Mechanistic Evaluation on Sorafenib Induced Hypophosphatemia.
CarcinomaRenal CellThe purpose of this study is to: To elucidate the mechanism involved in the sorafenib-induced hypophosphatemia and possible early effect of hypophosphatemia on bone mineral density A secondary objective to assess the effect sorafenib treatment on evaluate left ventricular function (LVEF) and Beta-type natriuretic peptide in plasma.
FGF-23 Suppressibility by Calcitonin
HypophosphatemiaIntroduction: Based on our experience with calcitonin as an FGF-23 suppressive agent in a patient with an FGF-23 producing tumor we hypothesize that calcitonin may be a physiologically important regulator of FGF-23 production and secretion in healthy humans. Aim: In this study we wish to examine the FGF-23 suppressive effects of calcitonin in healthy men. Study Design: placebo-controlled, cross-over study Method: All twelve subjects are examined on two occasions, once after exposure to placebo 1 ml NaCl 0.9% subcutaneously, and once following calcitonin 200 IU/ml subcutaneously On both occasions frequent bloodsampling will take place, out an indwelling catheter in de forearm vein. Sampling times: -15, 0, 60, 120, 240, 360, and 480 minutes Mealtimes: Calcium and Phosphate intake standardized on both occasions All samples are analyzed for FGF-23, using a C-terminal FGF-23 ELISA kit (Immunotopics, San Clemente, USA) that measures intact and C-terminal fragments of FGF-23, and one that measures only intact FGF-23 Samples obtained at T-15, T0, T240 and T480 are stored for later analysis of Ca, albumin, PO4, PTH, 25-OHD and 1,25-OHD Endpoint: A change of 25% in de serum FGF-23 levels in response to a single subcutaneous injection of calcitonin 200 IU.
Investigating a New Way of Giving Medicine to Newborn and Preterm Babies
HypophosphataemiaOsteopenia of PrematurityThere is a deficit in the number of 'age-appropriate' formulations available for the delivery of medicines to children. Liquid preparations are considered the 'gold standard' for delivering medicines to children however many of these are formulated using ingredients which can be toxic to children (e.g. preservatives, alcohols), particularly to neonatal babies (< 4 weeks old) who do not possess the metabolic processes and mature organ function of older children or adults. Rapidly dissolving oral thin films (OTFs) dissolve quickly in the saliva, releasing the active ingredient(s) without the need for chewing or water, making them ideally suited to patients who find it difficult to swallow other oral dosage forms such as tablets or capsules. The aim of this study is to demonstrate that OTFs can offer a safe and effective alternative for oral administration of phosphate supplements to neonatal infants for the treatment of hypophosphataemia and osteopenia of prematurity. It is hypothesised that this treatment will be equal to standard therapy using an oral solution. Babies born before 32 weeks gestational age are routinely supplemented with oral phosphate as soon as they have been established on oral feeds in order to prevent bone disorders such as osteopenia. Babies recruited to this study will be given phosphate supplementation as per NHS Greater Glasgow and Clyde guidelines. This single-centre cross-over study will take place in the intensive care and special care baby units at the Princess Royal Maternity in Glasgow. The investigators aim to recruit 20-30 babies and will use blood phosphate levels (obtained from routine sampling only) to evaluate treatment effect. Babies will be randomised to receive either OTFs or oral solution of potassium acid phosphate for 2 weeks followed by 2 weeks of the other therapy. The investigators hypothesise that OTF treatment will be equivalent to standard oral solution.
Using Different Doses of Active Vitamin D Combined With Neutral Phosphate in Children With X-linked...
X-linked HypophosphatemiaX-linked hypophosphatemia (XLH) is the most common form of heritable rickets. Current treatments include active vitamin D metabolites (e.g. calcitriol) and phosphate salts. There is no consistent weight-based dosing of calcitriol and phosphate now. The primary objective of this study is to establish the efficacy of different dose of calcitriol combined with neutral phosphate in children with XLH.
Burosumab in Children and Adolescents With X-linked Hypophosphatemia
Rare DiseasesX-linked HypophosphatemiaIn this prospective longitudinal cohort study we studied the efficacy and safety of burosumab in real-clinical practice for <13- and >13-years old children affected with X-linked hypophosphatemia. 57 children with XLH were switched from conventional treatment to burosumab. After 12 months we assessed the efficacy and safety of treatment with burosumab on the whole cohort and separately on the cohort of >13-years old adolescents.
FGF23 and Angiotensin-(1-7) in Hypophosphatemia (GAP)
HypophosphatemiaX-linked Hypophosphatemia2 moreHereditary hypophosphatemia encompasses rare genetic conditions characterized by renal phosphate wasting. Increased circulating levels of fibroblast growth factor 23 (FGF23), a key regulator of phosphorus metabolism, are critical to the pathophysiology of these diseases, most notably in X-linked hypophosphatemia (XLH). Increased FGF23 induces hypertrophy and scarring in the heart in part via stimulating the traditional renin-angiotensin system (RAS) pathway, angiotensin-converting enzyme (ACE)/angiotensin (Ang ll), particularly in patients with chronic kidney disease, but the effect of FGF23 on the heart in patients with FGF23-related hypophosphatemic diseases is unknown. In addition, the relationship between FGF23 and the angiotensin-converting enzyme 2 (ACE2)/angiotensin-(1-7) (Ang-(1-7) pathway of the RAS is unknown. The objective of this study is to describe the relationship between FGF23, which causes low phosphorus levels, and components of the RAS in the blood and urine to help the investigators understand why the disease occurs and how to better treat it. Subjects will be identified by querying the Electronic Medical Record according to medical diagnosis. Thirty subjects, 2-24 years of age, will be recruited from the tertiary care Pediatric Endocrinology and Pediatric Nephrology clinics at Brenner Children's Hospital. Inclusion criteria include a confirmed diagnosis of hereditary FGF23-related hypophosphatemia. Clinical data will be obtained from the Electronic Medical Record. Each subject will undergo study assessments at baseline, 6 months and 1 year that include blood work, an echocardiogram, and blood pressure measurements. The primary hypothesis is that subjects with higher Ang-(1-7) levels have lower rates of cardiac hypertrophy and thus are protected against high FGF23 levels. The secondary hypothesis is that subjects with higher Ang-(1-7) levels have lower systolic blood pressure.
Study of the Inappropriate Secretion of FGF23 in Patients Followed in Hospital in a Context of Hypophosphatemia...
Hypophosphatemia Without Immediate AnteriorityUnexplained HypophosphatemiaThe discovery of FGF23, the missing link in the long researched and finally found phosphate metabolism, marked a turning point in the understanding and physiopathology of specific hypophosphatemia. By inhibiting the renal reabsorption of phosphate and the production of calcitriol, FGF23 behaves like a hypophosphatemia hormone. Hypersecretion of FGF23 can occur in the case of genetic abnormalities (X-linked hypophosphatemic vitamin-resistant rickets, recessive or dominant hypophosphatemic rickets, McCune-Albright syndrome ...) or acquired abnormalities (oncogenic osteomalacia). Oncogenic osteomalacia can be induced by hyperproduction of FGF23 by benign tumours of mesenchymal origin. But more recently, several cases of malignant tumours secreting FGF23 have also been described (prostate, colon, breast, ovarian and lung cancers, pulmonary carcinoma, etc.)
Retrospective and Prospective Disease Progression and Quality of Life in XLH
X-linked Hypophosphatemia (XLH)There is limited empirical data documenting disease progression and impact on quality of life for patients with X-linked hypophosphatemia (XLH). This study seeks to investigate the impact of XLH in adults living in the UK retrospectively and prospectively over a 12 month period, using qualitative interviews, SEIQoL-DW, EQ-5D-5L, SF36 quality of life tools. XLH is a rare, genetic, chronically debilitating and deforming condition (www.nice.org.uk/guidance/HST8). XLH is characterised by renal phosphate wasting, hypophosphatemia and defective bone mineralisation. The incidence of XLH is reported to be between 1:20,000 and 1:25,000 live births. In the UK, it is estimated that there are around 250 paediatric XLH patients and around 2,500 adult XLH patients (Delmestri,et al [Unpublished report]2018). The clinical phenotype of XLH is varied amongst patients, even among affected members of the same family. This can range from no signs or symptoms, slow growth in children, short stature, bone abnormalities that can affect movement and result in pain, bowed legs and knocked knees (where lower legs are positioned at an outward angle), tooth abscesses and excessive dental caries and hearing loss (adult patients only). This study will recruit 36 adults living with XLH, who are aged 28 years or over and living in the UK. The study will be advertised by the Sponsor and funder Medialis Ltd and via the patient organisation Metabolic Support UK. All study activities will take place via tele-visits and online questionnaires. The study will last approximately 2 years, allowing for one-year recruitment and a further 12 months to conduct all study visits.
Examining the Effect of Burosumab on Muscle Function
X-linked HypophosphatemiaPatients with X-linked hypophosphatemia (XLH) often report symptoms of fatigue and weakness particularly after exertion, in addition to their skeletal complaints. In previous trials using KRN23 (same drug as burosumab/Crysvita®), patients report these symptoms improve. The investigators wish to test this hypothesis directly by measuring muscle energy when patients begin treatment with Crysvita® for the first time.
X-linked Hypophosphatemia and FGF21
X-linked HypophosphatemiaFibroblast Growth Factor 23 and Fibroblast Growth Factor 21 are two endocrine Fibroblast Growth Factors, requiring Klotho as a co-factor to promote their systemic actions. Fibroblast Growth Factor 21 is involved in the regulation of glucid and lipid metabolism. Fibroblast Growth Factor 21 Knock Out mice display obesity and hyperglycemia. In investigators experience, patients with X-linked hypophosphatemia often present with early-onset over-weight that could be partly explained by decreased physical activity because of bone pains and deformations after puberty; however, patients usually display progressive over-weight earlier in life, when there is no limitation of physical activity yet. To the knowledge of investigators the association between Fibroblast Growth Factor 23, Fibroblast Growth Factor 21 and Klotho in patients with X-linked hypophosphatemia has never been evaluated. Thus, the main objective of this study is to evaluate the glucid and lipid metabolism in patients with X-linked hypophosphatemia, the main working hypothesis being that the genetic deregulation in the Fibroblast Growth Factor 23 axis in patients with X-linked hypophosphatemia induces modifications of Klotho levels (namely decreased levels) that in turn will deregulate the Fibroblast Growth Factor 21 axis (resistance to Fibroblast Growth Factor 21 because of decreased Klotho levels).