Prevalence and characteristics of paediatric X-linked hypophosphataemia in Australia and New Zealand: Results from the Australian and the New Zealand Paediatric Surveillance Units survey.

BACKGROUND: X-linked hypophosphataemia (XLH) is the most common heritable form of rickets. Prevalence data varies across the literature between 1 in 20,000 and 1 in 200,000 per population. METHODS: Australian and New Zealand Paediatric Surveillance Units collected cross-sectional data from paediatricians on existing cases to estimate prevalence and characteristics of paediatric XLH in Australia and New Zealand. RESULTS: Seventy-five cases in Australia and 18 cases in New Zealand were identified. Estimated minimum prevalence based on these cases was 1.33 (1.04-1.66) per 100,000 and 1.60 per 100,000 (95%CI 0.97-2.58) in Australia and New Zealand respectively, with actual prevalence likely higher due to incomplete ascertainment. Despite a family history in most cases, delayed diagnosis was common, with 49 % diagnosed after 2 years of age. Delayed diagnosis was more common in sporadic versus familial cases. Most common clinical characteristics included leg bowing (89 %), bone and joint pain (68 %), abnormal gait (57 %) and short stature (49 %). There was a significant burden of orthopaedic disease and surgeries and a high rate of complications of nephrocalcinosis and hyperparathyroidism (32 % and 20 % respectively). Additionally, while guidelines stress the importance of multidisciplinary care, many did not have access to recommended health professionals, with only 3 % seeing a psychologist and 68 % seeing a dentist. This is despite the high psychological burden of XLH and a significant proportion (41 %) of this cohort having dental issues (tooth abscess, dental capping, tooth extraction). There were two cases from NZ without data available. Of the 91 cases with data collected, 46 % were on burosumab therapy. Consistent with clinical trials, those on burosumab had a higher serum phosphate levels (p < 0.001) at most recent follow-up. Three cases reported cancellation of orthopaedic surgery due to improvement in lower limb deformity after commencement of burosumab. CONCLUSION: These data describe the multisystem burden of disease for children with XLH with care impacted by delayed diagnosis and a lack of access to many health professionals, especially psychological support.

Acute hyperosmolar hyperglycaemic state in cystic fibrosis-related diabetes caused by glucocorticoid and itraconazole interaction.

Hyperosmolar hyperglycaemic state (HHS) has not previously been reported in cystic fibrosis-related diabetes (CFRD). We report the case of a 15-year old boy with stable CFRD who developed acute HHS after treatment with glucocorticoids and itraconazole for presumed allergic broncho-pulmonary aspergillosis (ABPA). This case highlights the dangerous and preventable combination of high glucose intake, glucocorticoids and itraconazole inhibition of CYP3A4 (with resultant glucocorticoid accumulation) that can result in a state of life- threatening HHS in an adolescent with previously stable CFRD.

Screening, assessment and management of type 2 diabetes mellitus in children and adolescents: Australasian Paediatric Endocrine Group guidelines.

INTRODUCTION: The incidence of type 2 diabetes mellitus has increased in children and adolescents due largely to the obesity epidemic, particularly in high risk ethnic groups. ß-Cell function declines faster and diabetes complications develop earlier in paediatric type 2 diabetes compared with adult-onset type 2 diabetes. There are no consensus guidelines in Australasia for assessment and management of type 2 diabetes in paediatric populations and health professionals have had to refer to adult guidelines. Recent international paediatric guidelines did not address adaptations to care for patients from Indigenous backgrounds. MAIN RECOMMENDATIONS: This guideline provides advice on paediatric type 2 diabetes in relation to screening, diagnosis, diabetes education, monitoring including targets, multicomponent healthy lifestyle, pharmacotherapy, assessment and management of complications and comorbidities, and transition. There is also a dedicated section on considerations of care for children and adolescents from Indigenous background in Australia and New Zealand. CHANGES IN MANAGEMENT AS A RESULT OF THE GUIDELINES: Published international guidelines currently exist, but the challenges and specifics to care for children and adolescents with type 2 diabetes which should apply to Australasia have not been addressed to date. These include: recommendations regarding care of children and adolescents from Indigenous backgrounds in Australia and New Zealand including screening and management; tighter diabetes targets (glycated haemoglobin, ≤ 48 mmol/mol [≤ 6.5%]) for all children and adolescents; considering the use of newer medications approved for adults with type 2 diabetes under the guidance of a paediatric endocrinologist; and the need to transition adolescents with type 2 diabetes to a diabetes multidisciplinary care team including an adult endocrinologist for their ongoing care.

A Brief History of Nutritional Rickets.

Since first described almost a century ago, vitamin D preparations have been successfully used as a public health intervention to prevent nutritional rickets. In this manuscript, we document the periods in history when nutritional rickets was described, examine early efforts to understand its etiology and the steps taken to treat and prevent it. We will also highlight that despite the wealth of historical data and multiple preventative strategies, nutritional rickets remains a significant public health disorder. Nutritional rickets has both skeletal and extraskeletal manifestations. While the skeletal manifestations are the most recognized features, it is the extraskeletal complications, hypocalcaemic seizure and cardiomyopathy that are the most devastating features and result in reported fatalities. Reviewing this history provides an opportunity to further promote recent global consensus recommendations for the prevention and management of nutritional rickets, as well as gain a greater understanding of the well-known public health measures that can be used to manage this entirely preventable disease.

Mitotane in the treatment of childhood adrenocortical carcinoma: a potent endocrine disruptor.

Adrenocortical carcinoma (ACC) during childhood is a rare malignant tumor that frequently results in glucocorticoid and/or androgen excess. When there are signs of microscopic or macroscopic residual disease, adjuvant therapy is recommended with mitotane, an adrenolytic and cytotoxic drug. In addition to the anticipated side effect of adrenal insufficiency, mitotane is known to cause gynecomastia and hypothyroidism in adults. It has never been reported to cause precocious puberty. A 4-year-old girl presented with a 6-week history of virilization and elevated androgen levels and 1-year advancement in bone age. Imaging revealed a right adrenal mass, which was subsequently surgically excised. Histology revealed ACC with multiple unfavorable features, including high mitotic index, capsular invasion and atypical mitoses. Adjuvant chemotherapy was started with mitotane, cisplatin, etoposide and doxorubicin. She experienced severe gastrointestinal side effects and symptomatic adrenal insufficiency, which occurred despite physiological-dose corticosteroid replacement. She also developed hypothyroidism that responded to treatment with levothyroxine and peripheral precocious puberty (PPP) with progressive breast development and rapidly advancing bone age. Five months after discontinuing mitotane, her adrenal insufficiency persisted and she developed secondary central precocious puberty (CPP). This case demonstrates the diverse endocrine complications associated with mitotane therapy, which contrast with the presentation of ACC itself. It also provides the first evidence that the known estrogenic effect of mitotane can manifest as PPP. LEARNING POINTS: Adrenocortical carcinoma is an important differential diagnosis for virilization in young childrenMitotane is a chemotherapeutic agent that is used to treat adrenocortical carcinoma and causes adrenal necrosisMitotane is an endocrine disruptor. In addition to the intended effect of adrenal insufficiency, it can cause hypothyroidism, with gynecomastia also reported in adults.Patients taking mitotane require very high doses of hydrocortisone replacement therapy because mitotane interferes with steroid metabolism. This effect persists after mitotane therapy is completedIn our case, mitotane caused peripheral precocious puberty, possibly through its estrogenic effect.

Consensus guidelines on the use of bisphosphonate therapy in children and adolescents.

Bisphosphonate therapy is the mainstay of pharmacological intervention in young people with skeletal fragility. The evidence of its use in a variety of conditions remains limited despite over three decades of clinical experience. On behalf of the Australasian Paediatric Endocrine Group, this evidence-based consensus guideline presents recommendations and discusses the graded evidence (using the GRADE system) for these recommendations. Primary bone fragility disorders such as osteogenesis imperfecta are considered separately from osteoporosis secondary to other clinical conditions (such as cerebral palsy, Duchenne muscular dystrophy). The use of bisphosphonates in non-fragility conditions, such as fibrous dysplasia, avascular necrosis, bone cysts and hypercalcaemia, is also discussed. While these guidelines provide an evidence-based approach where possible, further research is required in all clinical applications in order to strengthen the recommendations made.

Polycystic Kidney Disease with Hyperinsulinemic Hypoglycemia Caused by a Promoter Mutation in Phosphomannomutase 2.

Hyperinsulinemic hypoglycemia (HI) and congenital polycystic kidney disease (PKD) are rare, genetically heterogeneous disorders. The co-occurrence of these disorders (HIPKD) in 17 children from 11 unrelated families suggested an unrecognized genetic disorder. Whole-genome linkage analysis in five informative families identified a single significant locus on chromosome 16p13.2 (logarithm of odds score 6.5). Sequencing of the coding regions of all linked genes failed to identify biallelic mutations. Instead, we found in all patients a promoter mutation (c.-167G>T) in the phosphomannomutase 2 gene (PMM2), either homozygous or in trans with PMM2 coding mutations. PMM2 encodes a key enzyme in N-glycosylation. Abnormal glycosylation has been associated with PKD, and we found that deglycosylation in cultured pancreatic ß cells altered insulin secretion. Recessive coding mutations in PMM2 cause congenital disorder of glycosylation type 1a (CDG1A), a devastating multisystem disorder with prominent neurologic involvement. Yet our patients did not exhibit the typical clinical or diagnostic features of CDG1A. In vitro, the PMM2 promoter mutation associated with decreased transcriptional activity in patient kidney cells and impaired binding of the transcription factor ZNF143. In silico analysis suggested an important role of ZNF143 for the formation of a chromatin loop including PMM2 We propose that the PMM2 promoter mutation alters tissue-specific chromatin loop formation, with consequent organ-specific deficiency of PMM2 leading to the restricted phenotype of HIPKD. Our findings extend the spectrum of genetic causes for both HI and PKD and provide insights into gene regulation and PMM2 pleiotropy.

Permanent hypopituitarism is rare after structural traumatic brain injury in early childhood.

BACKGROUND: We sought to determine the incidence of permanent hypopituitarism in a potentially high-risk group: young children after structural traumatic brain injury (TBI). METHODS: We conducted a cross-sectional study with longitudinal follow-up. Dynamic tests of pituitary function (GH and ACTH) were performed in all subjects and potential abnormalities critically evaluated. Puberty was clinically staged; baseline thyroid function, prolactin, IGF-I, serum sodium, and osmolality were compared with age-matched data. Diagnosis of GH deficiency was based on an integrated assessment of stimulated GH peak (<5 µg/liter suggestive of deficiency), IGF-I, and growth pattern. ACTH deficiency was diagnosed based on a subnormal response to two serial Synacthen tests (peak cortisol <500 nmol/liter) and a metyrapone test. RESULTS: We studied 198 survivors of structural TBI sustained in early childhood (112 male, age at injury 1.7 ± 1.5 yr) 6.5 ± 3.2 yr after injury. Sixty-four of the injuries (33%) were inflicted and 134 (68%) accidental. Two participants had developed precocious puberty, which is within the expected background population rate. Peak stimulated GH was subnormal in 16 participants (8%), in the context of normal IGF-I and normal growth. Stimulated peak cortisol was low in 17 (8%), but all had normal ACTH function on follow-up. One participant had a transient low serum T(4). Therefore, no cases of hypopituitarism were recorded. CONCLUSION: Permanent hypopituitarism is rare after both inflicted and accidental structural TBI in early childhood. Precocious puberty was the only pituitary hormone abnormality found, but the prevalence did not exceed that of the normal population.

Interaction between mutations in the slide helix of Kir6.2 associated with neonatal diabetes and neurological symptoms.

ATP-sensitive potassium (K(ATP)) channels regulate insulin secretion from pancreatic beta-cells. Gain-of-function mutations in the genes encoding the Kir6.2 and SUR1 subunits of this channel cause neonatal diabetes. We report two novel mutations on the same haplotype (cis), F60Y and V64L, in the slide helix of Kir6.2 in a patient with neonatal diabetes, developmental delay and epilepsy. Functional analysis revealed the F60Y mutation increases the intrinsic channel open probability (Po(0)), thereby indirectly producing a marked decrease in channel inhibition by ATP and an increase in whole-cell K(ATP) currents. When expressed alone, the V64L mutation caused a small reduction in apparent ATP inhibition, by enhancing the ability of MgATP to stimulate channel activity. The V64L mutation also ameliorated the deleterious effects on the F60Y mutation when it was expressed on the same (but not a different) subunit. These data indicate that F60Y is the pathogenic mutation and reveal that interactions between slide helix residues can influence K(ATP) channel gating.

Initial growth deceleration during GnRH analogue therapy for precocious puberty.

OBJECTIVES: To compare the efficacy of goserelin and leuprolide on initial deceleration of growth and weight gain during the first 12 months of GnRH analogue treatment for precocious puberty. DESIGN: Retrospective cohort analysis. PATIENTS: Forty children with precocious puberty treated with either goserelin or leuprolide (33 females, mean age 7.3 and 7.7 years, respectively, at the start of treatment). MEASUREMENTS: The primary outcomes were baseline-to-6-months and 6-months-to-12-months change in height standard deviation score (SDS) and body mass index (BMI). Relative tall stature was calculated as the difference between height SDS and mid-parental height (MPH) SDS at baseline. RESULTS: Goserelin and leuprolide were associated with similar suppression of serum LH during the first 12 months of treatment (P = 0.62). Greater relative tall stature was strongly associated with more advanced bone age, greater BMI SDS and with greater reduction in height SDS in the first 6 months. Adjusted for relative tall stature, goserelin therapy was associated with significantly greater suppression of growth than leuprolide (P = 0.025) in the first 6 months of treatment, with no subsequent change in the second 6 months. A similar, significant increase in BMI was seen with both analogues. CONCLUSIONS: Both GnRH analogues were associated with effective biochemical suppression of puberty; however, goserelin was more effective at reducing linear growth during the first 6 months. Relative tall stature was a major determinant of the initial response to treatment.

Massive hepatic hemangioendothelioma and consumptive hypothyroidism.

Hypothyroidism was diagnosed in an infant with massive hepatic hemangioendothelioma. Markedly elevated serum reverse-triiodothyronine levels confirmed consumptive hypothyroidism. Large doses of thyroxine were initially required to normalise TSH. Thyroxine was tapered as the tumor regressed and was discontinued at 16 months old. Thyroid function remains normal without treatment.

Continuous glucose monitoring in adolescents with cystic fibrosis.

The presence of cystic fibrosis (CF)-related diabetes was evaluated in 19 adolescents with CF by continuous glucose monitoring system (CGMS) and oral glucose tolerance testing. CGMS confirmed diabetic glucose excursions in 7/19 subjects deemed diabetic on oral glucose tolerance testing. CGMS is a useful tool for detecting hyperglycemia in CF.

Muscle-specific Pten deletion protects against insulin resistance and diabetes.

Pten (phosphatase with tensin homology), a dual-specificity phosphatase, is a negative regulator of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Pten regulates a vast array of biological functions including growth, metabolism, and longevity. Although the PI3K/Akt pathway is a key determinant of the insulin-dependent increase in glucose uptake into muscle and adipose cells, the contribution of this pathway in muscle to whole-body glucose homeostasis is unclear. Here we show that muscle-specific deletion of Pten protected mice from insulin resistance and diabetes caused by high-fat feeding. Deletion of muscle Pten resulted in enhanced insulin-stimulated 2-deoxyglucose uptake and Akt phosphorylation in soleus but, surprisingly, not in extensor digitorum longus muscle compared to littermate controls upon high-fat feeding, and these mice were spared from developing hyperinsulinemia and islet hyperplasia. Muscle Pten may be a potential target for treatment or prevention of insulin resistance and diabetes.

Insulin resistance is not due to persistently elevated serum tumor necrosis-alpha levels in small for gestational age, premature, or twin children.

BACKGROUND: In pregnancies with small for gestational age (SGA) fetuses, elevated amniotic fluid tumor necrosis factor-alpha (TNF-alpha) levels have been reported. TNF-alpha has been shown to induce insulin resistance in rodents and humans. We hypothesized that an adverse fetal or early neonatal environment for SGA, twin, and premature children leads to persistently elevated TNF-alpha levels that induce insulin resistance in each of these groups. METHODS: The study group consisted of 16 SGA, 14 premature, 53 twin subjects, and the control group of 40 normal subjects (10 short-stature and 30 normal-stature). All subjects were prepubertal and non-obese. Insulin sensitivity (S(I)) was measured in all but the normal-statured control subjects. Fasting plasma TNF-alpha and cortisol levels were measured in all subjects. RESULTS: The study group had reduced S(I)[SGA 18.5 +/- 3, premature 17.8 +/- 2, twin 12.7 +/- 0.7 (x10(-4)/min/ microU/mL)] compared to the short normal control subjects (43 +/- 8 x 10(-4)/min/ microU/mL, p < 0.001). Plasma TNF-alpha levels were lower in the insulin-resistant study group when compared to the control group (2.9 +/- 0.1 vs. 5.0 +/- 0.2 pg/mL, p < 0.001). An association was present between reduced S(I) and low plasma TNF-alpha levels in the study group (p = 0.01, r = 0.4). Fasting plasma cortisol was lower in the study compared to the control group (266 +/- 16 vs. 341 +/- 28 nmol/L, p < 0.01) due to the influence of the twin study subgroup. There was no relationship between plasma cortisol and TNF-alpha levels (p = 0.3). CONCLUSION: SGA, premature, and twin children are insulin resistant and have low plasma TNF-alpha and cortisol levels. We speculate that the mechanism leading to insulin resistance in these subjects is also suppressing plasma TNF-alpha and cortisol concentrations.