Effects of increased thyroxine dosage pre-conception on thyroid function during early pregnancy

Mario Rotondi, Gherardo Mazziotti, Francesca Sorvillo, Marco Piscopo, Michele Cioffi, Giovanni Amato, Carlo Carella

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Objective: To compare the effects of pregnancy on the serum free thyroxine (FT4) levels in two cohorts of primary hypothyroid women treated with different levothyroxine (L-T4) doses before gestation. Design and method: Twenty-five women with compensated hypothyroidism of different aetiology (thyroidectomized and Hashimoto's thyroiditis) were enrolled in this prospective study. The women were receiving substitutive doses of L-T4 and were anticipating pregnancy. They were assigned to two groups: 14 patients (group I) were switched to partially suppressive treatment while 11 patients (group II) continued the same therapeutic regimen. Results: Pre-conceptional thyroid function evaluation demonstrated significantly higher FT4 and lower TSH in group I (P <0.001, for both hormones) and comparable free 3,5,3′-triiodothyronine (FT3) levels. The first post-conception thyroid function evaluation occurred at a median time of 6 (5-8) and 7 (5-9) weeks of gestation, for groups I and II respectively (P <0.05); all women in group I showed adequate serum FT4 levels while three patients in group II showed low-normal FT4 levels and one case was below normal levels. Statistical analysis demonstrated significantly higher frequencies (0% vs 36.4%; P <0.05) of low-normal FT4 levels in patients receiving substitutive doses of L-T4. None of the Hashimoto's-affected patients showed low or low-normal serum FT4 levels regardless of their therapeutic regimen. Conclusion: Our results suggest that in hypothyroid women anticipating pregnancy (with serum TSH in the lower quartile of normal range), the pre-conception adjustment of L-T4 doses may result in adequate maternal thyroid function up to the first post-conception evaluation. The procedure seems safe and inexpensive; it may be a worthwhile treatment, at least in thyroidectomized women, in view of the well-known potential effects of even marginal maternal thyroid hypofunction on the subsequent IQ of the progeny.

Original languageEnglish
Pages (from-to)695-700
Number of pages6
JournalEuropean Journal of Endocrinology
Volume151
Issue number6
DOIs
Publication statusPublished - Dec 2004

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Thyroxine
Thyroid Gland
Pregnancy
Serum
Mothers
Hashimoto Disease
Triiodothyronine
Therapeutics
Hypothyroidism
Reference Values
Hormones
Prospective Studies

ASJC Scopus subject areas

  • Endocrinology

Cite this

Effects of increased thyroxine dosage pre-conception on thyroid function during early pregnancy. / Rotondi, Mario; Mazziotti, Gherardo; Sorvillo, Francesca; Piscopo, Marco; Cioffi, Michele; Amato, Giovanni; Carella, Carlo.

In: European Journal of Endocrinology, Vol. 151, No. 6, 12.2004, p. 695-700.

Research output: Contribution to journalArticle

Rotondi, Mario ; Mazziotti, Gherardo ; Sorvillo, Francesca ; Piscopo, Marco ; Cioffi, Michele ; Amato, Giovanni ; Carella, Carlo. / Effects of increased thyroxine dosage pre-conception on thyroid function during early pregnancy. In: European Journal of Endocrinology. 2004 ; Vol. 151, No. 6. pp. 695-700.
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AU - Rotondi, Mario

AU - Mazziotti, Gherardo

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AU - Cioffi, Michele

AU - Amato, Giovanni

AU - Carella, Carlo

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