Implementation of genomic medicine for rare disease in a tertiary healthcare system: Mayo Clinic Program for Rare and Undiagnosed Diseases (PRaUD).

BACKGROUND: In the United States, rare disease (RD) is defined as a condition that affects fewer than 200,000 individuals. Collectively, RD affects an estimated 30 million Americans. A significant portion of RD has an underlying genetic cause; however, this may go undiagnosed. To better serve these patients, the Mayo Clinic Program for Rare and Undiagnosed Diseases (PRaUD) was created under the auspices of the Center for Individualized Medicine (CIM) aiming to integrate genomics into subspecialty practice including targeted genetic testing, research, and education. METHODS: Patients were identified by subspecialty healthcare providers from 11 clinical divisions/departments. Targeted multi-gene panels or custom exome/genome-based panels were utilized. To support the goals of PRaUD, a new clinical service model, the Genetic Testing and Counseling (GTAC) unit, was established to improve access and increase efficiency for genetic test facilitation. The GTAC unit includes genetic counselors, genetic counseling assistants, genetic nurses, and a medical geneticist. Patients receive abbreviated point-of-care genetic counseling and testing through a partnership with subspecialty providers. RESULTS: Implementation of PRaUD began in 2018 and GTAC unit launched in 2020 to support program expansion. Currently, 29 RD clinical indications are included in 11 specialty divisions/departments with over 142 referring providers. To date, 1152 patients have been evaluated with an overall solved or likely solved rate of 17.5% and as high as 66.7% depending on the phenotype. Noteworthy, 42.7% of the solved or likely solved patients underwent changes in medical management and outcome based on genetic test results. CONCLUSION: Implementation of PRaUD and GTAC have enabled subspecialty practices advance expertise in RD where genetic counselors have not historically been embedded in practice. Democratizing access to genetic testing and counseling can broaden the reach of patients with RD and increase the diagnostic yield of such indications leading to better medical management as well as expanding research opportunities.

Risk of substance use disorders among adolescents and emerging adults with type 1 diabetes: A population-based cohort study.

BACKGROUND: Adolescents and emerging adults with chronic health conditions such as type 1 diabetes mellitus (T1D) are more likely to engage in high-risk behaviors. Previous studies regarding substance use in adolescents and emerging adults with T1D are mostly derived from cross-sectional studies utilizing self-administered questionnaires and are limited by lack of population-based comparison groups. In addition, despite the rising popularity of vaping, little is known about the incidence of vaping in adolescents and emerging adults with T1D. METHODS: We explored the incidence and prospective risk of substance use disorders (SUD) and vaping in adolescents and emerging adults with T1D compared to age and gender matched nondiabetic referents residing in Olmsted County, Rochester, MN. RESULTS: Risk of incident SUD was higher in those with T1D compared to matched referents with alcohol, marijuana, and smoked tobacco being most common substances. When stratified by gender, these differences remained significant in males, but not females. CONCLUSIONS: While further work is needed to delineate the causative relationships between T1D, mental health, and substance abuse, our findings confirm the critical need for substance use screening and mental health support for adolescents and emerging adults with T1D.

Pediatric Endocrinology: Perspectives of Pediatric Endocrinologists Regarding Career Choice and Recruitment of Trainees.

OBJECTIVES: To examine main factors that influence the decision to choose pediatric endocrinology as a career among pediatric endocrinologists and assess their work satisfaction or stress level and suggested strategies to increase interest in subspecialty training in pediatric endocrinology. METHODS: A workforce survey was distributed among 1470 members of the Pediatric Endocrine Society. RESULTS: The response rate was 37.4%, with 550 members responding. The most common reasons for the respondents choosing pediatric endocrinology were intellectual stimulation (79%), exposure to endocrinology during residency (57%) or medical school (43%), and ability to establish relationships with patients with chronic disorders (54%). Of the respondents, 97% considered intellectual stimulation as the most favorable aspect of the specialty, and 84% considered financial compensation as the most unfavorable aspect of pediatric endocrinology. Majority (77%) were satisfied or very satisfied with their work environment. The mean work-related stress score (0 [none] to 10 [worst]) was 5.7, standard deviation was 2.1, and median was 6 (Q1, Q3: 4, 7). Increased financial compensation for the services and loan payment or forgiveness option were the top strategies suggested to enhance interest among residents for training in the subspecialty. One third (37%) felt that reducing the duration of the fellowship to 2 years would increase interest in training in pediatric endocrinology. CONCLUSION: The pediatric endocrinologists reported overall excellent career satisfaction, indicating the potential to attract high-quality doctors to the specialty. Improving reimbursement and loan forgiveness were the top strategies suggested for increasing interest in subspecialty training in pediatric endocrinology.

Bilateral pheochromocytoma: Clinical characteristics, treatment and longitudinal follow-up.

OBJECTIVE: Comprehensive data about patients with bilateral pheochromocytoma are limited. We aimed to describe the clinical presentation, genetic analysis, treatment and outcomes of patients with bilateral pheochromocytoma. DESIGN: A retrospective study at a tertiary care centre. PATIENTS: All patients with bilateral pheochromocytoma evaluated at Mayo Clinic in Rochester, Minnesota between January 1951 and December 2015. MEASUREMENTS: Tumour size, genetic testing, plasma/urine metanephrines and catecholamines. RESULTS: A total of 94 patients (51% women) were diagnosed with bilateral pheochromocytoma at a median age at first presentation of 31 years (range, 4-70). Bilateral disease was noted in 8.0% of pheochromocytoma patient overall and 37.5% of patients 18 years of younger. Most patients presented with synchronous tumours (80%). Median time to metachronous tumours was 4.5 years (range, 1-38). Genetic disease was identified in 75 (80%) patients, including MEN 2A (42.6%), VHL (19.1%), MEN 2B (9.6%) and NF1 (8.5%). Excess catecholamines were present in 97% of patients. Patients with synchronous pheochromocytoma commonly underwent simultaneous bilateral adrenalectomy (99%), and 18 (24%) had cortical-sparing surgery. Multicentric tumours were reported in 23 of 77 (30%) patients with available data. Recurrent disease was found in 9.6% of patients, and 8.5% developed metastatic disease. Median follow-up was 8.5 years. At the study conclusion, 4 patients had died due to pheochromocytoma or adrenalectomy. CONCLUSIONS: Bilateral pheochromocytoma occurred in 7.0% of adults with pheochromocytoma and 37.5% of paediatric patients. Genetic disease was identified in 80% of patients, predominantly MEN2A. Multicentric tumours were common, but most were still cured following adrenalectomy.

Pediatric applications of Dotatate: early diagnostic and therapeutic experience.

In recent years, new somatostatin receptor agents (SSTRs) have become available for diagnostic imaging and therapy in neuroendocrine tumors. The novel SSTR ligand DOTA-DPhel-Tyr3-octreotate (Dotatate) in particular can be linked with 68Gallium for diagnostic imaging purposes, and with the ß-emitter 177Lutetium for radiotherapy in the setting of neuroendocrine tumors. Dotatate imaging offers distinct advantages in the evaluation of neuroendocrine tumors compared to standard techniques, including greater target-to-background ratio and lesion conspicuity, high sensitivity/specificity, improved spatial resolution with positron emission tomography (PET)/CT or PET/MR, and decreased radiation exposure. Although currently off-label in pediatrics, Dotatate theranostics in children are being explored, most notably in the setting of neuroblastoma and hereditary neuroendocrine syndromes. This article provides a multicenter case series of Dotatate imaging and therapy in pediatric patients in order to highlight the spectrum of potential clinical applications.

Mild subclinical hypothyroidism is associated with paediatric dyslipidaemia.

BACKGROUND: There is a lack of consensus on the cardiometabolic consequences of mild subclinical hypothyroidism (SCH) among children. The objective of the current study was to compare lipid profiles in children with mild SCH with those of euthyroid children. STUDY DESIGN: Retrospective medical record review. PATIENTS: Children (ages 2-18 years) who had undergone simultaneous measurement of TSH, free thyroxine (T4) and lipids. Lipids in children with mild SCH (TSH 5-<10 mIU/L and normal free T4, n = 228) were compared with those in euthyroid children (n = 1215). RESULTS: TSH level was positively associated with total cholesterol and nonhigh density lipoprotein (non-HDL) cholesterol [ß 0.05(0.03-0.08), P < .0001 and ß 0.05(0.03-0.08), P < .0001, respectively]. Total cholesterol was significantly higher in children and adolescents with mild SCH compared with euthyroid children (4.43 ± 1.14 mmol/L vs 4.2 ± 0.85 mmol/L, P = .0005). Similarly, non-HDL cholesterol level was also higher in children with mild SCH relative to euthyroid children (3.08 ± 1.14 mmol/L vs 2.91 ± 0.8 mmol/L, P = .001). The adjusted odds ratio of having elevated total cholesterol and elevated non-HDL cholesterol was greater in children with mild SCH compared with euthyroid children (OR 1.88, 95% CI; 1.28-2.73; P = .001 and 1.72, 95% CI 1.2-2.5; P = .003, respectively). The presence of thyroid autoimmunity was not associated with higher rates of dyslipidaemia. CONCLUSIONS: Mild SCH in children and adolescents was associated with higher rates of elevated total cholesterol and elevated non-HDL cholesterol. Randomized placebo controlled studies are warranted to determine if treatment of mild SCH in children leads to improvement in lipid profile.

Obesity in children with congenital adrenal hyperplasia in the Minnesota cohort: importance of adjusting body mass index for height-age.

OBJECTIVES: To evaluate obesity and overweight in children with congenital adrenal hyperplasia (CAH) and associations with glucocorticoids, fludrocortisone and disease control. Adjusting body mass index-for-height-age (BMIHA ) percentile is proposed to correct misclassification of obese/overweight status in CAH children with advanced bone age and tall-for-age stature. DESIGN: Longitudinal. PATIENTS: One hundred and ninety-four children with CAH seen from 1970 to 2013: 124 salt wasting (SW); 70 simple virilizing (SV); 102 females. MEASUREMENTS: Body mass index (BMI) end-points were overweight (85-94 percentile) and obese (≥95 percentile). RESULTS: Approximately 50% of the children had at least one BMI measurement ≥95 percentile and about 70% had at least one ≥85 percentile. Using BMIHA percentiles, obesity incidence decreased slightly in SW children (47-43%) and markedly in SV children (50-33%); however, overweight status was not reduced. Only 6% of SW and 1% of SV children were persistently obese (≥3 clinic visits) when BMIHA was applied, whereas overweight status persisted in 35% of SW and 33% of SV children. Most obesity or overweight when using BMIHA occurred before age 10 and there was no association with hydrocortisone (HC) or fludrocortisone dosing. Adiposity rebound for SW children occurred by 3·3 years and in SV females by age 3·8 years, over a year earlier than the adiposity rebound for healthy children. CONCLUSION: Children with CAH are at higher risk for early onset obesity and overweight with or without using BMIHA but rates of persistent obesity were lower than previously reported. Careful HC dosing during early childhood is needed to prevent increased weight gain and an early adiposity rebound.

GLUCOCORTICOID REPLACEMENT REGIMENS IN CHRONIC ADRENAL INSUFFICIENCY: A SYSTEMATIC REVIEW AND META-ANALYSIS.

OBJECTIVE: Various glucocorticoid (GC) regimens have been used in the treatment of patients with adrenal insufficiency, yet the differences between such regimens on health outcomes are unclear. We performed a systematic review and meta-analysis to compare the effects of GC regimens on quality of life (QoL), bone density, incidence of adrenal crisis, and death. In pediatric studies, we also searched for final adult height. METHODS: We searched 6 databases through July 2016. Studies were selected and appraised by independent reviewers. Data were pooled using the profile likelihood random-effects model. RESULTS: We included 34 studies. We found no difference in QoL scores between higher (≥30 mg/day of hydrocortisone [HC] equivalence) vs. lower daily doses (<30 mg/day of HC equivalence) (P = .15) or based on frequency of daily dosing (once, twice or thrice daily). Extended-release (1 study), dual-/modified-release (3 studies), and continuous subcutaneous (3 studies) forms of GCs were associated with higher QoL scores. There was no significant association between dose and type of GC and the incidence of adrenal crises. The effect on bone mineral density was heterogeneous. No data were available on mortality or final adult height in children. The quality of evidence was low due to increased risk of bias, imprecision, and heterogeneity. CONCLUSION: Extended-/dual-release, and continuous subcutaneous forms of GC may be associated with higher QoL scores. However, this is derived from short-term and imprecise evidence, warranting low confidence. ABBREVIATIONS: AI = adrenal insufficiency BMD = bone mineral density GC = glucocorticoids HC = hydrocortisone QoL = quality of life RCT = randomized controlled trial.

Hypertension in children with congenital adrenal hyperplasia.

OBJECTIVES: Estimates of high blood pressure (BP) incidence in children with congenital adrenal hyperplasia (CAH) vary widely; risk factors are poorly understood. We estimated incidence of hypertension by CAH subtype and sex, and assessed its association with body mass index, hydrocortisone and fludrocortisone. DESIGN: Longitudinal. PATIENTS: Chart review of 180 paediatric CAH patients (120 salt wasting; 60 simple virilizing; 93 females) seen from 1970 to 2013. MEASUREMENTS: High BP was diagnosed by diastolic or systolic blood pressure measurement ≥95th percentile for age, sex and height; hypertension was diagnosed with high BP on at least three clinic visits. RESULTS: Children with classic CAH who received fludrocortisone had a significantly higher rate of hypertension (55% vs 31%) than those who did not. Hypertension incidence was higher in salt-wasting CAH (58%) than in simple-virilizing CAH (35%). Hypertension first occurred before age 5 years in 91% of salt-wasting males and 50% of cases in salt-wasting females; most simple-virilizing cases occurred during ages 10-18 years. Rates of hypertension were higher in children who had three or more measurements with 17-OHP < 400 ng/dl (12·12 nmol/l), and this difference was significant in salt-wasting males. Children on fludrocortisone who had three or more readings of 17-OHP < 400 ng/dl (12·12 nmol/l) had a significantly higher rate of hypertension than those who did not. Hydrocortisone dose was not associated with hypertension. CONCLUSION: Children with CAH are at higher risk for hypertension than the general paediatric population, and incidence differs by sex and CAH subtype. Hypertension was higher in children on fludrocortisone and who were oversuppressed.

Thiazide Diuretics in the Management of Young Children with Central Diabetes Insipidus.

OBJECTIVE: To report our experience in treating infants and toddlers with central diabetes insipidus (DI) with thiazide diuretics. STUDY DESIGN: A retrospective chart review of all infants and toddlers who were treated with thiazide diuretics for central DI at the Mayo Clinic between 1996 and 2014. RESULTS: Our cohort consisted of 13 patients. The median age at the start of therapy was 6 months (IQR, 1-14 months). Eight patients were given chlorothiazide at a starting dose of 5-10 mg/kg/day, and 5 patients were treated with hydrochlorothiazide at a starting dose of 1-2 mg/kg/day. The median age at the cessation of thiazide therapy was 18 months (IQR, 11.5-39 months). The main reason for stopping was the lack of continued response, in addition to hypernatremia. There was no hospitalization secondary to hyponatremia and only 1 hospitalization secondary to hypernatremia while receiving thiazide therapy. Calcium was checked periodically in 7 of the 13 patients, and 2 of these 7 patients had persistent hypercalcemia. CONCLUSION: Thiazide diuretics appear to be safe and effective in treating infants with central DI. They can be continued after the introduction of solid food, and until a lack of response is observed.

Impact of hydrocortisone on adult height in congenital adrenal hyperplasia-the Minnesota cohort.

OBJECTIVE: To estimate the impact of the average daily dose of hydrocortisone (HC) on the amount of growth attained in children with congenital adrenal hyperplasia (CAH). The effect of glucocorticoid therapy on adult height (AH) in children with CAH has yet to be elucidated. STUDY DESIGN: Triple-logistic models estimating components of growth and maturation were fitted to longitudinal records of 104 patients with classic CAH from 3 pediatric medical centers in Minnesota between 1955 and 2012. A total of 3664 clinical encounters were examined. Random-effects longitudinal models with time-related covariates were used to estimate the effect of HC therapy on linear growth. RESULTS: The predicted AH z-score (-0.7) was similar between the sexes and among CAH subtypes. The mean growth period HC dose was 18.9 ± 5.6 mg/m(2)/day. In the final regression model, HC dose was negatively associated with predicted AH, with each mg/m(2)/day increase in average growth period HC dose predicting a 0.37-cm decrease in AH (P < .004). CONCLUSION: This study has quantified the fractional reduction in predicted final AH with an incremental increase in HC dose. These findings have important clinical implications in the decision making balance between HC replacement dose and adrenal androgen suppression in children with CAH.

Cardiometabolic Risk Markers in Children With Obesity and Variants in MC4R Pathway-related Genes.

Context: Variants in melanocortin 4 receptor (MC4R) pathway-related genes have been associated with obesity. The association of these variants with cardiometabolic parameters are not fully known. Objective: We compared the severity of obesity and cardiometabolic risk markers in children with MC4R pathway-related clinically reported genetic variants relative to children without these variants. Methods: A retrospective chart review was performed in children with obesity who underwent multigene panel testing for monogenic obesity. Results: Data on a total of 104 children were examined, with 93 (89%) identified as White. Thirty-nine (37.5%) patients had clinically reported variants in the MC4R pathway, and the remaining 65 patients did not have reported MC4R pathway-related variants. Among the MC4R-related variants, PCSK1 risk alleles were most common, reported in 15 children (14%). The maximum body mass index percent of the 95th percentile was not different between groups (P = .116). Low-density lipoprotein cholesterol (LDL-C) was not different between groups (P = .132). However, subgroup analysis demonstrated higher LDL cholesterol in children with the PCSK1 c.661A>G risk allele relative to those with MC4R-related variant of uncertain significance (P = .047), negative genetic testing (P = .012), and those with non-MC4R related variants (P = .048). The blood pressure, fasting glucose, hemoglobin A1C, total cholesterol, alanine transaminase, and high-density lipoprotein cholesterol were not different between groups. Conclusion: Variants in the MC4R pathway-related genes were not associated with severity of obesity and cardiometabolic risk markers except for the c.661A>G PCSK1 risk allele, which was associated with higher LDL-C levels.

Can incorporating molecular testing improve the accuracy of newborn screening for congenital adrenal hyperplasia?

BACKGROUND: Single-tier newborn screening (NBS) for CAH using 17-hydroxyprogesterone (17OHP) measured by fluoroimmunoassay (FIA) in samples collected at 24-48 hours produces a high false-positive rate (FPR). 2nd tier steroid testing can reduce the FPR and has been widely implemented. We investigated the accuracy of an alternative multi-tier CAH NBS protocol that incorporates molecular testing of the CYP21A2 gene and reduces the 1st tier 17OHP cutoff to minimize missed cases. METHODS: Created a Minnesota-specific CYP21A2 pathogenic variants panel; develop a rapid, high-throughput multiplex, allele-specific-primer-extension assay; perform 1-year retrospective analysis of Minnesota NBS results comparing metrics between a conventional steroid-based two-tier protocol and a molecular-based multi-tier NBS protocol, applied post-hoc. RESULTS: CYP21A2 gene sequencing of 103 Minnesota families resulted in a Minnesota-specific panel of 21 pathogenic variants. Centers for Disease Control and Prevention (CDC) created a molecular assay with 100% accuracy and reproducibility. Two-tier steroid-based screening of 68,659 live births during 2015 resulted in 2 false negatives (FNs), 91 FPs, and 1 true positive (TP). A three-tier protocol with a lower 1st-tier steroid cutoff, 2nd-tier 21-variant CYP21A2 panel and 3rd-tier CYP21A2 sequencing would have resulted in 0 FNs, 52 FPs and 3 TPs. CONCLUSIONS: Incorporation of molecular testing could improve the accuracy of CAH NBS, although some distinct challenges of molecular testing may need to be considered before implementation by NBS programs.

Bilateral pheochromocytomas in a child who had hemihypertrophy and alteration in the VHL gene.

The association of hypertrophy with neoplasm is well-known. Pheochromocytoma is a rare neoplasm in children. Isolated hemihypertrophy and hemihypertrophy linked to other genetic disorders have rarely been associated with the development of pheochromocytoma, with only two cases reported to date. We report a novel case of a 4-year-old male with bilateral adrenal pheochromocytomas and lower extremity hemihypertrophy in the setting of von Hippel-Lindau syndrome.

Copeptin levels in hospitalized infants and children with suspected vasopressin-dependent disorders: a case series.

OBJECTIVES: There have been recent advances assessing copeptin levels in adults with suspected disorders of vasopressin release. Very limited data exits on copeptin levels in children and infants, especially in a critically-ill hospitalized population where hyper- and hypo-natremia are very common. Our objective is to describe the institutional experience assessing copeptin levels in hospitalized infants and children with hyper- or hypo-natremia. METHODS: We performed a single-center retrospective case series of all infants, children, and adolescents who had an ultrasensitive plasma copeptin level obtained between 2019-2021. RESULTS: A total of 29 critically ill patients (6 infants) were identified with 38 % of patients having copeptin levels after neurosurgical procedures for tumors or trauma. Approximately 13/17 children with hypernatremia had central diabetes insipidus (central diabetes insipidus) to diagnose CDI, A copeptin level ≤ 4.9 pmol/L resulted in an 88 % sensitivity (95 % CI 47-99 %), and 66 % specificity (95 % CI 30-93 %). Amongst those with hyponatremia levels were more variable, 8/12 children had syndrome of inappropriate antidiuresis (SIAD) with copeptin levels ranging 4.7-72.6 pmol/L. CONCLUSIONS: While difficult to conclude due to multiple limitations, this case series highlights that typical copeptin cutoffs used to diagnose DI in adults in an ambulatory setting may also translate to a critically-ill pediatric population. Large prospective studies are needed to confirm this observation. In addition, postoperative copeptin levels could potentially be utilized as an additional marker to predict permanent from transient DI, but much larger studies are needed. Further work is needed to establish normative copeptin levels in infants and patients with SIAD.

Update on treatment strategies for optimization of final adult height in children with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is one of the most common autosomal recessive disorders, caused by deficiency of an enzyme involved in adrenal synthesis of cortisol. Due to lack of feedback from cortisol, an elevation in ACTH occurs, shifting precursors of steroidogenesis into androgen synthesis. Both the disorder itself due to excess androgens and replacement with glucocorticoids can compromise final adult height. Also, unpredictable progression to precocious puberty in some patients can further compromise height. The achievement of normal growth remains the ultimate goal of treatment. This review will first examine the evidence behind deficits in adult height in CAH and implicated factors behind such compromise. The primary goal of the review is to identify therapies to optimize height in CAH. This will include variations in 'standard' medical therapy and recent single and combination therapies with growth hormone, GnRH analogs, aromatase inhibitors and anti androgens to optimize final height in CAH.

Initiation of Gender-Affirming Testosterone Therapy in a Lactating Transgender Man.

INTRODUCTION: Transgender and gender diverse individuals may choose to provide their infants with human milk. Lactating transgender men may experience gender dysphoria and desire to initiate or reinitiate gender-affirming testosterone therapy. However, there is limited safety data regarding use of testosterone during lactation. MAIN ISSUE: A 30-year-old G2P2 transgender man with gender dysphoria sought to initiate gender-affirming testosterone therapy while lactating. MANAGEMENT: Subcutaneous testosterone was self-administered beginning at 13 months post-partum. We prospectively collected data on circulating testosterone concentrations in parent serum, milk, and infant serum over 5 months until the infant self-weaned. The infant was monitored for growth and development at routine pediatric outpatient appointments. Parent serum testosterone concentrations rose with the initiation of testosterone therapy, reaching therapeutic concentrations by Day 14. Milk testosterone concentrations also increased with a maximum concentration of 35.9 ng/dl when the lactating parent was on a dose of 80 mg subcutaneous testosterone cypionate weekly. The calculated milk/plasma ratio remained under 1.0 and the calculated relative infant dose remained under 1%. The infant had no observable side effects, and his serum testosterone concentrations remained undetectable throughout the study period. CONCLUSION: This is the first study with data regarding human milk and infant serum testosterone concentrations during the initiation of gender-affirming testosterone therapy in a lactating individual. This evidence can help families and clinicians with decisions regarding lactation and testosterone use.

Vasopressin-Dependent Disorders: What Is New in Children?

Arginine vasopressin (AVP)-mediated osmoregulatory disorders, such as diabetes insipidus (DI) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are common in the differential diagnosis for children with hypo- and hypernatremia and require timely recognition and treatment. DI is caused by a failure to concentrate urine secondary to impaired production of or response to AVP, resulting in hypernatremia. Newer methods of diagnosing DI include measuring copeptin levels; copeptin is AVP's chaperone protein and serves as a surrogate biomarker of AVP secretion. Intraoperative copeptin levels may also help predict the risk for developing DI after neurosurgical procedures. Copeptin levels hold diagnostic promise in other pediatric conditions, too. Recently, expanded genotype and phenotype correlations in inherited DI disorders have been described and may better predict the clinical course in affected children and infants. Similarly, newer formulations of synthetic AVP may improve pediatric DI treatment. In contrast to DI, SIADH, characterized by inappropriate AVP secretion, commonly leads to severe hyponatremia. Contemporary methods aid clinicians in distinguishing SIADH from other hyponatremic conditions, particularly cerebral salt wasting. Further research on the efficacy of therapies for pediatric SIADH is needed, although some adult treatments hold promise for pediatrics. Lastly, expansion of home point-of-care sodium testing may transform management of SIADH and DI in children. In this article, we review recent developments in the understanding of pathophysiology, diagnostic workup, and treatment of better outcomes and quality of life for children with these challenging disorders.