Preconception Thyrotropin and Thyroid Function in Hashimoto Thyroiditis

Mariacarla Moleti, Angela Alibrandi, Maria Di Mauro, Giuseppe Paola, Laura Giovanna Perdichizzi, Roberta Granese, Annamaria Giacobbe, Angela Scilipoti, Marta Ragonese, Alfredo Ercoli, Salvatore Benvenga, Francesco Vermiglio
The Journal of Clinical Endocrinology & Metabolism, Volume 108, Issue 7, July 2023, Pages e464–e473
https://doi.org/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.

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