Congenital Hypothyroidism: Screening and Management

Incidence and associated risk factors of congenital hypothyroidism among newborns in Hainan, China: a retrospective study

OBJECTIVES

This study aims to investigate the incidence and risk factors of congenital hypothyroidism (CH) in newborns in Hainan Province, China, to provide a reference for early and effective prevention strategies.

METHODS

Newborns born in Hainan Province from 2017 to 2021 were the subjects of this study. Time-resolved immunofluorescence was used for initial screening and chemiluminescence for confirmatory diagnosis. Based on the diagnosis, newborns were classified into CH and non-CH groups. Statistical analysis was conducted on the initial screening and confirmed CH cases in newborns in Hainan Province, and potential risk factors for CH were explored.

RESULTS

From 2017 to 2021, a total of 585,886 newborns were screened, revealing 6,856 initial positive results, 614 positive rescreens, and 420 confirmed CH cases, yielding an incidence rate of 1/1,395 (420/585,886). The annual initial positive screening rate of newborns in Hainan Province showed a rising trend from 2017 to 2021 (p=0.000). No significant differences were found regarding gender (p=0.400) and ethnicity (p=0.836). Multivariate logistic regression analysis indicated that residing in coastal areas, especially those with salt fields (OR=2.151, 95 % CI: 1.364-3.390), was risk factors for the development of CH in newborns.

CONCLUSIONS

The incidence of CH in newborns showed a year-on-year increase in Hainan Province from 2017 to 2021. Residing in coastal areas, particularly those with salt fields, was identified as a risk factor for the development of CH.

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

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.

Screening for Delayed Thyroid Stimulation Hormone Rise and Atypical Congenital Hypothyroidism in Infants Born Very Preterm and Infants with Very Low Birth Weight

OBJECTIVE

To determine among infants born very preterm (VPT) or with very low birth weight (VLBW) the incidence of alterations in thyroid function and associated comorbidities; the incidence of atypical congenital hypothyroidism (CH) requiring thyroxine therapy; and reference ranges for rescreening at 1 month of age.

STUDY DESIGN

A retrospective review of infants born VPT or with VLBW and admitted to UC Irvine Medical Center between January 1, 2012, and December 31, 2020. Repeat thyroid screening was obtained at 1 month of life (+10 days). Infants with thyroid-stimulating hormone (TSH) >5 μIU/mL or free thyroxine <0.8 ng/dL underwent follow-up testing and endocrinology consultation. Initial newborn screening (NBS) and repeat thyroid screening data were collected via chart review. Demographic data and short-term outcomes were abstracted from the California Perinatal Quality Care Collaborative database.

RESULTS

In total, 430 patients were included; 64 of 429 patients (14.9%) had TSH >5 μIU/mL and 20 of 421 patients (4.8%) had free thyroxine <0.8 ng/dL. Logistic regression analysis identified small for gestational age (P = .044), patent ductus arteriosus (P = .013), and late-onset sepsis (P = .026) as risk factors associated with delayed TSH rise. Atypical CH requiring treatment through neonatal intensive care unit discharge was diagnosed in 6 patients (incidence of 1.4%); none were identified by NBS. The 90th percentile TSH for infants with extremely low birth weight (<1000 g) was 7.2 μIU/mL, and the 95th percentile for those with birth weight of 1000-1500 g was 6.1 μIU/mL; using these cutoff values identified all infants diagnosed with atypical CH with 100% sensitivity and 90%-95% specificity.

CONCLUSIONS

Abnormal thyroid function is common in infants born preterm. Those infants, including some with atypical CH, are missed by NBS. We recommend repeat thyroid screening with TSH at 1 month of age in infants born VPT or infants with VLBW to identify CH that may require therapy.

History of Neonatal Screening of Congenital Hypothyroidism in Portugal

Congenital hypothyroidism (CH) leads to growth and development delays and is preventable with early treatment. Neonatal screening for CH was initiated in Portugal in 1981. This study examines the history of CH screening in the country. Data were obtained from annual reports and from the national database of neonatal screening laboratory. The CH screening strategy primarily relies on the thyroid-stimulating hormone (TSH), followed by total thyroxine measurement as the second tier for confirmation. The TSH cutoff started at 90 mIU/L, decreasing to the actual 10 mIU/L. The coverage of the screening program has increased rapidly; although voluntary, it reached about 90% in 6 years and became universal in 10 years. Guideline and cutoff updates led to the identification of over 200 additional cases, resulting in specific retesting protocols for preterm and very-low-birth-weight babies. The actual decision tree considers CH when TSH levels are above 40 mIU/L. Data from the CH screening also provide an indication of the iodine status of the population, which is presently indicative of iodine insufficiency. The Portuguese neonatal screening for CH is a history of success. It has rapidly and continuously adapted to changes in knowledge and has become a universal voluntary practice within a few years.

Promoting Choosing Wisely Thyroid Function Test Guidelines in a Large Pediatric Hospital System

BACKGROUND

Free thyroxine (fT4) is often ordered when not indicated. The goal of the current study was to use quality improvement tools to identify and implement an optimal approach to reduce inappropriate fT4 testing throughout a large pediatric hospital system.

METHODS

After reviewing evidence-based guidelines and best practices, a thyroid-stimulating hormone with reflex to fT4 test and an outpatient thyroid order panel with clinical decision support at order entry, along with several rounds of provider education and feedback, were implemented. Outpatient and inpatient order sets and system preference lists were reviewed with subject matter experts and revised when appropriate. Tracking metrics were identified. Automated monthly run charts and statistical process control charts were created using data retrieved from the electronic health record. Charts established baseline data, balancing measure data, monitored the impact of interventions, and identified future interventions.

RESULTS

Over a 44-month period, among nonendocrinology providers, a reduction in fT4 and thyroid-stimulating hormone co-orders from 67% to 15% and an increase in reflex fT4 tests from 0% to 77% was obtained in inpatient and outpatient settings. Direct cost savings as a result of performing 5179 fewer fT4 tests over 3 years was determined to be $45 800.

CONCLUSIONS

After implementation of a reflex fT4 test, a novel order panel with clinical decision support, provider education, and changes to ordering modes, a large and sustainable reduction in fT4 tests that was associated with significant cost savings was achieved among nonendocrinology providers.

A literature review on the redundancy of additional thyroid function tests in neonates of mothers with hypothyroidism

AIM

Newborn thyroid screening tests are carried out during the first days after birth in many parts of the world. The aim of this review was to assess whether additional thyroid function tests of neonates born to mothers with hypothyroidism are necessary to diagnose newborns with congenital hypothyroidism (CH) missed by the usual screening test.

METHODS

A search in PubMed and Google Scholar databases was conducted for pertinent studies, using relevant keywords. All studies that were published in any language from 1 January 2000 to 30 June 2023 were included. Observational cohort studies were included in the analysis, while case reports and studies not referring to neonates were excluded.

RESULTS

Thirteen studies were identified comprising more than 4400 infants with CH. Studies with the larger study populations recommended against additional testing in healthy infants of hypothyroid mothers. Similar were the results of some smaller retrospective studies. Few studies identified in total 16 infants with CH that were missed on neonatal screening without, though, a definite causative link between the mother's and the infant's thyroid dysfunction.

CONCLUSION

Based on available data, additional thyroid function tests seem redundant in identifying undiagnosed cases of CH. Larger studies are needed to reach a definite conclusion.

Clinical indicators that influence a clinician's decision to start L-thyroxine treatment in prematurity with transient hypothyroxinemia

BACKGROUND

Transient hypothyroxinemia of prematurity (THOP) is defined as a low level of circulating thyroxine (T4), despite low or normal thyroid-stimulating hormone (TSH) levels.

AIMS

We aimed to evaluate the incidence of THOP, the clinical and laboratory findings of preterm infants with this condition and the levothyroxine (L-T4) treatment.

METHODS

Preterm infants (n = 181) delivered at 24-34 weeks of gestation were evaluated by their thyroid function tests that were performed between the 10th and 20th days of postnatal life and interpreted according to the gestational age (GA) references. Clinical and laboratory characteristics of the patients with THOP and normal thyroid function tests were compared. Patients with THOP and treated with L-T4 were compared with the ones who were not regarding laboratory, and clinical characteristics.

RESULTS

Incidence of hypothyroxinemia of prematurity was 45.8% (n = 83). Euthyroidism, primary hypothyroidism, and subclinical hypothyroidism were diagnosed in 47.5% (n = 86), 5% (n = 9) and 1.7% (n = 3) of the patients, respectively. Mean birth weight (BW) and GA were significantly lower in the hypothyroxinemia group than in the euthyroid group (p < 0.001). L-T4 was started in 43% (n = 36) of the patients with THOP. Treatment initiation rate was 44.4% (n = 16) in 24-27 wk, 41.6% (n = 15) in 28-30 wk, and 13.8% (n = 5) in 31-34 wk. As the GA increased, the incidence of THOP and the rate of treatment initiation decreased (p < 0.001). The lowest free thyroxine (FT4) cut-off value was 0.72 ng/dl in the treated group. In addition, incidences of vancomycin + amikacin, caffeine, dopamine treatments, RDS, IVH, BPD, central catheter, FFP transfusion, and ventilator support were higher in the treated group (P < 0.05).

CONCLUSION

This study revealed that prevalence of THOP increased as the GA and BW decreased. As the GA decreased, THOP patients requiring L-T4 treatment increased. Additionally, association with comorbid diseases increased the requirement of treatment.