The diagnosis and management of central hypothyroidism in 2018

Subclinical central hypothyroidism in patients with hypothalamic-pituitary disease: does it exist?

Central hypothyroidism (CH) is characterized by decreased thyroid hormone production due to insufficient stimulation of an otherwise normal thyroid gland by TSH. In patients with established hypothalamic-pituitary disease, a low FT4 concentration is considered highly specific, although poorly sensitive, for the diagnosis of CH. That would be comparable to diagnosing primary hypothyroidism in patients at risk only when serum FT4 concentrations are below the reference range, missing all patients with subclinical primary hypothyroidism and preventing proper therapy in patients in which thyroxine replacement is clearly beneficial. Cardiac time intervals, especially the isovolumic contraction time (ICT), have been considered the gold standard of peripheral thyroid hormone action. Using Doppler echocardiography, we have previously shown a very high proportion of prolonged ICT in patients with hypothalamic-pituitary disease and serum FT4 levels indistinguishable from controls. As ICT decreased/normalized after thyroxine-induced increases in FT4 concentrations within the normal reference range, prolonged ICT was considered a bona fide diagnostic biomarker of subclinical CH. Those findings challenge the usual interpretation that FT4 concentrations in the mid-reference range exclude hypothyroidism in patients with hypothalamic-pituitary disease. Rather, subclinical central hypothyroidism, a state analogous to subclinical primary hypothyroidism, seems to be frequent in patients with hypothalamic-pituitary disease and normal FT4 levels. They also challenge the notion that thyroid function is usually the least or the last affected in acquired hypopituitarism. The relevance of Doppler echocardiography to correctly diagnose and monitor replacement therapy in both clinical and subclinical forms of CH should improve quality of life and decrease cardiovascular risk, as already demonstrated in patients with clinical and subclinical primary hypothyroidism.

Reference intervals for thyroid function from the fifth to seventh day of life in twin-pregnancy preterm neonates: an 8-year retrospective study

PURPOSE

The immature and developing hypothalamic-pituitary-thyroid axis leads to different levels of thyroid function in twin neonates, including free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) levels. No reference intervals for twins have been established until now. To compensate for this lack, we collected data and established this standard across different gestational ages (GAs) and sexes.

METHODS

A total of 273 pairs of neonates admitted to the NICU in Southeast China from 2015 to 2022 were included. Each pair was divided into Neonate A (relatively heavy birth weight (BW)) and Neonate B (relatively light BW). Their thyroid functions were analyzed to establish reference intervals and comparisons were made stratified by GA and sex.

RESULTS

The FT3, FT4, and TSH reference intervals in twin neonates with a GA of 26-36 weeks were as follows: Neonate A and B: 3.59 ± 0.99 and 3.57 ± 1.00 pmol/L; Neonate A and B: 17.03 ± 5.16 and 16.77 ± 5.29 pmol/L; and Neonate A and B: 4.097 ± 3.688 and 4.674 ± 4.850 mlU/L, respectively. There were significant differences between serum FT3 and FT4 reference intervals and GA (p < 0.05). The serum FT3 and FT4 reference intervals for male neonates were lower than those for female neonates in the 29-32-week group (p < 0.05).

CONCLUSION

This was the first study, to our knowledge, to establish reference intervals for thyroid function in twin neonates from the fifth to seventh day of life, which will be beneficial for the diagnosis and management of congenital hypothyroidism.

Refractory Hypothyroidism: Unraveling the Complexities of Diagnosis and Management

INTRODUCTION

Refractory hypothyroidism (RH) represents a challenge in the diagnosis and treatment within the field of thyroidology. It is defined as the inability to achieve disease control despite using levothyroxine (LT4) doses of 1.9 μg/kg/d or higher.

METHODS

A comprehensive review, encompassing 103 articles, was conducted using the Scielo, Scopus, and EMBASE databases, providing an approach to evaluation and diagnosis of this condition.

RESULTS

LT4 disintegrates and dissolves within an acidic gastric environment before being absorbed in the jejunum and ileum. It then extensively binds to serum transporter proteins and undergoes deiodination to yield tri-iodothyronine, the biologically active hormone. There are various nonpathological causes of RH, such as noncompliance with treatment, changes in the brand of LT4, food and drug interferences, as well as pregnancy. Pathological causes include lactose intolerance, Helicobacter pylori infection, giardiasis, among others. The diagnosis of RH involves conducting a thorough medical history and requesting relevant laboratory tests to rule out causes of treatment resistance. The LT4 absorption test allows for the identification of cases of malabsorption. The treatment of RH involves identifying and addressing the underlying causes of noncompliance or malabsorption. In cases of pseudomalabsorption, supervised and weekly administration of LT4 may be considered.

DISCUSSION

Early recognition of RH and correction of its underlying cause are of utmost importance, as this avoids the use of excessive doses of LT4 and prevents cardiovascular and bone complications associated with this condition.

A Novel Pathogenic IGSF1 Variant in a Patient with GH and TSH Deficiency Diagnosed by High IGF-I Values at Transition to Adult Care

IGSF1 deficiency is a rare X-linked condition characterized by central hypothyroidism and a wide variety of other clinical features with variable prevalence, including a delayed pubertal testosterone rise and growth spurt in the context of normal or accelerated testicular growth, and adult macroorchidism with relatively low serum testosterone concentrations. Other features include increased waist circumference, attention deficit, prolactin deficiency and transient partial growth hormone (GH) deficiency in childhood, contrasting with an increased GH secretion in adulthood. Patients with this disorder are not detected shortly after birth if neonatal screening programs are based on thyroid-stimulating hormone (TSH) concentrations. A 13.2-year-old male patient was referred to pediatric endocrinology for evaluation of short stature. He was born large for gestational age into a nonconsanguineous family. During work-up for short stature, deficiencies of TSH, prolactin and GH were detected, leading to treatment with levothyroxine and GH. At 16.9 years, GH treatment was stopped and during transition to adult care, his insulin-like growth factor 1 level was above the normal range. This prompted an analysis of IGSF1, in which a novel hemizygous variant causing a stop codon at c.3559C>T (p.Q1187*) was found, confirming the diagnosis of IGSF1 deficiency syndrome. In this report, we describe his clinical and hormonal characteristics at presentation and during long-term follow-up.

Recurrent multinodular goitre and primary hyperparathyroidism due to adenoma arising in a parathyroid autotransplant more than 20 years after near-total thyroidectomy

The patient is a female in her 60s with a remote history of a near-total thyroidectomy in 1997 for multinodular goitre. At the initial operation, she sustained a left recurrent laryngeal nerve injury. A devascularised parathyroid gland was autotransplanted into the right sternocleidomastoid muscle. She had been off of thyroid hormone for long periods, and her most recent levothyroxine requirement had fallen to only 25 mcg daily. The patient presented more than 20 years after her thyroidectomy with hoarseness, fatigue and dyspnoea. Laboratory studies suggested primary hyperparathyroidism. Imaging demonstrated bilateral pulmonary emboli and bulky thyroid tissue extending into her mediastinum. She underwent a completion thyroidectomy with the removal of a parathyroid adenoma arising in the autotransplanted parathyroid. This case illustrates the possibility of regrowth of benign thyroid tissue after thyroidectomy. In addition, to our knowledge, this is the first case report of a parathyroid adenoma arising from autotransplantation of a normal parathyroid.

The Consensus on the Diagnosis and Management of Congenital Hypothyroidism in Term Neonates

Congenital hypothyroidism (CH) is one of the most treatable endocrine disorders in infants and children that can influence the function of many organs in the body. On-time diagnosis and treatment can prevent the adverse effects of thyroid hormone deficiency on the child's neurodevelopment. There are many challenges in screening, post-screening, diagnosis, and managing this disorder. Therefore, this article aimed to mention updated information on this issue. Although there are different approaches for the treatment of hypothyroidism, the authors decided to create a national approach based on the conditions of our country.

Approach to the Patient With Congenital Hypothyroidism

Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder and the most common preventable cause of development delay and growth failure if diagnosed and treated early. The thyroid is the first endocrine gland to develop during embryonic life and to be recognizable in humans. Thyroid development and maturation can be divided into 2 phases: a first phase of embryogenesis and a second phase of folliculogenesis and differentiation with thyroid hormone production at the final steps. Regulation of the thyroid function requires normal development of the hypothalamic-pituitary-thyroid axis, which occurs during the embryonic and neonatal period. Defects in any of steps of thyroid development, differentiation, and regulation lead to permanent CH. Newborn screening programs, established in only one-third of countries worldwide, detect CH and are cost-effective and highly sensitive and specific. During the last decade, epidemiology of CH has changed with increased frequency of thyroid in situ in primary CH. Advances in molecular testing have expanded knowledge and understanding of thyroid development and function. However, a molecular cause is identified in only 5% of CH due to thyroid dysgenesis. The purpose of this article is to describe the clinical approach to the child with CH, focusing on diagnostic work-up and future challenges on optimizing thyroid replacement therapy and regenerative medicine. The review is written from the perspective of the case of 2 girls referred for CH after newborn screening and diagnosed with thyroid ectopy. The genetic work-up revealed novel mutations in TUBB1 gene, associated with large platelets and abnormal platelet physiology.

Thyroid hormone resistance: Mechanisms and therapeutic development

As an essential primary hormone, thyroid hormone (TH) is indispensable for human growth, development and metabolism. Impairment of TH function in several aspects, including TH synthesis, activation, transportation and receptor-dependent transactivation, can eventually lead to thyroid hormone resistance syndrome (RTH). RTH is a rare syndrome that manifests as a reduced target cell response to TH signaling. The majority of RTH cases are related to thyroid hormone receptor β (TRβ) mutations, and only a few RTH cases are associated with thyroid hormone receptor α (TRα) mutations or other causes. Patients with RTH suffer from goiter, mental retardation, short stature and bradycardia or tachycardia. To date, approximately 170 mutated TRβ variants and more than 20 mutated TRα variants at the amino acid level have been reported in RTH patients. In addition to these mutated proteins, some TR isoforms can also reduce TH function by competing with primary TRs for TRE and RXR binding. Fortunately, different treatments for RTH have been explored with structure-activity relationship (SAR) studies and drug design, and among these treatments. With thyromimetic potency but biochemical properties that differ from those of primary TH (T3 and T4), these TH analogs can bypass specific defective transporters or reactive mutant TRs. However, these compounds must be carefully applied to avoid over activating TRα, which is associated with more severe heart impairment. The structural mechanisms of mutation-induced RTH in the TR ligand-binding domain are summarized in this review. Furthermore, strategies to overcome this resistance for therapeutic development are also discussed.

[Primary hypothyroidism and postmenopause as the causes of delayed diagnosis of panhypopituitarism in a patient with nonfunctional pituitary adenoma]

Hypopituitarism is a state of complete or partial deficiency of pituitary hormones, including adrenal insufficiency, hypothyroidism, hypogonadism, growth hormone deficiency, and, rarely, diabetes insipidus.The article describes a clinical case of hypopituitarism due to a pituitary tumor in a postmenopausal woman. Difficulties in diagnosing hypopituitarism were due to a history of primary hypothyroidism. The first identified component of panhypopituitarism in the patient, (central hypothyroidism) had previously been seen as laboratory indications of medication-induced hyperthyroidism.The non-specific nature of the clinical symptoms, as well as a relatively rare combination of endocrine diseases, led to a long examination period and delayed diagnosis of the pituitary tumor.Whether the development of hypopituitarism in a patient with a nonfunctional pituitary tumor is an indication for transsphenoidal pituitary surgery remains a controversial issue. The decision for surgery is made taking into account the characteristics of the course of the disease in a particular patient. In this clinical case, a conservative tactic was chosen with hormone replacement therapy for glucocorticoid and thyroid deficiency.

Redefinition of Successful Treatment of Patients With Hypothyroidism. Is TSH the Best Biomarker of Euthyroidism?

In recent years evidence has accumulated supporting a revised view of the nature of euthyroidism and the biomarkers of thyroid function. Within the normal range, variations in thyroid hormone levels are associated with variations in clinical parameters and outcomes. There are therefore no readily identified individually specific optimum levels of thyroid hormones for any individual. Levels around the middle of the normal population range may best reflect euthyroidism. These levels may have evolutionary advantages on the basis that adverse outcomes often increase with divergence from such levels, and physiological processes tend to minimise such inter-individual and intra-individual divergence. In populations of predominantly untreated individuals, levels of thyroid hormones and in particular levels of free thyroxine (FT4) correlate more often with clinical parameters than do levels of thyrotropin (TSH). Levels of thyroid hormones may therefore be regarded as the best available biomarkers of euthyroidism and dysthyroidism. It follows that 'subclinical hypothyroidism' (normal FT4/raised TSH levels), rather than being an accurate marker of peripheral tissue hypothyroidism is more a marker of decreased thyroid reserve and prognosis. The recent evidence suggests that treatment of hypothyroxinemia, regardless of the TSH level, and monitoring therapy using FT4 and/or triiodothyronine levels, depending on the replacement regime, may result in more successful treatment of hypothyroidism than relying on thyrotropin levels for patient selection and subsequent treatment monitoring. The equivalents of mid-range levels of thyroid hormones (especially FT4), adjusted by individual comorbidity concerns, may be rational general replacement targets. These implications of the new evidence may create opportunities for novel trials of thyroid replacement therapy.

Genetics of congenital hypothyroidism: Modern concepts

Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder and one of the most common preventable causes of intellectual disability in the world. CH may be due to developmental or functional thyroid defects (primary or peripheral CH) or be hypothalamic‐pituitary in origin (central CH). In most cases, primary CH is caused by a developmental malformation of the gland (thyroid dysgenesis, TD) or by a defect in thyroid hormones synthesis (dyshormonogenesis, DH). TD represents about 65% of CH and a genetic cause is currently identified in fewer than 5% of patients. The remaining 35% are cases of DH and are explained with certainty at the molecular level in more than 50% of cases. The etiology of CH is mostly unknown and may include contributions from individual and environmental factors. In recent years, the detailed phenotypic description of patients, high‐throughput sequencing technologies, and the use of animal models have made it possible to discover new genes involved in the development or function of the thyroid gland. This paper reviews all the genetic causes of CH. The modes by which CH is transmitted will also be discussed, including a new oligogenic model. CH is no longer simply a dominant disease for cases of CH due to TD and recessive for cases of CH due to DH, but a far more complex disorder.

Growth Velocity and Economic Aspects of Human Growth Hormone Treatment in an Egyptian Cohort with Multiple Pituitary Hormone Deficiency: A Retrospective Minireview

Abstract Background: Multiple pituitary hormone deficiency (MPHD) is a chronic lifelong disease. Human recombinant growth hormone (hGH) treatment is the optimal therapy for short stature in children with growth hormone (GH) deficiency in patients with MPHD and can effectively increase growth velocity (GV) to attain adult heights within the target range. Objective: to assess the GV during hGH treatment of children with MPHD, to analyze the characteristics of patients and to investigate the possible factors that might affect their height gain. Methods: Data from 18 (8 females) children and adolescents with MPHD with GH, thyroid stimulating hormone, gonadotropin and adrenocorticotropic hormone deficiencies were collected. Subjects were divided into groups: 12 pubescent patients and 6 pre-pubescent patients. Anthropometric measurements were reported regularly for one year. Results: age at onset of study was 13.44±4.66 years. CT and MRI findings were positive in 77.8 %. Peak GH levels after Clonidine and Insulin were 4.06±2.61 and 5.39±4.2 ng/ml respectively. GH was received in a dose of 0.95±0.5 mg/day. Height gain during the period of the study was 3.5±0.47cm /year. The predicted adult height at the first and last visits and delta predicted adult height between the first and last visits were 155.78±10.159, 156.71±7.22 and 0.93±4.64 cm respectively. The cost in dollars was identified using Markov cost-effectiveness simulation model as 98.87±52.4 dollars per one cm height gain, with a total of 346.07±183.42 US dollars/patient/year. For a hGH dose of 0.02±0.01 mg/kg/d (0.95±0.5mg/day). There was a positive correlation between height gain during the study period and both the height SDS at presentation and dose of GH mg/kg/d. Conclusion: the height gain and the cost were higher amongst females than males with MPHD. Height at presentation and hGH dose seemed to be an effective predictor for height gain in patients with MPHD.  

Genetics of Thyroid Disorders

Thyroid diseases in children and adolescents include acquired or congenital conditions, including genetic disorders either isolated or part of a syndrome. Briefly, we will review the physiology and pathophysiology of the thyroid gland and its disorders. The aim of this chapter is to describe genetic abnormalities of the thyroid gland.

Screening of 23 candidate genes by next-generation sequencing of patients with permanent congenital hypothyroidism: novel variants in TG, TSHR, DUOX2, FOXE1, and SLC26A7

PURPOSE

To date, many genes have been associated with congenital hypothyroidism (CH). Our aim was to identify the mutational spectrum of 23 causative genes in Turkish patients with permanent CH, including thyroid dysgenesis (TD) and dyshormonogenesis (TDH) cases.

METHODS

A total of 134 patients with permanent CH (130 primary, 4 central) were included. To identify the genetic etiology, we screened 23 candidate genes associated with CH by next-generation sequencing. For confirmation and to detect the status of the specific familial variant in relatives, Sanger sequencing was also performed.

RESULTS

Possible pathogenic variants were found in 5.2% of patients with TD and in 64.0% of the patients with normal-sized thyroid or goiter. In all patients, variants were most frequently found in TSHR, followed by TPO and TG. The same homozygous TSHB variant (c.162 + 5G > A) was identified in four patients with central CH. In addition, we detected novel variants in the TSHR, TG, SLC26A7, FOXE1, and DUOX2.

CONCLUSION

Genetic causes were determined in the majority of CH patients with TDH, however, despite advances in genetics, we were unable to identify the genetic etiology of most CH patients with TD, suggesting the effect of unknown genes or environmental factors. The previous studies and our findings suggest that TSHR and TPO mutations is the main genetic defect of CH in the Turkish population.

[Genetic of congenital hypothyroidism]

Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder. CH is due to thyroid development or thyroid function defects (primary) or may be of hypothalamic-pituitary origin (central). Primary CH is caused essentially by abnormal thyroid gland morphogenesis (thyroid dysgenesis, TD) or defective thyroid hormone synthesis (dyshormonogenesis, DH). DH accounts for about 35% of CH and a genetic cause is identified in 50% of patients. However, TD accounts for about 65% of CH, and a genetic cause is identified in less than 5% of patients. The pathogenesis of CH is largely unknown and may include the contribution of individual and environmental factors. During the last years, detailed phenotypic description of patients, next-generation sequence technologies and use of animal models allowed the discovery of novel candidate genes in thyroid development and function. We provide an overview of recent genetic causes of primary and central CH. In addition, mode of inheritance and the oligogenic model of CH are discussed.

Bexarotene-induced central hypothyroidism assessed by TRH stimulation test in cutaneous T-cell lymphoma patients

Bexarotene-induced central hypothyroidism (CH), for which levothyroxine (LT4) replacement is recommended, has been shown to be caused by pituitary but not hypothalamic disorder experimentally, though the underlying mechanism in humans remains unclear. Here, the pathophysiology of bexarotene-induced CH was examined using a TRH stimulation test in cutaneous T-cell lymphoma (CTCL) patients. In this retrospective longitudinal observational study, serum TSH and free T4 (F-T4) levels were measured in 10 euthyroid patients with CTCL during 24 weeks of bexarotene treatment. TRH stimulation testing was performed following CH diagnosis, with LT4 replacement dosage adjusted to maintain F-T4 at the pre-treatment level. After one week of bexarotene administration, all 10 patients developed CH, based on combined findings of low or low-normal F-T4 with low or normal TSH levels. TSH peak response after a stimulation test at one week was reached at 30 minutes. However, that was <4 μIU/mL in all patients, indicating a blunted though not exaggerated and delayed TSH response. In eight who continued bexarotene for 24 weeks, median LT4 replacement dosage was 125 (range, 75-150) μg/day. TSH level at 30 as well as 15, 60, 90, and 120 minutes after TRH stimulation was significantly correlated with LT4 replacement dosage (ρ = -0.913, p = 0.002), whereas TSH and F-T4 basal levels at one week were not. These results suggest that pituitary hypothyroidism is responsible for bexarotene-induced CH, while TSH levels after TRH stimulation precisely reflect residual pituitary-thyroid function in patients receiving bexarotene.

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Congenital hypothyroidism is one of the common diseases causing delayed intelligence development and growth retardation in children. In 2021, the ENDO-European Reference Network updated the practice guidelines for the diagnosis and management of congenital hypothyroidism. The guidelines give a comprehensive and detailed description of the screening, diagnosis, and management of congenital hypothyroidism in neonates. This article gives an interpretation of the guidelines in order to provide a reference for clinicians in China.

Patients with Central Hypothyroidism are Less Sufficiently Treated with Levothyroxine than Patients with Primary Hypothyroidism

BACKGROUND

Contrary to patients with hypothyroidism after radioiodine (HRI) or after thyroidectomy (HTh), patients with central hypothyroidism (CH) cannot rely on thyrotropin (TSH) level to guide their treatment with L-thyroxine (L-T4). Consequently, they are at constant risk of under- or overtreatment. We aimed to establish the adequacy of L-T4 treatment in patients with CH in our cohort.

METHODS

Consecutive patients with CH on L-T4 treatment were compared with patients adequately treated for HRI or HTh. Levels of free thyroxine (fT₄) and free triiodothyronine (fT₃) were evaluated and the fT₄/fT₃ ratio was calculated.

RESULTS

Forty patients with CH, 136 patients with HRI and 43 patients with HTh were included in this study. Patients with HRI were significantly younger than patients with HTh and CH (p<0.001 for both). Levels of fT₄ were significantly lower in CH than in adequately treated patients with HRI and HTh (median (range), 15.6 (12.7-21.3), 18.4 (12.2-28.8), and 18.7 (13.8-25.5) pmol/L, respectively, p<0.001 for both comparisons). Levels of fT₃ did not differ significantly (p=0.521) between CH, HRI and HTh (median (range), 4.5 (2.7-5.9), 4.3 (3.2-6.2), and 4.4 (2.9-5.5) pmol/L, respectively). Accordingly, the fT₄/fT₃ ratio was significantly lower in the CH group than in HRI and HTh groups (median (range), 3.7 (2.5-5.2), 4.2 (1.2-7.7), and 4.4 (2.5-6.1), respectively, p<0.001 for both comparisons).

CONCLUSIONS

Patients with CH have lower fT₄ levels and lower fT₄/fT₃ ratios than patients adequately treated for HRI or HTh. The cause for this difference may be the unreliable TSH levels in patients with CH.

Multi-omic profiling of pituitary thyrotropic cells and progenitors

BACKGROUND

The pituitary gland is a neuroendocrine organ containing diverse cell types specialized in secreting hormones that regulate physiology. Pituitary thyrotropes produce thyroid-stimulating hormone (TSH), a critical factor for growth and maintenance of metabolism. The transcription factors POU1F1 and GATA2 have been implicated in thyrotrope fate, but the transcriptomic and epigenomic landscapes of these neuroendocrine cells have not been characterized. The goal of this work was to discover transcriptional regulatory elements that drive thyrotrope fate.

RESULTS

We identified the transcription factors and epigenomic changes in chromatin that are associated with differentiation of POU1F1-expressing progenitors into thyrotropes using cell lines that represent an undifferentiated Pou1f1 lineage progenitor (GHF-T1) and a committed thyrotrope line that produces TSH (TαT1). We compared RNA-seq, ATAC-seq, histone modification (H3K27Ac, H3K4Me1, and H3K27Me3), and POU1F1 binding in these cell lines. POU1F1 binding sites are commonly associated with bZIP transcription factor consensus binding sites in GHF-T1 cells and Helix-Turn-Helix (HTH) or basic Helix-Loop-Helix (bHLH) factors in TαT1 cells, suggesting that these classes of transcription factors may recruit or cooperate with POU1F1 binding at unique sites. We validated enhancer function of novel elements we mapped near Cga, Pitx1, Gata2, and Tshb by transfection in TαT1 cells. Finally, we confirmed that an enhancer element near Tshb can drive expression in thyrotropes of transgenic mice, and we demonstrate that GATA2 enhances Tshb expression through this element.

CONCLUSION

These results extend the ENCODE multi-omic profiling approach to the pituitary gland, which should be valuable for understanding pituitary development and disease pathogenesis.

Diagnosis and Management of Neuroendocrine Disorders of Survivors of Brain Tumors

Advances in the treatment of brain tumors have led to an increase in the number of survivors of this disease. Consequently, the long-term complications associated with past and current treatments are becoming more apparent. Of relevance to patients who receive treatment of brain tumors are the potential neuroendocrine complications that develop either acutely or several years following treatment. Presentation may differ between adults and children (e.g., short stature or adult growth hormone deficiency) but in both settings can complicate treatment and impact quality of life. The risk for the development of these complications depends on the location of the tumor (proximity to the pituitary/hypothalamus) and/or the treatment delivered (chemotherapy/surgery/radiation). Given the potential overlap in symptoms attributable to the underlying brain tumor and neuroendocrine dysfunction, a high level of suspicion, appropriate investigation, and administration of treatment may reduce morbidity and mortality for patients with brain tumors experiencing neuroendocrine dysfunction.

New genetics in congenital hypothyroidism

INTRODUCTION

Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder and one of the most common preventable forms of mental retardation worldwide. CH is due to thyroid development or thyroid function defects (primary) or may be of hypothalamic-pituitary origin (central). Primary CH is caused essentially by abnormal thyroid gland morphogenesis (thyroid dysgenesis, TD) or defective thyroid hormone synthesis (dyshormonogenesis, DH). TD accounts for about 65% of CH, however a genetic cause is identified in less than 5% of patients.

PURPOSE

The pathogenesis of CH is largely unknown and may include the contribution of individual and environmental factors. During the last years, detailed phenotypic description of patients, next-generation sequence technologies and use of animal models allowed the discovery of novel candidate genes in thyroid development, function and pathways.

RESULTS AND CONCLUSION

We provide an overview of recent genetic causes of primary and central CH. In addition, mode of inheritance and the oligogenic model of CH are discussed.

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

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

Insights into non-classic and emerging causes of hypopituitarism

Hypopituitarism is defined as one or more partial or complete pituitary hormone deficiencies, which are related to the anterior and/or posterior gland and can have an onset in childhood or adulthood. The most common aetiology is a sellar or suprasellar lesion, often an adenoma, which causes hypopituitarism due to tumour mass effects, or the effects of surgery and/or radiation therapy. However, other clinical conditions, such as traumatic brain injury, and autoimmune and inflammatory diseases, can result in hypopituitarism, and there are also genetic causes of hypopituitarism. Furthermore, the use of immune checkpoint inhibitors to treat cancer is increasing the risk of hypopituitarism, with a pattern of hormone defects that is different from the classic patterns and depends on mechanisms that are specific for each drug. Moreover, autoantibody production against the pituitary and hypothalamus has been demonstrated in studies investigating the development or worsening of some cases of hypopituitarism. Finally, evidence suggests that posterior pituitary damage can affect oxytocin secretion. The aim of this Review is to summarize current knowledge on non-classic and emerging causes of hypopituitarism, so as to help clinicians improve early identification, avoid life-threatening events and improve the clinical care and quality of life of patients at risk of hypopituitarism.

The Laboratory Features of Congenital Hypothyroidism and Approach to Therapy

Congenital hypothyroidism (CH) is one of the most common preventable causes of intellectual disability. Thyroid hormone is required for normal brain development, but neonates with CH typically appear healthy at birth, which leads to delays in diagnosis and treatment. In developed countries, newborn screening programs have led to earlier diagnosis and treatment of CH, resulting in improved neurodevelopmental outcomes. Neonates with an abnormal newborn screen require prompt confirmatory serum thyroid function tests and treatment with thyroid hormone. Further evaluation for the etiology of CH should not delay treatment decisions.

Screening for Mutations in Isolated Central Hypothyroidism Reveals a Novel Mutation in Insulin Receptor Substrate 4

BACKGROUND

Central hypothyroidism (CeH) is a rare condition affecting approximately 1:16 000- 100 000 individuals. Congenital forms can harm normal development if not detected and treated promptly. Clinical and biochemical diagnosis, especially of isolated CeH, can be challenging. Cases are not usually detected in neonatal screening, which, in most countries, is focused on detection of the more prevalent primary hypothyroidism. Until now, five genetic causes for isolated CeH have been identified. Here we aimed to identify the genetic cause in two brothers with impaired growth diagnosed with CeH at the age of 5 years. We further evaluated the candidate gene variants in a large genetic database.

METHODS

Clinical and biochemical characterization together with targeted next-generation sequencing (NGS) was used to identify the genetic cause in a family of two brothers presenting with CeH. Screening of insulin receptor substrate 4 (IRS4) variants was carried out in the FinnGen database.

RESULTS

A novel monoallelic frameshift mutation c.1712_1713insT, p.Gly572Trp fs*32 in the X-linked IRS4 gene was identified by NGS analysis in both affected males and confirmed using Sanger sequencing. Their mother was an unaffected carrier. In addition to the declined growth at presentation, central hypothyroidism and blunted TRH test, no other phenotypic alterations were found. Diagnostic tests included head MRI, thyroid imaging, bone age, and laboratory tests for thyroid autoantibodies, glucose, insulin and glycosylated hemoglobin levels. Examination of the IRS4 locus in FinnGen (R5) database revealed the strongest associations to a rare Finnish haplotype associated with thyroid disorders (p = 1.3e-7) and hypothyroidism (p = 8.3e-7).

CONCLUSIONS

Here, we identified a novel frameshift mutation in an X-linked IRS4 gene in two brothers with isolated CeH. Furthermore, we demonstrate an association of IRS4 gene locus to a general thyroid disease risk in the FinnGen database. Our findings confirm the role of IRS4 in isolated central hypothyroidism.

Central hypothyroidism or subclinical hyperthyroidism: can they be confused with each other?

SUMMARY

Isolated, adult-onset central hypothyroidism is very rare, and its diagnosis can be challenging. A 42-year-old patient was referred for evaluation of a 2.8 cm thyroid nodule. She referred symptoms that could be attributed to hypothyroidism and thyroid tests showed low TSH and normal-low levels of free T4. However, evaluation of the remaining pituitary hormones and pituitary MRI were normal, yet a radionuclide scanning revealed that the thyroid nodule was 'hot' and the tracer uptake in the remaining thyroid tissue was suppressed. Interpretation of these studies led to a misdiagnosis of subclinical hyperthyroidism and the patient was treated with radioiodine. Soon after treatment, she developed a frank hypothyroidism without appropriate elevation of TSH and the diagnosis of central hypothyroidism was made a posteriori. Long term follow-up revealed a progressive pituitary failure, with subsequent deficiency of ACTH and GH. This case should alert to the possibility of overlooking central hypothyroidism in patients simultaneously bearing primary thyroid diseases able to cause subclinical hyperthyroidism.

LEARNING POINTS

Although rarely, acquired central hypothyroidism can occur in the absence of other pituitary hormone deficiencies. In these cases, diagnosis is challenging, as symptoms are unspecific and usually mild, and laboratory findings are variable, including low, normal or even slightly elevated TSH levels, along with low or low-normal concentrations of free T4. In cases with low TSH levels, the coexistence of otherwise common disorders able to cause primary thyroid hyperfunction, such as autonomous nodular disease, may lead to a misdiagnosis of subclinical hyperthyroidism.

Distinct pituitary hormone levels of 184 Chinese children and adolescents with multiple pituitary hormone deficiency: a single-centre study

Background

Pituitary tumors and/or their treatment are associated with multiple pituitary hormone deficiency (MPHD) in adults, but the distinct pituitary hormone profile of MPHD in Chinese children and adolescents remains unclear.

Methods

Patients with MPHD were divided into four groups according to their MRI results: 1) pituitary stalk interruption syndrome (PSIS); 2) hypoplasia; 3) normal; and 4) tumor survivor.

Results

Among the 184 patients, 93 patients (50.5%) were with PSIS, 24 (13.0%) had hypoplastic pituitary gland, 10 (5.4%) patients were normal, and 57 (31.0%) were tumor survivors. There was an association between abnormal fetal position and PSIS (P ≤ 0.001). The CA/BA in PSIS, hypoplasia, normal, tumor survivor groups were 2.27 ± 1.05, 1.48 ± 0.39, 1.38 ± 0.57, 1.49 ± 0.33, and HtSDS were − 3.94 ± 1.39, − 2.89 ± 1.09, − 2.50 ± 1.05, − 1.38 ± 1.63. Patients in PSIS group had the largest CA/BA (P ≤ 0.001 vs. hypoplasia group, P = 0.009 vs. normal group, P ≤ 0.001 vs. tumor survivors) and lowest HtSDS (P ≤ 0.001 vs. hypoplasia group, P = 0.003 vs. normal group, P ≤ 0.001 vs. tumor survivors). The levels of TSH in the PSIS, hypoplasia, normal, and tumor survivor groups were 1.03 ± 1.08 (P = 0.149 vs. tumor survivors), 1.38 ± 1.47 (P = 0.045 vs. tumor survivors), 2.49 ± 1.53 (P < 0.001 vs. tumor survivors), and 0.76 ± 1.15 μIU/ml. The levels of GH peak in PSIS, hypoplasia, normal, tumor survivor groups were 1.37 ± 1.78, 1.27 ± 1.52, 3.36 ± 1.79, 0.53 ± 0.52 ng/ml and ACTH were 27.50 ± 20.72, 25.05 ± 14.64, 34.61 ± 59.35, 7.19 ± 8.63 ng/ml. Tumor survivors had the lowest levels of GH peak (P ≤ 0.001 vs. PSIS group, P = 0.002 vs. hypoplasia group, P ≤ 0.001 vs. normal group) and ACTH (all the P ≤ 0.001 vs. the other three groups).

Conclusion

The frequency of PSIS is high among children and adolescents with MPHD. The severity of hormone deficiencies in patients with MPHD was more important in the tumor survivor group compared with the other groups.