Intellectual outcome at 12 years of age in congenital hypothyroidism

Quality of life and socioeconomic and educational status in patients with congenital hypothyroidism

BACKGROUND

The aim of this study was to investigate the influence of primary congenital hypothyroidism (CH) on quality of life, level of education and socioeconomic status (SES).

METHODS

Two independent study cohorts, a national and a regional, were collected from Finnish national registers and patient records. Data on social security benefits, SES, marital status, and education were collected from Statistics Finland. Health-related quality of life (HRQoL) was studied in the regional patient cohort with the standardized 15D and 16D instruments.

RESULTS

There were no statistically significant differences in education level, marital status, or SES between CH patients (n = 40) and their matched controls at the age of 25 years. The mean 15D score was both statistically significantly and clinically importantly lower in CH patients (n = 29) than controls (0.904 vs. 0.953, p = 0.008). CH patients reported significantly lower scores across various dimensions of physical and mental HRQoL, including breathing, sleeping, speech, excretion, mental function, distress, and vitality. The mean 16D score was lower in CH patients compared to controls (0.917, vs. 0.947), but without statistical significance.

CONCLUSION

SES of CH patients did not differ from matched controls. Thus, most CH patients integrate well into society, but their HRQoL is impaired.

IMPACT

Most patients with primary congenital hypothyroidism integrate well into society. In the current study, their socioeconomic and marital status did not differ from matched controls at the age of 25 years. However, health-related quality of life measured using 15D instrument was impaired. Every fourth patient reported that congenital hypothyroidism influenced everyday life.

Cognitive outcome of 458 children over 25 years of neonatal screening for congenital hypothyroidism

OBJECTIVES

To describe the neurocognitive profile of 458 children with congenital hypothyroidism detected by neonatal screening, followed under the same treatment protocol over 25 years. To correlate estimated full-scale IQ (FSIQ) scores with age at the start of treatment, disease severity, and maternal education.

METHODS

Observational, analytical, retrospective, and longitudinal cohort study, that evaluated children detected between 1991 and 2014, who underwent at least one psychometric assessment (WPPSI- R and/or WISC-III). Estimated FSIQ scores are described and correlated with prognosis determinants.

RESULTS

Median T4 at diagnosis was 2.8 μg/dL (0.0-16.5), the median age at the start of treatment was 18.5 days (3-309). Maternal education (n = 445): 2.7% of illiteracy, 59.8% with basic education. Estimated FSIQ scores were 88.0 (±11.8) in WPPSI-R (age 5.6 ± 0.5 years) and 84.1 (±13.0) in WISC-III (age 9.1 ± 1.4 years). The intellectual deficit was identified in 11.6%. Correlation between age at the start of treatment and estimated FSIQ was found only in the WPPSI-R test (p = 0.02). Initial T4 and maternal education significantly correlated with estimated FSIQ scores in both tests, with the latter being the most important determining factor.

CONCLUSIONS

In this large cohort of mainly low socioeconomic status children, most children achieved normal cognitive levels; however, a significant percentage presented with below-average estimated FSIQ scores and intellectual deficits. Maternal education was the main determining factor in cognitive level followed by hypothyroidism severity.

Global prevalence of congenital hypothyroidism among neonates from 1969 to 2020: a systematic review and meta-analysis

Little is known about the global prevalence of congenital hypothyroidism (CH), though it is known to vary across countries and time periods. This meta-analysis aims to estimate the global and regional prevalence of CH among births between 1969 and 2020. PubMed, Web of Sciences, and Embase databases were searched for relevant studies between January 1, 1975, and March 2, 2020. Pooled prevalence was calculated using a generalized linear mixed model, and expressed as a rate per 10,000 neonates. The meta-analysis involved 116 studies, which analyzed 330,210,785 neonates, among whom 174,543 were diagnosed with CH. The pooled global prevalence of CH from 1969 to 2020 was 4.25 (95% confidence interval (CI) 3.96-4.57). The geographic region with highest prevalence was the Eastern Mediterranean (7.91, 95% CI 6.09-10.26), where the prevalence was 2.48-fold (95% CI 2.04-3.01) that in Europe. The national income level with the highest prevalence was upper-middle (6.76, 95% CI 5.66-8.06), which was 1.91-fold (95% CI 1.65-2.22) that in high-income countries. Global prevalence of CH was 52% (95% CI 4-122%) higher in 2011-2020 than in 1969-1980, after adjusting for geographic region, national income level, and screening strategy.  Conclusion: The global prevalence of CH increased from 1969 to 2020, which may reflect the implementation of national neonatal screening, neonatal testing for thyroid-stimulating hormone, and a lowering of the diagnostic level of this hormone. Additional factors are likely to be driving the increase, which should be identified in future research. What is Known: • Cumulated evidence had suggested that the occurrences of congenital hypothyroidism (CH) among newborns were varied in different countries.. • Up-trends of the birth prevalence of CH were observed in many European and American countries. What is New: • This is the first meta-analysis to estimate global and regional prevalence of CH among newborns. • The global prevalence of CH has increased by 127% since 1969. The Eastern Mediterranean has the highest prevalence and stands out with the most pronounced escalation in the prevalence of CH.

Congenital Hypothyroidism: Screening and Management

ABSTRACT

Untreated congenital hypothyroidism (CH) leads to intellectual disabilities. Prompt diagnosis by newborn screening (NBS) leading to early and adequate treatment results in grossly normal neurocognitive outcomes in adulthood. However, NBS for hypothyroidism is not yet established in all countries globally. Seventy percent of neonates worldwide do not undergo NBS.The initial treatment of CH is levothyroxine, 10 to 15 mcg/kg daily. The goals of treatment are to maintain consistent euthyroidism with normal thyroid-stimulating hormone and free thyroxine in the upper half of the age-specific reference range during the first 3 years of life. Controversy remains regarding detection of thyroid dysfunction and optimal management of special populations, including preterm or low-birth weight infants and infants with transient or mild CH, trisomy 21, or central hypothyroidism.Newborn screening alone is not sufficient to prevent adverse outcomes from CH in a pediatric population. In addition to NBS, the management of CH requires timely confirmation of the diagnosis, accurate interpretation of thyroid function testing, effective treatment, and consistent follow-up. Physicians need to consider hypothyroidism in the face of clinical symptoms, even if NBS thyroid test results are normal. When clinical symptoms and signs of hypothyroidism are present (such as large posterior fontanelle, large tongue, umbilical hernia, prolonged jaundice, constipation, lethargy, and/or hypothermia), measurement of serum thyroid-stimulating hormone and free thyroxine is indicated, regardless of NBS results.

Neuropsychological Alterations in Patients with Congenital Hypothyroidism Treated with Levothyroxine: Linked Factors and Thyroid Hormone Hyposensitivity

Eighty-five percent of the studies of patients with congenital hypothyroidism (CH) treated with Levothyroxine (L-T₄) report neuropsychological sequelae throughout life. In neonates and infants, there is a deficit in sensorimotor skills (impaired balance). In preschool and elementary school children and adolescents, there are alterations in intellectual quotient (low scores), language (delayed phonological acquisition), memory (visual, verbal, visuospatial, visuoconstructive, autobiographical, and semantic), sensorimotor skills (impaired fine and gross motor control), and visuoconstructive–visuospatial domain (low scores in spatial location, block design, and object assembly). These neuropsychological domains are also affected in young adults, except for language (adequate verbal fluency) and visuoconstructive–visuospatial domain (no data). The onset and severity of neuropsychological sequelae in patients with treated CH depend on several factors: extrinsic, related to L-T₄ treatment and social aspects, and intrinsic, such as severity and etiology of CH, as well as structural and physiological changes in the brain. In this review, we hypothesized that thyroid hormone hyposensitivity (THH) could also contribute to neuropsychological alterations by reducing the effectiveness of L-T₄ treatment in the brain. Thus, further research could approach the THH hypothesis at basic and clinical levels to implement new endocrinological and neuropsychological therapies for CH patients.

Effect of initial levothyroxine dose on neurodevelopmental and growth outcomes in children with congenital hypothyroidism

OBJECTIVES

We designed a multicentre open prospective randomized trial to evaluate the risk-benefit profile of two different initial treatment schemes with levothyroxine (L-T4), 10-12.5 μg/kg/day vs 12.6-15 μg/kg/day, on growth and neurodevelopmental outcomes in children with congenital hypothyroidism (CH) detected by neonatal screening to identify the best range dose to achieve optimal neurocognitive development.

DESIGN PATIENTS AND METHODS

Children detected by neonatal screening were randomly assigned to receive an initial L-T4 dose of 10-12.5 μg/kg/day (Low) or 12.6-15 μg/kg/day (High). All patients underwent periodical clinical examination with measurement of growth parameters and measurement of TSH and FT4. Neurocognitive development was evaluated at the age of 24 months using Griffiths Mental Development Scales (GMDS) and cognitive and behavioral assessment was performed at 48 months of age using Wechsler Preschool and Primary scale of Intelligence (WIPPSI-III). The study was registered with clinicaltrials.gov (NCT05371262).

RESULTS

Treatment schemes below or above 12.5 μg/kg/day were both associated with rapid normalization of TSH and thyroid hormone levels in most patients with no differences in the risk of over- and under-treatment episodes in the first months of life. Growth parameters were normal and comparable between the two groups. Developmental quotients at 24 months of age were normal in both groups (Low 100.6 ± 15.5 vs High 96.9 ± 16.6). Likewise, at 4 years of age IQ and subtest scores were comparable between patients from Low and High (Total IQ 104.2 ± 11.4 vs 101.0 ± 20.3, Verbal IQ 103.9 ± 11.5 vs 98.7 ± 15.1, Performance IQ 105.3 ± 10.4 vs 100.3 ± 19.8). 6/45 CH patients (13.3%) showed a total IQ below 85 (73.7 ± 5.9) regardless of age at diagnosis, L-T4 starting dose, time of FT4 and TSH normalization and episodes of over and undertreatment. Worse socioeconomic status and delayed bone age at diagnosis were the only predictors of an increased risk of having suboptimal IQ at 24 and IQ at 48 months.

CONCLUSIONS

Our results indicate that initial treatment with L-T4, 10-12.5 μg/kg/day vs 12.6-15 μg/kg/day, are both associated with normal growth and neurodevelopmental outcomes in children with CH detected by neonatal screening. Further studies with a long-term follow-up on a larger number of patients are needed to confirm these results.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT05371262?term=NCT05371262&draw=2&rank=1 identifer NCT05371262.

Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology

Background: An ENDO-European Reference Network (ERN) initiative was launched that was endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology with 22 participants from the ENDO-ERN and the two societies. The aim was to update the practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). A systematic literature search was conducted to identify key articles on neonatal screening, diagnosis, and management of primary and central CH. The evidence-based guidelines were graded with the Grading of Recommendations, Assessment, Development and Evaluation system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Summary: The recommendations include the various neonatal screening approaches for CH as well as the etiology (also genetics), diagnostics, treatment, and prognosis of both primary and central CH. When CH is diagnosed, the expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up including laboratory testing to keep thyroid hormone levels in their target ranges, timely assessment of the need to continue treatment, attention for neurodevelopment and neurosensory functions, and, if necessary, consulting other health professionals, and education of the child and family about CH. Harmonization of diagnostics, treatment, and follow-up will optimize patient outcomes. Lastly, all individuals with CH are entitled to a well-planned transition of care from pediatrics to adult medicine. Conclusions: This consensus guidelines update should be used to further optimize detection, diagnosis, treatment, and follow-up of children with all forms of CH in the light of the most recent evidence. It should be helpful in convincing health authorities of the benefits of neonatal screening for CH. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition.

[Formula: see text]Socioeconomic aspects are crucial to better intellectual outcome in early-treated adolescents with congenital hypothyroidism

Congenital hypothyroidism (CH) is an important cause of preventable intellectual disability. Implementation of CH neonatal screening programs leading to early treatment has improved cognitive outcome. However, more subtle cognitive impairments are still reported, and there is lack of clarity regarding factors that impact long-term cognitive outcome. Research to better understand these factors can lead to further improvements in the cognitive prognosis for these patients. The current study aimed to evaluate the cognitive performance of adolescents who were early-treated for primary permanent CH and possible associated variables. Neurocognitive evaluation was carried out in 66 adolescents, 11 to 16 years old: 34 with CH and 29 paired controls. Intellectual quotient (IQ), verbal fluency, processing speed, executive functions, and memory were investigated. CH patients and control subjects were comparable regarding sex, age, schooling, family's socioeconomic status and caregiver's educational level. Both groups presented not only similar IQ scores but also equivalent performances regarding Perceptual Reasoning, Working Memory and Processing Speed index scores. Patients presenting different CH etiologies (dysgenesis and dyshormonogenesis) showed similar cognitive performance. Socioeconomic aspects along with the initial levothyroxine dose were the main variables to positively influence the cognitive performance, the family's socioeconomic status having the strongest association with patients' cognitive skills.

Intelligence Quotient, Anxiety, and Depression in Congenital Hypothyroid Children at School Age

Background:

Many studies who evaluated the outcome of the congenital hypothyroidism (CH) screening reported some intellectual and behavioral deficit despite early diagnose and treatment. The aim of the present study was to compare the intellectual and behavioral adjustment of CH children with controls.

Methods:

This study was conducted among a group of 135 children aged 8--12 years in Isfahan, including transient and permanent congenital hypothyroidism (TCH and PCH) and a matched group of their classmate. Demographic characteristics collected using a designed data collecting form completed by parents. Intellectual quotient (IQ) was evaluated using Wechsler Intelligence Scale for Children aged 6--16 years (WISC-III). Depression and anxiety were evaluated using The Children's Depression Inventory (CDI) and the Multidimensional Anxiety Scale for Children (MASC), respectively. The SPSS software version 20.0 was used for data analysis. Nonparametric tests (Mann--Whitney) were used to investigate the association between variables. A significant level of less than 0.05 was considered in all analyzes.

Results:

There was no significant difference in the IQ scores between PCH and TCH groups (P = NS). However, neither of them had intellectual disability (defined as IQ <70). IQ scores were significantly lower in PCH comparing to controls (P < 0.001). Total IQ and verbal IQ were significantly differenct between TCH and control group (P = 0.007 and P = 0.001). No significant difference was found in anxiety and depression scores between CH children and controls.

Conclusions:

There is no significant difference in anxiety and depression scores between congenital hypothyroidism children and controls, although IQ scores in children with congenital hypothyroidism is lower than controls.

Individualized treatment to optimize eventual cognitive outcome in congenital hypothyroidism

BACKGROUND

In congenital hypothyroidism (CH), age-specific reference ranges (asRR) for fT₄ and thyrotropine (TSH) are usually used to signal over/under-treatment. We compared the consequences of individual fT₄ steady-state concentrations (SSC's) and asRR regarding over-treatment signaling and intelligence quotient at 11 y (IQ₁₁) and the effect of early over-treatment with high L-T₄ dosages on IQ₁₁.

METHODS

Sixty-one patients (27 severe, 34 mild CH) were psychologically tested at 1.8, 6, and 11 y. Development scores were related to over-treatment in the period 0-24 mo, relative to either individual fT₄SSC's or asRR. Three groups were formed, based on severity of over/under-treatment 0-5 mo (severe, mild, and no over/under-treatment).

RESULTS

FT₄ and TSH asRR missed 41-50% of the over-treatment episodes and consequently 22% of the over-treated patients, classified as such by fT₄SSC's. Severe over-treatment 0-5 mo led to lowered IQ₁₁'s and to a 5.5-fold higher risk of IQ₁₁ < 85 than other treatment regimes. Under-treatment had no effect on development scores. Initial L-T₄ dosages >10 µg/kg resulted in a 3.7-fold higher risk of over-treatment than lower dosages.

CONCLUSIONS

Data suggest that asRR, compared to fT₄SSC's, signal over-treatment insufficiently. Using fT₄SSC's and avoiding over-treatment may optimize cognitive outcome. Lowered IQ₁₁'s are usually a late complication of severe early over-treatment.

Levothyroxine requirement in congenital hypothyroidism: a 12-year longitudinal study

The aim of the replacement therapy with levothyroxine in congenital hypothyroidism (CH) is to correct hypothyroidism and ensure normal growth and neuropsychological development. Few data are available about the appropriate dose during childhood and early adolescence; therefore, we performed a multicenter observational study in a large population of patients with CH to assess the required levothyroxine dose to obtain euthyroidism. We recruited 216 patients with permanent CH classified into three groups (agenesia, ectopia, and in situ gland) on the basis of the thyroid imaging. The levothyroxine dose was recorded at 6 and 12 months and then yearly until 12 years of age. The daily levothyroxine requirement progressively decreased during the follow-up, irrespective of etiology. It was significantly lower in patients with in situ gland than in patients with athyreosis during the entire study period and with ectopic gland from the age of 1 year. The levothyroxine requirement at 6 months of age was correlated with the requirement at each later time-point. The daily dose was modified less frequently in patients with in situ thyroid (36 %) than in patients with ectopic gland (41.4 %) or with athyreosis (43.6 %). Patients with in situ gland required a lower dose than the other two subgroups. The dose at 6 months seems predictive of the requirement until 12 years of age. Euthyroidism may be achieved in pre-school and in-school patients by 3-4 and 2-3 µg/kg/day (70-90 and 60-80 µg/m(2)/day) of levothyroxine, respectively.

Final height in Italian patients with congenital hypothyroidism detected by neonatal screening: a 20-year observational study

BACKGROUND

Linear growth and final height are reported as normal in congenital hypothyroid patients in the neonatal screening era.

METHODS

We evaluated the final height in 215 patients with congenital hypothyroidism to assess if it improved over the last 2 decades.

RESULTS

Final height (-0.1 ± 1.0 SDS) was higher than target height (-0.8 ± 1.0 SDS, p < 0.001) and not different among the 4 quartiles for birthdate. It was correlated with target height (r(2) = 0.564, p < 0.001) and height at puberty onset (r(2) = 0.685, p < 0.001), but not with age at diagnosis or the starting LT4/kg/day dose. The curve fitting analysis showed that the age at diagnosis progressively decreased during the 20-year study period, while the target height and the starting LT4/kg/day increased. Final height was not affected by the birthdate, the age at diagnosis, the starting LT4 dose.

CONCLUSIONS

The final height is higher than the target height, but despite the improvement in the screening and the treatment, it did not improve over the last 20 years. These findings are in keeping with the described secular trend and suggest that earlier diagnosis and replacement therapy do not significantly modify final height in these patients.

An explanatory randomised placebo controlled trial of levothyroxine supplementation for babies born <28 weeks' gestation: results of the TIPIT trial

BACKGROUND

Babies born before 28 weeks' gestation have lower plasma thyroid hormone concentrations than more mature infants. This may contribute to their risk of poor developmental outcome. Previous studies have suggested that thyroxine supplementation for extremely preterm neonates may be beneficial. The aim of this study was to investigate the effect of administration of supplemental thyroxine to very premature babies on brain size and somatic growth at 36 weeks' corrected gestational age (CGA).

METHODS

In this explanatory multicentre double blind randomised placebo controlled trial, 153 infants born below 28 weeks' gestation were randomised to levothyroxine (LT4) supplementation or placebo until 32 weeks' CGA. The primary outcome was brain size assessed by the width of the subarachnoid space measured by cranial ultrasound at 36 weeks' CGA. Lower leg length was measured by knemometry.

RESULTS

Babies in the LT4-supplemented and placebo groups had similar baseline characteristics. There were no significant differences between infants given LT4 (n=78) or placebo (n=75) for width of the subarachnoid space, head circumference at 36 weeks' CGA, body weight at 36 weeks' CGA or mortality. Infants who received LT4 had significantly shorter leg lengths at 36 weeks' CGA although adjusted analysis for baseline length did not find a statistical difference. There was a significant correlation between low FT4 and wider subarachnoid space. No unexpected serious adverse events were noted and incidence of adverse events did not differ between the two groups.

CONCLUSION

This is the only randomised controlled trial of thyroxine supplementation targeting extremely premature infants. Supplementing all babies below 28 weeks' gestation with LT4 had no apparent effect on brain size. These results do not support routine supplementation with LT4 for all babies born below 28 weeks' gestation.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN89493983EUDRACT number: 2005-003-09939.

Early adiposity rebound and obesity in children with congenital hypothyroidism

BACKGROUND

Earlier adiposity rebound (AR) is correlated with obesity. Our goal is to examine rates of obesity and AR in congenital hypothyroidism (CHT) and analyze the risk factors of obesity.

METHODS

We retrospectively reviewed the cases with abnormal newborn screens of thyroid-stimulating hormone (TSH) from 1990 to 2005 and enrolled permanent CHT patients who continued to receive treatment after the 3(rd) year of life. We determined subgroups of obesity/being overweight and normal body mass index (BMI) by the latest BMI at 6-7 years of age. BMI at each age and the age of AR were compared with the general population in Taiwan. The statistical correlation of obesity with the age and BMI at both AR and first peak, and thyroid function was calculated.

RESULTS

A total of 90 cases of CHT were enrolled. The prevalence of obesity/being overweight was 32.2%. The age of AR was 4.94 ± 1.81 and 4.58 ± 1.86 years old in boys and girls, respectively. The age of AR in the girls with CHT was earlier than in girls in general, but no statistical significance was found in boys with CHT compared to the general population. Obesity was correlated with earlier age of AR, higher BMI at first peak and AR, and lower T4 after treatment, but not with the age of first peak of BMI, T4/TSH at diagnosis and AR, and TSH after treatment.

CONCLUSION

Children with CHT have a higher risk of obesity due to earlier age of AR. We recommend that supervision and intervention on weight control should be provided to prevent the occurrence of obesity later.

Optimising outcome in congenital hypothyroidism; current opinions on best practice in initial assessment and subsequent management

Congenital hypothyroidism (CH), usually of the primary and permanent variety, is an eminently preventable cause of growth retardation and mental handicap whose outlook has been transformed by newborn screening, usually involving the measurement of capillary thyroid stimulating hormone (TSH). Severe primary CH, due for example to athyreosis, may result in subtle cognitive, behavioural and sensori-motor deficits, but the extent to which these can be offset by optimal postnatal diagnosis and management remains uncertain. This is because the available adult follow-up data reflect the outcome of previous management in the 1970's and 1980's, and also because the accurate neuro-psychological assessment of children is difficult, particularly in the preschool population. There is an urgent need to develop new consensus guidelines and to ensure that the children managed according to such guidelines are systematically and prospectively assessed so that good quality outcome data become available. In this review, key recommendations in the management of CH include: screening at day 3 so that severely affected infants can begin treatment within the first 10 days of life; setting the TSH referral cut-off at 8-10 mU/L; adopting a disciplined diagnostic algorithm to evaluate referred cases, with measurement of venous free thyroxine (T4), TSH and thyroglobulin combined with dual ultrasound and radioisotope imaging; initial treatment with a T4 dose of 50 μg daily in infants weighing ≥ 2.5 kg and 15 μg/kg/day in infants weighing < 2.5 kg followed by weekly review until thyroid function is normalised; and maintenance of free T4 levels between 15-26 pmol/L and TSH between 0.5-5 mU/L thereafter to avoid both under- and overtreatment.

A 7-year experience with low blood TSH cutoff levels for neonatal screening reveals an unsuspected frequency of congenital hypothyroidism (CH)

CONTEXT

The guidelines of the National Academy of Clinical Biochemistry advocated the use of low bloodspot TSH (b-TSH) threshold for newborn screening of congenital hypothyroidism (CH). The impact generated by the application of this indication is largely unknown.

OBJECTIVE

To determine the impact on CH epidemiology and classification generated by the introduction of low b-TSH cutoff.

DESIGN

Retrospective study of 629,042 newborns screened with b-TSH cutoffs of 12 (years 1999-2002) or 10 mU/l (2003-2005).

MEASUREMENTS

Congenital hypothyroidism incidence and classification. Results were compared with those virtually obtained with the previous cutoff (20 mU/l). Clinical re-evaluation after L-T4 withdrawal of a representative group of 140 CH children at 3-5 years.

RESULTS

Low b-TSH cutoffs allowed the detection of 435 newborns with confirmed CH (incidence 1:1446). Forty-five percent of CH infants, including 12/141 dysgenesis, would have been missed using the 20 mU/l cutoff. In contrast to current classification, 32% CH newborns had thyroid dysgenesis and 68% had a gland in situ (GIS). Premature birth was present in 20% of cases being associated with a 3-5 fold increased risk of GIS CH. Re-evaluation at 3-5 years showed a permanent thyroid dysfunction in 78% of 59 CH toddlers with GIS.

CONCLUSIONS

The use of low b-TSH cutoff allowed the detection of an unsuspected number of children with neonatal hypothyroidism, evolving in mild permanent thyroid dysfunction later in life. The incidence of CH in this Italian population appears to be double than previously thought with a clear-cut prevalence of functional defects over dysgenetic ones.

Follow-up study of behavioral development and parenting stress profiles in children with congenital hypothyroidism

Recent longitudinal experiences have emphasized that the follow-up of children with treated congenital hypothyroidism (CHT) should not be limited to the cognitive domain. This study attempted to evaluate the emotional-behavioral profiles in children with CHT together with maternal parenting stress profiles. Data for child and family characteristics were collected from 47 families with a 3-12-year-old CHT child diagnosed and treated since the newborn period. Cognitive assessments were performed. The main caregiver completed the following questionnaires: (1) Strengths and Difficulties Questionnaire, which rated behavioral symptoms in children; (2) Parenting Stress Index, which determined the quality and magnitude of parenting stress experienced by the caregiver; and (3) Symptom Checklist-90-R, which evaluated the psychopathological symptoms of the caregiver. In addition, 31 unaffected siblings were recruited as a comparative control group. The results revealed that children with treated CHT had normal intelligence quotients (mean, 93.6 +/- 16.2) at the time of the study. However, CHT children had more problems in emotional-behavioral domains than sibling controls (p = 0.01). Overall, 29.8% (14/47) of the CHT children had emotional-behavioral problems above the clinical cutoff. In addition, 13% of the caregivers of CHT children had parenting stress above the clinical cutoff. Therefore, professional intervention is warranted in these subgroups of CHT children and parents.

Children with congenital hypothyroidism: long-term intellectual outcome after early high-dose treatment

We aim to determine long-term intellectual outcome of adolescents with early high-dose treated congenital hypothyroidism (CH). Sixty-three prospectively followed children with CH were assessed at age of 14 y with the Wechsler Intelligence Scale for Children-Revised and compared with 175 healthy controls. Median age at onset of treatment was 9 d (range 5-18 d) and median starting dose of levothyroxine (L-T4) was 14.7 microg/kg/d (range 9.9-23.6 microg/kg/d). Full-scale intelligence quotient (IQ) was significantly lower than in controls after adjustment for socioeconomic status (SES) and gender (101.7 versus 111.4; p < 0.0001). Children with athyreosis had a lower performance IQ than those with dysgenesis (adjusted difference 7.6 IQ scores, p < 0.05). Lower initial thyroxine (T4) levels correlated with poorer IQ (r = 0.27, p = 0.04). Lower SES was associated with poorer IQ, in particular in children with CH (interaction, p = 0.03). Treatment during childhood was not related to IQ at age 14 y. Adolescents with CH manifest IQ deficits when compared with their peers despite early high-dose treatment and optimal substitution therapy throughout childhood. Those adolescents with athyreosis and lower SES are at particular risk for adverse outcome. Therefore, early detection of intellectual deficits is mandatory in children with CH.

High versus low dose of initial thyroid hormone replacement for congenital hypothyroidism

BACKGROUND

Congenital hypothyroidism (CHT) affects approximately one in 3000 to 4000 infants. CHT is one of the most common preventable causes of learning difficulties. Optimal management of CHT requires early diagnosis and prompt treatment to avoid abnormal neurodevelopmental outcome. One of the main issues in the management of CHT relates to the initial dose of levothyroxine to be used in order to achieve optimal results in terms of intellectual development. Currently, it remains unclear whether high dose thyroid hormone replacement is more effective than low dose in the treatment of CHT. Further research is required to determine an appropriate dose that improves mental and psychomotor developmental outcomes.

OBJECTIVES

To determine the effects of high versus low dose of initial thyroid hormone replacement for congenital hypothyroidism.

SEARCH STRATEGY

Randomised controlled trials were identified by searching The Cochrane Library, MEDLINE and EMBASE and reference lists of published papers.

SELECTION CRITERIA

Randomised controlled clinical trials investigating the effects of high versus low dose of initial thyroid hormone replacement for congenital hypothyroidism were included.

DATA COLLECTION AND ANALYSIS

Both authors independently selected trials, assessed risk of bias and extracted data.

MAIN RESULTS

The initial search identified 1014 records which identified 13 publications for further examination. After screening the full text of the 13 selected papers, only one study evaluating 47 babies finally met the inclusion criteria. Using the same cohort at two different time periods, the study investigated the effects of high versus low dose thyroid hormone replacement in relation to (1) time taken to achieve euthyroid status and (2) neurodevelopmental outcome. The study reported that a high dose is more effective in rising serum thyroxine and free thyroxine concentrations to the target range and earlier normalisation of thyroid stimulating hormone compared to a lower dose. Similarly, full scale intelligence quotient was noted to be significantly higher in children who received the high dose compared to the lower dose. However, the verbal intelligence quotient and performance intelligence quotient were similar in both groups. Growth and adverse effects were not reported in the included trial.

AUTHORS' CONCLUSIONS

There is currently only one randomised controlled trial evaluating the effects of high versus low dose of initial thyroid hormone replacement for CHT. There is inadequate evidence to suggest that a high dose is more beneficial compared to a low dose initial thyroid hormone replacement in the treatment of CHT.

Hypothyroxinemia of prematurity: cause, diagnosis and management

Infants born at extreme prematurity are at a high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone, described as hypothyroxinemia, which is recognized to be a frequent phenomenon in these infants. At present, there is uncertainty among clinicians regarding the most appropriate method of managing hypothyroxinemia of prematurity. The literature suggests that some, but not all, forms of thyroid supplementation may reduce the incidence of disability in infants born at extreme prematurity. There is a pressing need to confirm the benefit of treatment and to establish the optimal way to treat transient hypothyroxinemia in these infants.

Long-term cardiovascular effects of levothyroxine therapy in young adults with congenital hypothyroidism

CONTEXT

Congenital hypothyroidism (CH) is the most prevalent endocrine disorder in the newborn and is routinely treated with life-long levothyroxine replacement therapy. Although several studies have demonstrated that such therapy may impact on the cardiovascular system, little is known with regard to the effects of long-term levothyroxine administration in patients with CH.

OBJECTIVE

The aim of the current study was to evaluate whether long-term levothyroxine replacement therapy in young adults with CH is associated with cardiovascular abnormalities.

PATIENTS AND METHODS

Thirty young adults with CH aged 18.1 +/- 0.2 yr and 30 age- and sex-matched controls underwent cardiac and carotid Doppler ultrasound and symptom-limited cardiopulmonary exercise testing. Hypothyroidism was diagnosed by neonatal screening, and levothyroxine treatment was initiated within the first month of life and carefully adjusted to maintain TSH levels in the normal range and free T(4) in the high-normal range.

RESULTS

Compared with controls, hypothyroid patients exhibited left ventricular diastolic dysfunction, impaired exercise capacity, and increased intima-media thickness. At multiple regression analysis, the number of episodes of plasma TSH levels less than 0.5 mU/liter and greater than 4.0 mU/liter from the age of 1 yr onward, and mean TSH plasma levels during puberty were independent predictors of diastolic filling and cardiopulmonary performance indexes (multiple r values: 0.61-0.75).

CONCLUSIONS

Long-term levothyroxine treatment in young adults with congenital hypothyroidism is associated with impaired diastolic function and exercise capacity and increased intima-media thickness.

Intellectual outcome, motor skills and BMI of children with congenital hypothyroidism: a population-based study

AIM

To evaluate intellectual outcome, motor skills and anthropometric data of children with congenital hypothyroidism (CH).

METHODS

Children with permanent CH who were born in 1999 in Bavaria were eligible for this prospective, population-based study. Cognitive performance was evaluated by the Kaufman Assessment Battery for Children and motor skills were assessed by the motor test, Motoriktest für vier-bis sechsjahrige Kinder (MOT) 4-6.

RESULTS

Eighteen of 21 eligible children participated (86%). Median age of the children was 5.5 years (range 4.9-5.8). Treatment with levothyroxine was started after a median of 7.2 days (range 4-15) with a median dose of 12.0 microg/kg (range 7.2-17.0). Mean intelligence quotient (IQ) of the children was 100.4 (standard deviation [SD] 10.1): no children had IQ values below the normal range. Reactivity and speed of movement were significantly reduced in children with CH. Children with an initial thyroid-stimulating hormone (TSH) value of >200 mU/L performed significantly worse than children with TSH value of <or=200 mU/L (p=0.003). Children with CH had a significant increased risk for overweight (risk ratio [RR] 3.91, 95% confidence interval [CI] 1.22-11.75, p=0.005) compared to the Bavarian reference children.

CONCLUSION

In this study, children with CH had an increased prevalence of overweight compared to reference data. Partially impaired motor skills could be shown, whereas the intellectual development was normal.

TIPIT: A randomised controlled trial of thyroxine in preterm infants under 28 weeks' gestation

BACKGROUND

Infants born at extreme prematurity (below 28 weeks' gestation) are at high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone which is recognised to be a frequent phenomenon in these infants. At present it is unclear whether low levels of thyroid hormone are a cause of disability, or a consequence of concurrent adversity.

METHODS

We propose an explanatory multi-centre double blind randomised controlled trial of thyroid hormone supplementation in babies born below 28 weeks' gestation. All infants will receive either levothyroxine or placebo until 32 weeks' corrected gestational age. The primary outcome will be brain growth. This will be assessed by the width of the sub-arachnoid space measured using cranial ultrasound and head circumference at 36 weeks' corrected gestational. The secondary outcomes will be (a) thyroid hormone concentrations measured at increasing postnatal age, (b) status of the hypothalamic pituitary axis, (c) auxological data between birth and 36 weeks' corrected gestational age, (d) thyroid gland volume, (e) volumes of brain structures (measured by magnetic resonance imaging), (f) determination of the extent of myelination and white matter integrity (measured by diffusion weighted MRI) and brain vessel morphology (measured by magnetic resonance angiography) at expected date of delivery and (g) markers of morbidity including duration of mechanical ventilation and chronic lung disease.We will also examine how activity of the hypothalamic-pituitary-adrenal axis modulates the effects of thyroid supplementation. This will contribute to decisions about which confounding variables to assess in large-scale studies.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN89493983.

Importância do fonoaudiólogo no acompanhamento de indivíduos com hipotireoidismo congênito

TEMA: o hipotireoidismo congênito é uma alteração metabólica que traz conseqüência graves para indivíduos não tratados e mesmo as crianças que realizam o tratamento podem apresentar distúrbios do desenvolvimento. O Programa Nacional de Triagem Neonatal, instituído pelo Ministério da Saúde, prevê o acompanhamento longitudinal de indivíduos com equipe multidisciplinar. Entretanto, a Fonoaudiologia não é incluída nesta equipe. Deste modo, considerando a ocorrência de distúrbios da comunicação nestes indivíduos, realizou-se levantamento bibliográfico nas bases de dados Lilacs, MedLine e PubMed, no período de 1987 a 2007, referente às alterações em habilidades do desenvolvimento decorrentes do hipotireoidismo congênito. OBJETIVO: verificar, na literatura científica, presença de alterações do desenvolvimento em indivíduos com hipotireoidismo congênito e refletir sobre a importância da atuação fonoaudiológica, em conjunto com equipe multidisciplinar especializada, no acompanhamento dos mesmos. CONCLUSÃO: a literatura relata alterações nas habilidades do desenvolvimento (motoras, cognitivas, lingüísticas e de autocuidados) e destaca que crianças com hipotireoidismo congênito são de risco para alterações no desenvolvimento lingüístico e, portanto, necessitam do acompanhamento longitudinal do desenvolvimento comunicativo. Torna-se evidente a importância da atuação do fonoaudiólogo nos Programas de Triagem Neonatal credenciados pelo Ministério da Saúde. Ressalta-se ainda a necessidade de investigações referentes às outras alterações metabólicas contempladas nestes programas, nas quais o fonoaudiólogo pode atuar de modo a prevenir, habilitar e reabilitar os distúrbios da comunicação, contribuindo para o trabalho em equipe, promovendo saúde nesta população.

How should we be treating children with congenital hypothyroidism?

Early detection by newborn screening and appropriate L-thyroxine treatment leads to normal or near-normal neurocognitive outcome in infants with congenital hypothyroidism. Many newborns with congenital hypothyroidism have some residual thyroid hormone production, and even in those with athyreosis, transplacental passage of maternal thyroid hormone offers some protection for a time. Given the serum T4 half-life of 6 days, the neonatal T4 level will fall and disappear over the first 2-3 weeks of life. Thus, there is a crucial 'window of opportunity' to correct the hypothyroidism and minimize the time the brain is exposed to hypothyroxinemia. While there are few truly prospective, randomized clinical trials investigating treatment parameters, studies measuring IQ outcome support a starting L-thyroxine dose of 10-15 microg/kg/day. Further, studies show that the most severely hypothyroid infants are at risk for a 5-20 point decrease in IQ. Such infants may benefit from a starting dose of 12-17 microg/kg/d, which has been shown to normalize T4 in 3 days and TSH in 2 weeks. Target serum T4 or free T4 levels appear to be higher in the first two weeks of treatment. Infants require more frequent laboratory monitoring, every 1-2 months in the first 6 months and every 3-4 months until age 3 years, as the developing brain has a critical dependence on thyroid hormone in the first 2-3 years of life.

Longitudinal Assessment of Levo-Thyroxine Therapy for Congenital Hypothyroidism: Relationship with Aetiology, Bone Maturation and Biochemical Features

AIMS

To evaluate therapy and dose adjustments in patients with congenital hypothyroidism (CH), longitudinally followed up until 16 years old, according to aetiology, Beclard's nuclei presence, and thyroxine (T4) level at diagnosis.

METHODS

L-T4/kg/day and dose change ratio (CR) were assessed in 74 CH patients.

RESULTS

The dose was statistically larger in athyreosis than in dyshormonogenesis (1-10 and beyond 14 years) and in ectopy (2, 15, 16 years). The ectopic children required statistically larger L-T4/kg than the dyshormonogenetic ones (3-7 years). The L-T4/kg/day was increased, not statistically, in patients or with T4 <30 nmol/l or without Beclard's nuclei at diagnosis. The CR progressively dropped after the 6th month at each attendance, without any difference in terms of aetiology, T4 level at diagnosis, or Beclard's nuclei. The total CR was greater (significantly) in patients without Beclard's nuclei, and (not significantly) in those with T4 <30 nmol/l at diagnosis or with agenesia.

CONCLUSION

The L-T4 dose in CH is highly affected by the aetiology. The CR is higher in patients with delayed bone maturation at diagnosis. We suggest that these latter patients need blood tests more frequently to obtain a proper titration of the therapy.

Genetics, clinical management and natural history of congenital hypothyroidism

Congenital hypothyroidism has an incidence of 1:3000-4000 newborns. In the past, it was a common cause of mental retardation, although newborn screening has improved the prognosis. Several transcription factors are crucial to the early organogenesis of the thyroid, including TITF1, FOXE1, PAX8 and HHEX. Nevertheless, a small minority of humans with congenital hypothyroidism carry mutations in these genes. Long-term follow-up studies show that with appropriate therapy, the mental and physical development of congenital hypothyroidism patients is in the normal range, although somewhat delayed when compared with appropriate controls. Critical issues of treatment include early diagnosis and rapid correction of hypothyroidism by ensuring rapid initiation of treatment and rapid normalization of thyroid-stimulating hormone levels, especially in cases of severe congenital hypothyroidism. There has been recent question of the need to treat premature infants with hypothyroxinemia but no elevation of the thyroid-stimulating hormone concentration. Numerous controlled studies of the short- and long-term effects of thyroid hormone supplementation have not shown a consistent benefit in this group of patients. Future research will investigate further the genetic underpinnings of the condition. There is a worldwide need to prevent congenital hypothyroidism by ensuring adequate dietary iodine and to develop infrastructure to diagnose and treat congenital hypothyroidism in developing countries.

Influence of timing and dose of thyroid hormone replacement on mental, psychomotor, and behavioral development in children with congenital hypothyroidism

OBJECTIVES

To evaluate the influence of initial and postinitial treatment factors on cognitive, psychomotor, and psychological outcome in schoolchildren with congenital hypothyroidism (CH).

STUDY DESIGN

We studied 45 patients (19 with severe CH and 26 with mild CH) and 37 control children by correlating initial and postinitial treatment factors (free thyroxine and thyroid-stimulating hormone [TSH] concentrations, and the percentage of overtreatment and undertreatment periods) with the results of neuropsychological tests and behavior (as reported on the Teacher Report Form [TRF]).

RESULTS

The global IQ of the children with CH was comparable to that of the controls; visuomotor and verbal scores were lower, and total TRF scores were higher. Ethnic group, previous development, and overtreatment predicted IQ and verbal scores, with higher scores seen for the overtreated patients than for the control children and those patients who had not been overtreated. As initial treatment was less satisfactory, total TRF scores were higher.

CONCLUSIONS

Our study suggests that initial and postinitial suboptimal treatment of CH leads to abnormalities in IQ and specific fields. Overtreatment may advance cognitive development in 5-1/2- to 7-year-olds. Suboptimal initial treatment may lead to behavioral problems. We recommend that TSH concentrations be maintained within the normal range in patients with CH.

Head circumference and linear growth during the first 3 years in treated congenital hypothyroidism in relation to aetiology and initial biochemical severity

AIMS

To determine the head circumference and linear growth in children with congenital hypothyroidism (CH) during the first 3 years of life in relation to the aetiology of CH and initial biochemical severity of thyroid function.

METHODS

We examined the head circumference and linear growth of 125 patients with CH from diagnosis up to 3 years of age. All infants had radionuclide scans prior to treatment. Patients were categorized into athyreosis, ectopia and dyshormonogenesis. Occipito-frontal circumference (OFC) SD, length SD, initial plasma TSH, initial plasma thyroxine (T4) and age of suppression of plasma TSH were compared between the groups. Multiple linear regression analysis was used to determine factors affecting OFC SD at 3 years of age.

RESULTS

There were 125 children in the study: athyreosis (n = 34), ectopia (n = 73) and dyshormonogenesis (n = 18). No difference was found in gestation, birth weight, age of starting L-T4 and initial dose of L-T4 in mcg/kg/day between groups. Confirmatory plasma total T4 at diagnosis was significantly lower for athyreosis when compared with ectopia and dyshormonogenesis. Median values for confirmatory TSH were significantly lower in dyshormonogenesis compared with the other two groups. At diagnosis, OFC were similar in all three groups. Children with athyreosis showed significantly larger OFCs compared with ectopia and dyshormonogenesis from 1 to 3 years. Length SD was within 1 SD of normal population standards at diagnosis and did not differ between the three groups throughout the 3 years. Spearman's correlation for OFC SD at 3 years of age showed a significant negative correlation with initial confirmatory plasma T4 (r = -0.35, P = 0.01). Multivariate analysis for OFC SD at 3 years of age showed confirmatory T4 as the only independent risk factor.

CONCLUSION

Children with athyreosis showed significantly larger OFC from 1 to 3 years of age compared with ectopia and dyshormonogenesis, independent of linear growth. Our data shows that initial confirmatory T4 at diagnosis is an independent factor influencing head growth in the first 3 years of life.

Cognition and behavior at school entry in children with congenital hypothyroidism treated early with high-dose levothyroxine

OBJECTIVE

To document cognition and behavior at school entry in these patients. Study design Eighteen children with congenital hypothyroidism (CH; 9 severe and 9 moderate, based on a surface of the knee epiphyses at diagnosis<or >or=0.05 cm(2)) treated from a median of 14 days with a median of 12.0 microg/kg per day of levothyroxine were evaluated at 5 years, 9 months, with the McCarthy Scale and the Questionnaire for Evaluation of Social Behavior, as were 40 control children.

RESULTS

The global IQs at 5 years, 9 months, were similar: medians (range) were 102 (87 to 133), 102 (84 to 135), and 115 (88 to 136) (not significant) for severe CH, moderate CH, and control children, respectively. The behavioral scores of CH children were within the normal range. However, the number of times when plasma TSH was >6.0 mIU/L during treatment was correlated positively with anxiety (P=.02) and inattention (P=.05), whereas the number of times TSH was <0.8 mIU/L was correlated with lower verbal scores (P=.05).

CONCLUSIONS

Children with severe CH treated early with a high dose of levothyroxine have normal global development and behavior at school entry.

Congenital hypothyroidism: developmental outcome in relation to levothyroxine treatment variables

Neonatal screening programs for congenital hypothyroidism (CH) were initiated in the 1970s to ensure early treatment in order to prevent mental retardation. With screening, developmental prognosis is considerably improved, but follow-up studies still report developmental delay compared to controls. To explain the delay, most studies have focused on effects of CH severity, supposedly caused by prenatal hypothyroidism. Nonoptimal treatment could also be an explanatory factor. Treatment guidelines have changed; now, a higher levothyroxine starting dose is recommended. In this review, we first summarize outcome studies in CH versus controls and in mild versus severe CH. Second, we report results on the association between levothyroxine treatment variables and developmental outcome. Six research groups have reported results on the association between levothyroxine starting dose and intelligence, and eight groups on the association between circulating thyroid hormones and intelligence. Most studies found a positive association between a high level of treatment, primarily treatment during the first year and later intelligence. However, negative associations between high-dose treatment and outcome have been reported, and the question of optimal treatment in relation to developmental outcome has not been answered. Effects of high levothyroxine dosage should be documented in samples that have been treated according to recent recommendations.

Congenital hypothyroidism: a review of current diagnostic and treatment practices in relation to neuropsychologic outcome

Because thyroid hormone is essential for normal brain development, children born with congenital hypothyroidism who lack thyroid hormone during a circumscribed period of early development are at risk of brain damage and mental retardation. Since the advent of newborn screening programs in the 1980s, the diagnosis and treatment of this condition are now provided in the first 2-3 weeks of birth in most regions. While this is usually sufficient to prevent mental retardation, the children so identified attain mildly reduced IQs from expectation, and may still experience subtle and specific neurocognitive deficits. Their particular deficits are related to the brief period of thyroid hormone insufficiency they undergo, especially factors reflecting the severity of hypothyroidism at the time of diagnosis, the duration of hypothyroidism in infancy, and thyroid hormones at time of testing. In this article, we review the specific kinds of deficits demonstrated by children with congenital hypothyroidism who were diagnosed by screening and treated early, as well as the factors associated with their disease and its management that contribute to these deficits. The disease-related factors that will be reviewed will include the etiology of hypothyroidism and severity of disease at the time of diagnosis, while the treatment-related factors will include age at onset of therapy, starting and subsequent dose levels, compliance, and treatment-adequacy issues. Also examined will be the effects of hormone levels at the time of testing. In addition, the role of moderating variables such as social, genetic, and environmental influences, as well as the child's gender, will be discussed. Furthermore, several new issues including the quality of subsequent management, ultimate outcome, and pregnancy will be additionally reviewed. In conclusion, while outcome in congenital hypothyroidism is substantially improved by screening, affected children do still experience mild neuropsychologic deficits. To reduce the impact of persisting deficits, further research is needed to determine the optimal starting dose for the different etiologies, guidelines for subsequent management, and alternative therapies. Moreover, now that the original samples are reaching adulthood and, in females, childbearing age, further research is also needed regarding treatment during pregnancy in women with congenital hypothyroidism, as is research to determine how this population ultimately fares in adulthood.

Effect of different starting doses of levothyroxine on growth and intellectual outcome at four years of age in congenital hypothyroidism

To evaluate the effect of different initial levothyroxine (LT4) replacement doses on growth and intellectual outcome in patients with congenital hypothyroidism (CH) detected by neonatal screening program, the longitudinal growth and intelligence quotient (IQ) were assessed and compared at 4 years of age in 83 patients with CH. The patients were divided into three groups according to the initial LT4 dose used: (1) group 1 (n = 42) received the previously recommended dose of 6.0-8.0 microg/kg per day; (2) group 2 (n = 21) received a dose of 8.1-10.0 microg/kg per day; (3) Group 3 (n = 20) a dose of 10.1-15.0 microg/kg per day. The IQ, evaluated by the Wechsler Preschool and Primary Scale of Intelligence test at 4 years of age, was significantly higher in group 3 (IQ 98 +/- 9) compared to group 1 (IQ 88 +/- 13; p < 0.05) but not compared to group 2 (IQ 94 +/- 13). However, the IQs were below the normal range (< 85) in six patients from group 2 (28%), but in none of the patients from group 3 (p = 0.03). Patients from group 3, with severe CH at diagnosis, had an IQ (97 +/- 9) at 4 years of age, which was not different from that of patients from the same group with moderate CH at diagnosis (IQ 99 +/- 9). Similar results were also observed in patients from group 2 however, mean IQ scores in these patients (93 +/- 12) were several points lower than those observed in patients from group 3 (95 +/- 15). After the first month of treatment, optimal serum levels of thyroxine (T4) and free thyroxine (FT4) were achieved in all groups, however, only patients from group 3 were able to normalize thyrotropin (TSH) (group 1, 16.0 +/- 12.0; group 2, 9.2 +/- 10.0; and group 3, 2.4 +/- 3.3 mU/L; p < 0.0001). Twelve patients from group 2 treated with an initial LT4 dose above 9 microg/kg per day were able to normalize TSH levels within the first 3 months of life and this resulted in a better IQ (97 +/- 16) compared to the remaining patients from the same group (IQ 90 +/- 9). In the whole group of 83 patients the IQ at 4 years of age was positively correlated to both initial LT4 dosage (r = 0.27, p < 0.02) and FT4 concentrations after the first month of treatment (r = 0.29, p < 0.02), and negatively correlated to TSH concentrations after the first month of treatment (r = -0.27, p < 0.02). No significant differences were observed in height, weight, head circumference, and bone age maturation among the three groups of patients. No clinical signs or symptoms of overtreatment were observed during follow-up in patients receiving the higher LT4 dosage. Our results indicate that high LT4 starting doses rapidly normalize serum TSH concentrations resulting in an improvement of the IQ at 4 years of age, even in patients with severe CH at diagnosis. Growth and bone age maturation are not affected by such a high dose.

The influence of etiology and treatment factors on intellectual outcome in congenital hypothyroidism

To determine the effects of hypothyroidism and hormonal patterns on outcome, we tested 65 7- to 12-year-old children with congenital hypothyroidism using standardized tests of intelligence, neuropsychological functioning, memory, and achievement. Results were analyzed by etiology, time to thyrotropin normalization, and hormone levels at testing. Children with athyreosis scored below other etiologies on visuospatial, attention, and arithmetic indices. Children whose thyroid-stimulating hormone levels normalized by 1 to 2 months of age scored higher than later normalizers on indices of visual memory, attention, and arithmetic. Normalization of thyroid-stimulating hormone by 3 months of age was associated with better memory and learning abilities than later normalization. Thyroid hormone levels at testing were correlated with indices of sensorimotor, spatial, and language abilities. Two children with persistently elevated thyrotropin levels were not adversely affected. Present findings signify the need to establish etiology, normalize thyrotropin early, and maintain hormone levels in the normal range throughout childhood in children with congenital hypothyroidism.