Refeeding Syndrome in Pediatric Age, An Unknown Disease: A Narrative Review.

Refeeding syndrome (RS) is characterized by electrolyte imbalances that can occur in malnourished and abruptly refed patients. Typical features of RS are hypophosphatemia, hypokalemia, hypomagnesemia, and thiamine deficiency. It is a potentially life-threatening condition that can affect both adults and children, although there is scarce evidence in the pediatric literature. The sudden increase in food intake causes a shift in the body's metabolism and electrolyte balance, leading to symptoms such as weakness, seizures, and even heart failure. A proper management with progressive increase in nutrients is essential to prevent the onset of this condition and ensure the best possible outcomes. Moreover, an estimated incidence of up to 7.4% has been observed in pediatric intensive care unit patients receiving nutritional support, alone or as an adjunct. To prevent RS, it is important to carefully monitor feeding resumption, particularly in severely malnourished individuals. A proper strategy should start with small amounts of low-calorie fluids and gradually increasing the calorie content and amount of food over several days. Close monitoring of electrolyte levels is critical and prophylactic use of dietary supplements such as thiamine may be required to correct any imbalances that may occur. In this narrative review, we aim to provide a comprehensive understanding of RS in pediatric clinical practice and provide a possible management algorithm.

Diagnosis and management of tumor-induced osteomalacia: a single center experience.

PURPOSE: The aim of this study is to review the clinical and laboratory characteristics, diagnostic and treatment modalities of tumor-induced osteomalacia (TIO) cases managed in a single center. MATERIAL METHODS: Demographic and clinical features, biochemical findings, diagnostic procedures, treatment modalities, and outcomes of nine patients who had the diagnosis of TIO were reviewed retrospectively. RESULTS: Mean age of the study group (F/M: 4/5) was 45.8 ± 10.8 years, and mean time from the onset of symptoms to diagnosis was 4.7 ± 2.8 years. The clinical manifestations were muscle weakness and difficulty in walking (8/9), hip pain (3/9), multiple fractures (2/9), stress fracture (2/9). Mean plasma phosphorus concentration was 1.28 ± 0.4 mg/dl at presentation. We performed radionuclide imaging modalities (18F-FDG PET/CT, Ga68-DOTATATE PET/CT, octreotide scintigraphy) in seven of nine patients, and tumor was detected in all. Lower extremity (n = 6; %67), head region (n = 2; %22) and thorax (n = 1; %11) were the tumor locations of our cases. Eight patients underwent surgery and remission was achieved postoperatively in all of the operated patients and plasma phosphorus level normalized in 4 ± 2 days. Pathological examination revealed mesenchymal tumors with different subtypes. Recurrence occurred in three patients at 13 ± 10.5 months after the first surgery. Two patients were reoperated and radiotherapy was also performed in one of them. CONCLUSION: Hypophosphatemia necessitates careful evaluation for the etiology. TIO is one of the important causes of adult-onset hypophosphatemic osteomalacia. Diagnosis of TIO is essential because the laboratory and clinical findings resolve after appropriate treatment.

A Retrospective Chart Review to Determine Hypophosphatemia Incidence and Phosphorus Supplementation Requirements in Patients With Severe Thermal Cutaneous Injuries Receiving High-Volume Hemofiltration.

Patients with severe thermal injuries have increased metabolic demands necessitating frequent phosphate supplementation. Patients with acute renal failure may have less requirements, due to reduced elimination. However, patients being supported with renal replacement therapy have varying degree of requirements. Little published evidence depicts the incidence of hypophosphatemia and repletion requirements in patients with severe thermal injuries treated with high-volume hemofiltration (HVHF) and a high-flux membrane. The objective of this retrospective chart review was to determine the incidence of hypophosphatemia and characterize repletion requirements and response in this population. Enrolled patients had at least 20% TBSA thermal injuries and required continuous hemofiltration with prefilter replacement fluid doses ≥35 mL/kg IBW/hr. A randomly selected cohort without acute kidney injury (AKI) and matched based on age and extent of TBSA was used to compare phosphorus requirements over an initial 14-day period. Demographics, diet, and variables affecting phosphorus concentrations were collected. Sixteen patients were included in the retrospective HVHF group and 16 patients in a case-control cohort to better depict the impact of HVHF. The average age was 60.2 ± 15.1 years and median TBSA was 30% (23.4, 56.3) in the HVHF group, compared to 53.3 ± 16.4 years (P = .22) and TBSA 29% (26.4, 33.9; P = .73). All patients in the HVHF group were started on HVHF with a 1.6 m2 polyethersulfone membrane for AKI. As expected, the HVHF group exhibited statistically higher than normal baseline potassium and phosphorous laboratory values. The HVHF group experienced more days with hypophosphatemia (49.6 ± 12.4% vs 29.3 ± 16.3%, P = .012), despite 0.75 mmol/kg/day phosphorous supplementation (compared to 0.66 mmol/kg/day for the control group, P = .45). Patients with longer durations of HVHF therapy experienced increasing risk of hypophosphatemia, reaching 100% by the end of the study period. This study demonstrates severe thermally injured patients receiving HVHF for AKI are at increased risk for hypophosphatemia, and require high phosphate supplementation.

Early hypophosphatemia in critically ill children and the effect of parenteral nutrition: A secondary analysis of the PEPaNIC RCT.

BACKGROUND & AIMS: Hypophosphatemia during critical illness has been associated with adverse outcome. The reintroduction of enteral or parenteral nutrition, leading to refeeding hypophosphatemia (RFH), has been presented as potential risk factor. We investigated the occurrence of early RFH, its association with clinical outcome, and the impact of early parenteral nutrition (PN) on the development of early RFH in pediatric critical illness. METHODS: This is a secondary analysis of the PEPaNIC randomized controlled trial (N = 1440), which showed that withholding supplemental parenteral nutrition (PN) for 1 week (late-PN) in the pediatric intensive care unit (PICU) accelerated recovery and reduced new infections compared to early-PN (<24 h). Patients with renal replacement therapy or unavailable phosphate concentrations were excluded from this analysis. Early RFH was defined as serum/plasma phosphate <0.65 mmol/L and a drop of >0.16 mmol/L within 3 days of admission to the PICU. The association between baseline characteristics and early RFH, and the association of early RFH with clinical outcome were investigated using logistic and linear regression models, both uncorrected and corrected for possible confounders. To examine the impact of nutritional intake on phosphate concentrations, structural nested mean models with propensity score and censoring models were used. RESULTS: A total of 1247 patients were eligible (618 early-PN, 629 late-PN). Early RFH occurred in 40 patients (3%) in total, significantly more in the early-PN group (n = 31, within-group occurrence 5%) than in the late-PN-group (n = 9, within-group occurrence 1%, p < 0.001). Patients who were older (OR 1.14 (95% CI 1.08; 1.21) per year added, p < 0.001) and who had a higher Pediatric Risk of Mortality (PIM3) score had a higher risk of developing early RFH (OR 1.36 (95% CI 1.15; 1.59) per unit added, p < 0.001), whereas patients in the late-PN group had a lower risk of early RFH (OR 0.24 (95% CI 0.10; 0.49), p < 0.001). Early RFH was significantly associated with a 56% longer PICU stay (p = 0.003) and 42% longer hospital stay (p = 0.007), but not with new infections (OR 2.01 (95% CI 0.90; 4.30), p = 0.08) or length of mechanical ventilatory support (OR 1.05 (95% CI -3.92; 6.03), p = 0.68), when adjusted for possible confounders. Increase of parenteral nutrition intake (in % kcal of predicted resting energy expenditure) decreased phosphate concentrations (c = -0.002 (95% CI -0.002; -0.001). CONCLUSIONS: Early RFH occurred in 3% of critically ill children. Patients randomized to late-PN had a lower chance of developing early RFH, which may be explained by the more gradual build-up of nutrition. As early RFH might impact recovery, it is important to closely monitor phosphate concentrations in patients, especially of those at risk for early RFH.

Hypophosphatemia: A Practical Guide to Evaluation and Management.

Phosphate plays a critical and diverse role in human physiology. In addition to its importance in skeletal mineralization, it is essential for energy homeostasis, enzyme function, and cell membrane integrity. These diverse functions of phosphate provide an explanation for the range of symptoms and clinical manifestations observed in patients with both acute and chronic causes of hypophosphatemia. Normal phosphate homeostasis involves several major systems, including the gastrointestinal tract, bones, and kidneys. Phosphate balance is maintained directly and indirectly by 1α,25-dihydroxyvitamin D3, parathyroid hormone, and the osteocyte-derived phosphatonin fibroblast growth factor 23. This review discusses normal phosphate homeostasis, the clinical manifestations and causes of hypophosphatemia, and an approach to establish a diagnosis and appropriate management.

Clinical Challenges in Diagnosis, Tumor Localization and Treatment of Tumor-Induced Osteomalacia: Outcome of a Retrospective Surveillance.

Tumor-induced osteomalacia (TIO) is an acquired fibroblast growth factor 23 (FGF23)-related hypophosphatemic osteomalacia caused by phosphaturic mesenchymal tumors (PMTs) developed in the bone or soft tissue. Diagnostic delay should be addressed, and ideal techniques to localize PMTs and efficient treatment options should be explored to improve the outcomes of this rare disease. To clarify the detailed clinical course and outcomes of TIO patients, retrospective questionnaire surveys were conducted among physicians from the Japanese Society for Bone and Mineral Research (JSBMR) and the Japan Endocrine Society (JES). The primary survey collected the number of TIO patients between January 2007 and December 2018. The secondary survey aimed to obtain the detailed characteristics, laboratory data, and outcomes. Eighty-eight patients (52 males, mean: 52 years old) were included, and 24 patients were clinically diagnosed with TIO without localized PMTs. The median duration from the onset to detection of high FGF23 levels was 3.4 years, with 77 patients being initially misdiagnosed. Among the methods used to detect small, localized PMTs (≤10 mm), fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography and somatostatin receptor scintigraphy were less sensitive than somatostatin receptor positron emission tomography/computed tomography (SRPET/CT). Systemic venous sampling (SVS) of FGF23 was performed in 53 patients; among them, SVS was considered useful for detecting localized PMTs in 45 patients with diverse tumor sizes. Finally, 45 patients achieved biochemical remission by surgery, 39 patients continued pharmaceutical treatment, including burosumab (11 patients), and four patients died. These results encouraged us to further increase the awareness of TIO and to improve the accessibility of SRPET/CT and SVS. Further evidence about the efficacy of new pharmaceutical treatments is awaited. © 2022 American Society for Bone and Mineral Research (ASBMR).

Hypophosphatemia Is Associated With Postoperative Morbidity After Cytoreductive Surgery and Heated Intraperitoneal Chemotherapy: A Retrospective Study.

INTRODUCTION: Hypophosphatemia following surgery is associated with a higher rate of postoperative complications; however, the significance of postoperative hypophosphatemia after cytoreductive surgery and heated intraperitoneal chemotherapy (CRS/HIPEC) is unknown. METHODS: A prospectively maintained database was queried for all patients who underwent CRS/HIPEC for any histology at the Mount Sinai Health System. The perioperative serum phosphate levels, postoperative complications, and comorbidities were compared between patients with or without major complications. RESULTS: From 2007 to 2018, 327 patients underwent CRS/HIPEC. Most of the patients had low phosphate levels on postoperative day (POD) 2, reaching a median nadir of 2.3 mg/dL on POD 3. Patients with major complications had significantly lower levels of serum phosphate on POD 5-7 compared with patients without complications, with median serum phosphate 2.2 mg/dL (IQR 1.9-2.4) versus 2.7 mg/dL, (IQR 2.3-3), P < 0.01. Hypophosphatemia on POD 5-7 was also more frequent in patients who developed an anastomotic leak, with median serum phosphate 2.2 mg/dL (IQR 1.9-2.6) versus 2.8 mg/dL (IQR 2.2-3.2), P = 0.001. On multivariate analysis, the number of organs resected at surgery, diaphragm resection, postoperative intensive care unit stay, and serum phosphate level <2.4 mg/dL on POD 5-7 were independently associated with a major complication after CRS/HIPEC. CONCLUSIONS: Following CRS/HIPEC, POD 5-7 hypophosphatemia is associated with severe postoperative complications and anastomotic leak.

Early high amino-acid intake is associated with hypophosphatemia in preterm infants.

OBJECTIVE: To estimate the incidence of hypophosphatemia in preterm infants according to parenteral nutrition received and to evaluate associated risk factors. DESIGN: A prospective multicenter cohort study included 111 patients ≤ 1250 g (7 NICUs of the NEOCOSUR Network). Two groups were compared according to the amino-acid supply in the first 48 h: aggressive parenteral group ≥ 3 g/kg/day and standard parenteral group: <2.9 g/kg/day. Hypophosphatemia was defined as serum phosphate < 4 mg/dl. A logistic regression analysis was performed to evaluate associated risk factors. RESULTS: Fifty-eight infants received aggressive parenteral nutrition. The incidence of hypophosphatemia was significantly higher in the aggressive parenteral group (77.5% vs 53.8%, p = 0.009). Hypophosphatemia was independently associated with aggressive parenteral nutrition (aOR 4.16 95% CI 1.54-12.24) and negatively associated with phosphorous intake (aOR 0.92 95% CI 0.87-0.97). CONCLUSION: Both high amino-acid intake and low phosphorus supply during the first days after birth were independently associated with hypophosphatemia.

[Strategy diagnostic and therapeutic of an hypophosphatemia]. / Stratégie diagnostique et thérapeutique d'une hypophosphatémie.

Hypophosphatemia is an electrolyte disorder frequently faced in inpatient and outpatient practice. Associated symptoms are very variable but are often nonspecific. The consequence is that it might be overlooked. Yet, when severe, hypophosphatemia is associated with a significant morbi-mortality and, therefore, needs to be identified and treated appropriately. Treatment goes from identifying the cause to substitution according to whether it is symptomatic or not and its severity. Mild to moderate hypophosphatemia needs substitution only when symptomatic which will be administrated orally, while severe hypophosphatemia requires an intravenous substitution. We review here situations at risk of hypophosphatemia, its clinical manifestations and its management in terms of diagnostic and treatment.

L'hypophosphatémie est un désordre électrolytique fréquemment rencontré, tant en milieu hospitalier qu'ambulatoire. Sa symptomatologie est très variable et souvent aspécifique. De ce fait, elle peut parfois être manquée. Pourtant, lorsque sévère, elle est grevée d'une morbimortalité non négligeable. Le traitement passe par l'identification de sa cause, puis une substitution en fonction de la présentation clinique et de sa sévérité. Une hypophosphatémie légère à modérée nécessite une supplémentation en cas de symptômes et sera administrée par voie orale, tandis qu'une hypophosphatémie sévère justifie une supplémentation intraveineuse. Cet article intègre un rappel du métabolisme du phosphate, les situations associées à un risque d'hypophosphatémie, ses manifestations cliniques et sa gestion tant sur le plan diagnostique que thérapeutique.

Cortisol and Phosphate Homeostasis: Cushing's Syndrome Is Associated With Reversible Hypophosphatemia.

Objectives: The influence of hypercortisolism on phosphate homeostasis is relatively unknown. A few previous studies have reported on patients with Cushing's syndrome (CS) with hypophosphatemia in whom serum phosphate normalized after initiation of treatment for CS. We aimed to investigate the prevalence of hypophosphatemia in CS, the association between the degree of hypercortisolism and serum phosphate and the change in serum phosphate after remission of CS. We compared the prevalence of hypophosphatemia in CS with the prevalence in the population-based Rotterdam Study (RS). Methods: Patients diagnosed with CS and treated at the Department of Endocrinology of Erasmus MC in the period of 2002-2020 were included and data was collected on age at diagnosis, sex, serum phosphate, calcium and potassium levels, kidney function and BMI. Using multivariate linear regression, we analyzed the association between 24h urinary free cortisol excretion (UFC) and serum phosphate. Changes in serum phosphate and covariates were tested with a repeated measurement ANOVA, using mean levels of laboratory values for the periods before remission, and 0-14 days and 15-180 days after remission. Results: Hypophosphatemia before treatment was present in 16% of the 99 CS patients with data on serum phosphate, 24h UFC and covariates. In comparison, the prevalence of hypophosphatemia in RS was 2.0-4.2%. Linear regression showed a negative association between the level of UFC and serum phosphate at diagnosis, which remained significant after adjusting for covariates [ß -0.002 (95%CI -0.004; -0.0004), p=0.021]. A subset of 24 patients had additional phosphate measurements at 0-14 days and 15-180 days after remission. In this subgroup, serum phosphate significantly increased from 1.03 ± 0.17 mmol/L prior to remission to 1.22 ± 0.25 mmol/L 15-180 days after remission (p = 0.008). BMI decreased after remission [-1.1 kg/m2, (95%CI -2.09 to -0.07), p=0.037]. Other covariates did not show an equivalent change over time. Conclusion: In this retrospective study, we found that 16% of patients with CS had hypophosphatemia. Moreover, serum phosphate was related to the level of cortisoluria and increased after remission of CS. Potential underlying mechanisms related to urinary phosphate excretion and possibly involving FGF23, BMI and parathyroid hormone levels should be further explored.

[Impact of hypophosphatemia on weaning from mechanical ventilation].

OBJECTIVE: To explore the influence of hypophosphatemia on weaning from mechanical ventilation. METHODS: An observational study was conducted. The medical records of 30 mechanical ventilated patients with hypophosphatemia admitted to intensive care unit of Sun Yat-sen Memorial Hospital of Sun Yat-sen University from January 2018 to August 2020 were analyzed; another 60 mechanical ventilated patients with normophosphatemia around the same time were enrolled as controls by 1:2 case-control matching based on gender, age, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score. And then the duration of invasive mechanical ventilation, times of spontaneous breathing trial (SBT), the diaphragmatic ultrasonography movement indexes, and outcome of weaning and prognosis during hospitalization were compared between the two groups. Receiver operator characteristic curve (ROC curve) was plotted to calculate the areas under ROC curve (AUC) and cut-off values of serum phosphorus for successful weaning and hospital survival. The correlations between the diaphragmatic ultrasonography movement indexes and serum phosphorus were analyzed by Pearson partial correlation analysis. RESULTS: Compared with normophosphatemic group, the duration of invasive mechanical ventilation in hypophosphatemia group was significantly longer [days: 13.0 (7.0, 22.0) vs. 10.0 (5.5, 14.0), P < 0.05], and SBT attempts were more often [times: 3 (0, 5) vs. 1 (1, 2), P < 0.01], while the rate of successful weaning was lower (53.3% vs. 91.7%, P < 0.01), and the hospital mortality was higher (20.0% vs. 1.7%, P < 0.01). ROC curve analysis showed that serum phosphorus could predict successful weaning of mechanical ventilated patients, the AUC was 0.795, and the optimum cut-off value of serum phosphorus was 0.85 mmol/L with sensitivity of 73.2% and specificity of 84.2%. Serum phosphorus could predict hospital survival of mechanical ventilated patients, the AUC was 0.782, and the optimum cut-off value of serum phosphorus was 0.48 mmol/L with sensitivity of 81.9% and specificity of 85.7%. Compared with normophosphatemic group, diaphragm thickness at the end of inspiration (DTei), diaphragm thickness at the end of expiration (DTee), diaphragm thickening fraction (DTF), diaphragm excursion (DE) in hypophosphatemia group were all significantly decreased [DTei (cm): 0.19±0.07 vs. 0.27±0.08, DTee (cm): 0.14±0.05 vs. 0.19±0.06, DTF: (33.55±16.17)% vs. (45.04±18.66)%, DE (cm): 1.17±0.49 vs. 2.28±0.69, all P < 0.01]. Pearson partial correlation analysis showed that linear correlations were found between serum phosphorus and DTei, DTee, DTF, DE (r values were 0.442, 0.351, 0.293, 0.628 respectively, all P < 0.01). CONCLUSIONS: Serum phosphorus may have correlation with the diaphragmatic ultrasonography movement indexes. Hypophosphatemia may impair the contractile properties of diaphragm, induce more SBT attempts and longer duration of invasive mechanical ventilation, and affect outcome of weaning and prognosis.

Role and knowledge of critical care nurses in the assessment and management of hypophosphataemia and refeeding syndrome. A descriptive exploratory study.

OBJECTIVE: To assess the perceived and actual role of critical care nurses in nutritional care, and their knowledge regarding the identification and management of hypophosphataemia and refeeding syndrome. DESIGN AND METHODS: Data were collected in one intensive care unit in Israel, from a self-administered questionnaire completed by 42 critical care nurses. The questionnaire was designed to assess their perceived and actual roles in the administration of nutritional care, and knowledge regarding electrolyte monitoring, hypophosphataemia and refeeding syndrome, including risk factors, consequences, and treatment. RESULTS: The majority participants that dieticians are solely responsible for nutrition care and follow-up. Most agreed that the measurement of phosphate levels was not important and that patients should receive full nutrition upon admission, while important risk factors for the development of refeeding syndrome were not recognised or considered. This informed their actual practice. A correlation was found between nurses' knowledge and their actual practice so that the greater the nurses' knowledge, the more they adhered to current nutrition guidelines (p < 0.05). CONCLUSIONS: This study revealed critical care nurses' lack of clarity of their role and lack of knowledge regarding nutrition care. We suggest that this complex task is best managed by a multidisciplinary team, including nurses and dieticians, with clear role definitions.

Challenges in the management of tumor-induced osteomalacia (TIO).

Tumor-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare acquired paraneoplastic disease, which is challenging to diagnose and treat. TIO is characterized by hypophosphatemia resulting from excess levels of tumor-secreted fibroblast growth factor 23 (FGF23), one of the key physiological regulators of phosphate metabolism. Elevated FGF23 results in renal phosphate wasting and compromised vitamin D activation, ultimately resulting in osteomalacia. Patients typically present with progressive and non-specific symptoms, including bone pain, multiple pathological fractures, and progressive muscle weakness. Diagnosis is often delayed or missed due to the non-specific nature of complaints and lack of disease awareness. Additionally, the disease-causing tumour is often difficult to detect and localize because they are often small, lack localizing symptoms and signs, and dwell in widely variable anatomical locations. Measuring serum/urine phosphate should be an inherent diagnostic component when assessing otherwise unexplained osteomalacia, fractures and weakness. In cases of hypophosphatemia with inappropriate (sustained) phosphaturia and inappropriately normal or frankly low 1,25-dihydroxy vitamin D, differentiation of the potential causes of renal phosphate wasting should include measurement of FGF23, and TIO should be considered. While patients experience severe disability without treatment, complete excision of the tumour is typically curative and results in a dramatic reversal of symptoms. Two additional key current unmet needs in optimizing TIO management are: (1 and 2) the considerable delay in diagnosis and consequent delay between the onset of symptoms and surgical resection; and (2) alternative management. These may be addressed by raising awareness of TIO, and taking into consideration the accessibility and variability of different healthcare infrastructures. By recognizing the challenges associated with the diagnosis and treatment of TIO and by applying a stepwise approach with clear clinical practice guidelines, patient care and outcomes will be improved in the future.

Association between phosphate disturbances and mortality among critically ill patients with sepsis or septic shock.

OBJECTIVE: The aim of this study is to examine the association of hypophosphatemia and hyperphosphatemia on the first day of ICU admission with mortality in septic critically ill patients. METHODS: In this retrospective cohort study, all adult patients who were admitted to the medical-surgical ICUs between 2014 and 2017 with sepsis or septic shock were categorized as having hypophosphatemia, normophosphatemia and hyperphosphatemia based on day 1 serum phosphate values. We compared the clinical characteristics and outcomes between the three groups. We used multivariate analysis to examine the association of hypophosphatemia and hyperphosphatemia with these outcomes. RESULTS: Of the 1422 patients enrolled in the study, 188 (13%) had hypophosphatemia, 865 (61%) normophosphatemia and 369 (26%) had hyperphosphatemia. The patients in the hyperphosphatemia group had significantly lower GCS, higher APACHE II scores, higher serum creatinine, increased use of vasopressors, and required more mechanical ventilation with lower PaO2/FiO2 ratio compared with the other two groups. In addition, the hyperphosphatemia group showed significantly higher ICU and hospital mortality in comparison with the other two groups. CONCLUSION: Hyperphosphatemia and not hypophosphatemia on the first ICU admission day was associated with an increase in the ICU and hospital mortality in septic critically ill patients.

Burden of disease and clinical targets in adult patients with X-linked hypophosphatemia. A comprehensive review.

X-linked hypophosphataemia (XLH) is a lifelong condition. Despite the mounting clinical evidence highlighting the long-term multi-organ sequelae of chronic phosphate wasting and consequent hypophosphatemia over the lifetime and the morbidities associated with adult age, XLH is still perceived as a paediatric disease. INTRODUCTION: Children who have XLH need to transition from paediatric to adult healthcare as young adults. While there is general agreement that all affected children should be treated (if the administration and tolerability of therapy can be adequately monitored), there is a lack of consensus regarding therapy in adults. METHODS: To provide guidance in both diagnosis and treatment of adult XLH patients and promote better provision of care for this potentially underserved group of patients, we review the available clinical evidence and discuss the current challenges underlying the transition from childhood to adulthood care to develop appropriate management and follow-up patterns in adult XLH patients. RESULTS AND CONCLUSIONS: Such a multi-systemic lifelong disease would demand that the multidisciplinary approach, successfully experienced in children, could be transitioned to adulthood care with an integration of specialized sub-disciplines to efficiently control musculoskeletal symptoms while optimizing patients' QoL. Overall, it would be desirable that transition to adulthood care could be a responsibility shared by the paediatric and adult XLH teams. Pharmacological management should require an adequate balance between the benefits derived from the treatment itself with complicated and long-term monitoring and the potential risks, as they may differ across age strata.

New onset adrenal insufficiency in a patient with COVID-19.

SARS-CoV-2 is the cause of COVID-19. Since the outbreak and rapid spread of COVID-19, it has been apparent that the disease is having multi-organ system involvement. Still its effect in the endocrine system is not fully clear and data on cortisol dynamics in patients with COVID-19 are not yet available. SARS-CoV-2 can knock down the host's cortisol stress response. Here we present a case of a 51-year-old man vomiting for 10 days after having confirmed COVID-19 infection. He had hypotension and significant hyponatraemia. Work-up was done including adrenocorticotropic hormone stimulation test. He was diagnosed as suffering from adrenal insufficiency and started on steroids with subsequent improvement in both blood pressure and sodium level. COVID-19 can cause adrenal insufficiency. Clinicians must be vigilant about the possibility of an underlying relative cortisol deficiency in patients with COVID-19.

Parenteral iron therapy and phosphorus homeostasis: A review.

Phosphorus has an essential role in cellular and extracellular metabolism; maintenance of normal phosphorus homeostasis is critical. Phosphorus homeostasis can be affected by diet and certain medications; some intravenous iron formulations can induce renal phosphate excretion and hypophosphatemia, likely through increasing serum concentrations of intact fibroblast growth factor 23. Case studies provide insights into two types of hypophosphatemia: acute symptomatic and chronic hypophosphatemia, while considering the role of pre-existing conditions and comorbidities, medications, and intravenous iron. This review examines phosphorus homeostasis and hypophosphatemia, with emphasis on effects of iron deficiency and iron replacement using intravenous iron formulations.