Prevalence and Determinants of Transient Congenital Hypothyroidism in Children With Eutopic Gland in France: A Retrospective Cohort Study

Paediatric thyroid disease

The spectrum of thyroid disorders presenting to paediatricians is different to that seen by adult physicians. Referrals reflect cases detected by the neonatal screening programme for congenital hypothyroidism and many of the inherited defects of thyroid hormone generation or action will be manifest in early life. Autoimmune thyroid disease can be particularly challenging to manage in the young and the potential impact of thyroid status on neurodevelopment and schooling are key considerations throughout childhood and adolescence.

A practical gestational age-based algorithm for timely detection of hypothyroidism in premature infants

OBJECTIVES

To assess utility and accuracy of a gestational age-based screening targeting premature infants to detect congenital hypothyroidism.

STUDY DESIGN

A prospective cohort study was conducted in infants <35 weeks' gestational age with clinical outcomes at 2-3 years of age. Patients received newborn screenings at 24 hours and 10-14 days of life. Free T4 (FT4) and thyroid-stimulating hormone (TSH) levels were measured at one month of life and repeated based on algorithm by corrected gestational age.

RESULTS

Among infants <35 weeks gestation (n = 938), the incidence of hypothyroidism requiring treatment was 1:58. TSH levels at one month of age was predictive of treatment (AUC 0.96, 95% CI 0.88-1). The optimal TSH threshold of 8 mIU/L (8 µU/ml) increased the specificity to 0.97 and sensitivity to 0.88. Following initiation of treatment for hypothyroidism during NICU hospitalization, 43.8% (n = 7) were diagnosed with permanent congenital hypothyroidism.

CONCLUSIONS

Our study supports a gestational age-based screening algorithm for early detection of hypothyroidism in premature infants.

Iatrogenic hyperthyroidism in primary congenital hypothyroidism: prevalence and predictive factors

OBJECTIVES

Primary congenital hypothyroidism (CH) is a preventable cause of mental retardation. Iatrogenic hyperthyroidism has occasionally been reported using the recommended LT4 dosage. Currently, information regarding iatrogenic hyperthyroidism and predictive factors for permanent hypothyroidism (P-CH) among Thai patients is lacking. The aim of this study is to determine the prevalence and factors for predicting iatrogenic hyperthyroidism at one month after LT4 initiation and for predicting P-CH in primary CH infants.

METHODS

This retrospective cohort study involved 87 infants with primary CH. Patients were classified by thyroid status at one month after LT4 initiation. At 3 years, patients were reevaluated after LT4 cessation and assigned as P-CH or transient CH (T-CH). Differences between groups were analyzed.

RESULTS

One month after LT4 initiation, 35.6% of patients were classified as having iatrogenic hyperthyroidism. An initial LT4 dose of 10.2 μg/kg/day (sensitivity 64.5%, specificity 71.4%) was a suitable cutoff value for predicting iatrogenic hyperthyroidism, wherein 55.6 and 21.6% of patients were treated with initial doses of ≥10.2 and <10.2 μg/kg/day, respectively (p=0.004). Initial LT4 dose was the only predictive factor for thyroid status after initial treatment. At reevaluation, 47.4% of patients were diagnosed with P-CH. LT4 dosage at 3 years of age was significantly higher in patients with P-CH (3.3 vs. 2.85 μg/kg/day, p=0.02) and the only relevant factor for predicting P-CH.

CONCLUSIONS

Iatrogenic hyperthyroidism is common among infants with primary CH when treated with the recommended LT4 dosage. LT4 dose was the only factor for predicting iatrogenic hyperthyroidism after LT4 initiation and the diagnosis of P-CH.

Congenital hypothyroidism after newborn screening program reorganization in the Apulia region

Background

Congenital hypothyroidism (CH) is the most frequent congenital endocrine disorder. The purpose of the present study was to evaluate the incidence and etiological classification of CH in Apulia in a three-year period according to the reorganization of the regional screening program in a single central laboratory, as well as to analyze the growth characteristics and the associated risk factors of the CH newborns diagnosed during the study period.

Methods

Data derived from the reorganization of the newborn screening program for CH in a single central laboratory that collects dried blood spot (DBS) from 27 Maternity Hospitals are analyzed over a three-year period. Birth weight and length, daily dose of L-T4 at specific key points (3, 6, 12 and 18 months, 2, 2.5 and 3 years) were also obtained from medical records of the CH newborns during the study period and calculated as standard deviation score (SDS).

Results

The screening program diagnosed 90 newborns with confirmed CH (incidence 1:990; recall rate: 3.6%). In detail, 75.6% newborns had an eutopic thyroid, and 24.4% had thyroid dysgenesis; 33 out of the 90 newborns (36.6%) had one or more risk factors. Among these, the multiple pregnancies are the most important because they tripled the risk of CH. At diagnosis, TSH levels were different between patients with dysgenesis and those with an eutopic thyroid (p = 0.005). Treatment was started at a mean of 18.5 ± 12.8 days of life. The mean starting dose of levothyroxine (L-T4) was 11.38 ± 2.46 μg/kg/day.

Conclusions

The results of these study show an increase of CH cases in newborns with an eutopic thyroid compared to the traditional classification. The centralization of the screening program allows a closer cooperation between laboratory and clinical centers and facilitates the implementation of appropriate diagnostic evaluations and timely initiation of treatment, with positive effects on the management of the condition.

MECHANISMS IN ENDOCRINOLOGY: The pathophysiology of transient congenital hypothyroidism

Transient congenital hypothyroidism (TCH) refers to congenital hypothyroidism which spontaneously resolves in the first few months or years of life. Currently, there is a paucity of reliable markers predicting TCH at diagnosis, and the diagnosis is established following the withdrawal of levothyroxine therapy around 3 years of age. The incidence of TCH is increasing, and it is a major contributor to the overall increase in the incidence of CH in recent studies. Both genetic factors, in particular mutations affecting DUOX2 and DUOXA2, and environmental factors, for example, iodine deficiency and excess, anti- TSHR antibodies and exposure to antithyroid or iodine-rich medications, may cause TCH. Resolution of TCH in childhood may reflect both normal thyroid physiology (decreased thyroid hormone biosynthesis requirements after the neonatal period) and clearance or cessation of environmental precipitants. The relative contributions and interactions of genetic and environmental factors to TCH, and the extent to which TCH may be prevented, require evaluation in future population-based studies.

Incidence of congenital hypothyroidism by gestational age: a retrospective observational study

BACKGRUOUND

Congenital hypothyroidism (CH) is the leading cause of preventable physical and intellectual disabilities. This study aimed to assess the incidence and clinical characteristics of CH in newborns.

METHODS

We retrospectively reviewed the medical records of all newborns delivered at the Pusan National University Hospital between January 2011 and March 2021. The incidence of CH was compared according to gestational age, birth weight, and small for gestational age (SGA). The patients aged ≥3 years who could not maintain normal thyroid function and required levothyroxine treatment were diagnosed with permanent CH. Logistic regression analysis was performed to compare CH risks.

RESULTS

Of 3,722 newborns, 40 were diagnosed with CH (1.07%). Gestational age and birth weight were significantly associated with CH incidence. The odds ratios (ORs) of CH in infants delivered at 32-37, 28-31, and <28 weeks were 2.568 (95% confidence interval [CI], 1.141-5.778), 5.917 (95% CI, 2.264-15.464), and 7.441 (95% CI, 2.617-21.159) times higher, respectively, than those delivered at term. The ORs of CH in infants weighing 1,500-2,499 g, 1,000-1,499 g, and <1,000 g were 4.664 (95% CI, 1.928-11.279), 11.076 (95% CI, 4.089-29.999), and 12.544 (95% CI, 4.350-36.176) times greater, respectively, than those in infants weighing ≥2,500 g. The OR of CH was 6.795 (95% CI, 3.553-13.692) times greater in SGA than in non-SGA infants.

CONCLUSION

The CH incidence in South Korea has increased significantly compared with that in the past. Gestational age, birth weight, and SGA were significantly associated with CH incidence.