Thyrotropin-releasing hormone stimulation tests in infants.

Rapaport, Robert; Sills, Irene N.; Patel, Usha; Oppenheimer, Enid T.; Skuza, Kathryn A.; Horlick, Mary; Goldstein, Susanna; DiMartino, Jorge; Saenger, Paul

doi:10.1210/jcem.77.4.8408462

Cited by 18 publications

(19 citation statements)

References 16 publications

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“…However, it is impossible to deny that patients with subclinical hypothyroidism are at considerable risk for adverse neurodevelopmental consequences. No guideline exists for such subclinical patients but the presence of excessive TSH response to TRH administration strongly indicates that they should be diagnosed with hypothyroidism and accordingly receive replacement therapy (30). The authors of a recent study advocate the administration of low-dose levothyroxine to infants with borderline hypothyroidism in order to prevent possible adverse effects of mild hypothyroidism on the developing brain (31).…”

Section: Discussionmentioning

confidence: 99%

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Clinical significance of heterozygous carriers associated with compensated hypothyroidism in R450H, a common inactivating mutation of the thyrotropin receptor gene in Japanese

Kanda

Mizuno

Sugiyama

et al. 2006

Endocr

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Loss-of-function mutations in the thyrotropin receptor (TSHR) gene were described as a syndrome characterized by thyroid hyposensivity to biologically active TSH, ranging from euthyroid to severe hypothyroidism. In Japanese, a common mutation in the TSHR gene is R450H, which demonstrated moderately impaired receptor function. We studied six subjects of Japanese origin whose major abnormality was persistent hyperthyrotropinemia by genetic sequence analysis of the TSHR gene. Three subjects were homozygous for the R450H mutation, whereas the three remaining subjects were single heterozygous. Homozygous subjects displayed mild hypothyroidism confirmed by moderately elevated basal TSH levels and excessive TSH response to TRH administration. Heterozygous subjects also demonstrated fully or partially compensated hypothyroidism, but less severe than that of homozygous subjects. More frequent involvement of the R450H mutation in the TSHR gene in Japanese was identified. In addition, a good correlation between phenotype and genotype was demonstrated in respect to biochemical analysis and drug dosage. Our observations showed clinical significance of heterozygosity associated with compensated hypothyroidism in spite of only mildly impaired receptor function.

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Section: Discussionmentioning

confidence: 99%

“…Ultrasound scanning and 123 I iso- Normal range value of serum TSH is 0.54-4.26 µU/mL, thyroglobulin is under 30 ng/mL, and the time of measurement is reported between parentheses. Peak TSH values above 35 µU/mL were considered hyperresponsive (30). Antithyroid autoantibodies were negative in all these subjects.…”

Section: Clinical and Biochemical Observationsmentioning

confidence: 99%

Clinical significance of heterozygous carriers associated with compensated hypothyroidism in R450H, a common inactivating mutation of the thyrotropin receptor gene in Japanese

Kanda

Mizuno

Sugiyama

et al. 2006

Endocr

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“…injection of TRH (7 mg/kg, maximum 200 mg). Patients with TSH response over 35 mIU/ml TSH units were considered to have subclinical hypothyroidism (16). Serum TPO-Ab and TG-Ab levels were measured with RIA using kits from Brahms Diagnostica (Berlin, Germany).…”

Section: Methodsmentioning

confidence: 99%

Thyroid hormones in children with epilepsy during long-term administration of carbamazepine and valproate

Verrotti

Laus

Sereno

et al. 2009

European Journal of Endocrinology

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Objective: This study evaluates the effects of long-term carbamazepine (CBZ) and valproate acid (VPA) therapy on thyroid function in epileptic children. Design: A prospective study performed in 32 newly diagnosed pediatric patients, subdivided into two groups: 18 patients treated with CBZ and 14 patients treated with VPA. Thirty-two sex-and agematched subjects served as controls. Methods: Serum TSH, thyroxine (T 4 ), triiodothyronine (T 3 ), free thyroxine (fT 4 ), free triiodothyronine (fT 3 ), thyroid peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (TG-Ab) were evaluated at baseline and at the 3rd, 6th, and 12th month in all patients and in the control group. A TRH stimulation test was performed in all epileptic patients at baseline and at the 3rd, 6th, and 12th month evaluations while in controls only baseline assessment was carried out. Results: At baseline evaluation, thyroid function was normal in all epileptic children. After 3 months, CBZ-treated patients showed serum T 4 and fT 4 levels significantly lower than baseline evaluation and control subjects. Serum T 4 and fT 4 concentrations were unaffected by VPA monotherapy. Serum T 3 and fT 3 were normal in both CBZ-treated and VPA-treated patients. TRH test was normal in all patients. At 6th and 12th month evaluations, the same alterations were present in CBZ-treated patients while thyroid function remained normal in VPA-treated patients. TRH test responses were normal in all epileptic patients. TPO-Ab and TG-Ab were always absent in all patients. Conclusions: Our data suggest that VPA monotherapy does not alter thyroid hormones. On the contrary, alterations of thyroid hormones occur in CBZ-treated children. However, the patients are euthyroid and thyroid hormone alterations are not associated with clinical or subclinical hypothyroidism.

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“…In 8 children the test could not be carried out due to technical difficulties or parental refusal. A TSH value higher than 35 mU/liter after TRH administration was considered abnormally elevated based on data from the literature (10). No TRH test was carried out in control children for ethical reasons.…”

Section: Thyroid Function and Morphologymentioning

confidence: 99%

Subclinical Hypothyroidism in Early Childhood: A Frequent Outcome of Transient Neonatal Hyperthyrotropinemia

Calaciura

Motta

Miscio

et al. 2002

The Journal of Clinical Endocrinology &Amp; Metabolism

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Newborns with high TSH at birth and with normal free T(4) and normal or slightly elevated TSH at the confirmatory examination are considered false positive for congenital hypothyroidism. We evaluated thyroid function, thyroid antibodies, thyroid volume and morphology, thyroperoxidase and TSH receptor genes, and auxological data in 56 false positive children at 16-44 months of age. In these children thyroid function at confirmatory examination was fully normal in 33 (TSH, 0.8-4.9 mU/liter; group I) and nearly normal (borderline elevated TSH, 5.0-11.7 mU/liter) in the other 23 (group II). Compared with 65 control children with normal TSH at birth, false positive children had significantly higher basal serum TSH (mean +/- SD, 4.38 +/- 2.2 vs. 1.4 +/- 0.8 mU/liter; P < 0.01). Subclinical hypothyroidism, indicated by increased basal TSH and/or increased TSH response to TRH, was present in 36% children in group I and 70% in group II. Free T(4) was within the normal range in all children. Compared with the control group, false positive children had significantly higher free T(3) values (4.9 +/- 0.8 vs. 3.7 +/- 1.0 pmol/liter; P < 0.01) and a higher prevalence of antithyroid antibodies (25% vs. 1.5%; P < 0.001). Frequent thyroid morphology abnormalities and frequent thyroperoxidase and TSH receptor gene sequence variations were also observed. In conclusion, newborns classified false positive at congenital hypothyroidism screening have a very high risk of subclinical hypothyroidism in infancy and early childhood.

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Thyrotropin-releasing hormone stimulation tests in infants.

Cited by 18 publications

References 16 publications

Clinical significance of heterozygous carriers associated with compensated hypothyroidism in R450H, a common inactivating mutation of the thyrotropin receptor gene in Japanese

Clinical significance of heterozygous carriers associated with compensated hypothyroidism in R450H, a common inactivating mutation of the thyrotropin receptor gene in Japanese

Thyroid hormones in children with epilepsy during long-term administration of carbamazepine and valproate

Subclinical Hypothyroidism in Early Childhood: A Frequent Outcome of Transient Neonatal Hyperthyrotropinemia

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