Serum thyrotrophin concentration measured by sensitive assays in normal pregnancy

Chan, B.Y.; Swaminathan, R.

doi:10.1111/j.1471-0528.1988.tb06828.x

Cited by 20 publications

(9 citation statements)

References 16 publications

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“…Con siderable evidence indicates that the in crease in serum TBG concentration is due to increased hepatic synthesis, stimulated by the increased serum estrogen levels associ ated with pregnancy, and largely derived from placental production [9], Despite ele vated total levels of serum thyroid hor mones, we have observed that the biologi cally active forms (FT3 and FT4) remain within the euthyroid range, in agreement with previous reports [10,11]. In addition, the slight decrease observed for maternal TSH levels, which is also in accord with recently published data [12], may be attrib uted to the presence of other thyroid stimu lators, human chorionic gonadotropin and human chorionic thyrotropin [13][14][15],…”

Section: Discussionsupporting

confidence: 82%

Thyroid Function in Fetus and Mother during the Second Half of Normal Pregnancy

Radunovic

Nastic²,

Mandelbrot³

et al. 1991

Neonatology

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Thyroid hormones, thyroxine-binding globulin (TBG) and thryrotropin (TSH) concentrations were measured in 46 paired fetal and maternal blood samples collected between 17 and 36 weeks of gestation. The samples were selected retrospectively from fetuses that had undergone cordocentesis for prenatal diagnosis, had been found to be unaffected and confirmed healthy at birth. In maternal serum, total thyroxine (TT₄) and triiodothyronine (TT₃) concentrations were high, but free thyroxine (FT₄) and free triiodothyronine (FT₃) were within normal adult ranges; reverse T₃ (RT₃) increased and TSH levels decreased towards term. Fetal TT₄, FT₄, TT₃, FT₃, TBG and TSH levels significantly increased whereas RT₃ sharply decreased with gestational age. The ratio of fetal TSH/FT₄ significantly decreased, suggesting that the set point for negative feedback of pituitary TSH secretion is changing while the sensitivity of the thyroid gland to TSH increases throughout gestation. There was no significant correlation between the maternal and fetal TBG, TSH, TT₄ and FT₄, whereas maternal TT₃ was positively correlated with fetal TT₄, FT₄, TT₃ and FT₃. Normal reference values for maternal and fetal iodothyronines, TBG and TSH throughout the second half of gestation provide insight into fetal thyroid development and may be useful for prenatal diagnosis.

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Section: Discussionsupporting

confidence: 82%

Thyroid Function in Fetus and Mother during the Second Half of Normal Pregnancy

Radunovic

Nastic²,

Mandelbrot³

et al. 1991

Neonatology

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“…Twelve healthy pregnant women (mean age 28.2 years, range [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37], who attended the First Obstetric and Gynecology Clinic of the University of Milan, participated in this study after giving informed consent. Seven of them were primiparous.…”

Section: Methodsmentioning

confidence: 99%

“…5, 23], decreased [1,8. 18-22, 24, 25] or even increased [2,3], with higher [4,24,25], unmodified [2,7,22] or lower [3] TSH values. In some instances, these different results have been related to methodological aspects of TSH and free thyroid hormone assays.…”

Section: Introductionmentioning

confidence: 99%

“…6-8], These results have been related to the presence of elevated hCG levels, the intrin sic thyroid stimulating activity of which has been shown by several authors in various in vivo and in vitro bioas say systems [9][10][11][12][13][14][15], However, Amir et al [16,17] did not confirm hCG thyroid stimulating activity, at least on human thyroid tissue. Other studies of thyroid function in humans showed no modifications [18][19][20] or even a decrease [21,22] in free thyroid hormone levels in the presence of decreased [20. 22] or increased [21] TSH concentrations.…”

Section: Introductionmentioning

confidence: 99%

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Maternal Thyroid Function in Early and Late Pregnancy<sup>1</sup>

et al. 1991

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Thyroid function was investigated during and after pregnancy in 12 healthy euthyroid women. During pregnancy, serum total T₄ (TT₄) levels were significantly elevated and nearly stable, while thyroxine-binding globulin (TBG) levels progressively increased till the 7th month. A slight elevation, though not significant, of free T₄ (fT₄) was recorded in early pregnancy. In the following months, fT₄, free T₃ (fT₃) and the T₄/TBG ratio progressively diminished, reaching a plateau at the 7th month. Serum TSH levels, measured by an ultrasensitive immunofluorometric assay, were comparable to postpartum values during the first trimester and showed a moderate upward trend with the progression of pregnancy. The evaluation of 24-hour TSH profiles was performed in 5 women during the first trimester of pregnancy. In all women, the circadian rhythm of TSH was present with a normal nocturnal surge, though anticipated in 1 case. In summary (1) during the first trimester of pregnancy, the increased thyroid activity does not seem to be only sustained by pituitary TSH which remains unmodified; the negative correlation between TSH and hCG levels might suggest that hCG also stimulates the gland to increase thyroid hormone output, and the presence of a normal TSH circadian rhythm indicates that the central mechanism of neuroregulation of the pituitary-thyroid axis is preserved in early pregnancy, and (2) in late pregnancy, a marked decrease in free thyroid hormone fractions is accompanied by serum TSH levels still in the normal range, indicating a modification of thyroid homeostasis which might recognize various etiological factors.

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“…The concentration of thyroid-binding globulins increases with gestation as a result of estrogen stimulation and therefore measurement of the total amount of thyroid hormones does not provide an accurate reflection of active free (F) fraction of these hormones [11,12] . Previous studies reporting reference ranges of thyroid function in early pregnancy examined a small number of patients, or the gestational range was wide, maternal history of thyroid disease was not recorded, anti-thyroid antibodies were either not measured or patients with such antibodies were not excluded, or they did not examine serum TSH with both FT3 and FT4 [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] .…”

Section: Introductionmentioning

confidence: 99%

Maternal Thyroid Function at 11–13 Weeks of Gestation

et al. 2010

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Objective: To establish normal ranges of maternal serum thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) at 11–13 weeks of gestation. Methods: Maternal serum concentrations of FT3, FT4, TSH, anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) antibodies were measured at 11–13 weeks. Normal ranges were constructed from the data of singleton pregnancies with no anti-thyroid antibodies resulting in live births after 34 weeks of phenotypically normal neonates with birth weight above the 5th percentile. Adjustments were made for maternal characteristics found by multiple regression analysis to affect the levels of TSH, FT3 and FT4. Results: 3,592 of the 4,318 pregnancies examined were antibody negative, and in this group serum TSH increased whereas FT3 and FT4 decreased with gestation, and all three were lower in black than in white women. Serum FT3 and FT4 decreased but TSH did not change significantly with maternal age; TSH and FT3 increased whereas FT4 decreased with body mass index; TSH decreased whereas FT3 and FT4 increased with serum free β-hCG. In the antibody-positive group, compared to the negative group, median TSH was higher and median FT3 and FT4 were lower. Conclusion: The study established normal ranges for maternal thyroid function at 11–13 weeks.

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Serum thyrotrophin concentration measured by sensitive assays in normal pregnancy

Cited by 20 publications

References 16 publications

Thyroid Function in Fetus and Mother during the Second Half of Normal Pregnancy

Thyroid Function in Fetus and Mother during the Second Half of Normal Pregnancy

Maternal Thyroid Function in Early and Late Pregnancy<sup>1</sup>

Maternal Thyroid Function at 11–13 Weeks of Gestation

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