X-linked hypophosphatemic rickets (XLH) is the first cause of inherited hypophosphatemia and is caused by mutation in the PHEX gene, resulting in excessive expression of the phosphaturic factor FGF23. Symptoms are mainly related to rickets in children and osteomalacia in adults and cause several complications that can be highly invalidating. Due to its rarity, XLH is poorly known and diagnosis is frequently delayed. Conventional treatment is based on oral phosphate salts supplementation and activated vitamin D analogs, which however, cannot cure the disease in most cases. Due to the low prevalence of XLH, an experts’ opinion survey was conducted across Italian centers to collect data on XLH and on its management. A questionnaire was developed by a group of experts to collect data on XLH epidemiology, diagnosis and treatment in Italy. Data from 10 Italian centers (nine of which pediatric) on 175 patients, followed between 1998 and 2017, were included in the survey. Most patients were followed since childhood and 63 children became adults during the investigated period. The diagnosis was made before the age of 1 and between 1 and 5 years in 11 and 50% of cases, respectively. Clinically apparent bone deformities were present in 95% of patients. These were ranked moderate/severe in 75% of subjects and caused growth stunting in 67% of patients. Other frequent complications included bone pain (40%), dental abscesses (33%), and dental malpositions (53%). Treatment protocols varied substantially among centers. Nephrocalcinosis was observed in 34% of patients. Tertiary hyperparathyroidism developed in 6% of patients. XLH remains a severe condition with significant morbidities.

In recent years, a more stable AVP surrogate, called copeptin, has been used as an adjuvant diagnostic tool for dysnatremia in adults and appears to be promising even in the pediatric age. The aim of this study is to present the distribution of plasma copeptin in a large pediatric cohort and to observe the influence of fluid consumption and obesity on its values. A cohort of 128 children and adolescents was divided into two groups on the basis of nocturnal deprivation (group A) or free access to oral fluids in the 6–8 h before blood collection (group B). At all distribution percentiles, copeptin levels were higher (p < 0.0001) in group A, as were plasma sodium levels and osmolality (p = 0.02 and p = 0.008, respectively). The influence of BMI on copeptin levels was investigated by dividing the cohort into nonobese (group C) and obese children and adolescents (group D). Copeptin levels were higher in group D (p = 0.04).Conclusion: The measurement of copeptin could represent a useful tool for the diagnostic pathway of dysnatremic conditions, but its interpretation should take into consideration the state of hydration. Furthermore, it could also be a promising marker for obesity and metabolic syndrome, although this hypothesis needs further studies to be confirmed. What is Known:• Copeptin use as a diagnostic tool in AVP-related disorders, such as diabetes insipidus or syndrome of inappropriate secretion of antidiuretic hormone, is well established in adults• In pediatric age, few studies are available, but the preliminary data, including our previous study, seems to be promising. What is New:• In this study, we represent the distribution of copeptin levels in a pediatric cohort and show the significant influence of fluid ingestion on its plasma levels.• Also BMI seems to be a significant variable on copeptin levels and may be used as an obesity marker in pediatric age

McCune-Albright Syndrome (MAS) is a congenital endocrine disorder due to mosaic tissutal hyper-function. We describe a boy with a molecularly confirmed MAS, clinically evident with congenital café-au-lait spots, bone fibrous dysplasia, hyperthyroidism, and renal phosphate wasting syndrome. At 4.6 years of age he disclosed a rapid progression of peripheral puberty, so we decided to treat him with bicalutamide 25 mg/day and anastrozole 1 mg/day. Combined third generation aromatase inhibitors - competitive androgen receptor blockers were employed in familial male precocious puberty (FMPP). Combined treatment was performed for 49 months from the age of 4.6 to 6.7 years. The patient underwent clinical, laboratory, and instrumental evaluation twice a year from the first admission to the current age. This treatment caused a rapid normalization of growth velocity, subsequent reduction of penile androgenization, and stabilization of testicular volume. The therapy was well tolerated for all its duration and neither side effects, nor secondary hypothalamic activation were noted. This report provides further evidence of effectiveness and safety of combined third generation aromatase inhibitors - competitive androgen receptor blockers in male precocious peripheral puberty, firstly employed in male MAS, and contributes to expand the spectrum of disorders in which their employment may reveal promising.

Primary hyperparathyroidism (PHPT) is a rare disorder in children and adolescents. Typical biochemical features are hypercalcemia and hypophosphatemia, but the clinical features can be heterogeneous, and in some cases, symptoms are vague and nonspecific, leading to misdiagnosis or late diagnosis. Herein, we report two cases of PHPT in pediatric age with different presenting symptoms, pain in the foot, and progressive alteration of the gait in the first case and recurrent abdominal pain with emotional lability in the second. Biochemical and radiological assessment confirmed PHPT. Both cases were treated surgically as definitive treatment, but in the second case, previous medical treatment with cinacalcet, a calcimimetic agent, was required to reduce serum PTH and calcium levels. After surgery, despite conventional treatment with calcium and calcitriol, case 1 developed a hungry bone syndrome. The analysis of the MEN‐1 (Multiple Endocrine Neoplasia) gene was negative in both cases. A diagnosis of PHPT should be considered when children or adolescents present bone pain with radiological imaging of osteolytic lesion and biochemical feature of hypercalcemia associated with hypophosphatemia. In PHPT, the gold standard treatment is represented by surgery followed by strict postoperative endocrine monitoring to maintain adequate homeostasis of calcium and bone metabolism.

McCune-Albright syndrome (MAS) is characterized by the triad of polyostotic bone fibrous dysplasia (PFD), endocrine disorders, and café-au-lait skin pigmentation. Ninety percent of MAS patients have fibrous dysplasia (FD) craniofacial lesions. Osteonecrosis of the jaw (ONJ) has been described as an adverse side effect of bisphosphonate therapy. The aim of the study was to investigate evidence of clinical and/or radiological signs of ONJ in FD/MAS pediatric patients due to bisphosphonate therapy and describe odontoiatric tools in this population.Thirteen FD/MAS patients were enrolled. All patients during pediatric age have been treated with pamidronate infusions. They underwent complete oral clinical examination. Ortopantomography and/or CT were evaluated in all cases.No patient developed ONJ. None of them showed radiological signs different from jaw FD. In spite of the low number of patients enrolled, results confirm that, in this population, ONJ can be ruled out as a chronic adverse side effect of bisphosphonate therapy.