Clinical performance of a new intact FGF23 immunoassay in healthy individuals and patients with chronic hypophosphatemia

Katô, Hajime; Miyazaki, Hiromi; Kimura, Takehide; Hoshino, Yoshitomo; Hidaka, Naoko; Koga, Minoru; Nangaku, Masaomi; Makita, Noriko; Ito, Nobuaki

doi:10.1016/j.bonr.2023.101659

Cited by 4 publications

(4 citation statements)

References 41 publications

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“…The Kainos and MedFrontier assays were reported to use the same primary anti-FGF-23 antibodies with different secondary antibodies. 35 Validation of the MedFrontier assay was presented in the study by Miyakawa et al 32 Information about the antibodies used in the MyBioSource and Deyihengda kits was not available. Assay validation for the Deyihengda assay was published in the study by Lin et al 28 At the time of writing, there was no published validation of the MyBioSource assay but information on the precision of the assay was available from the manufacturer.…”

Section: Resultsmentioning

confidence: 99%

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Blood fibroblast growth factor 23 concentration in cats with and without chronic kidney disease: a scoping review

Summers,

Michael,

Szlosek

et al. 2024

Journal of Feline Medicine and Surgery

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Objectives This study undertook a scoping review of research on blood fibroblast growth factor 23 (FGF-23) concentrations in healthy non-azotemic cats and cats with chronic kidney disease (CKD) to describe the volume and nature of existing literature, to determine whether published studies provide adequate evidence to support the use of FGF-23 as a biomarker in clinical practice and to identify any existing gaps in knowledge. Methods PRISMA Extension for Scoping Reviews guidelines were used to design and perform the scoping review. Online databases were used to identify observational and clinical studies of blood FGF-23 concentrations in healthy cats and cats with CKD published before December 2022. Study and population characteristics and descriptive data on FGF-23 concentrations were extracted. Results A total of 205 publications were reviewed; 17 were retained for inclusion. Most studies were retrospective. Most studies included cats with International Renal Interest Society stage 2–4 CKD, with some variation. Key concepts explored in the literature include FGF-23 concentrations by CKD stage, effect of dietary phosphate restriction on FGF-23 concentrations, relationship between FGF-23 concentrations and blood phosphorus, calcium and magnesium concentrations, and FGF-23 concentrations in cats with progressive CKD. FGF-23 concentrations tended to be higher in cats with CKD compared with healthy cats, with an overlap between healthy and CKD populations, and there was significant variation within stages of CKD. Conclusions and relevance FGF-23 is a biomarker of interest for the management and monitoring of phosphate overload in cats. Studies support several potential clinical applications for measuring FGF-23 concentration in practice; however, evidence is limited. Research on FGF-23 in cats with CKD would benefit from longitudinal, prospective studies that standardize CKD diagnosis and categorize cats by stage using current guidelines. Studies should include cats with early-stage, non-azotemic CKD and use commercially available assays so such results are comparable across studies.

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Section: Resultsmentioning

confidence: 99%

“…36 Studies comparing FGF-23 concentration measurements between manufacturers in human and feline samples have found assay-based differences that preclude direct comparison across methodologies. 35 , 37 Therefore, FGF-23 concentrations were not compared across the different kit manufacturers in this study.…”

Section: Resultsmentioning

confidence: 99%

Blood fibroblast growth factor 23 concentration in cats with and without chronic kidney disease: a scoping review

Summers,

Michael,

Szlosek

et al. 2024

Journal of Feline Medicine and Surgery

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“…Intact FGF-23 concentrations were determined by SRL (Tokyo, Japan) using sandwich ELISA kits (Determinar CL FGF23 [Minaris Medical Corporation, Tokyo, Japan]). The intra-assay coefficients of variation (CVs,%) of this measurement were 0.3–6.4, while the inter-assay CVs (%) were 1.9–3.5 [ 17 ]. Lumbar spine densitometry revealed a reduced bone mineral density (mean L2–L4 level, 0.567g/m 2 ; T-score, −4.0).…”

Section: Case Reportmentioning

confidence: 99%

Successful Superficial Blood Sampling to Localize a Fibroblast Growth Factor-23-Producing Tumor

Rikitake,

Ashida,

Nagayama

et al. 2024

Am J Case Rep

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Patient: Male, 64-year-old Final Diagnosis: Tumor-induced osteomalacia Symptoms: Arthralgia • bone fractures • bone pain • gait disturbance Clinical Procedure: — Specialty: Endocrinology and Metabolic • Oncology • Orthopedics and Traumatology Objective: Rare disease Background: Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome caused by aberrant fibroblast growth factor-23 (FGF-23)-producing tumors. Early surgical resection is the optimal strategy for preventing TIO progression. Thus, tumor localization is a priority for successful treatment. A simple and safe examination method to identify functional endocrine tumors is essential to achieve better outcomes in patients with TIO. Case Report: A 64-year-old Japanese man with recurrent fractures, hypophosphatemia, and elevated alkaline phosphatase and FGF-23 levels (109 pg/mL) was admitted to our university hospital and was diagnosed with FGF23-related hypophosphatemic osteomalacia. Notably, the superficial dorsal vein in the patient’s left foot exhibited a high FGF-23 level (7510 pg/mL). Octreotide and 18 F-fluorodeoxyglucose (FDG) scintigraphy and systemic venous sampling revealed that the tumor in the third basal phalanx of the left foot was responsible for FGF-23 overproduction. Tumor resection resulted in a rapid decrease in serum FGF-23 levels and an increase in serum phosphorus levels. Conclusions: Octreotide scintigraphy, FDG-positron emission tomography, and systemic venous sampling are the standard methods for localizing functional endocrine tumors. However, the limited availability and invasive nature of these examinations hinder effective treatment. Here, we highlight the importance of peripheral superficial blood sampling as an alternative to conventional systemic methods for confirming the presence of FGF-23-producing tumors. Clinicians should consider TIO as a potential cause of acquired hypophosphatemic osteomalacia. Furthermore, peripheral superficial vein blood sampling may be useful for confirming the localization of FGF-23-producing tumors.

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“…However, FGF23 measurement for patients with hypophosphatemia is not clinically approved in many countries including those in Europe and North America. On the other hand, an automated chemiluminescent enzyme immunoassay (CLEIA) for biologically active full-length FGF23 has been approved for the diagnosis of patients with FGF23-related hypophosphatemic disorders in Japan [6,7].…”

Section: Introductionmentioning

confidence: 99%

Recent advances in fibroblast growth factor 23-related hypophosphatemic disorders

Takashi,

Kawanami,

Fukumoto

2024

Current Opinion in Endocrinology, Diabetes &Amp; Obesity

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Purpose of review Fibroblast growth factor 23 (FGF23) is a hormone to reduce blood phosphate concentration. Excessive actions of FGF23 induce FGF23-related hypophosphatemic disorders, such as X-linked hypophosphatemic rickets (XLH) and tumor-induced osteomalacia (TIO). We will summarize recent advances in the diagnosis and treatment of FGF23-related hypophosphatemic disorders. Recent findings The measurement of blood FGF23 is useful to make a diagnosis of FGF23-related hypophosphatemic disorders. It was reported that many patients with FGF23-related hypophosphatemic disorders, especially TIO, were misdiagnosed, therefore, it is necessary to enhance the awareness of these diseases. A novel method to inhibit excessive actions of FGF23 by a human monoclonal antibody for FGF23, burosumab, has been approved in several countries. In more long-term observation than clinical trials, burosumab has also been shown to improve biochemical abnormalities and symptoms of rickets/osteomalacia. Following these advances, several registries and consensus recommendations on FGF23-related hypophosphatemic disorders, especially XLH, have been established in each country or region. Summary Further long-term effects of burosumab and the precise mechanism of FGF23 overproduction in patients with FGF23-related hypophosphatemic disorders need to be clarified in the future studies.

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Clinical performance of a new intact FGF23 immunoassay in healthy individuals and patients with chronic hypophosphatemia

Cited by 4 publications

References 41 publications

Blood fibroblast growth factor 23 concentration in cats with and without chronic kidney disease: a scoping review

Blood fibroblast growth factor 23 concentration in cats with and without chronic kidney disease: a scoping review

Successful Superficial Blood Sampling to Localize a Fibroblast Growth Factor-23-Producing Tumor

Recent advances in fibroblast growth factor 23-related hypophosphatemic disorders

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