Clinical recognition of juvenile hypothyroidism in the early stage

Evaluation of catch-up growth in severe pediatric Hashimoto's hypothyroidism

BACKGROUND

We aimed to evaluate catch-up growth in children with severe Hashimoto's hypothyroidism (HH) after thyroid hormone replacement therapy (HRT).

METHODS

A multicenter retrospective study was conducted including children referred for growth slowdown that led to the diagnosis of HH between 1998 and 2017.

RESULTS

A total of 29 patients were included, with a median age of 9.7 years (13-172 months). Median height at diagnosis was -2.7 [-4.6; -0.1] standard deviation score (SDS), with a height loss of 2.5 [0.7; 5.4] SDS compared to height before growth deflection (p<0.0001). At diagnosis, the median TSH level was 819.5 mIU/L [100; 1844], the median FT4 level was 0 pmol/L [undetectable; 5.4], and the median anti-thyroperoxidase antibody level was 1601 UI/L [47; 25,500]. In the 20 patients treated only with HRT, there were significant differences between height at diagnosis and height at 1 year (n = 19, p<0.0001), 2 years (n = 13, p = 0.0005), 3 years (n = 9, p = 0.0039), 4 years (n = 10, p = 0.0078), and 5 years (n = 10, p = 0.0018) of treatment but not in the case of final height (n = 6, p = 0.0625). Median final height was -1.4 [-2.7; 1,5] SDS (n = 6), with a significant difference between height loss at diagnosis and total catch-up growth (p = 0.003). The other nine patients were also given growth hormone (GH). They were smaller at diagnosis (p = 0.01); however, there was no difference in final height between those two groups (p = 0.68).

CONCLUSION

Severe HH can lead to a major height deficit, and catch-up growth seems to be insufficient after treatment with HRT alone. In the most severe cases, administration of GH may enhance this catch-up.

Radioactive Iodine-induced hypothyroidism interferes with the maturation of reproductive organs during puberty in immature female rats

Animal and human studies suggest that thyroid hormone may have critical roles in the development of the ovary. For example, thyroid deficiency disrupts the ovarian microarchitecture and menstrual cycle in neonate and adult women, respectively. Therefore, it is conceivable that thyroid deficiency might disrupt sexual maturation during the peri-pubertal period. To investigate the impact of radioactive iodine-induced thyroid deficiency on reproductive organs throughout puberty, immature female rats were given water containing radioactive iodine (0.37 MBq/g body weight) twice, on postnatal days 22 and 29. Radioactive iodine-induced hypothyroidism was revealed by low free thyroxin levels. Thyroid deficiency delayed the onset of vaginal opening, reduced ovarian weight and the number of medium-sized follicles and led to elongated uteri. However, there was no effect on the estrous cycle or absolute uterus weight. We conclude that radioactive iodine-induced thyroid deficiency delays sexual maturation and alters normal ovarian growth in peri-pubertal rats.

Early Detection of Abnormal Growth Associated with Juvenile Acquired Hypothyroidism

CONTEXT

Development of the typical growth phenotype in juvenile acquired hypothyroidism (JHT), the faltering linear growth with increasing weight, has not been thoroughly characterized.

OBJECTIVE

To describe longitudinal growth pattern in children developing JHT and investigate how their growth differs from the general population in systematic growth monitoring.

DESIGN

Retrospective case-control study.

SETTING

JHT cases from 3 Finnish University Hospitals and healthy matched controls from primary health care.

PATIENTS

A total of 109 JHT patients aged 1.2 to 15.6 years (born 1983-2010) with 554 height and weight measurements obtained for 5 years preceding JHT diagnosis. Each patient was paired with 100 healthy controls (born 1983-2008) by sex and age. Longitudinal growth pattern was evaluated in mixed linear models. Growth monitoring parameters were evaluated using receiver operating characteristics analysis.

RESULTS

At diagnosis, JHT patients were heavier (mean adjusted body mass index-for-age [BMISDS] difference, 0.65 [95% CI, 0.46-0.84]) and shorter (mean adjusted height-for-age deviation from the target height [THDEVSDS] difference, -0.34 [95% CI, -0.57 to -0.10]) than healthy controls. However, 5 years before diagnosis, patients were heavier (mean BMISDS difference, 0.33 [95% CI, 0.12-0.54]) and taller (mean THDEVSDS difference, 0.29 [95% CI, 0.06-0.52]) than controls. JHT could be detected with good accuracy when several growth parameters were used simultaneously in screening (area under the curve, 0.83 [95% CI, 0.78-0.89]).

CONCLUSIONS

Abnormal growth pattern of patients with JHT evolves years before diagnosis. Systematic growth monitoring would detect abnormal growth at an early phase of JHT and facilitate timely diagnosis of JHT.

Thyroid hormone receptor-β1 signaling is critically involved in regulating secondary ossification via promoting transcription of the Ihh gene in the epiphysis

Thyroid hormone (TH) action is mediated through two nuclear TH receptors, THRα and THRβ. Although the role of THRα is well established in bone, less is known about the relevance of THRβ-mediated signaling in bone development. On ther basis of our recent finding that TH signaling is essential for initiation and formation of secondary ossification center, we evaluated the role of THRs in mediating TH effects on epiphysial bone formation. Two-day treatment of TH-deficient Tshr(-/-) mice with TH increased THRβ1 mRNA level 3.4-fold at day 7 but had no effect on THRα1 mRNA level at the proximal tibia epiphysis. Treatment of serum-free cultures of tibias from 3-day-old mice with T3 increased THRβ1 expression 2.1- and 13-fold, respectively, at 24 and 72 h. Ten-day treatment of Tshr(-/-) newborns (days 5-14) with THRβ1 agonist GC1 at 0.2 or 2.0 μg/day increased BV/TV at day 21 by 225 and 263%, respectively, compared with vehicle treatment. Two-day treatment with GC1 (0.2 μg/day) increased expression levels of Indian hedgehog (Ihh) 100-fold, osterix 15-fold, and osteocalcin 59-fold compared with vehicle at day 7 in the proximal tibia epiphysis. Gel mobility shift assay demonstrated that a putative TH response element in the distal promoter of mouse Ihh gene interacted with THRβ1. GC1 treatment (1 nM) increased Ihh distal promoter activity 20-fold after 48 h in chondroctyes. Our data suggest a novel role for THRβ1 in secondary ossification at the epiphysis that involves transcriptional upregulation of Ihh gene.

Pediatric obesity. An introduction

The prevalence of child and adolescent obesity in the United States increased dramatically between 1970 and 2000, and there are few indications that the rates of childhood obesity are decreasing. Obesity is associated with myriad medical, psychological, and neurocognitive abnormalities that impact children's health and quality of life. Genotypic variation is important in determining the susceptibility of individual children to undue gains in adiposity; however, the rapid increase in pediatric obesity prevalence suggests that changes to children's environments and/or to their learned behaviors may dramatically affect body weight regulation. This paper presents an overview of the epidemiology, consequences, and etiopathogenesis of pediatric obesity, serving as a general introduction to the subsequent papers in this Special Issue that address aspects of childhood obesity and cognition in detail.

Pediatric obesity: etiology and treatment

This article reviews factors that contribute to excessive weight gain in children and outlines current knowledge regarding approaches for treating pediatric obesity. Most of the known genetic causes of obesity primarily increase energy intake. Genes regulating the leptin signaling pathway are particularly important for human energy homeostasis. Obesity is a chronic disorder that requires long-term strategies for management. The foundation for all treatments for pediatric obesity remains restriction of energy intake with lifestyle modification. There are few long-term studies of pharmacotherapeutic interventions for pediatric obesity. Bariatric surgical approaches are the most efficacious treatment but, because of their potential risks, are reserved for those with the most significant complications of obesity.

Does clinical management impact height potential in children with severe acquired hypothyroidism?

BACKGROUND

Severe acquired hypothyroidism often results in significant height deficit due to rapid bone age advancement following treatment. Whether gradual correction of hypothyroidism and/or adjunctive growth-promoting therapies (GPTs) augment final adult height (FAH) is controversial.

OBJECTIVE

To investigate time to euthyroidism, pace of bone age advancement (deltaBA/deltaCA), and impact of GPTs on FAH.

METHODS AND PATIENTS

Retrospective review of 21 children (10.1 +/- 3.0 years) with profound hypothyroidism.

RESULTS

Baseline bone age standard deviation score (SDS) was -4.1 +/- 1.8, whereas height SDS was -3.0 +/- 1.1. Average time to euthyroidism was 9.7 months (2.3-33.7 months). Average deltaBA/deltaCA was 2.3 +/- 0.9. Six of 13 patients at FAH received GPTs. No correlation was found between time to euthyroidism and rate of skeletal maturation. No difference in height outcome was seen between those who received GPTs and those who did not.

CONCLUSIONS

Neither time to euthyroidism nor use of GPTs significantly affected height potential in our patients.

Treatment of paediatric hyperthyroidism but not hypothyroidism has a significant effect on weight

OBJECTIVE

Thyroid hormones are involved in metabolic regulation, but the degree to which they affect body weight and body mass index (BMI) in children is unclear. We examined the effect of hypo- and hyperthyroidism on weight and BMI at the time of diagnosis and after appropriate treatment.

DESIGN

Prospective and retrospective case series.

PATIENTS

Children referred for thyroid dysfunction were enrolled prospectively if their total or free T4 was elevated with TSH <0·05 mIU/ml (N = 57) or if they had a subnormal total or free T4 and TSH >20 (N = 29).

RESULTS

Almost all patients had at least 2 classic signs or symptoms including goitre, but hyperthyroid patients had more symptoms. Mean BMI z scores at the time of diagnosis did not significantly differ between the two groups. Males with hyperthyroidism complained of weight loss more frequently and had a lower pretreatment BMI z score than hyperthyroid females. Hypothyroid patients lost a minimal amount of weight by the first follow-up (mean of 0·3 kg) and on average gained weight by the second follow-up visit. In contrast hyperthyroid patients gained a mean of 3·4 kg at the first follow-up visit and a mean of 7·1 kg by the second.

CONCLUSIONS

Correction of hypothyroidism resulted in minimal weight loss, suggesting that hypothyroidism does not cause significant weight gain in children. In contrast, correction of the hyperthyroid state had a somewhat greater impact on weight status. These results are consistent with prior reports but surprising given the opposite metabolic effects of hypo- and hyperthyroidism.

Pediatric obesity: etiology and treatment

This article reviews factors that contribute to excessive weight gain in children and outlines current knowledge regarding approaches for treating pediatric obesity. Most of the known genetic causes of obesity primarily increase energy intake. Genes regulating the leptin signaling pathway are particularly important for human energy homeostasis. Obesity is a chronic disorder that requires long-term strategies for management. The foundation for all treatments for pediatric obesity remains restriction of energy intake with lifestyle modification. There are few long-term studies of pharmacotherapeutic interventions for pediatric obesity. Bariatric surgical approaches are the most efficacious treatment but, because of their potential risks, are reserved for those with the most significant complications of obesity.

Catch-up growth in severe juvenile hypothyroidism: treatment with a GnRH analog

Anecdotal reports suggest that the addition of a gonadotropin releasing hormone (GnRH) analog (GnRHa) in addition to L-thyroxine (LT4) replacement may increase adult stature in children with severe longstanding hypothyroidism by prolonging the pubertal growth period. This retrospective chart review compares the height outcome and body mass index in 33 children (21 treated with LT4 alone and 12 treated with LT4 + GnRHa) with severe longstanding hypothyroidism and bone age delay. Seventeen controls and six GnRHa-treated patients were followed to adult height (BA >14 yr [F]/16 yr [M] and/or growth velocity < 2 cm/yr). At diagnosis, GnRHa-treated patients were 1) older and shorter for chronological age, and 2) more advanced in puberty and bone age. Despite these differences, at adult height, both groups had similar improvements in height Z scores, similar height deficits, and comparable adult heights. Changes in BMI Z score were similar for both groups. Our study suggests that the addition of GnRHa to LT4 may improve interval growth without imposing a risk of obesity in children with longstanding severe hypothyroidism.

Ectopic lingual thyroid: an otolaryngologic emergency beyond childhood

Ectopic thyroid is rare and occasionally presents suddenly in childhood. Adult patients with thyroid ectopy who develop local symptoms commonly have an enlarged ectopic gland and hypothyroidism. We describe the first case of an adult patient who sudden presented with sudden dysphagia and dyspnea caused by a large lingual thyroid in clinical and biochemical euthyroidism. Treatment consisted of surgical removal of the ectopic gland and thyroid hormone replacement therapy.

Utility of thyroid function screening in adolescent psychiatric inpatients

OBJECTIVE

Thyroid function abnormalities have been associated with psychiatric symptoms. This study examines the utility of thyroid screening among adolescent psychiatric inpatients.

METHOD

A retrospective chart review of 196 first-time admissions to an adolescent psychiatric unit was conducted. Charts were screened for demographics, presence/absence of thyroid function testing, history of thyroid disease, medication/illicit substance use, and other factors of influence on thyroid testing. Thyroid test results were reviewed for abnormalities.

RESULTS

Thyroid function testing was conducted in 150 of the 196 admissions. Fifty-two patients had abnormalities, most of which were isolated abnormalities of thyroxine (T4) or triiodothyronine uptake (T3U). Laboratory diagnosis of hyperthyroidism and mild hypothyroidism was met by two and eight patients, respectively; five had profiles that were normal upon subsequent testing 1 week later. None of the patients was symptomatic, and none required thyroid supplementation or antithyroid medications. Gender differences in T4 and T3U were noted, and age was positively correlated with T3U.

CONCLUSIONS

Thyroid function tests may be spuriously abnormal in routine screening of newly admitted psychiatric patients. Routine thyroid screening among adolescent psychiatric inpatients is unwarranted except in patients who display physical signs or symptoms suggestive of thyroid disease.

Growth prognosis and growth after menarche in primary hypothyroidism

The long term growth of 20 girls and nine boys with juvenile primary hypothyroidism was studied until they reached final height. At diagnosis the girls had a mean age of 8.8 years (range 3.0-13.0); mean bone age was 5.4 years. The mean age of the boys at diagnosis was 9.5 years (range 3.7-14.2); mean bone age was 6.3 years. The patients were treated with thyroxine 100 micrograms/m2/day and serum thyroxine concentrations were maintained in the normal range. During treatment the rate of skeletal maturation exceeded the change in chronological age. Initial mean height SD score for bone age before treatment in the girls was +0.59 and after 11 years of treatment fell to -0.55 Mean height SD score for bone age in the boys decreased from +1.6 to -0.87 during treatment. In the girls the onset of puberty was 1.2 years later than the normal population but the duration of puberty was reduced. Mean age (SD) of menarche was 13.8 (1.7) years. The pattern of growth in girls with treated hypothyroidism was abnormal as growth continued after menarche, at a time when normal girls have almost stopped growing. During the second year after menarche our patients still had a mean growth velocity of 4.1 cm/year. Our data suggest that juvenile primary hypothyroidism results in a permanent height deficit. In addition, there is a loss of the normal harmony between growth and sexual maturation in girls, despite adequate treatment, in that growth continues for much longer after menarche than in normal girls.

Long-term growth in juvenile acquired hypothyroidism: the failure to achieve normal adult stature

It has been suggested that complete catch-up growth is achieved with treatment in patients with juvenile acquired hypothyroidism. We tested this assumption by examining long-term growth in 18 girls (mean [+/- SD] age, 11.4 +/- 2.7 years; bone age, 6.2 +/- 3.1 years) and 6 boys (age, 10.6 +/- 4.7 years; bone age, 6.4 +/- 2.7 years) with severe primary hypothyroidism (serum thyroxine level 1.1 +/- 0.3 micrograms per deciliter [13 +/- 4 nmol per liter]). At diagnosis, heights were 4.04 +/- 0.5 and 3.15 +/- 0.4 SD below the mean heights for age of normal girls and boys, respectively. The patients were treated with levothyroxine (3.4 +/- 0.3 micrograms per kilogram of body weight per day) to maintain normal thyroid function. During the first 18 months of therapy, the children's skeletal maturation exceeded the maturation expected for their statural growth, regardless of whether or not they were undergoing pubertal development. Predictions of decreased adult height were based on these observations. At maturity, girls and boys stood approximately 2 SD below normal adult stature, at 149 +/- 5.0 cm and 168 +/- 5.1 cm, respectively. Heights at maturity were also lower than midparental heights (P less than 0.01) and lower than pre-illness standard-deviation scores for height (P less than 0.01). The deficit in adult stature was significantly related to the duration of hypothyroidism before treatment (P less than 0.01). We conclude that despite treatment, prolonged juvenile acquired hypothyroidism results in a permanent height deficit related to the duration of thyroxine deficiency before treatment.