Relation between Early Over- and Undertreatment and Behavioural Problems in Preadolescent Children with Congenital Hypothyroidism

OBJECTIVE

Congenital hypothyroidism (CH) per se, when not treated or undertreated, may lead to severe behavioural problems (cretinism), whereas overtreatment of CH seems associated with attention problems.

DESIGN AND METHODS

For 55 CH patients, prospectively followed from birth until 11 years, parents rated the Child Behaviour Checklist and teachers the Teacher's Report Form at children's ages 6 and 11 years. We related scores regarding Attention, Delinquency, and Aggression (ADA scores, indicative for attention deficit hyperactivity syndrome, ADHD), and scores regarding Withdrawn, Anxious, Social, and Thought problems (WAST scores, indicative for autism) to the occurrence of over- and undertreatment in five age periods. Over- and undertreatment were defined as free thyroxine (fT4) concentrations above/below the range of the patient's individual fT4 steady state concentration.

RESULTS

ADA scores at 6 and 11 years for patients overtreated in the period 1-3 months postnatally were higher than those for patients who were not overtreated. Patients with severe CH undertreated in the period 3-6 months postnatally had higher WAST scores at 6 and 11 years than all other patients.

CONCLUSIONS

This is the first study suggesting that permanent ADHD as well as autism in CH patients at ages 6 and 11 years are the result of early overtreatment and undertreatment, respectively.

Maternal early-pregnancy thyroid function is associated with subsequent hypertensive disorders of pregnancy: the generation R study

CONTEXT

Hypertensive disorders during pregnancy are associated with a wide range of maternal and fetal complications, and only a few risk factors are known for the development of these disorders during pregnancy. Conflicting and limited data are available on the relationship between thyroid (dys)function and the risk of hypertensive disorders of pregnancy.

OBJECTIVE

The objective of the investigation was to study the associations between early-pregnancy thyroid dysfunction, thyroid function within the normal range, and the risk of hypertensive disorders.

DESIGN, SETTING, AND PARTICIPANTS

In early pregnancy, serum TSH, free T4 (FT4), and thyroperoxidase antibody (TPOAb) levels were determined in 5153 pregnant women. No interventions were done. The associations of thyroid function with the risk of hypertensive disorders were studied.

MAIN OUTCOME MEASURES

Mean blood pressures and hypertensive disorders, including pregnancy-induced hypertension (n = 209) and preeclampsia (n = 136), were measured.

RESULTS

Hyperthyroid mothers had a higher risk of hypertensive disorders [odds ratio (OR) 3.40 [95% confidence interval (CI) 1.46-7.91], P = .005], which was mainly due to an increased risk of pregnancy-induced hypertension [OR 4.18 (95% CI 1.57-11.1), P = .004]. Hypothyroidism and hypothyroxinemia were not associated with hypertensive disorders. Within the normal range, the high-normal FT4 levels were associated with an increased risk of hypertensive disorders [OR 1.62 (95% CI 1.06-2.47), P = .03], which was mainly due to an increased risk of preeclampsia [OR 2.06 (95% CI 1.04-4.08), P = .04]. The TPOAb status was not associated with hypertensive disorders.

CONCLUSIONS

We show that biochemical hyperthyroidism and also high-normal FT4 levels during early pregnancy are associated with an increased risk of hypertensive disorders. These data demonstrate that these associations are even seen for a mild variation in thyroid function within the normal range.

Soluble Flt1 and placental growth factor are novel determinants of newborn thyroid (dys)function: the generation R study

CONTEXT

Adequate thyroid hormone availability during fetal and early life is crucial for normal child growth and development. Fetal growth heavily depends on angiogenesis. Placental growth factor (PlGF) is a proangiogenic factor sharing high homology with vascular endothelial growth factor, whereas soluble FMS-like tyrosine kinase-1 (sFlt1) is a potent antagonist of vascular endothelial growth factor and PlGF signaling. Because the thyroid is a highly vascularized organ, we hypothesized that fetal angiogenic factors influence in utero thyrogenesis and impair newborn thyroid function. Therefore, we investigated the association between sFlt1 and PlGF on newborn thyroid function.

DESIGN, SETTING, AND PARTICIPANTS

sFlt1, PlGF, TSH, and free T4 (FT4) were determined in cord serum of 3525 newborns from a large prospective cohort study. Analyses were adjusted for relevant maternal and child covariates.

RESULTS

sFlt1 levels were positively associated with TSH (β 0.07 ± 0.02 mU/L; P < .001) and inversely with FT4 (β -0.58 ± 0.11; P < .001). PlGF showed a positive association with FT4 (β 0.19 ± 0.02; P < .001). Elevated levels of sFlt1 were associated with a 2.8-fold increased risk of hypothyroxinemia (P = .04). Decreased levels of PlGF were associated with a 6.7-fold increased risk of hypothyroxinemia (P < .001). Within the normal range, a dose-dependent effect of sFlt1 on thyroid dysfunction was observed: high-normal sFlt1 levels were associated with a 17.7-fold increased risk of hypothyroxinemia (P < .001) and a 2.7-fold increased risk of hyperthyrotropinemia (P = .01).

CONCLUSION

Fetal angiogenic factors sFlt1 and PlGF are associated with newborn thyroid function. Possible effects are most likely mediated through effects on in utero thyrogenesis. Abnormal as well as normal-range fetal sFlt1 and PlGF levels influence the risk of impaired newborn thyroid function, which has been associated with adverse neurodevelopmental effects. These data provide important novel insights into the physiology of thyrogenesis and into the etiology of newborn thyroid (dys)function.

Maternal thyroid hormones during pregnancy, childhood adiposity and cardiovascular risk factors: the Generation R Study

OBJECTIVE

Variation in maternal thyroid function during early pregnancy may permanently affect childhood growth and cardiovascular development. We examined the associations of early pregnancy maternal TSH and free T4 (FT4) levels with childhood growth, body composition and cardiovascular characteristics.

METHODS

We performed a population-based prospective cohort study among 5646 mothers and their children. Maternal thyroid parameters were assessed in early pregnancy (median: 13·2 weeks; 95% range: 9·7-17·6 weeks). Childhood growth was repeatedly measured from birth to 6 years. At the age of 6 years, childhood body mass index (BMI), total body and abdominal fat distribution, blood pressure and left ventricular mass were measured.

RESULTS

Maternal thyroid parameters were not consistently associated with childhood length and weight growth characteristics. Lower maternal TSH levels were associated with lower childhood BMI, total fat mass, abdominal subcutaneous fat mass area and diastolic blood pressure (P-values <0·05), but not with preperitoneal abdominal fat mass area, systolic blood pressure or left ventricular mass. Higher maternal FT4 levels were associated with lower childhood BMI, abdominal subcutaneous and preperitoneal fat mass area (P for trends <0·05), but not with other cardiovascular characteristics. Clinically maternal hypothyroid or hyperthyroid statuses were not associated with childhood growth, body fat or cardiovascular outcomes.

CONCLUSIONS

Maternal thyroid function during early pregnancy may influence childhood body composition and cardiovascular development. Further studies are needed to replicate these findings and to examine the influence of maternal thyroid hormone levels during pregnancy on long-term growth and cardiovascular development in the offspring.

Women with high early pregnancy urinary iodine levels have an increased risk of hyperthyroid newborns: the population-based Generation R Study

OBJECTIVE

Iodine deficiency during pregnancy results in thyroid dysfunction and has been associated with adverse obstetric and foetal effects, leading to worldwide salt iodization programmes. As nowadays 69% of the world's population lives in iodine-sufficient regions, we investigated the effects of variation in iodine status on maternal and foetal thyroid (dys)function in an iodine-sufficient population.

DESIGN, PARTICIPANTS AND MEASUREMENTS

Urinary iodine, serum TSH, free T4 (FT4) and TPO-antibody levels were determined in early pregnancy (13·3 (1·9) week; mean (SD)) in 1098 women from the population-based Generation R Study. Newborn cord serum TSH and FT4 levels were determined at birth.

RESULTS

The median urinary iodine level was 222·5 μg/l, indicating an iodine-sufficient population. 30·8% and 11·5% had urinary iodine levels <150 and >500 μg/l, respectively. When comparing mothers with urinary iodine levels <150 vs ≥150 μg/l, and >500 vs ≤500 μg/l, there were no differences in the risk of maternal increased or decreased TSH, hypothyroxinaemia or hyperthyroidism. Mothers with urinary iodine levels >500 μg/l had a higher risk of a newborn with decreased cord TSH levels (5·6 ± 1·4 (mean ± SE) vs 2·1 ± 0·5%, P = 0·04), as well as a higher risk of a hyperthyroid newborn (3·1 ± 0·9 vs 0·6 ± 0·3%, P = 0·02). These mothers had newborns with higher cord FT4 levels (21·7 ± 0·3 vs 21·0 ± 0·1 pm, P = 0·04). Maternal urinary iodine levels <150 μg/l were not associated with newborn thyroid dysfunction.

CONCLUSIONS

In an iodine-sufficient population, higher maternal urinary iodine levels are associated with an increased risk of a hyperthyroid newborn.

Cognitive development in congenital hypothyroidism: is overtreatment a greater threat than undertreatment?

BACKGROUND

Optimal treatment of children with congenital hypothyroidism (CHT) is still debated. Our objective was to evaluate whether early undertreatment (UT) and overtreatment (OT) influence cognitive development at age 11 years.

METHODS

Sixty-one patients (27 severe CHT, 34 mild CHT) were psychologically tested at ages 1.8 (Mental Development Index), 6 [intelligence quotient (IQ) 6], and 11 years (IQ11). Scores for cognitive development were related to initial levels of TSH normalization (fast, moderate, or slow) and to total durations of the UT and OT episodes within the first 2 years of life (no, short, or long UT/OT). UT and OT were defined as a free T4 (fT4) concentration below or above the individual fT4 steady-state concentration range (±2 SD).

RESULTS

Patients with fast and moderate TSH normalization had higher Mental Development Index scores than patients with slow TSH normalization; 14.2 and 7.7 points higher, respectively (P = .001). TSH normalization had no significant effect on IQ11. Patients with long and short overtreatment had IQ11s that were -17.8 and -13.4 points lower, respectively, than the IQ11s of patients with no overtreatment (P = .014). UT without OT was associated with normal development scores, but UT with OT was associated with -14.7 points lower IQ11s than UT without OT (P = .005).

CONCLUSIONS

Our study suggests that CHT overtreatment during the first 2 years leads to lowered cognitive outcomes at 11 years, whereas undertreatment, if not complicated by overtreatment, results in a normal cognitive development. Fast TSH normalization at initial treatment leads to above-normal development scores at a young age but does not affect IQ at age 11 years.

Hypothyroxinemia and TPO-antibody positivity are risk factors for premature delivery: the generation R study

CONTEXT

Premature delivery is an important risk factor for child mortality and psychiatric, metabolic, and cardiovascular disease later in life. In the majority of cases, the cause of prematurity cannot be identified. Currently, it remains controversial whether abnormal maternal thyroid function during pregnancy increases the risk of premature delivery. Therefore, we investigated the relation between maternal serum thyroid parameters and the risk of premature delivery in a large prospective population-based study.

DESIGN

Serum TSH, free T4 (FT4), T4, and TPO antibodies (TPOAbs) were determined during early pregnancy in 5971 pregnant women from the Generation R study. Data were available on maternal age, parity, smoking, socioeconomic status, ethnicity, maternal anthropometrics, and urinary iodine levels.

RESULTS

Of all women, 5.0% had a premature delivery (<37 weeks), 4.4% had a spontaneous premature delivery, and 1.4% had a very premature delivery (<34 weeks). High TSH levels and subclinical hypothyroidism were associated with premature delivery but not with spontaneous premature delivery. Maternal hypothyroxinemia was associated with a 2.5-fold increased risk of premature delivery, a 3.4-fold increased risk of spontaneous premature delivery, and a 3.6-fold increased risk of very premature delivery (all P < .01). TPOAb positivity was associated with a 1.7-fold increased risk of premature delivery (P = .01), a 2.1-fold increased risk of spontaneous premature delivery (P = .02), and a 2.5-fold increased risk of very premature delivery (P = .04). These effects remained similar after correction for TSH and FT4 levels.

CONCLUSIONS

Hypothyroxinemia and TPOAb positivity are associated with an increased risk of premature delivery. The increased risk in TPOAb-positive women seems to be independent of thyroid function.

Ethnic differences in maternal thyroid parameters during pregnancy: the Generation R study

CONTEXT

Abnormal maternal thyroid function during pregnancy is associated with various complications. International guidelines advocate the use of population-based trimester-specific reference ranges for thyroid function tests. When unavailable, an upper TSH limit of 2.5 for the first trimester and 3.0 mU/L for the second and third trimesters is recommended. Although interindividual differences in thyroid function tests can partially be explained by ethnicity, data on the influence of ethnicity on TSH and free T4 reference ranges during pregnancy are sparse.

DESIGN

Serum TSH, free T4, T4, and TPO-antibody levels were determined during early pregnancy in 3944 women from the Generation R study, Rotterdam, The Netherlands.

RESULTS

The study population consisted of 2765 Dutch, 308 Moroccan, 421 Turkish, and 450 Surinamese women. Mean TSH levels were higher in Dutch and Turkish women than in Moroccan or Surinamese women (1.50-1.48 vs 1.29-1.33 mU/L; P < .01). Although no differences in free T4 were seen, T4 was lowest in Dutch women (142 vs 150-156 nmol/L; P < .01). Turkish women had the highest frequency of TPO-antibody positivity (9.3% vs 5.0-5.8%; P < .05) and of elevated TSH levels in the second trimester (11.0% vs 3.8-7.3%; P < .01). A comparison of disease prevalence between a population-based vs an ethnicity-specific reference range changed the diagnosis for 18% of women who were initially found to have abnormal thyroid function test results.

CONCLUSIONS

We show ethnic differences in serum TSH, T4, and TPO-antibody positivity and found significant diagnostic discrepancies depending on whether population or ethnicity-specific reference ranges were used to diagnose thyroid disease.

Experience in treating congenital hypothyroidism: implications regarding free thyroxine and thyrotropin steady-state concentrations during optimal levothyroxine treatment

BACKGROUND

A major problem in the treatment of patients with congenital hypothyroidism (CHT) is that the optimal individual target values of thyrotropin (TSH) and free thyroxine (fT(4)) are unknown. We investigated whether patients with CHT have during treatment considered optimal stable fT(4) and TSH steady-state concentrations (SSCs) that can be used as target values, and whether TSH or fT(4) is more useful in guiding decisions regarding therapy.

METHODS

From 60 early-treated patients with CHT, TSH and fT(4) follow-up samples within the age interval 1.5-132 months (postinitial period) and within TSH interval 0.5-10 mU/L were selected. TSH and fT(4) SSCs were estimated by taking the individual mean values of a series of determinations, under the most euthyroid conditions possible (n=1257), for the whole age and TSH intervals, as well as for the age intervals 1.5-24, 25-72, and 73-132 months, as well as, for fT(4), for the two split TSH intervals 0.5-4.49 and 4.5-10 mU/L. For all SSCs, the within-subject coefficient of variation (CV(w)) was determined. Further, fT(4) SSCs were assessed for the first 6 weeks after therapy initiation.

RESULTS

For both TSH and fT(4), individual SSCs differed significantly (p<0.001). The 95% confidence interval for TSH SSCs was 1.1-5.7 mU/L and for fT(4) SSCs 16.6-28.7 pmol/L. Mean CV(w) values for TSH and fT(4) SSCs were 60.9% and 13.1%, respectively. Individual fT(4) and TSH SSCs were reproducible when assessed for the three age intervals, both slightly decreasing with age (p≤0.033), and fT(4) SSCs were reproducible for the two split TSH intervals, with a slight fT(4) difference (p<0.001). fT(4) SSCs were largely independent of the administered LT(4) dosage (range 2.4-6.1 μg/kg). fT(4) SSCs of the initial period were comparable to those of postinitial period with a mean±SD difference of 1.0±3.5 pmol/L, p=0.07.

CONCLUSIONS

Our study suggests that in CHT during therapy considered optimal, stable TSH and fT(4) SSCs can be found slightly decreasing with age and largely independent of the administered LT(4) dosage (range 2.4-6.1 μg/kg). In clinical follow-up, fT(4) SSCs may be more valuable as individual target values than TSH SSCs.

Maternal thyroid hormone parameters during early pregnancy and birth weight: the Generation R Study

CONTEXT

Maternal hyperthyroidism during pregnancy is associated with an increased risk of low birth weight, predisposing to neonatal morbidity and mortality. However, the effects of variation in maternal serum thyroid parameters within the normal range on birth weight are largely unknown.

OBJECTIVE

The aim was to study the effects of early pregnancy maternal serum thyroid parameters within the normal range on birth weight, as well as the relation between umbilical cord thyroid parameters and birth weight.

DESIGN, SETTING, AND PARTICIPANTS

In early pregnancy, serum TSH, FT4 (free T(4)), and thyroid peroxidase antibody levels were determined in 4464 pregnant women. Cord serum TSH and FT4 levels were determined in 2724 newborns. Small size for gestational age at birth (SGA) was defined as a gestational age-adjusted birth weight below the 2.5th percentile. The associations between normal-range maternal and cord thyroid parameters, birth weight, and SGA were studied using regression analyses.

RESULTS

In mothers with normal-range FT4 and TSH levels, higher maternal FT4 levels were associated with lower birth weight [β = -15.4 (3.6) g/pmol · liter, mean (SE); P = 1.6 × 10(-5)], as well as with an increased risk of SGA newborns [odds ratio (95% confidence interval) = 1.09 (1.01-1.17); P = 0.03]. Birth weight was positively associated with both cord TSH [β = 4.1 (1.4) g/mU · liter; P = 0.007] and FT4 levels [β = 23.0 (3.2) g/pmol · liter; P = 9.2 × 10(-13)].

CONCLUSIONS

We show that maternal high-normal FT4 levels in early pregnancy are associated with lower birth weight and an increased risk of SGA newborns. Additionally, birth weight is positively associated with cord TSH and FT4 levels. These data demonstrate that even mild variation in thyroid function within the normal range can have important fetal consequences.

Low urinary iodine excretion during early pregnancy is associated with alterations in executive functioning in children

The rare but deleterious effects of severe iodine deficiency during pregnancy on cognitive functioning of children are well known. Reports on possible associations between mild-to-moderate maternal iodine deficiency and child development, however, are scarce. In a population-based cohort we examined the association between maternal urinary iodine during early pregnancy and executive functioning in children at 4 y of age. In addition, we investigated the modification of this association by maternal diet and thyroid function. During pregnancy, we measured urinary iodine and thyroid hormone concentrations in 1156 women. In 692 of their children impairment of executive functioning was assessed by the Behavior Rating Inventory of Executive Function. Five hundred mothers of Dutch national origin completed an FFQ. Analyses were performed by using regression models. The children of mothers with low urinary iodine showed higher scores on the problem scales of inhibition [β = 0.05 (95% CI: 0.01, 0.10), P = 0.03] and working memory [β = 0.07 (95% CI: 0.02, 0.12), P = 0.003]. Although maternal dietary intake and thyroid hormone concentration did not significantly modify these associations, the associations between urinary iodine and problems of inhibition were attenuated after adjustment for maternal psychological symptoms. In addition, the consumption of bread [β = 0.61 (95% CI: 0.27, 0.95), P < 0.001] and eggs (β = 1.87 (95% CI: 0.13, 3.62), P = 0.04] was associated with higher urinary iodine. Thus, low maternal urinary iodine during pregnancy is associated with impaired executive functioning in children. Because these symptoms were subclinical and occurred at an early age, future studies are needed to show whether these children are more vulnerable to develop later clinical disorders.

Maternal early pregnancy and newborn thyroid hormone parameters: the Generation R study

CONTEXT

Abnormal maternal thyroid parameters are associated with adverse pregnancy outcomes, with consequences for both mother and child. Although various studies have studied maternal thyroid parameters during the first half of pregnancy, little is known about their relations with thyroid parameters of the child.

OBJECTIVE

The objective was to study maternal thyroid parameters during the first half of pregnancy as well as their relations with cord thyroid parameters.

DESIGN, SETTING, AND PARTICIPANTS

Serum TSH, free T(4) (FT4), T(4), and thyroid peroxidase antibody (TPOAb) levels were determined once between gestational wk 9 and 18 in 5393 pregnant women from the population-based Generation R study. Cord serum TSH and FT4 levels were determined in 3036 newborns.

RESULTS

Between gestational wk 9 and 18, the maternal TSH reference range (2.5th to 97.5th percentile) was 0.03-4.04 mU/liter. Gestational age was positively correlated with maternal TSH (r = 0.06, P = 6.3 × 10(-5)) and total T(4) (r = 0.21, P = 1.4 × 10(-44)) and negatively with FT4 (r = -0.27, P=7.3 × 10(-76)) and TPOAb-positivity (r=-0.04, P = 0.01). TPOAb positivity was associated with more subclinical (20.1 vs. 2.4%, P = 1.5 × 10(-39)) and overt hypothyroidism (3.3 vs. 0.1%, P = 1.4 × 10(-10)). Maternal and cord TSH were positively associated (β = 0.47 ± 0.15, P = 1.3 × 10(-5)) as well as maternal and cord FT4 (β = 0.11 ± 0.02, P = 4.5 × 10(-6)).

CONCLUSIONS

We confirm correlations of maternal thyroid parameters with gestational age during the first half of pregnancy and show a substantially increased risk of (subclinical) hypothyroidism in TPOAb-positive mothers. A substantial part of the mothers had a TSH level above 2.5 mU/liter, underlining the importance of using population-specific reference ranges. Maternal and cord thyroid parameters were positively correlated, the exact biological basis of which remains to be determined.

Maternal thyroid autoimmunity during pregnancy and the risk of attention deficit/hyperactivity problems in children: the Generation R Study

BACKGROUND

Maternal thyroid status and autoimmunity during pregnancy have been associated with impaired development of the offspring in animal and human studies. Our objective was to examine whether elevated titers of maternal thyroid peroxidase antibodies (TPOAbs) in early pregnancy increased the risk of cognitive impairment and problem behavior in preschool children. Second, we aimed at exploring to what extent any effect on child behavior was mediated by maternal thyroid parameters during pregnancy.

METHODS

In the Generation R Study, a population-based cohort of 3139 children and their mothers, we measured maternal thyroid parameters (thyrotropin [TSH], free Thyroxine, and TPOAbs) at 13.5±1.8 weeks of gestation. Children's verbal and nonverbal cognitive functioning was measured at 2.5 years using the Language Development Survey and the Parent Report of Children Abilities. At 3 years, children's behavior was assessed using the Child Behavior Checklist.

RESULTS

Elevated titers of TPOAbs during pregnancy did not predict the verbal and nonverbal cognitive functioning of the children. However, elevated titers of TPOAbs in mothers were associated with externalizing problems in children (odds ratio [OR]=1.64, 95% confidence interval [CI]: 1.17-2.29, p=0.004). In particular, children of TPOAb-positive mothers were at a higher risk of attention deficit/hyperactivity problems (OR=1.77, 95% CI: 1.15-2.72, p=0.01). To explore whether the effect of maternal TPOAbs on child problem behavior was mediated by maternal thyroid parameters, we added maternal TSH to the model. After correcting for TSH, the effect of TPOAbs on externalizing problems was attenuated slightly but remained significant (OR=1.56, 95% CI: 1.14, 2.14, p=0.005).

CONCLUSIONS

Our findings imply that the elevated titers of TPOAbs during pregnancy impact children's risk of problem behavior, in particular, attention deficit/hyperactivity. The observed effect is only partially explained by maternal TSH levels. These findings may point to a specific mechanism of Attention Deficit/Hyperactivity Disorder in children. Nevertheless, we can only speculate about public health implication of the study, as there is no specific treatment for TPOAb-positive pregnant women with normal thyroid function. Further investigation is needed to explore whether TPOAb-positive pregnant women and their children can benefit from close monitoring and early detection of developmental delay in populations at risk.

Maternal thyroid function during pregnancy and behavioral problems in the offspring: the generation R study

Maternal thyroid function during pregnancy is implicated in the neurodevelopment of the offspring, yet little is known about the effect of maternal thyroid parameters on the behavior of children. We investigated the association of maternal thyroid function during the first half of pregnancy with parent-reported problem behavior of the offspring up to age of 3 y. In the Generation R study, a population-based cohort of 3736 children and their mothers, data on maternal thyroid function and child's behavior were examined. The degree of internalizing and externalizing problems in the children were assessed with the Child Behavior Checklist at ages 1½ and 3 y. Higher levels of maternal TSH during pregnancy predicted a higher externalizing scores in children at 1½ and 3 y (B = 0.22 per SD of TSH; 95% CI: 0.04, 0.40; B = 0.10 per SD for internalizing scores; 95% CI: -0.01, 0.21). Maternal free thyroxine (T4) and total T4 were not associated with internalizing or externalizing scores of children. The linear relationship with more externalizing scores was across the range of TSH; this implies that subtle impairments of maternal thyroid function may affect the child. The results suggest that thyroid function is crucial for fetal brain development, which determines problem behavior later in life.

Maternal thyroid function during early pregnancy and cognitive functioning in early childhood: the generation R study

CONTEXT

Thyroid hormones are essential for neurodevelopment from early pregnancy onward. Yet population-based data on the association between maternal thyroid function in early pregnancy and children's cognitive development are sparse.

OBJECTIVE

Our objective was to study associations of maternal hypothyroxinemia and of early pregnancy maternal TSH and free T(4)(FT(4)) levels across the entire range with cognitive functioning in early childhood.

DESIGN AND SETTING

We conducted a population-based cohort in The Netherlands.

PARTICIPANTS

Participants included 3659 children and their mothers.

MAIN MEASURES

In pregnant women with normal TSH levels at 13 wk gestation (SD = 1.7), mild and severe maternal hypothyroxinemia were defined as FT(4) concentrations below the 10th and 5th percentile, respectively. Children's expressive vocabulary at 18 months was reported by mothers using the MacArthur Communicative Development Inventory. At 30 months, mothers completed the Language Development Survey and the Parent Report of Children's Abilities measuring verbal and nonverbal cognitive functioning.

RESULTS

Maternal TSH was not related to the cognitive outcomes. An increase in maternal FT(4) predicted a lower risk of expressive language delay at 30 months only. However, both mild and severe maternal hypothyroxinemia was associated with a higher risk of expressive language delay across all ages [odds ratio (OR) = 1.44; 95% confidence interval (CI) = 1.09-1.91; P = 0.010 and OR = 1.80; 95% CI = 1.24-2.61; P = 0.002, respectively]. Severe maternal hypothyroxinemia also predicted a higher risk of nonverbal cognitive delay (OR = 2.03; 95% CI = 1.22-3.39; P = 0.007).

CONCLUSIONS

Maternal hypothyroxinemia is a risk factor for cognitive delay in early childhood.

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.

Developmental trends in cord and postpartum serum thyroid hormones in preterm infants

The purpose of this study was first to clarify postnatal trends in sera T(4), free T(4) (FT(4)), T(4)-binding globulin, TSH, T(3), rT(3), and T(4) sulfate levels in cord and at 7, 14, and 28 d in groups of preterm infants at 23-27 wk (n = 101), 28-30 wk (n = 196), and 31-34 (n = 253) wk gestation, and second to compare these trends to those of term infants and also with cord sera levels of equivalent gestational ages (n = 812; 23-42 wk gestation). In all preterm groups, TSH and rT(3) decrease to below, T(4)-binding globulin increases to within, and T(3) and T(4) sulfate increase to above cord levels of equivalent gestational age. Term infants are hyperthyroxinemic relative to cord and nonpregnant adult levels of T(4). Postnatal T(4) increases are attenuated in 31- to 34-wk infants, absent in 28- to 30-wk infants (although levels are equivalent to gestational age), and crucially reversed in 23- to 27-wk infants. This immature group is hypothyroxinemic relative to other groups and to cord levels of equivalent gestational age. Compared with term infants, postnatal FT(4) increases are lower in 31- to 34-wk infants, attenuated in 28- to 30-wk infants, and absent in 23- to 27-wk infants. The 23- to 27-wk group is distinctive; they are hypothyroxinemic on T(4) levels, yet FT(4) levels are within the cord levels of equivalent gestational age.

Pre- and postnatal brain development in neonates with congenital hypothyroidism

Patients with early treated congenital hypothyroidism (CH) often develop subnormally and display subtle neurological defects. Can optimal treatment fully prevent these abnormalities, especially in patients with severe CH? This question was addressed by examining 61 patients (27 severe, 34 mild CH) aged 10-30 months using the Bayley Scales of Infant Development, a developmental test appropriate for this age. According to age at start of treatment (Early <13 days, Late > or = 13 days) and levothyroxine dose at the onset of treatment (High > or = 9.5 microg/kg/day, Low <9.5 microg/kg/day), four treatment groups were formed: Early/High, Early/Low, Late/High and Late/Low. Within the severe group, only the Early/High-treated patients reached normal developmental scores. Within the mild group, the Late/Low-treated infants had lower scores than the other patients with mild CH. The results suggest that if patients are treated early with a relatively high dosage of levothyroxine, normal psychomotor development can be expected, irrespective of the type of CH. When treated later on with a lower dose, suboptimal development is likely in infants exhibiting both types of CH. These cerebral abnormalities can originate during the pre- or postnatal period. The most important argument for a prenatal origin of the abnormalities is the relationship between bone age at diagnosis and subsequent developmental scores. We found, however, that this relationship can also be the result of late and inadequate treatment. In a series of 21 infants with CH (10 severe, 11 mild), somatosensory evoked potentials (SEP) were used to assess neurological maturation at diagnosis and after 12 months of treatment. At diagnosis, which was late (21 days after birth), SEP values were significantly less retarded than bone age (3.1 versus 6.5 weeks of delay, p < 0.001), measured using Sénécal's method. At 21 days, SEP and bone age values did not correlate, but they did correlate at 12 months (r = 0.47, p = 0.012). Therapy was inadequate in the whole group (mean initial dosage of levothyroxine 6.2 microg/kg/day), and in the severe group hypothyroidism persisted longer than in the mild group. The results suggest that the relationship between bone age and SEP values at 12 months was caused by late and inadequate hormone substitution more than intrauterine thyroid hormone deficiency.

Unexpected life-threatening complications in Kabuki syndrome

Kabuki syndrome is a rare multiple congenital anomalies/mental retardation syndrome comprising a distinct facial appearance and fetal fingertip pads. We observed two patients with Kabuki syndrome and describe unusual life-threatening complications, including stenosis of the central airways (not previously reported), extrahepatic biliary atresia, and congenital diaphragmatic hernia.

Influence of timing and dose of thyroid hormone replacement on development in infants with congenital hypothyroidism

OBJECTIVES

To test whether early treatment with a high initial dose of levothyroxine can prevent suboptimal mental development in all neonates with congenital hypothyroidism (CH).

STUDY DESIGN

Sixty-one patients, 27 with severe CH and 34 with mild CH, were treated either early (<13 days) or late (> or =13 days) with either a high initial dose of levothyroxine (> or =9.5 microg/kg/d) or a low initial dose (<9.5 microg/kg/d). With these criteria, 4 treatment groups were formed. The results of the Bayley test, performed at the age of 10 to 30 months and expressed as mental developmental index (MDI) and psychomotor developmental index (PDI), were related to socioeconomic status, treatment group, initial free thyroxine (FT(4)) concentration, and mean FT(4) concentration during the first 3 months of treatment (FT(4)-A) and the ensuing 9 months (FT(4)-B).

RESULTS

Mean (+/- SD) MDI was 113 +/- 14, and mean PDI was 114 +/- 12. In the severe CH group, only the patients treated early with a high initial dose had normal MDI scores (124 +/- 16), whereas the scores of the other groups ranged from 97 to 103. In contrast, all patients in the mild CH group had normal scores (range, 122-125), except those in the group treated late with a low initial dose, whose score was 110 +/- 10. Forty-three percent of the variance in MDI and PDI scores was explained by treatment factors, such as the treatment group, initial FT(4) concentration, FT(4)-A, and FT(4)-B.

CONCLUSIONS

Our data suggest that optimal treatment includes achievement of euthyroidism before the third week of life by initiation of therapy before 13 days with a levothyroxine dose above 9.5 microg/kg/d and maintenance of FT(4) concentrations in the upper normal range during the first year. Thus treated, patients with CH can achieve normal psychomotor development at 10 to 30 months, irrespective of the severity of the disease.

Thyroid hormone concentrations in preterm infants born to pre-eclamptic women with placental insufficiency

The aim of this study was to compare thyroid function in preterm infants born to women with placental insufficiency (n = 15) and those born to women without placental insufficiency (n = 13). Gestational ages ranged between 28 and 33 weeks. Concentrations of free thyroxine (FT4), thyrotropin (TSH), triiodothyronine (T3) and reverse T3 (rT3) were measured by radioimmmunoassays in cord blood and on d 1, 3, 5, 7, 14 and 21. Infants born to the women with placental insufficiency had significantly lower mean FT4 (p = 0.001), TSH (p = 0.002) and rT3 values (p = 0.025) in cord blood, and higher rT3 values on d 5 (p = 0.019) and d 7 (p = 0.025). The following conclusions were reached: (i) preterm infants born to pre-eclamptic women with placental insufficiency have intact hypothalamic-pituitary-thyroid axes; (ii) compared to preterm infants born to healthy women, preterm infants born to pre-eclamptic women with placental insufficiency have lower FT4 and TSH concentrations before birth and (iii) elevated rT3 concentrations after birth, suggesting a temporarily impaired hepatic type 1 deiodination process.

Influence of treatment on the maturation of the somesthetic pathway in infants with primary congenital hypothyroidism during the first year of life

To assess the influence of treatment on the development of the somesthetic pathway in infants with congenital hypothyroidism receiving early treatment, median nerve somatosensory evoked potentials were measured during the 1st y of life. Twenty-nine infants were studied with six to seven somatosensory evoked potential tests per infant. The cervical latency (N13) divided by arm length and the first (N19) and second (N32) cephalic latencies as well as N13-N32 latency were measured. At diagnosis, all components showed a small but significant delay, which was not related to thyroxine (T4) levels before treatment. During treatment, T4 ranged from 50 to 290 nmol/L. At 12 mo, the cervical latency divided by arm length had normalized, whereas N19 and N13-N32 were more abnormal than at diagnosis. For N19, these abnormalities were related to a slow initial rise of T4 (< or = 100 nmol/L after 1 wk of treatment) and the initial N19 values. Abnormal N13-N32 values were associated with high T4 values during treatment (> 200 nmol/L) and the type of congenital hypothyroidism (partial or total deficiency in T4 production). Induction of therapy with l-triiodothyronine rather than l-thyroxine and the occurrence of low T4 values (< 100 nmol/L) after the 4th wk of therapy had no such effect. Our data suggest that, for normal CNS development, euthyroidism should be reached as soon as possible by adequate induction therapy. Thereafter, T4 supplementation should be strictly dosed, keeping the serum T4 values within narrow limits around the mean normal for age, because overtreatment, like initial undertreatment, may lead to CNS abnormalities at the end of the first year.

Somatosensory evoked potentials in term and preterm infants in relation to postconceptional age and birth weight

The effect of age on the maturation of median nerve somatosensory evoked potentials (SEPs) was studied in 103 normal neonates (24 preterm, 79 term) at the postconceptional age (PCA) of 36-48 weeks. The influence of birth weight was evaluated in 44 term neonates, aged 0-7 days, according to their gestational age (GA) stratified into three groups: A: 38-39 weeks (n = 15); B: 39.5-40.5 weeks (n = 15); C: 41-43 weeks (n = 14). The mean birth weight was not different in the three groups. For all infants the N13 latency recorded at cervical (CS2-Fz) level as well as the N19 onset and peak latency at cortical (C3'/C4'-Fz) level were measured. For these parameters and for the N13 latency divided by arm length (N13/AL) and the N19 ascending time (N19AT) the P50, P97 and P3 were calculated as a function of PCA. They were all decreasing in the 36-48 weeks period, fast before 40 weeks and slowly thereafter. The SEP values of groups, A, B and C were not different, but in each group the wave pattern of the cortical SEPs was more mature in the larger than in the smaller infants. For the groups A, B and C together birth weight (in SDS) correlated inversely with the N13/AL and the N19AT (both in SDS) (r = 0.73 and 0.52 respectively, p less than 0.001). Our data indicate that the progression of maturation of the various SEP components in the period of 36-48 PCA is non-linear.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatosensory evoked potentials in neonatal jaundice

Somatosensory evoked potentials (SEPs) were studied in jaundiced and normal neonates on the day the highest bilirubin values were reached, 2-3 days later, and at five weeks. During the first week three groups were formed according to peak bilirubin values: A: greater than or equal to 250 mumol/l (n = 20), B: 125-250 mumol/l (n = 6), C: less than 125 mumol/l or no jaundice (n = 19). At five weeks 10 infants of group A were reinvestigated, together with 17 controls. Cervical (N13) and scalp SEPs (N19) were recorded with a variable number of stimuli. The SEPs of group B and C did not differ from each other. In group A the N13 peak latencies were within the range of group C at the first investigation, but prolonged at the second and third. The cortical components were prolonged at the first investigation, improved but still prolonged at the second, while the N19 peak latency was still prolonged at the third investigation. The central conduction time (CCT) correlated positively with the bilirubin level. Since a rapid decrease in the N19 amplitude was found for all groups from 25 to 100 stimuli, recordings should be done with a low number of stimuli (less than 100). Our findings indicate that both the periferal and the central components of the SEPs in the neonatal period are delayed by jaundice and that full recovery is not obtained at five weeks. The non-invasive SEP technique can be used as a daily monitor of the effect of bilirubin on the CNS.

Thyroid function in healthy normal, low birthweight and preterm infants

To delineate more precisely the role of gestational age, weight at birth and thyroid status at birth on the postnatal changes in thyroid hormone levels, serum T4, T3, TSH and in some cases FT3I were measured at birth and at 3-4 h, 24-30 h, 6-9 days and 13-20 days. Subjects studied were healthy appropriate-for-date (AFD) and small-for-date (SFD) term neonates and healthy AFD and SFD preterm children. At birth T4 and T3 are related to both gestational age and weight with T4 and T3 showing lower values in preterm and SFD term neonates than in AFD term children. After birth T4 and T3 concentrations show a better correlation with gestational age than with weight at birth. For TSH no correlation was found at birth, a positive correlation at 24-30 h, no correlation at 6-9 days and a negative correlation at 13-20 days both with gestational age and weight at birth. In term and close-to-term infants (36 weeks) individual T4 levels at 6-7 days show a close relationship with those at birth; in the younger children (34 and 35 weeks) lower T4 values are found, despite equal cord blood values. The individual cord blood FT3I/TSH values correlate well with those at 6-7 days of age. It is concluded that after birth all children have changing T4 and T3 values, but the pattern and level are influenced by the maturity of the child and its thyroid status at birth measured by T4 and by the FT3I/TSH ratio.(ABSTRACT TRUNCATED AT 250 WORDS)