Preconception Thyrotropin Levels and Thyroid Function at Early Gestation in Women With Hashimoto Thyroiditis

[helvella]

Of course, research is necessary. We can all make lots of assumptions, guesses, which turn out to be entirely wrong. But this paper does seem to endorse what many here have said.

If you are going to become pregnant, that itself will tend to raise TSH levels.

If you want to keep below any chosen TSH target, start out with a lower TSH. Therefore, when TSH rises (which is expected), there is more headroom before hitting the target.

Please will everyone who has anything to do with IVF point this out to everyone who works in such clinics?

We've seen far too many cases where IVF and other fertility clinics seem grossly unaware of thyroid issues.

(It would have been great if they had even considered T3 - at all. But we never actually expect that, do we?)

If you are hypothyroid due to Hashimoto's, best get TSH down to 1.25 before conception.

J Clin Endocrinol Metab. 2023 Jun 16;108(7):e464-e473.

doi: 10.1210/clinem/dgac748.

Preconception Thyrotropin Levels and Thyroid Function at Early Gestation in Women With Hashimoto Thyroiditis

Mariacarla Moleti 1 , Angela Alibrandi 2 , Maria Di Mauro 1 , Giuseppe Paola 1 , Laura Giovanna Perdichizzi 1 , Roberta Granese 3 , Annamaria Giacobbe 4 , Angela Scilipoti 4 , Marta Ragonese 5 , Alfredo Ercoli 3 , Salvatore Benvenga 1 , Francesco Vermiglio 1

PMID: 36620924 DOI: 10.1210/clinem/dgac748

Abstract

Context: Preconception optimization of thyroid function in women with Hashimoto thyroiditis (HT) is highly recommended to prevent/reduce the risk of thyroid insufficiency at early gestation.

Objective: This work aimed to evaluate the prevalence of first-trimester thyroid insufficiency in HT women with preconception thyrotropin (T0-TSH) values consistently less than or equal to 2.5 mIU/L with or without levothyroxine (LT4) treatment, and to calculate T0-TSH cutoffs that best preconceptionally identified HT women requiring first-trimester LT4 adjustment/prescription.

Methods: Serum TSH was obtained at 4- to 6-week intervals from 260 HT pregnant women (122 on LT4 [Hypo-HT]; 138 euthyroid without LT4 [Eu-HT]), prospectively followed from preconception up to pregnancy term. Receiver operating characteristic (ROC) curves were plotted to identify T0-TSH cutoffs best predicting first-trimester TSH levels greater than 2.5 mIU/L (diagnostic criterion [DC] 1) and greater than 4.0 mIU/L (DC 2).

Results: At first trimester, TSH was greater than 2.5 mIU/L in approximately 30% of both Hypo-HT and Eu-HT women, and greater than 4.0 mIU/L in 19.7% Hypo-HT and 10.1% Eu-HT women (P = .038). The optimal ROC-based T0-TSH cutoffs found were 1.24 mIU/L/1.74 mIU/L in Hypo-HT, and 1.73 mIU/L/2.07 mIU/L in Eu-HT women, for DC 1 and DC 2, respectively. T0-TSH values exceeding these cutoffs resulted in a statistically significantly increased risk of first-trimester thyroid insufficiency (odds ratio [OR] [95% CI)] 15.92 [5.06-50.15] and 16.68 [5.13-54.24] in Hypo-HT; 16.14 [6.47-40.30] and 17.36 [4.30-70.08] in Eu-HT women, for DC 1 and DC 2, respectively).

Conclusion: The preconception TSH cutoffs that guaranteed a first-trimester TSH less than 2.5 mU/L in hypothyroid- and euthyroid-HT women were, respectively, almost 50% (1.24 mU/L) and 30% (1.73 mU/L) lower than this gestational target, and 1.74 mU/L and 2.07 mU/L in hypothyroid- and euthyroid-HT women, respectively, for a gestational target of 4.0 mU/L.

Keywords: pregnancy; thyroid gland; thyroid peroxidase antibodies; thyrotropin.

As so often, the full paper is behind a paywall:

pubmed.ncbi.nlm.nih.gov/366...

[humanbean]

If you are hypothyroid due to Hashimoto's, best get TSH down to 1.25 before conception.

Ooh yes - that's a good idea. A TSH of 1.25 is the most common result in healthy people with healthy thyroids :

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

...

Edit : Actually I was being a bit facetious with my reply. Most hypothyroid women probably feel at their best with a TSH of 1 or less, so there should be no need to "get TSH down to 1.25" before conceiving because these women should already be there!

[helvella Administrator Thyroid UK in reply to humanbean]

Thyroid seems to bring out the facetious in all of us.

I like your edit! I'm just pleased it isn't 2.5 or higher. And it is in print.

[HealthStarDust]

This is pretty amazing, and roughly correlates with my plan. Thank you!

[Tythrop]

Just a thought , and I'm far to old for pregnancy anyway , but these numbers are interesting to me because they only talk about tsh . What I'm wondering is this: what about the t4 numbers ? Ditto T3 ,although I haven't yet got to grips with t3 / t4 ratios but I do know that I need to do so . So going back to the T4 thing ,given that tsh is not a metabolic hormone as such ,but is a signal hormone for the release of t4 the metabolic hormone , I'm wondering what the t4 numbers might be for pre- conception and early gestation . I'm also thinking whether these researchers are aware of those of us who have downregulation of tsh ( following Graves disease), in the case of these people, the range numbers operate differently I have found .

[helvella Administrator Thyroid UK in reply to Tythrop]

I think your points absolutely must be considered.

This paper simply represents one tiny step in the right direction.