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Unexpected Elevated Free Thyroid Hormones in Pregnancy.
- Source :
-
Thyroid : official journal of the American Thyroid Association [Thyroid] 2016 Nov; Vol. 26 (11), pp. 1640-1644. Date of Electronic Publication: 2016 Sep 14. - Publication Year :
- 2016
-
Abstract
- Background: The use of thyrotropin and free thyroid hormone assays to evaluate thyroid function is widespread, but in some situations the results are inconsistent with the patient's thyroid status.<br />Summary: A 35-year-old woman with a known diagnosis of chronic autoimmune thyroiditis was referred to the authors' clinic at week 26 of her second pregnancy. The patient was clinically euthyroid. Consistent with this, her serum thyrotropin (TSH) was normal (0.79 mIU/L), but she had elevated free thyroid hormones-free triiodothyronine (fT3) and free thyroxine (fT4)-as determined by a one-step chemiluminescent assay. The patient was taking levothyroxine replacement therapy (125 μg/day), and the dose was confirmed. Previous blood tests showed concordance between TSH and free thyroid hormone values. The patient was followed up throughout gestation and at 12 months postpartum. During gestation, her free thyroid hormones remained high using one-step methods, while the total thyroid hormone concentration values were within the reference range, in agreement with the TSH values. Postpartum fT4 and fT3 values returned progressively to normality, in agreement with the TSH values. The presence of circulating thyroid hormone autoantibodies (THAb) was hypothesized, which are known to interfere, although to a variable extent, with thyroid hormone one-step assays. Using stored frozen sera, this hypothesis was confirmed indirectly by measuring normal levels of fT3 and fT4 with a two-step method, and directly by demonstrating THAb against the two hormones.<br />Conclusion: Despite their relative rarity, circulating THAb may be suspected when laboratory data are not consistent and contrast with the clinical picture. To the authors' knowledge, no previous case of transient appearance of THAb in pregnancy has been described.
- Subjects :
- Adult
Autoantibodies analysis
Female
Hormone Replacement Therapy
Humans
Postpartum Period
Pregnancy
Pregnancy Complications drug therapy
Pregnancy Complications immunology
Pregnancy Complications physiopathology
Term Birth
Thyroid Gland immunology
Thyroid Gland metabolism
Thyroid Gland physiopathology
Thyroiditis, Autoimmune drug therapy
Thyroiditis, Autoimmune immunology
Thyroiditis, Autoimmune physiopathology
Thyrotropin metabolism
Thyroxine metabolism
Thyroxine therapeutic use
Triiodothyronine metabolism
Pregnancy Complications blood
Thyroiditis, Autoimmune blood
Thyrotropin blood
Thyroxine blood
Triiodothyronine blood
Up-Regulation
Subjects
Details
- Language :
- English
- ISSN :
- 1557-9077
- Volume :
- 26
- Issue :
- 11
- Database :
- MEDLINE
- Journal :
- Thyroid : official journal of the American Thyroid Association
- Publication Type :
- Academic Journal
- Accession number :
- 27538922
- Full Text :
- https://doi.org/10.1089/thy.2016.0112