Ann Pediatr Endocrinol Metab.  2014 Sep;19(3):141-145. 10.6065/apem.2014.19.3.141.

Earlier re-evaluation may be possible in pediatric patients with eutopic congenital hypothyroidism requiring lower L-thyroxine doses

• Cho MS
• Cho GS
• Park SH
• Jung MH
• Suh BK
• Koh DG

• KMID: 2134081
• DOI: http://doi.org/10.6065/apem.2014.19.3.141

Abstract

PURPOSE
The incidence of congenital hypothyroidism (CH) has increased in several countries. Lower cut-off in screening programs have led to an increase in the proportion of transient hypothyroidism (TH) cases diagnosed, leading to debate on the associated clinical and economic impact. This study aimed to identify factors that would allow discrimination between TH and permanent CH (PH) in patients with a eutopic thyroid gland.
METHODS
Sixty-six patients with CH from 3 different hospitals were studied: 26 cases of TH, and 40 cases of PH. Laboratory findings and clinical parameters were analysed in 56 patients with eutopic thyroid gland.
RESULTS
Initial serum thyroid stimulating hormone levels and L-thyroxine dose at 12 and 24 months of age were significantly higher in PH than TH patients with a eutopic thyroid gland. The area under the curve for the 12-month and 24-month dose for the prediction of TH in eutopic CH was 0.799 (95% confidence interval [CI], 0.678-0.919; P<0.001) and 0.925 (95% CI, 0.837-1.000; P<0.001), respectively. The optimum 12-month and 24-month dose in predicting TH is 3.25 microg/kg (12-month: sensitivity, 87.1%; specificity, 68.0%; 24-month: sensitivity 93.5%, specificity 88%).
CONCLUSION
Infants with CH requiring lower L-thyroxine doses (<3.25 microg/kg) are likely to have TH, and thus might be re-evaluated at 12 months or 24 months rather than 3 years of age.

Keyword

Congenital hypothyroidism; Thyroxine; Thyroid gland

MeSH Terms

Congenital Hypothyroidism*
Discrimination (Psychology)
Humans
Hydrogen-Ion Concentration
Hypothyroidism
Incidence
Infant
Mass Screening
Thyroid Gland
Thyrotropin
Thyroxine*
Thyrotropin
Thyroxine

Figure

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  Fig. 1 Flow diagram of the study population with congenital hypothyroidism. TBG, thyroxine binding globulin; TSH, thyroid-stimulating hormone.

• 

  Fig. 2 Receiver operating characteristic (ROC) curve of initial serum TSH, L-thyroxine dose at 12 months of age (12M dose), and 24 months of age (24M dose) reflecting transient congenital hypothyroidism. The cutoff values of 12M dose and 24M dose were 3.25 µg/kg (area under the curve=0.799; 95% CI, 0.678-0.919; P<0.001; sensitivity, 87.1%; specificity, 68.0%) and 3.25 µg/kg (area under the curve=0.925; 95% CI, 0.837-1.000; P<0.001; sensitivity, 93.5%; specificity, 88%), respectively. TSH, thyroid-stimulating hormone; CI, confidence interval.

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