values. This may have clinical implications in the diagnosis and management of hypothyroidism, especially SCH.

Cooper27 profile image
Cooper27 in reply toSlowDragon

That graph is very interesting, and very telling...

tattybogle profile image
tattybogle

I agree with Helvella, it,s not predominantly our well being they are interested for the pregnancy guidelines, it's to protect the fetus from damage.

Cooper27 profile image
Cooper27

Potentially. It's that from where I'm sitting, this seems to acknowledge that there is an optimal level. Potentially an opportunity for the under-medicated to to give their GP a logic lesson...

helvella profile image
helvellaAdministrator

Is that why more women are diagnosed hypothyroid... ? :-) :-) :-)

tattybogle profile image
tattybogle in reply tohelvella

No such luck , they just write 'well, but tired' on your notes , and then call it 'post natal depression' afterwards ! . if i'd realised how long it would take em to think about thyroids i would have encouraged my baby into becoming a Gp,she'd be nearly qualified by now , .......and i still haven't got to try any T3....Oh well!

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