Neurodevelopmental retardation, as assessed clinically and with magnetoencephalography and electroencephalography, associated with perinatal dioxin exposure

In 1980s Western Europe, human perinatal exposure to background levels of dioxins was rather high. We therefore evaluated the neurodevelopment of our cohort during the prepubertal period and in adolescence. At prepubertal age (7-12 years) 41 children were tested. Both neuromotor functioning and psychological testing were performed (Dutch version of the Wechsler Intelligence Scale for Children (WISC-R) and the Dutch version of the Child Behavior Checklist for ages 4-18 years (CBCL 4-18) and the Teacher Report Form (TRF)). Neurophysiological tests were performed using magnetoencephalography and electroencephalography. In adolescence (14-18 years) the behavior of 33 children was studied again (CBCL and TRF). And the levels of dioxins and dioxin-like PCBs (dl-PCBs) were measured in serum.

RESULTS

At prepubertal age no association was found between perinatal dioxin exposure and verbal, performal and total IQ or with the Touwen's test for neuromotor development. There were behavioral problems associated with both prenatal and postnatal dioxin exposure. In adolescence there were problems associated with the current dioxin levels and dioxin-like-PCBs. Neurophysiological tests revealed clear negative dysfunction. An increase in latency time after a motion stimulus (N2b) of 13 ms (= a delay of 10%) is associated with the higher prenatal dioxin exposure. A similar delay was measured in testing cognitive ability by analyzing the odd ball measurements, N200 and P300, together with an amplitude decrease of 12 %. The delay is indicative of a defective myelinisation and the decrease in amplitude of a loss of neurons.

CONCLUSION

We found effects on behavior in association with the perinatal dioxin exposure and in adolescence in association with the current dioxin levels. Neurophysiological testing is instrumental in the detection of effects of perinatal background levels of chemicals on brain development in normal, healthy children. The clinical, neurological and psychological tests commonly used are not sensitive enough to detect important effects.

[Neonatal screening for congenital hypothyroidism: more than 30 years of experience in the Netherlands]

OBJECTIVE

To describe the Dutch neonatal screening programme for congenital hypothyroidism (CH).

DESIGN

Descriptive study.

METHOD

Data on neonatal screening for CH in the period 1 January 1981 through 31 December 2011 were obtained from the Department for Vaccine Supply and Prevention Programmes of the Dutch National Institute for Public Health and the Environment (RIVM), laboratories and paediatricians to whom babies with abnormal screening results were referred. The screening procedure has been amended several times. In the period 1981-1994, only T4 and TSH were measured in heel prick blood, for example. From 1995, thyroxine-binding globulin (TBG) was added to the screening protocol.

RESULTS

The participation rate was 99.7%. Before 1995 the sensitivity, specificity and positive predictive value were 94%, 99.51% and 6%, respectively. From 1995 these percentages were 98%, 99.85% and 21%, respectively. The total prevalence of CH was 1:2670 (prevalence of CH of thyroidal origin was 1:3100 and CH of central origin was 1:21,600). The percentages of patients with severe CH treated before day 15 in the periods 1981-1990, 1991-2000 and 2001-2011 were 24% (63/263), 63% (170/269) and 96% (176/184), respectively.

CONCLUSION

The sensitivity and specificity of the screening procedure has considerably increased since 1995 compared with the period before 1995. In recent years patients with severe CH were treated considerably earlier than in the first years of the screening. Neonatal screening for CH may be considered as an important success for public health care.

Health- related quality of life and self-worth in 10-year old children with congenital hypothyroidism diagnosed by neonatal screening

BACKGROUND

Much is written about cognitive and motor development; less is known about social and emotional consequences of growing up with congenital hypothyroidism (CH).The objectives of the study were: (1) to compare health related quality of life (HRQoL) and self-worth of 10 year old patients with CH with the general population; (2) to explore associations of disease factors, IQ and motor skills with the outcomes.

METHODS

Children with CH and their parents completed several questionnaires. Patients were classified to 'severe CH, n = 41' or 'moderate/mild CH, n = 41' based on pre-treatment FT4 concentration.Differences between CH and the general population were tested by analysis of covariance and one sample t-tests (mean scale scores HRQoL and self-worth), chi-square tests and binomial tests (% at risk of impaired HRQoL and self-worth). Linear regression analyses corrected for gender were conducted to explore associations of the outcomes with disease factors, IQ and motor skills.

RESULTS

Patients with CH reported lower mean HRQoL on motor, cognitive and social functioning, and on autonomy and positive emotions (p < 0.0001). Patients were also more often at risk for impaired HRQoL and self-worth. No differences were found between the severity groups. Lower IQ was only significant associated with worse cognitive HRQoL. Initial FT4 plasma, age at onset of therapy, initial T4 dose and motor skills were not significantly associated with HRQoL and self-worth.

CONCLUSIONS

Negative consequences in terms of HRQoL and self-worth are prevalent in children with CH, independent of disease factors, IQ and motor skills. Physicians should to be attentive to these consequences and provide attention and supportive care.

Thyroid hormone metabolism and environmental chemical exposure

BACKGROUND

Polychlorinated dioxins and -furans (PCDD/Fs) and polychlorinated-biphenyls (PCBs) are environmental toxicants that have been proven to influence thyroid metabolism both in animal studies and in human beings. In recent years polybrominated diphenyl ethers (PBDEs) also have been found to have a negative influence on thyroid hormone metabolism. The lower brominated flame retardants are now banned in the EU, however higher brominated decabromo-diphenyl ether (DBDE) and the brominated flame retardant hexabromocyclododecane (HBCD) are not yet banned. They too can negatively influence thyroid hormone metabolism. An additional brominated flame retardant that is still in use is tetrabromobisphenol-A (TBBPA), which has also been shown to influence thyroid hormone metabolism.Influences of brominated flame retardants, PCDD/F's and dioxin like-PCBs (dl-PCB's) on thyroid hormone metabolism in adolescence in the Netherlands will be presented in this study and determined if there are reasons for concern to human health for these toxins. In the period 1987-1991, a cohort of mother-baby pairs was formed in order to detect abnormalities in relation to dioxin levels in the perinatal period. The study demonstrated that PCDD/Fs were found around the time of birth, suggesting a modulation of the setpoint of thyroid hormone metabolism with a higher 3,3', 5,5'tetrathyroxine (T4) levels and an increased thyroid stimulating hormone (TSH). While the same serum thyroid hormone tests (- TSH and T4) were again normal by 2 years of age and were still normal at 8-12 years, adolescence is a period with extra stress on thyroid hormone metabolism. Therefore we measured serum levels of TSH, T4, 3,3',5- triiodothyronine (T3), free T4 (FT4), antibodies and thyroxine-binding globulin (TBG) in our adolescent cohort.

METHODS

Vena puncture was performed to obtain samples for the measurement of thyroid hormone metabolism related parameters and the current serum dioxin (PCDD/Fs), PCB and PBDE levels.

RESULTS

The current levels of T3 were positively correlated to BDE-99. A positive trend with FT4 and BDE-99 was also seen, while a positive correlation with T3 and dl-PCB was also seen. No correlation with TBG was seen for any of the contaminants. Neither the prenatal nor the current PCDD/F levels showed a relationship with the thyroid parameters in this relatively small group.

CONCLUSION

Once again the thyroid hormone metabolism (an increase in T3) seems to have been influenced by current background levels of common environmental contaminants: dl-PCBs and BDE-99. T3 is a product of target organs and abnormalities might indicate effects on hormone transporters and could cause pathology. While the influence on T3 levels may have been compensated, because the adolescents functioned normal at the time of the study period, it is questionable if this compensation is enough for all organs depending on thyroid hormones.

Neonatal thyroid screening results are related to gestational maternal thyroid function

OBJECTIVE

To study the relationship between maternal thyroid function at each pregnancy trimester and neonatal screening results.

BACKGROUND

Overt maternal thyroid dysfunction during gestation is associated with poor neonatal thyroid function. However, research on the relationship between suboptimal maternal thyroid function (assessed at three trimesters) and neonatal thyroid screening outcome is scarce.

DESIGN/PATIENTS

Prospective follow-up study during three trimesters of gestation in 886 Dutch Caucasian healthy pregnant women followed from 12-week gestation until term delivery (>37 weeks) and their neonates.

MEASUREMENTS

The relation between neonatal data from the Congenital Hypothyroidism (CH) screening and maternal thyroid determinants [TSH, FT4 and thyroid peroxidase (TPO)-Ab] assessed at 12-, 24- and 36-week gestation.

RESULTS

Boys have lower screening TT4 levels and their mothers have higher TSH levels at 24- and 36-week gestation. Higher maternal TSH levels (>97·5th percentile, as defined in 810 women without TPO-Ab at 12 weeks) at one or more times during pregnancy (O.R: 2·26, 95% CI: 1·20-4·29) and lower gestational age (O.R: 1·22, 95% CI: 1·05-1·41) are independently related to lower screening TT4 levels.

CONCLUSIONS

Maternal thyroid function during gestation is related to neonatal TT4 at screening. The finding of both lower neonatal TT4 levels in boys and higher TSH levels in mothers carrying boys is worthy of further investigation, as both observations may be meaningfully related.

Delayed initiation of breast development in girls with higher prenatal dioxin exposure; a longitudinal cohort study

OBJECTIVES

While many studies have assessed the health impacts of PCDD/Fs and PCBs on animals and humans, long-term consequences for especially adolescents, have not (yet) been well documented. This is certainly also true for the effects of PBDE exposure. As part of a longitudinal cohort study, now well into its second decade, effects of perinatal and current PCDD/F exposure, as well as current dl-PCB and PBDE exposures, on puberty, were assessed.

STUDY DESIGN

Prenatal, lactational and current PCDD/F, dl-PCB and PBDE concentrations were determined using GC-MS. Pubertal development and growth were assessed by means of physical examination and the Tanner scale. 33 Children (born between 1986 and 1991) consented to the current follow-up study. Outcomes were evaluated using linear regression or the non parametric Spearman's correlation coefficient.

RESULTS

A delay in initiation of breast development was found in girls (n = 18) with higher prenatal (p = 0.023) and lactational PCDD/F exposure (p = 0.048). The males revealed a negative trend with age at first ejaculation. For other endpoints on puberty and growth (pubic hair, axillary hair, genital stage, length, BMI, testicular volume, menarche) no significant relation was found with any of the measured compounds.

DISCUSSION AND CONCLUSION

A relation between prenatal PCDD/F exposure and later initiation of breast development was seen. A Belgian study found a delay in breast development with higher current serum concentrations of dioxin-like compounds. The initiation of puberty is a complex process and it is yet not clear how dioxin-like compounds precisely affect this process prenatally. Further follow-up into adulthood is warranted, in order to detect the possibility of developing malignancies and fertility problems.

Quality of life, developmental milestones, and self-esteem of young adults with congenital hypothyroidism diagnosed by neonatal screening

CONTEXT

With advances in the treatment of congenital hypothyroidism (CH), the neuropsychological functioning of CH patients is considerably improved. Although much is written about cognitive and motor development, little is known about emotional and social consequences for patients growing up with CH, diagnosed by neonatal screening.

OBJECTIVES

The objectives of the study were to: 1) compare health-related quality of life (HRQoL), developmental milestones also called course of life (CoL), sociodemographical outcomes, and self-esteem of CH patients with the general population; and 2) explore whether severity of CH was related to these outcomes.

DESIGN/SETTING/PATIENTS

A total of 69 young adults with CH, born in The Netherlands in 1981-1982, completed the "TNO-AZL Questionnaire for Adult's Health related Quality of Life" questionnaire, the CoL survey (developmental milestones and sociodemographical outcomes), and a self-esteem questionnaire.

MAIN OUTCOME MEASURES

HRQoL, CoL, social demographical outcomes, and self-esteem in young adults with CH were determined.

RESULTS

CH patients are more often at risk for HRQoL impairment and reported lower HRQoL on several domains (cognitive functioning, P < 0.0001; sleeping, P < 0.004; pain, P < 0.0001; daily activities, P < 0.004; vitality, P < 0.0001; aggressiveness, P < 0.0001; and depressive moods, P < 0.0001) compared with healthy adults. Patients reported a lower self-esteem (P < 0.005) and had a delayed CoL on the domain of social development (P < 0.016). There were no significant within-group differences between the severity groups for HRQoL, CoL, and self-esteem.

CONCLUSIONS

Negative consequences in terms of HRQoL, development, and self-esteem are prevalent in young adults with CH. Health care physicians should be attentive to these consequences and provide additional support (emotional and educational guidance) if necessary.

The effect of life-long thyroxine treatment and physical activity on bone mineral density in young adult women with congenital hypothyroidism

OBJECTIVE

Normalization of plasma thyrotropin in T4-supplemented patients with thyroidal congenital hypothyroidism (CH) requires elevated plasma FT4-concentrations compared to patients with acquired thyroidal hypothyroidism. We investigated bone mineral density (BMD) in patients with CH.

PATIENTS AND METHODS

BMD was measured in 14 adult women with thyroidal CH and nine age-matched female controls.

RESULTS

There were no significant differences between patients and controls for femoral neck bone mineral content (BMC) (38.6 vs 37.6 g), BMD (0.98 vs 1.01 g/cm(2)), T-score (0.1 vs 0.3 SD) and z-score (0.1 vs 0.3 SD) and for spine BMC (63.1 vs 71.9 g). The differences in spine BMD (0.97 vs 1.09 g/cm(2)), T-score (-0.7 vs 0.4 SD) and z-score (-0.5 vs 0.6 SD) were significant (p = 0.025, p = 0.023, and p = 0.021, respectively).

CONCLUSIONS

Although BMD in patients with CH was slightly lower compared to controls, all scores were within the reference range. This does not support the hypothesis that the upwards shifted plasma FT4-concentrations in patients treated for CH have a deleterious effect on BMD.

Neonatal screening for congenital hypothyroidism based on thyroxine, thyrotropin, and thyroxine-binding globulin measurement: potentials and pitfalls

CONTEXT

The Dutch T(4)-TSH-TBG-based neonatal screening program detects patients with congenital hypothyroidism (CH) of thyroidal (CH-T) as well as central (CH-C) origin. The numbers and characteristics of true-positive and false-positive referrals will differ from other, predominantly TSH-based, screening methods.

OBJECTIVE

The present study describes the characteristics of the referred neonates, both CH patients and false positives, and of the reported CH patients with a false-negative screening result born in the study period.

DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURE

For each referred child born between April 1, 2002, and May 31, 2004, screening results and first venous sample results were recorded and classified as transient or permanent CH-T or CH-C or as no CH.

RESULTS

In the study period, 430,764 children were screened. Of the 772 children with abnormal screening results, 224 (29%) had CH; another 13 CH patients did not have abnormal screening results, giving an overall CH incidence of 1:1800. Incidences of permanent CH, permanent CH-T, permanent CH-C, and transient CH were 1:2200, 1:2500, 1:21,000, and 1:12,000, respectively. The most frequent explanations for the 548 false-positive referrals (71% of the referred cohort) were severe illness and TBG deficiency (occurring in 198 and 200 children, respectively).

CONCLUSIONS

The Dutch incidence figures for CH belong to the highest worldwide, suggesting that the T(4)-TSH-TBG screening program is an efficient method to detect CH of variable etiology and severity. Still, a small percentage of children with CH escaped detection via this screening approach. Severe illness and TBG deficiency appear to be responsible for the majority of false-positive referrals.

Endocrine intervention during irradiation does not prevent damage to the thyroid gland

Radiation to the head-neck region may damage the thyroid gland, leading to hypothyroidism or thyroid carcinoma. Outcomes of radiation protection by lowering plasma thyroid-stimulating hormone (TSH) have thus far been ambiguous. Our aim was to evaluate the radioprotective effect of inhibiting the thyroid gland's activity during x-radiation. For this purpose, of 80 5-week old Wistar rats, 64 received cervical irradiation with 15 Gy (single dose). During irradiation, endocrine intervention was done, using thyroxine (T(4)), T(4) plus iodine, or iodine alone compared to placebo. During the endocrine interventions and follow-up, TSH and T(4) concentrations were measured periodically. Histologic examination of thyroid, pituitary gland, or the hypothalamus and any suspect lymph nodes, lungs, and liver was performed after 6 and 54 weeks. It was found that during the endocrine intervention, plasma levels of TSH were lower in rats given T(4) and higher in rats given iodine. After 6 and 54 weeks, no significant reduction in hypothyroidism or thyroid carcinoma was found between the different groups of rats given any endocrine intervention or no intervention. In conclusion, the administration of T(4), iodine or the combination during x-irradiation does not protect against radiation-induced thyroid damage.

Intellectual and motor development of young adults with congenital hypothyroidism diagnosed by neonatal screening

CONTEXT

Long-term follow-up data on cognitive and motor functioning in adult patients with congenital hypothyroidism, diagnosed by neonatal screening, are scarce. Hence, it is still unclear whether the frequently reported cognitive and motor deficits observed during childhood persist in adulthood.

OBJECTIVE

The objective of this study was to examine cognitive and motor functioning in young adults with congenital hypothyroidism, born in the first 2 yr after the introduction of the Dutch neonatal screening program.

DESIGN/SETTING/PATIENTS

Seventy patients were tested (mean age, 21.5 yr); 49 of them were previously tested at 9.5 yr. The median age at the start of treatment was 28 d (range, 4-293 d). Congenital hypothyroidism was classified as severe, moderate, or mild, according to pretreatment T(4) concentrations.

MAIN OUTCOME MEASUREMENT

The main outcome measurement was the influence of the severity of congenital hypothyroidism and age at which T(4) supplementation was started on cognitive and motor outcome.

RESULTS

Patients, particularly those with severe congenital hypothyroidism, had significantly higher (i.e. worse) motor scores (total score, 7.8; ball skills, 2.0; balance, 4.1) compared with controls (total score, 3.2; ball skills, 0.7; balance, 1.1), and lower full-scale (95.8), verbal (96.4), and performance (95.6) intelligence quotient (IQ) scores than the normal population. No significant change in IQ from childhood to adulthood was found, and for the majority of patients, motor score classification remained the same. The severity of congenital hypothyroidism, but not the starting day of treatment, was correlated with IQ and motor scores.

CONCLUSIONS

It is concluded that the severity of congenital hypothyroidism, but not the timing of treatment initiation, is an important factor determining long-term cognitive and motor outcome. Clearly, detrimental effects on developmental outcome in patients with congenital hypothyroidism persist over time.

Skeletal dysplasia and myelopathy in congenital disorder of glycosylation type IA

We report on a boy with a congenital disorder of glycosylation (CDG) Ia and a severe narrowing of the spinal canal caused by atlantoaxial subluxation with anterior displacement of C1. C1-laminectomy improved the progressive paresis. Progressive paresis caused by spinal cord compression is a hitherto unrecognized complication in patients with CDG-Ia.

Endocrine late effects from multi-modality treatment of neuroblastoma

Thyroid dysfunction has been reported after 131I-MIBG-treatment for neuroblastoma. In this study, we have evaluated all endocrine functions from patients who were given multi-modality treatment including 131I-MIBG. Twenty-five neuroblastoma survivors who were off therapy for a median period of 6.0 years (range 1.3-11.1) were evaluated and their median age was 8.1 years (range 2.2-14.7). All patients had received 131I-MIBG, 16 chemotherapy, and 16 surgery. Fourteen patients (56%) had permanently elevated thyrotropin levels and 9 received thyroxine. Two patients had a small thyroid volume while 6 had thyroid nodules or cysts. Two boys showed hypergonadotropic hypogonadism. Growth was retarded in 39% of children. Mean Target Height Standard Deviation Score of patients with thyrotropin elevation was lower than those without (P=0.019). Children treated for neuroblastoma with 131I-MIBG, chemotherapy and surgery were seen to be at risk from developing irreversible thyroid function loss, thyroid nodules, hypergonadotropic hypogonadism, and growth retardation. We recommend that during follow-up of neuroblastoma children, special attention should be paid to their endocrine state.

Disturbance of the fetal thyroid hormone state has long-term consequences for treatment of thyroidal and central congenital hypothyroidism

BACKGROUND

During T(4) supplementation of patients with thyroidal (primary) congenital hypothyroidism (CH) TSH concentrations are frequently elevated despite free T(4) (FT(4)) concentrations being well within the reference range. To examine the thyroid's regulatory system, we analyzed thyroid function determinants in children with congenital and acquired thyroid disorders and in controls.

METHODS

Retrospectively, plasma FT(4), TSH, and T(3) concentrations were analyzed in T(4)-supplemented children aged 0.5-20.0 yr with thyroidal CH, central (secondary or tertiary) CH, or autoimmune thyroid disease and in control children with type 1 diabetes mellitus.

RESULTS

When TSH was within the reference range (0.4-4.0 mU/liter), mean FT(4) in thyroidal CH [1.65 ng/dl; 95% confidence interval (CI), 1.62-1.67] was significantly higher than in autoimmune thyroid disease (1.15 ng/dl; 95% CI, 1.11-1.19) and diabetes (1.08 ng/dl; 95% CI, 1.06-1.10). In central CH, when TSH was less than or equal to 0.02 mU/liter, mean FT(4) was 1.27 ng/dl (95% CI, 1.24-1.29). When FT(4) was within the reference range (0.78-1.79 ng/dl), 43% of the TSH measurements in thyroidal CH were more than 4.0 mU/liter, compared with 18% in autoimmune thyroid disease and 0% in type 1 diabetes mellitus; in central CH, 95% of TSH measurements were less than 0.4 mU/liter.

CONCLUSIONS

In T(4)-supplemented patients with thyroidal CH, when TSH concentrations are established within the reference range, FT(4) concentrations tend to be elevated, and vice versa. Because this phenomenon could not be observed in acquired thyroidal hypothyroidism, we hypothesize that a pre- and/or perinatal hypothyroid state shifts the setpoint of the thyroid's regulatory system. In central CH, when FT(4) concentrations are established within the reference range, the pituitary secretes only minute amounts of TSH. For monitoring T(4) supplementation, reference ranges for FT(4) and TSH should be adapted to the etiology of hypothyroidism.

Disseminated medullary thyroid carcinoma despite early thyroid surgery in the multiple endocrine neoplasia-2A syndrome

A 51/2-year-old boy, with a family history of multiple endocrine neoplasia (MEN)-2A syndrome, was evaluated for presence of MEN-2A and medullary thyroid carcinoma (MTC). DNA diagnostics confirmed MEN-2A. Basal (360 ng/L) and pentagastrin stimulated (430 ng/L) calcitonin (CT) levels were slightly elevated, plasma carcinoembryonic antigen (CEA) was normal. Within a year both tumor markers increased and total thyroidectomy was performed. Histologic examination did not show MTC. In the following years, both tumor markers increased progressively but despite the use of multiple imaging techniques no metastases were localized. After 6 years, biopsy of a palpable lymph node showed MTC. The boy was treated with total cervical, suprahyoidal, and mediastinal lymph node dissection, showing MTC in almost all nodes. Again, the tumor markers remained high. At this point in time, the disadvantages of further medical interventions were outweighed against the chance for cure and it was decided to shift the goal of treatment toward palliation rather than cure. At the last visit the boy was clinically well with persistent extremely high levels of plasma CEA and CT. In conclusion, when prophylactic thyroidectomy in the MEN-2A syndrome has failed, it may be best to withdraw from further interventions to prevent more damage.

The effect of cervical X-irradiation on activity index of thyrocytes and plasma TSH: a pre-clinical model for radiation-induced thyroid damage

Because radiotherapy in the head and neck region is necessary in the treatment of childhood cancer, possibilities to prevent damage to the thyroid gland must be explored. We developed a model in which radiation-induced effects can be investigated in a way that these effects can be quantified, using thyroid dysmorphology and plasma TSH. Thirty-five Wistar rats, 5 weeks old, were X-irradiated on the cervical region, with a single dose varying from 0 to 20 Gy. After 6 weeks, TSH, T4 and T3 were determined, and thyroid glands were processed for histological examination by two independent pathologists. A histological classification scale was developed, using follicular size, colloid density and cell height of thyrocytes to measure hyperplasia and hypertrophy. By the sum of these scores, a cell-activity index was calculated, which was related to plasma TSH concentration. Numbers of PAS-positive droplets and epithelial desquamation were also counted. Inter-observer reliability was assessed. Good to very good reliability was found for scores of follicular size, colloid density and cell height. Significant increase of cell-activity index was found after 10, 15 and 20 Gy. The plasma TSH concentration was positively correlated to the cell-activity index, increasing with radiation-doses up to 15 Gy. The number of desquamated cells was significantly increased after radiation doses >10 Gy, with moderate reliability. In conclusion, this model using cell-activity index of thyrocytes together with plasma thyrotropin concentrations and desquamation of cells can be used for interpretation and future (pre-clinical) studies of prevention of radiation-induced thyroid damage.

Changes in thyroid hormone state in children receiving chemotherapy

OBJECTIVE

The concentrations of thyroid function determinants may change during severe illness. Our goal was to quantify their changes in children with cancer during chemotherapy, and to correlate them to clinical condition and type of drugs.

DESIGN

During a 3-month period all patients admitted for chemotherapy to the paediatric oncology ward were evaluated for inclusion. Patients with brain tumours, neuroblastoma (cranio)spinal irradiation and use of dexamethasone before the first blood sample were excluded.

MEASUREMENTS

Plasma concentrations of T4, T3, rT3, thyroxine-binding globulin (TBG), thyroglobulin (Tg), TSH, IGF-1, cortisol, PRL and physical well-being by means of questionnaires were measured before and during chemotherapy.

RESULTS

In 19 children, 46 courses of chemotherapy and 123 plasma samples were analysed. During chemotherapy, mean concentrations of TSH, T3, Tg and cortisol decreased to 53, 67, 69 and 15% of the baseline value, respectively. Mean plasma rT3 increased to 217% of baseline. In 87% of all courses, one or more thyroid parameter(s) was aberrant. Furthermore, in 23 samples (19%) from 10 patients (53%), the concentration of IGF-1 was below the reference value (adjusted for sex and age). Small changes were seen in scores for clinical condition but none was related to a change in thyroid function determinant. Most changes in thyroid hormones could be attributed to using dexamethasone.

CONCLUSIONS

These results demonstrate that, in children, thyroid hormone state changes significantly during chemotherapy, apparently not related to physical well-being but to the drugs administered. Future investigations should focus on the impact for patient care and possibilities of (preventive) intervention.

Frequent adverse events after treatment for childhood-onset differentiated thyroid carcinoma: a single institute experience

Since the mortality rate for childhood differentiated thyroid carcinoma is nearly zero, the focus must be to minimise morbidity following treatment. Our aim was to analyse early and late adverse events. Twenty-five of 26 children treated between 1962 and 2002 were evaluated. Median follow-up was 14.2 years (range 0.9-39.4 years). All underwent total thyroidectomy, 15 (60%) with lymph node dissection and 15 (60%) with adjuvant radio-iodide therapy. Mortality was zero. Seven developed recurrent disease, two developed a third recurrence. Twenty-one (84%) had > or =1 adverse event. Eight had permanent hypoparathyroidism (PH), six permanent recurrent nerve paralysis (PRNP) and two Horner's syndrome. Risk factors for PH and PRNP were total thyroidectomy with lymph node dissection (RR: 6.45, P = 0.015) and recurrent nerve tumour encasement (RR: 8.00, P = 0.001), respectively. Other adverse events were fatigue (n = 5), scar problems (n = 4) and chronic myeloid leukaemia (n = 1). These results emphasise the need to improve treatment strategies.

Lower neonatal screening thyroxine concentrations in down syndrome newborns

There is an unexplained higher incidence of congenital hypothyroidism (CH) detected by T(4)-based neonatal screening programs and a very high prevalence of (mild) plasma TSH elevation in young children with Down syndrome (DS). To determine whether newborns with DS have decreased blood T(4) concentrations at the time of the neonatal screening, we conducted an observational study in a large and representative cohort of Dutch children with DS born in 1996 and 1997. CH screening results (T(4), TSH, and T(4)-binding globulin concentrations) were analyzed in comparison with clinical information obtained by interviewing the parents and data from the general newborn population and a large control group. The mean T(4) concentration of the studied children with DS (n = 284) was significantly decreased. The individual T(4) concentrations were normally (Gaussian) distributed but shifted to lower concentrations. This could not be explained by prematurity, nonthyroidal illness, or iodine exposure. Mean TSH and T(4)-binding globulin concentrations were significantly increased and normal, respectively. The decreased T(4) concentration, left-shifted normal distribution, and mildly elevated TSH concentrations point to a mild hypothyroid state in newborns with DS and support the existence of a DS-specific thyroid (regulation) disorder. The question remains whether this contributes to the brain maldevelopment.

Longitudinal analysis of growth and puberty in 21-hydroxylase deficiency patients

AIMS

To evaluate growth from diagnosis until final height (FH) in 21-hydroxylase deficiency patients.

METHODS

A retrospective longitudinal study was performed. Only patients treated with hydrocortisone and fludrocortisone (in case of salt wasting) were evaluated. This resulted in a sample of 34 (21 male, 13 female) salt wasting patients (SW) and 26 (13 male, 13 female) non-salt wasting patients (NSW). Auxological data were compared to recent Dutch reference values.

RESULTS

In the first three months of life, the mean length SDS decreased to -1.50, probably because of the high average glucocorticoid dose (40 mg/m2/day). FH corrected for target height (FH(corr)TH) was -1.25 and -1.27 SDS in females and males, respectively. Patients treated with salt supplements during the first year, had a better FH(corr)TH (-0.83 SDS). In NSW patients, FH(corr)TH was -0.96 and -1.51 SDS in females and males, respectively. In SW and NSW, age at onset of puberty was within normal limits, but bone age was advanced. Mean pubertal height gain was reduced in males. Body mass index was only increased in NSW females.

CONCLUSION

In SW, loss of final height potential might be a result of glucocorticoid excess in the first three months and sodium depletion during infancy. In NSW, loss of FH potential was caused by the delay in diagnosis. In SW and NSW, the advanced bone age at onset of puberty (undertreatment in prebertal years) resulted in loss of height gain during puberty. The effect of intensive sodium chloride support in early infancy should be examined prospectively. Neonatal screening is required if the height prognosis in NSW patients is to be improved.

[From gene to disease; POU1F1- and PROP1-mutations in pituitary hormone deficiency]

Multiple pituitary hormone deficiency can be caused by mutations in at least three pituitary transcription factors: POU1F1 (formerly called PIT1), PROP1 or HESX1. The role of the various pituitary transcription factors in pituitary ontogeny has been elucidated in part for the mouse. In humans, mutations in POU1F1 result in a total deficiency of growth hormone and prolactin, and a variable deficiency of TSH. Cases of mutations in PROP1 exhibit the same deficiencies, with additional deficiencies of gonadotrophins and a variable deficiency of ACTH. In the Netherlands, cases of multiple pituitary hormone deficiency are not only detected on the basis of the classical signs and symptoms of pituitary deficiency, but also by means of screening on congenital hypothyroidism with an incidence of approximately 1:20,000.

Behavioural correlates of early-treated congenital hypothyroidism

Parents' and teachers' ratings were used to evaluate the behavioural characteristics of children with early-treated congenital hypothyroidism (CH). Comparisons were made between 63 children with early-treated CH and 34 healthy controls at the ages of 7.5 and 9.5 y. Additional comparisons were made between the two largest CH subgroups (thyroid agenesis, thyroid dysgenesis) and controls. The most marked differences were found on the introversion cluster and the motor clumsiness scale within it. Children with CH, particularly those with thyroid agenesis, showed introversion and motor clumsiness rather than social negativity and inattention. It is suggested that this behavioural profile may well have its origins in the often-reported inefficient motor behaviour of these children. Results are discussed in the light of recent findings suggesting an association between thyroid hormone problems and attention deficit hyperactivity disorder.

CONCLUSION

Early-treated CH is associated with introversion rather than with social negativity.

Serum thyroglobulin and urinary iodine concentration are the most appropriate indicators of iodine status and thyroid function under conditions of increasing iodine supply in schoolchildren in Benin

Iodine deficiency control programs have greatly reduced iodine deficiency disorders worldwide. For monitoring changes in iodine status, different indicators may be used. The aim of this study was to evaluate the suitability of indicators of iodine status and thyroid function, thyroglobulin (Tg), thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in serum, thyroid volume and urinary iodine concentration, in iodine-deficient schoolchildren under conditions of increasing iodine supply. The study was established as a double-blind, placebo-controlled oral administration of a single dose of iodized oil to schoolchildren (7-10 y old), living in an iodine-deficient area of Benin, with an observation period of 10 mo. However, 3-4 mo after supplementation, iodized salt became available in the area. The study population therefore comprised an iodized oil-supplemented group and a nonsupplemented group, both of which had variable, uncontrolled intakes of iodized salt during the last 6 mo of the study. Initial mean serum concentrations of TSH and FT4 were within the normal range, whereas serum Tg concentration, urinary iodine concentration and thyroid volume were indicative of moderate-to-severe iodine deficiency. At the end of the study, all indicators had improved significantly, except thyroid volume, which had decreased only in the supplemented group. The supplemented group also still had significantly lower serum Tg and higher urinary iodine concentrations than the nonsupplemented group. Serum Tg and urinary iodine concentrations are the indicators most influenced by a changing iodine supply. Current normal reference ranges of serum concentrations of TSH and FT4 are too wide for detecting iodine deficiency in this age group.

Maternal isodisomy for chromosome 2p causing severe congenital hypothyroidism

Severe congenital hypothyroidism (CH) due to a total iodide organification defect (TIOD) is usually due to mutations in the thyroid peroxidase (TPO) gene located at chromosome 2p25. A homozygous deletion [DeltaT2512 (codon 808)] in exon 14 was identified in a patient with classical TIOD. The transmission pattern of the TPO gene in this family was anomalous; the mother was heterozygous for the deletion; and the mutation was absent in the father. Polymorphic short tandem repeat (STR) markers confirmed paternity and demonstrated on chromosome 2 that the propositus was homozygous for most markers on chromosome 2p and that these were identical to one of the maternal 2p homologs. A normal karyotype was found in the propositus, his parents and sister. We conclude that the homozygosity in the patient is due to partial maternal isodisomy of the short arm of chromosome 2, carrying a defective TPO gene. The patient, born small for gestational age, develops and grows well and appears healthy (while being treated with thyroxine) and has a normal phenotype except for a unilateral preauricular skin tag. This shows that partial maternal isodisomy for chromosome 2p (2pter - 2p12) is compatible with a minimal influence on normal development.

Adult height and age at menarche in childhood cancer survivors

The aim of this study was to assess the long-term effects of cancer treatments on adult height and age at menarche in survivors of various types of childhood cancer. 285 childhood cancer survivors (161 men and 124 women), at least 18 years old and having been off treatment for at least 5 years, were examined. The effects of cranial (CrRT) and craniospinal irradiation (CrSpRT), other treatments and age at diagnosis on adult height and age at menarche were investigated. Patients who did not receive CrRT or CrSpRT, reached normal adult heights. However, a significant reduction in adult height was observed in men and women treated with CrRT or CrSpRT, especially if the treatment was given at the age of 8 years or younger. In girls, CrRT resulted in a significantly earlier menarche, compared with the Dutch population. Chemotherapy, radiation dose and age at menarche did not affect adult height. The relative risk (RR) of attaining an adult height below the 3rd percentile (20% 49/244) of the study population) was 6 times increased (RR=6.4; 95% confidence interval (CI) 1.46-28.52) after CrSpRT, 4 times (RR=4.2; 95% CI 1.81-9.63) after Crth and 5 times (RR=51; 95% CI 2.23-11.59) when irradiation was administered at the age of 8 years or younger. CrRT and CrSpRT and age at treatment are the main determinants of short stature in male and female childhood cancer survivors.

Plasma thyrotropin bioactivity in Down's syndrome children with subclinical hypothyroidism

OBJECTIVE

Subclinical hypothyroidism occurs in a number of children with Down's syndrome (DS). The reason for the mildly elevated plasma thyrotropin (TSH) concentrations is not known. The present study investigated whether decreased TSH bioactivity plays a role in this phenomenon.

DESIGN

A retrospective study of plasma specimens from DS children with mildly elevated plasma TSH concentrations and thyroid hormone levels within the reference range, using a TSH receptor-adenylate cyclase mediated bioassay.

METHODS

Strain JP26 Chinese hamster ovary (CHO) cells, stable transfected with the human TSH receptor, were incubated with unfractionated plasma (1/10 diluted in hypotonic incubation medium) of 10 DS children with subclinical hypothyroidism and nine euthyroid children with insulin-dependent diabetes mellitus as controls. cAMP released in the incubation medium was measured by RIA. Mock-transfected CHO cells were used to correct for non-specific CHO response. WHO Second International Reference Preparation of human TSH was dissolved and diluted in pooled normal human plasma and simultaneously bioassayed to match patient and control results.

RESULTS

Plasma TSH levels were slightly increased in DS (mean +/- S.D., 6.5+/-1.3 mU/l, reference range 0.4-4.0 mU/l). Plasma TSH levels for controls (1.3+/-0.4 mU/l) were within the reference range. Plasma thyroid hormone levels in patients and controls were normal, plasma TSH binding inhibitory immunoglobulin and thyroid peroxidase antibodies were negative. cAMP levels (corrected for non-specific CHO response) in DS patients (18.4+/-3.9 pmol/well) and in controls (14.3+/-1.3 pmol/well) did not significantly differ from cAMP levels generated by patient-TSH equivalent TSH standards (16.3+/-0.9 pmol/well).

CONCLUSIONS

The present results demonstrate normal TSH bioactivity in plasma of DS children, indicating that subclinical hypothyroidism in these patients is of primary (thyroidal) origin.

Two decades of screening for congenital hypothyroidism in The Netherlands: TPO gene mutations in total iodide organification defects (an update)

Presented is a cohort study to assess the nature and frequency of thyroid peroxidase (TPO) mutations in 45 patients (35 families) with congenital hypothyroidism due to a total iodide organification defect; incidence is 1:66,000 in The Netherlands. The presentation is consistently similar with a severe form of congenital hypothyroidism and also characterized by a complete and immediate release of accumulated radioiodide from the thyroid after sodium perchlorate administration. Sixteen different mutations were found, including eight novel mutations; the majority occurs in exons 8, 9, or 10. The GGCC insertion in exon 8 at nucleotide 1277, leading to an early termination signal in exon 9, is the most frequently occurring mutation. These mutations were detected in 29 families in both TPO alleles (13 homozygous and 16 compound heterozygous). In one family, partial maternal isodisomy of 2p was detected, in four families only one mutated TPO allele could be detected, and in one family no inactivating TPO mutation could be found. Because all patients clearly had the clinicopathologic features of a total iodide organification defect, we conclude that in these five families the mutations in the (other) alleles could be either located in the intronic sequences or in the promoter region. Mutations in the TPO gene result in total iodide organification defects.

Neurologic development of the newborn and young child in relation to maternal thyroid function

A prospective observational study was performed in pregnant women with known thyroid disease. We studied the effect of maternal thyroid function in the first half of pregnancy on the neurologic development of the infant in the first 2 y of life. Clinical and thyroid function data were collected from 20 pregnant women with known thyroid disease and their newborn children. Infants were divided into three groups according to their maternal thyroid function within the first half of pregnancy: Group A (n = 7): maternal subclinical hypothyroidism, Group B (n = 6): maternal euthyroidism, and Group C (n = 7): maternal hyperthyroidism or subclinical hyperthyroidism. Neurophysiologic, i.e. motor nerve conduction velocity and somatosensory evoked potentials and neurologic and developmental (Bayley scales) assessments were done. One infant, born to a mother with Graves' disease, developed transient hyperthyroidism. At the age of 6 and 12 mo, the mean mental developmental index (MDI) score was 16 points lower for infants in Group A than for those in Group B (p = 0.03 and 0.02, respectively). At the age of 24 mo, the mean MDI score was 6 points lower, which was not statistically significant. Neurophysiologic and neurologic assessments and the mean Psychomotor Developmental scores did not differ among the three groups. In conclusion, maternal subclinical hypothyroidism in the first half of pregnancy was associated with a lower mean MDI score in their infants during the first year of life.

Normalization of height in girls with Turner syndrome after long-term growth hormone treatment: results of a randomized dose-response trial

Short stature and ovarian failure are the main features in Turner syndrome (TS). To optimize GH and estrogen treatment, we studied 68 previously untreated girls with TS, age 2-11 yr, who were randomly assigned to one of three GH dosage groups: group A, 4 IU/m2 day (approximately 0.045 mg/kg x day); group B, first yr 4, thereafter 6 IU/m2 x day (approximately 0.0675 mg/kg/day); group C, first yr 4, second yr 6, thereafter 8 IU/m2 x day (approximately 0.090 mg/kg x day). In the first 4 yr of GH treatment, no estrogens for pubertal induction were given to the girls. Thereafter, girls started with 17beta-estradiol (5 microg/kg bw x day, orally) when they had reached the age of 12 yr. Subjects were followed up until attainment of adult height or until cessation of treatment because of satisfaction with the height achieved. Seven-year data of all girls were evaluated to compare the growth-promoting effects of three GH dosages during childhood. After 7 yr, 85% of the girls had reached a height within the normal range for healthy Dutch girls. The 7-yr increment in height SD-score was significantly higher in groups B and C than in group A. In addition, we evaluated the data of 32 of the 68 girls who had completed the trial after a mean duration of treatment of 7.3 yr (range, 5.0 - 8.75). Mean (SD) height was 158.8 cm (7.1), 161.0 cm (6.8), and 162.3 cm (6.1) in groups A, B, and C, respectively. The mean (SD) difference between predicted adult height before treatment and achieved height was 12.5 cm (2.1), 14.5 cm (4.0), and 16.0 cm (4.1) for groups A, B, and C, respectively, being significantly different between group A and group C. GH treatment was well tolerated in all three GH dosage groups. In conclusion, GH treatment starting in relatively young girls with TS results in normalization of height during childhood, as well as of adult height, in most of the individuals. With this GH and estrogen treatment regimen, most girls with TS can grow and develop much more in conformity with their healthy peers.

Acquired protein S deficiency caused by estrogen treatment of tall stature

OBJECTIVE

To evaluate the potential thrombogenic changes in the coagulation and fibrinolytic system related to treatment with ethinyl estradiol (200 and 300 microg).

SUBJECTS AND METHODS

Twenty-five healthy girls with expected final height exceeding 185 cm, as calculated by the method of Bayley and Pinneau, were treated with 200 microg or 300 microg of ethinyl estradiol. Coagulation and fibrinolytic parameters were determined before and during estrogen treatment and 2 and 4 weeks after estrogen withdrawal.

RESULTS

No difference in the effects on hemostasis was found between the 2 treatment groups. All 25 patients developed protein S deficiency during estrogen treatment, which in most girls lasted for 4 weeks after cessation of estrogen administration. During therapy, protein C activity increased, whereas antithrombin did not change. Plasminogen and plasmin-alpha(2) antiplasmin complexes significantly increased. Protein S deficiency was accompanied by significantly increased prothrombin fragment 1+2 and fibrinopeptide A. In contrast, thrombin-antithrombin complexes did not change.

CONCLUSION

High-dose estrogen treatment to reduce the final height in tall girls is associated with a reversible acquired protein S deficiency with indications of a pre-thrombotic state. Risk of venous thrombo-embolism may be enhanced, especially when additional risk factors for thrombosis are present.

A negative iodine balance is found in healthy neonates compared with neonates with thyroid agenesis

We studied the effects of the presence or absence of the thyroid gland on the iodine metabolism and excretion in term Dutch newborns by performing a retrospective study of the urinary iodine excretion in 193 term newborns with abnormal congenital hypothyroidism screening results. Thirty-six euthyroid newborns with decreased thyroxine-binding globulin levels were compared with 157 hypothyroid patients, 54 due to thyroid agenesis and 103 due to thyroid dysgenesis. A significant difference in the urinary iodine excretion was observed between the agenesis group (mean: 28 micrograms/24 h) and the euthyroid newborns (mean: 46 micrograms/24 h, P=0.001). In conclusion, healthy, euthyroid, term newborns excreted more iodine in their urine than newborns with thyroid agenesis. These results strongly indicated the existence of a temporarily negative iodine balance: the excretion of iodine prevailed over the intake and the newborn's thyroidal iodine, stored during pregnancy, could be used for thyroxine synthesis in the postnatal period. Since healthy term neonates were able to maintain adequate plasma free thyroxine concentrations under normal TSH stimulation, the prenatally acquired iodine stores could be considered sufficiently high to compensate for the transient postnatal losses.

Low maternal free thyroxine concentrations during early pregnancy are associated with impaired psychomotor development in infancy

BACKGROUND

Maternal thyroid function during early pregnancy is an important determinant of early fetal brain development because the fetal thyroid is unable to produce any T4 before 12-14 weeks' gestation. Overt maternal hypothyroidism as seen in severe iodine-deficient areas is associated with severely impaired neurological development of the offspring. At present, it is not known whether low free T4 (fT4) levels during pregnancy in healthy women from iodine sufficient areas may affect fetal neurodevelopment.

METHODS

Neurodevelopment was assessed at 10 months of age in a cohort of 220 healthy children, born after uncomplicated pregnancies and deliveries, using the Bayley Scales of Infant Development. Maternal TSH, fT4 and TPO antibody status were assessed at 12 and 32 weeks' gestation. Maternal gestational fT4 concentration was defined as an independent parameter for child development.

RESULTS

Children of women with fT4 levels below the 5th (< 9.8 pmol/l, n = 11) and 10th (< 10.4 pmol/l, n = 22) percentiles at 12 weeks' gestation had significantly lower scores on the Bayley Psychomotor Developmental Index (PDI) scale at 10 months of age, compared to children of mothers with higher fT4 values (t test, mean difference: 14.1, 95% confidence interval (CI): 5.9-22 and 7.4, 95% CI: 1.1-13.9, respectively). At 32 weeks' gestation, no significant differences were found. In the group of women with the lowest 10th percentile fT4 concentrations at 12 weeks' gestation, a positive correlation was found between the mothers' fT4 concentration and children's PDI scores (linear regression, R: 0.46, P = 0.03). After correction for confounding variables, a fT4 concentration below the 10th percentile at 12 weeks' gestation was a significant risk factor for impaired psychomotor development (RR): 5.8, 95% CI: 1.3-12.6).

CONCLUSIONS

Low maternal plasma fT4 concentrations during early pregnancy may be an important risk factor for impaired infant development.

Final height in girls with Turner's syndrome treated with once or twice daily growth hormone injections. Dutch Advisory Group on Growth Hormone

OBJECTIVES

To study final height in girls with Turner's syndrome treated with once or twice daily injections of growth hormone (GH) in combination with low dose ethinyl oestradiol.

DESIGN

Until final height was reached, the effect of fractionated subcutaneous injections given twice daily was compared with once daily injections of a total GH dose of 6 IU/m2/day. Twice daily injections were given as one third in the morning and two thirds at bedtime. All girls concurrently received low dose oestradiol (0.05 microgram ethinyl oestradiol/kg/day, increased to 0.10 microgram/kg/day after 2.25 years).

PATIENTS

Nineteen girls with Turner's syndrome aged > or = 11 years (mean (SD) 13.6 (1.7) years).

MEASUREMENTS

To determine final height gain, we assessed the difference between the attained final height and the final height predictions at the start of treatment. These final height predictions were calculated using the Bayley-Pinneau (BP) prediction method, the modified projected adult height (mPAH), the modified index of potential height (mIPHRUS), and the Turner's specific prediction method (PTSRUS).

RESULTS

The gain in final height (mean (SD)) was not significantly different between the once daily and the twice daily regimens (7.6 (2.3) v 5.1 (3.2) cm). All girls exceeded their adult height prediction (range, 1.6-12.3 cm). Thirteen of the 19 girls had a final height gain > 5.0 cm. Mean (SD) attained final height was 155.5 (5.4) cm. A "younger bone age" at baseline and a higher increase in height standard deviation score for chronological age (Dutch-Swedish-Danish references) in the first year of GH treatment predicted a higher final height gain after GH treatment.

CONCLUSIONS

Division of the total daily GH dose (6 IU/m2/day) into two thirds in the evening and one third in the morning is not advantageous over the once daily GH regimen with respect to final height gain. Treatment with a GH dose of 6 IU/m2/day in combination with low dose oestrogens can result in a significant increase in adult height in girls with Turner's syndrome, even if they start GH treatment at a relatively late age.

Inborn errors of thyroid hormone biosynthesis

Permanent congenital hypothyroidism in the Netherlands (incidence 1:3000) is caused for 70-80% by a- or dysgenesis of the thyroid gland, for about 15% by dyshormonogenesis and for 10-15% by hypothalamic-pituitary disturbances. The heredity of congenital hypothyroidism caused by dyshormonogenesis is mendelian in character and follows, with a few exceptions, an autosomal recessive pattern. The diagnosis of these inborn errors is based on a combination of imaging studies, plasma hormone and thyroglobulin concentrations, and the concentration of iodide and iodinated peptides in the urine. The contribution of molecular biology is becoming an important factor in the classification of hereditary congenital hypothyroidism.

Protection of the maternal and fetal thyroid from radioactive contamination by the administration of stable iodide during pregnancy. An experimental evaluation in chimpanzees

The safety and efficacy of the administration of stable iodide to protect the fetal thyroid from exposure to radioactive iodide were investigated in chimpanzees in weeks 19 to 21 of pregnancy. The mean 24-h uptake of iodide in the fetal thyroid, determined with 123I-, was 1.8%. Administration of stable potassium iodide (KI), 0.65, 1.95 or 6.5 mg per kg body weight, 1 h before tracer injection reduced the fetal uptake satisfactorily. Only the higher doses were effective after 20 h. Excess iodide may impair a child's thyroid status. However, adverse effects were not found during the 11 days the animals ingested these doses. Tracer concentrations in the amniotic fluid were 30- to 130-fold lower than in the urine. The dose to the fetus from radioactivity in the maternal bladder was estimated by computer simulation. The potential increment of the risk from this dose during the ingestion of stable iodide is smaller than the reduction of risk achieved by inhibiting the uptake of radioactive iodide by the fetal thyroid. The conclusion of the experiments is that stable iodide can be used safely and effectively to protect the fetal thyroid against contamination with radioactive iodine.

Protection of the infant thyroid from radioactive contamination by the administration of stable iodide. An experimental evaluation in chimpanzees

Protection of the thyroid from radioactive contamination by the administration of stable iodide was investigated in chimpanzees aged 2 to 98 weeks. The uptake of iodide in the thyroid was measured with 123I-. The animals were subjected to a control measurement first, and subsequently the thyroid uptake of 123I- was determined twice; once at the start and once at the end of 11 days of ingestion of 0.5, 1.5 or 5.0 mg of stable iodide per kg body weight per day. The three doses of iodide reduced the control thyroid iodide uptake of 10 to 30% to lower than 1% when ingested 1 h before exposure to the tracer and to 2-4% when ingested 20 h before exposure. In the latter experiments 0.5 mg iodide/kg was less effective than doses of 1.5 mg/kg or higher. The physiological state of the thyroid of control infant chimpanzees does not differ from that of human infants. Incidentally, an increased level of TSH was found during the ingestion of iodide, but with unaltered thyroxine levels. Therefore, it is concluded that a daily dose of 1.5 mg stable iodide/kg body weight and higher offers optimal protection of the thyroid against exposure to radioactive iodine in infants and that, when used during 10 days, it leaves the thyroid unaffected.

Growth response and levels of growth factors after two years growth hormone treatment are similar for a once and twice daily injection regimen in girls with Turner syndrome. (Dutch Working Group on Growth Hormone)

GH is known to improve height velocity in girls with Turner syndrome (TS) but the optimal dosage regimen has yet to be defined.

OBJECTIVE

We attempted to improve the growth response by trying to mimic normal pulsatile GH secretion more closely.

DESIGN

In a 2-year study the effect of fractionated twice daily (BID) was compared with once daily (OD) s.c. injections of a total GH dose of 6 IU/m2/day. BID injections were administered as two-thirds at bedtime and one-third in the morning. The subjects concurrently received low dose ethinyl oestradiol (0.05 mg/kg/day, orally).

SUBJECTS

Nineteen girls with TS aged 11 years or over, who were previously involved in a 10-week GH cross-over study.

MEASUREMENTS

Height and bone age were evaluated in relation to untreated Turner reference data. Final height (FH) was predicted using the Bayley and Pinneau (BP) method, the modified index of Potential Height (mIPHRUS), and a recently developed Turner-specific method (PTSRUS) based on regression coefficients for height (H), chronological age (CA) and bone age (BA). Plasma levels of GH, GHBP, IGF-1, and IGFBP-3 were determined by RIA.

RESULTS

After 2 years treatment the growth response expressed as HV, HVSDS, the change in HSDSCA, the gain in height over estimated untreated values and in FH prediction all showed significant improvements. Although mean values tended to be higher with OD injections, significant differences between groups were not found. Bone maturation was similar between groups and compared with untreated estimated values. Independent of treatment group, the change in HSDSCA after 2 years of GH treatment was related negatively to the baseline CA and HSDSCA, and positively to BA delay at baseline. After 18 months of GH treatment the significant decrease in GHBP plasma levels observed after 6 months was no longer significant. In contrast, IGF-1 and IGFBP-3 plasma levels and the IGF-1 to IGFBP-3 ratio increased significantly during 18 months GH therapy. None of these growth related factors showed a difference between groups in their 18 months change. Relevant side-effects were not observed during the first 2 years of GH treatment.

CONCLUSIONS

The present growth data are in conformity with the data of the earlier 24-hour GH profiles. The growth response and plasma levels of growth related factors after 2 years GH on a total dose of 6 IU/m2/day in combination with low-dose oestrogens were not significantly different between the once daily and the twice daily GH injection regimen.

Effects of thyroxine supplementation on neurologic development in infants born at less than 30 weeks' gestation

BACKGROUND

Premature infants who have transient hypothyroxinemia in the first weeks of life may have developmental delay and neurologic dysfunction. Whether thyroxine treatment during this period results in improved developmental outcomes is not known.

METHODS

We carried out a randomized, placebo-controlled, double-blind trial of thyroxine supplementation in 200 infants born at less than 30 weeks' gestation. Thyroxine (8 microg per kilogram of birth weight) or placebo was administered daily, starting 12 to 24 hours after birth, for six weeks. Plasma free thyroxine concentrations were measured weekly for the first eight weeks after birth. Scores on the Bayley Mental and Psychomotor Development Indexes and neurologic function were assessed at 6, 12, and 24 months of age (corrected for prematurity).

RESULTS

Mortality and morbidity up to the time of discharge from the hospital were similar in the study groups. At 24 months of age, 157 infants were evaluated. Overall, neither mental nor psychomotor scores differed significantly between the study groups at any time, nor was the frequency of abnormal neurologic outcome significantly different. In thyroxine-treated infants born at gestational ages of less than 27 weeks, the score on the Bayley Mental Development Index at 24 months of age was 18 points higher than the score for the infants with similar gestational ages at birth in the placebo group (P=0.01); for thyroxine-treated infants born at 27 weeks or later, the mental-development score was 10 points lower than that of their counterparts in the placebo group (P=0.03). There was no relation between the initial plasma free thyroxine concentration and the effect of treatment.

CONCLUSIONS

In infants born before 30 weeks' gestation, thyroxine supplementation does not improve the developmental outcome at 24 months.

Yearly stepwise increments of the growth hormone dose results in a better growth response after four years in girls with Turner syndrome. Dutch Working Group on Growth Hormone

To optimize the growth promoting effect of growth hormone (GH), 65 previously untreated girls with Turner syndrome (TS), chronological age (CA) 2-11 yr, were randomized into 3 dosage regimen groups: A, B, and C, with a daily recombinant-human GH dose during 4 study years of 4-4-4-4, 4-6-6-6, and 4-6-8-8 IU/m2 b.s. The first GH dosage increase in groups B and C resulted in a significantly higher mean height velocity (HV) compared with constant dose group A. During the third year, when the dose was raised again only in group C, mean HV was significantly higher in groups B and C than in group A, and in group C compared with group B. In year 4 only group C mean HV remained significantly higher than group A. The pattern of change in HSDSCA (Dutch-Swedish-Danish Turner references) was identical; however, in year 4 mean delta HSDSCA in group B also remained significantly higher than group A. After 4 yr GH treatment, the following was determined. 1) The mean delta HSDSCA was significantly higher for groups B and C compared with group A, but not significantly different between groups B and C. 2) Although significantly higher compared with estimated values for untreated Dutch girls with TS, bone maturation of the GH treated girls was not significantly different between groups. 3) It was positively related with the degree of bone age (BA) retardation at start of study and negatively with baseline CA. 4) Both the modified Index of Potential Height (mIPHRUS) and a recently developed Turner-specific final height (FH) prediction method (PTSRUS), based on regression coefficients for H, CA, and bone age, showed significant increases in mean FH prediction, without significant differences between groups. PTSRUS values were markedly higher than the mIPHRUS values. Dose dependency could be shown for the area under the curve (AUC) for GH, but delta HSDSCA was not linearly related with AUC. Baseline GH binding protein (BP) levels were in 84% of the cases within the normal age range; the decrease in mean levels after 6 months GH was not significant. Mean insulin-like growth factor I (IGF-I) and IGFBP-3 plasma levels increased significantly, without significant differences between groups. delta HSDSCA during GH was dependent on IGF-I plasma levels at baseline and during the study period, beta-0.002 and beta-0.0004. Thus, a stepwise GH-dosing approach reduced the "waning" effect of the growth response after 4 yr treatment without undue bone maturation. FH prediction was not significantly different between treatment groups. Irrespective of the GH dose used, initiation of GH treatment at a younger age was beneficial after 4 yr GH when expressed as actual cm gained or as gain in FH prediction, but was not statistically significant when expressed as delta HSDSCA over the study period.

Type II and type III deiodinase activity in human placenta as a function of gestational age

Thyroid hormones are essential for fetal development. T4 can be activated by type I (ID-I) and type II (ID-II) iodothyronine deiodinase or inactivated by type III deiodinase (ID-III). The influence of placental ID-II and ID-III on the regulation of fetal thyroid hormone levels was investigated. Using [125I]T4 and [125I]T3, respectively, ID-II and ID-III activities were measured in homogenates of normal human placentas from 6-43 weeks gestational age and in placentas from five term neonates with a total thyroid hormone synthesis defect. ID-II and ID-III activities related to protein or DNA concentration decreased and total placental ID-III activity increased significantly during pregnancy, whereas the increase in total placental ID-II activity was not significant. Absolute placental ID-II activity was approximately 200 times lower than ID-III activity at all gestational ages. Therefore, fluctuations in ID-II activity were not likely to have a significant influence on fetal thyroid hormone concentrations, but may play a role in the regulation of intraplacental T3 generation. The high ID-III activity most likely influences the thyroid hormone economy of the fetus. Severely hypothyroid newborns showed strongly decreased serum T4 levels, but serum T3 and placental ID-III activities were similar to those in euthyroid newborns. These results suggest that placental ID-III activity is regulated by serum T3, but not by serum T4.

Sustained attention problems in children with early treated congenital hypothyroidism

Sustained attention was studied in 48 children with early treated congenital hypothyroidism and 35 healthy controls, using a computer-paced and a self-paced continuous performance task. The performance of the patients, particularly those in the low T4 group (38 patients with T4 levels < 50 nmol/l at neonatal screening), declined in the final stage of the computer-paced task, suggesting a problem in remaining attentive over time. The performance of all children declined in the first and improved in the final stage of the self-paced task. This pattern was most pronounced in the low T4 group, reflecting greater variability in their task performance over time, again indicating a problem in sustaining attention. No correlation was found between onset of treatment and sustained attention. The small size of the intermediate T4 group (10 patients with T4 levels > or = 50 nmol/l at neonatal screening) made the results more difficult to interpret and may have concealed a problem with sustained attention in this group.

Identification of five novel inactivating mutations in the human thyroid peroxidase gene by denaturing gradient gel electrophoresis

Thyroid peroxidase (TPO) is the key enzyme in the synthesis of thyroid hormones. Defects in the TPO gene are reported to be the cause of congenital hypothyroidism due to a Total Iodide Organification Defect (TIOD). This type of defect, where iodide taken up by the thyroid gland cannot be oxidized and bound to protein, is the most common hereditary inborn error causing congenital hypothyroidism in the Netherlands. Denaturing Gradient Gel Electrophoresis (DGGE) of PCR amplified genomic DNA was used to screen for mutations in the TPO gene of TIOD patients from nine apparently unrelated families, and seven different mutations were detected. Three frameshift mutations were found: a 20 bp duplication in exon 2, a 4 bp duplication in exon 8, and an insertion of a single nucleotide (C) at pos. 2505 in exon 14. In addition, four single nucleotide substitutions were identified: one single-base mutation resulted in a premature termination codon (C-->T at pos. 1708 in exon 10), two single-base substitutions changed an amino acid in highly conserved regions of the gene (Tyr-->Asp in exon 9 and Glu-->Lys in exon 14). The fourth single-base mutation located at the exon 10/intron 10 border altered a conserved Gly into Ser and could also affect splicing. Nine TIOD patients from five families were compound heterozygotes and six patients from four families were homozygous for one of the mentioned mutations in the TPO gene.