Evaluation of the congenital hypothyroidism screening programme in Iran: a 3-year retrospective cohort study

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.

Hypothyroidism

Hypothyroidism is the common clinical condition of thyroid hormone deficiency and, if left untreated, can lead to serious adverse health effects on multiple organ systems, with the cardiovascular system as the most robustly studied target. Overt primary hypothyroidism is defined as elevated thyroid-stimulating hormone (TSH) concentration in combination with free thyroxine (fT₄) concentration below the reference range. Subclinical hypothyroidism, commonly considered an early sign of thyroid failure, is defined by elevated TSH concentrations but fT₄ concentrations within the reference range. Hypothyroidism is classified as primary, central or peripheral based on pathology in the thyroid, the pituitary or hypothalamus, or peripheral tissue, respectively. Acquired primary hypothyroidism is the most prevalent form and can be caused by severe iodine deficiency but is more frequently caused by chronic autoimmune thyroiditis in iodine-replete areas. The onset of hypothyroidism is insidious in most cases and symptoms may present relatively late in the disease process. There is a large variation in clinical presentation and the presence of hypothyroid symptoms, especially in pregnancy and in children. Levothyroxine (LT4) is the mainstay of treatment and is one of the most commonly prescribed drugs worldwide. After normalization of TSH and fT₄ concentrations, a considerable proportion of patients treated with LT4 continue to have persistent complaints, compromising quality of life. Further research is needed regarding the appropriateness of currently applied reference ranges and treatment thresholds, particularly in pregnancy, and the potential benefit of LT4/liothyronine combination therapy for thyroid-related symptom relief, patient satisfaction and long-term adverse effects.

Development of a risk prediction model for early discrimination between permanent and transient congenital hypothyroidism

OBJECTIVE

To develop a risk prediction model for early discrimination between transient and permanent congenital hypothyroidism (CH).

DESIGN AND SETTING

In a retrospective cohort, 1047 confirmed CH neonates, from 15 randomly selected provinces in Iran, were entered to the study. Clinical and biochemical information of transient and permanent cases, distinct at the age of 3 years were retrospectively gathered.

RESULTS

Among CH neonates, the overall prevalence of permanent CH was 57.1%. Using forward stepwise multivariable logistic regression analysis, confirmatory venous TSH, total T4 < 8.2 ng/dl, requiring levothyroxine dosage increase, venous TSH ≥ 10 mU/l between 6 and 12 months of age, parental consanguinity and family history of thyroid diseases were associated with increased risk of permanent CH. The prediction model achieved a very good power in discriminating patients with transient and permanent CH with an optimism-corrected area under the ROC curve of 0.86 (95% CI:0.84-0.88) with a very good calibration. Integrated discrimination improvement (IDI) test indicated significantly greater diagnostic performance of the model compared to serum TSH alone.

CONCLUSIONS

Using several potential predictors for permanent CH, we developed a relatively powerful risk prediction model as a cost-saving screening tool in order to avoid unnecessary long-term treatment of transient cases which might empower clinicians for prognostication of the CH course and tailoring treatment up to 1 year of age.

Familial-Related Risks for Congenital Hypothyroidism in Iranian Newborns: A Population-Based Case-Control Study

BACKGROUND

Congenital hypothyroidism (CH), as one of the most common endocrine disorders, is a preventable cause of mental retardation.

OBJECTIVE

This study aimed to identify familial-related risk factors for CH in Iranian newborns.

METHODS

A population-based case-control study was performed on the National Registry System of patients with CH in Iran. In this study, 906 controls and 454 cases were studied for one year. Familial related factors were investigated using logistic regression models. Population attributable fraction (PAF) was also calculated for each significant risk factor.

RESULTS

Using multivariate analysis, an increased risk for CH was observed in patients with congenital anomalies (odds ratio (OR): 5.77, 95% confidence interval (CI): 2.37 - 14.01), history of mental retardation in family (OR:2.10, 95% CI: 1.15-3.83), mother's hypothyroidism during pregnancy (OR: 2.01, 95% CI: 1.33 - 3.03), intra-family marriage (OR:1.49, 95% CI: 1.18 - 1.89), gestational diabetes (OR: 1.69, 95% CI: 1.09 - 2.63), having a hypothyroid child in the family (OR: 2.48, 95% CI: 1.39 - 4.42), and twins or more (OR: 2.61, 95% CI: 1.31 - 5.21). The highest PAF among familial-related risk factors for CH is related to the intra-family marriage (14.9%).

CONCLUSIONS

This study revealed that familial-related risk factors and consanguine marriages play an essential role in the high incidence of CH in Iran. About 15% of CH in Iran could be attributed to intra-family marriage alone.

Assessment of intelligence quotient score in children at the age of six with suspected congenital hypothyroidism: A retrospective cohort study

Background: The clinical suspicion of Congenital Hypothyroidism (CH) is identified by abnormal results in the first test of Thyroid Stimulating Hormone (TSH) (5-9.9 mIU/L), and normal results in re-test (TSH<4 mIU/L). The CH has a contribution to physical and mental health. This study aimed to determine the Intelligence Quotient (IQ) score in children with suspected congenital hypothyroidism.

Methods: This research is a retrospective cohort study conducted in Mashhad, Iran. The IQ scores of 1976 children at the age of 6 were considered as an outcome variable. The history of CH screening for each newborn was assessed, then all suspected CH newborns that diagnosed healthy in re-test were considered as an exposed group, the effects of this situation on IQ score was assessed using logistic regression. All analysis was performed in STATA.

Results: The averages of IQ score (p<0.001), weight (p=0.024), and height (p<0.001) in the exposed group were lower than the unexposed group. The exposed group was related to those whose parental education was less or equal to 12 years (p<0.001). Similarly, the history of CH and maternal education for ≤12 years were detected as risk factors for having an IQ score of <90 in children.

Conclusion: Aside from the link between parental education and clinical suspicion of CH in neonates, our findings underline the possible strong effect of CH status and maternal education for ≤12 years on reducing IQ scores in the next years of child life.

A Success Story: Review of the Implementation and Achievements of the National Newborn Screening Program for Congenital Hypothyroidism in Iran

CONTEXT

Today, newborn screening for congenital hypothyroidism (CH) as one of the significant achievements in preventive medicine is integrated into the health systems of many countries worldwide. The national newborn screening for early identification of CH disorder in Iran was established in 2004. The purpose of this study was to review the national newborn screening for CH and its achievements in Iran.

EVIDENCE ACQUISITION

In this study, we reviewed the structures, processes, main indicators, and achievements during the 15 years of implementing the national neonatal screening program for the diagnosis and treatment of CH in Iran.

RESULTS

Primary TSH measurement with backup thyroxine (T4) determination in infants with high TSH levels was used as the screening strategy in Iran. The coverage of this screening program was higher than 98%. By the end of 2017, 1,501,624 neonates were screened, among which 40,773 were diagnosed with CH and treated based on the national guidelines. The average incidence rate of CH during these years was approximately 2.6:1,000 live births.

CONCLUSIONS

The performance of the newborn screening program for congenital hypothyroidism in Iran is favorable, with over a 95% coverage rate. Due to the high recall rate and incidence rate of CH, it is essential to monitor the screening program in the country and also to conduct further studies to determine the main risk factors for the high recall rate and incidence of this congenital error.

Cases Referred from the Turkish National Screening Program: Frequency of Congenital Hypothyroidism and Etiological Distribution

OBJECTIVE

The aim of this study was to evaluate cases referred from the congenital hypothyroidism (CH) newborn screening program.

METHODS

Infants referred to Pediatric Endocrinology between 30.09.2015 - 01.04.2018 because of suspected CH identified by National Neonatal Screening Program were prospectively evaluated.

RESULTS

Of the 109 newborns referred to our clinic, 60 (55%) were diagnosed with elevated neonatal thyroid stimulating hormone (TSH). The diagnosis of elevated neonatal TSH was made in 52 (47.7%) and eight (7.3%) infants at initial evaluation and after follow up, respectively of all referrals with 86.7% (52/60) diagnosed at initial visit. The median first and second heel prick times were 1.8 (0-7) and 8.72 (4-30) days. The median age at starting treatment of the infants diagnosed as a result of initial evaluation was 22.13 (7-53) days. Clinical findings associated with CH were present in 19 (36%) of patients. Etiology in patients diagnosed with elevated neonatal TSH on admission was: agenesis in one (2.08%); ectopia in one (2.08%); hypoplasia in 14 (29.16%); normal gland in situ 16 (33.3%); and hyperplasia in 16 (33.3%). The median time to normalization of TSH and free thyroxine concentrations after treatment initiation was 11.02 (4-30) and 9.03 (3-30) days, respectively.

CONCLUSION

The rate of diagnosis in the first month was found to be 87%. The etiological incidence of both dysgenesis and dyshormonogenesis was equal at 33.3%. The majority of cases with normal thyroid gland will be diagnosed with transient hypothyroidism but some of them may be diagnosed with thyroid dyshormonogenesis so the rate of dyshormonogenesis will increase later after final diagnosis.

Monitoring of salt iodisation programme in Iran; Health outcomes, shortages and perspective

Iodine deficiency disorders include a wide range of metabolic and nonmetabolic disorders including goiter. To control IDDs, the World Health Organization and responsible agencies in countries established daily iodine uptake. Almost all the countries in the world provide the required iodine through salt iodisation. IDDs are not completely eradicable, so monitoring the salt iodisation programme is necessary for control of IDDs. In Iran, a salt iodisation programme was started in 1996. In this study, we took salt samples from all legally produced salt brands in Iran in 30 provinces and measured iodine concentration. The results of the monitoring programme for iodine concentration in schoolchildren's urine was used to compare accessibility to iodized salts and health outcomes. The results show that more than 80% of available salts have a suitable or acceptable concentration of iodine. Despite large variance in iodine concentration in available salt in some provinces, the median of iodine concentration in salts is within an acceptable range. Also, the urinary concentration of iodine (national median = 161) confirms that shortage of iodine intake is very low in Iran. The high rate of salt consumption of the Iranian people also has a significant effect on iodine uptake, but can lead to hyperthyroidism and hypertension that must be controlled.