Biomedica Immunoassays

525 €

Contact us!

C-terminal FGF23 ELISA (BI-20702)

The Biomedica C-terminal FGF-23 ELISA quantitively measures human FGF-23 in serum and plasma samples. - Standardized quantification in pmol/l. - CE marked - approved for IVD use in EU.


Assay characteristics:

Cat.No.: BI-20702
Method: Sandwich ELISA, HRP/TMB, 12x8-well strips
Sample type:Serum, plasma (EDTA, hep, citrate)
Standard range:0-20 pmol/l (7 serum based standards)
Standard points:0/0.2/0.6/1.8/5/10/20 pmol/l
Control:2 serum based controls
Sample size:50 µl / well
Incubation time:20-24 h / 1 h / 30 min
Unit conversion:1 pg/ml = 0.133 pmol/l (MW: 7.52 kDa)

LOD: 0.08 pmol/l (0 pmol/l + 3 SD); LLOQ: 0.1 pmol/l

Intra-assay: 2 samples of known concentrations were tested 6 times within 1 kit lot by 1 operator.
Inter-assay: 2 samples of known concentrations were tested 10 times within 2 different kit lots by 4 different operators.

Intra-assay (n=6) Sample 1 Sample 2
Mean (pmol/l) 0.6 10.0
SD (pmol/l) 0.07 0.06
CV (%) 12 6
Inter-assay (n=10) Sample 1 Sample 2
Mean (pmol/l) 0.6 9.9
SD (pmol/l) 0.06 0.50
CV (%) 10 5

The recovery of FGF23 was evaluated by adding 2 concentrations of human recombinant C-terminal FGF23 (5 + 10 pmol/l) to different human sample matrices. 

Matrix Mean S/R [% ]
+5 pmol/l +10 pmol/l
Serum (n=13) 96 89
EDTA plasma (n=7) 97 94
Hep plasma (n=8) 101 92
Citrate plasma (n=7) 100 90

Dilution linearity:
Dilution linearity was assessed by serially diluting samples containing endogenous FGF23 with assay buffer.

Matrix Mean R of dilution steps [%]
1+1 1+3 1+7
Serum (n=9) 105 100 108
EDTA plasma (n=4) 103 103 106
Hep plasma (n=10) 107 106 104
Citrate plasma (n=5) 102 106 101

The assay measures both intact FGF23 and C-terminal FGF23. The assay recognizes endogenous (natural) and recombinant human FGF23.

This immunoassay is calibrated against recombinant human FGF23 (C-terminal) peptide.

Values from apparently healthy individuals:
Median serum (n=35): 0.8 pmol/l
Median EDTA plasma (n=22): 1.3 pmol/l
Median hep plasma (n=22): 1.2 pmol/l
Median citrate plasma (n=30): 1.4 pmol/l
It is recommended to establish the normal range for each laboratory.

Principle of the assay: 

Manual ELISAs - easily adaptable for automation! 

Back to top


Click link for:


Biomedica Analytical Service Quotation Form

Back to top


Click link for: 

BI-20702 FGF23 ELISA Validation Data (S/R, dilution linearity, precision, ...)

BI-20702 FGF23 ELISA Sample Stability Data

Back to top


FGF23 (fibroblast growth factor 23) is a 32-kDa protein with 251 amino acids that is proteolytically processed between arginine179 and serine180 to generate N-terminal and C-terminal fragments. FGF23 is mainly secreted by osteocytes and controls phosphate and 1,25(OH)2 vitamin D homeostasis.

Click link for: 


BI-20702 FGF23 ELISA Leaflet



CORRELATION DATA between different FGF23 assays


BI-20702 FGF23 ELISA Flyer in deutscher Sprache


Additional background information:

Alternative Names: FGF23, ADHR, FGFN, HPDR2, HYPF, PHPTC, fibroblast growth factor 23

Regarding the human FGF-23 gene:
Entrez/NCBI ID: 8074
Genecards: FGF23
OMIM: 605380

Regarding FGF-23's structure:
PDB: 2p39, 5w21

Expression pattern and disease relevance:
Protein Atlas: FGF23
Uniport ID: Q4GZV9
Pubmed references: NCBI 8074

Back to top


Click links to download: 

BI-20702 FGF23 ELISA Reference List

Oral iron supplementation with sodium ferrous citrate reduces the serum intact and cterminal fibroblast growth factor 23 levels of maintenance haemodialysis patients
Kazuomi Yamashita, Sonoo Mizuiri, Yoshiko Nishizawa, Shigemoto Kenichiro, Shigehiro Doi, and Takao Masaki
Nephrology (Carlton). 2017 Dec; 22(12): 947–953.
PMCID: PMC5725691

Study population: maintenance haemodialysis (MHD) patients (n=31)
Sample type:
Conclusion: “Short
term oral iron supplementation with sodium ferrous citrate replenished the iron stores and reduced the serum iFGF23 and cFGF23 levels of maintenance haemodialysis (MHD) patients with iron deficiency without affecting their serum phosphate, Ca, or iPTH levels.”

Fibroblast growth factor 23 in patients with acute dyspnea: Data from the Akershus Cardiac Examination (ACE) 2 Study.
Magnus Nakrem Lyngbakkena, Mohammad Osman Perveza, Jon Brynildsena, Marit Holmefjord Pedersena, Janne Sølvernesa, Geir Christensen, Arne Didrik Høisethb, Torbjørn Omland, Helge Røsjø.
Clin Biochem. 2017 Oct 24. pii: S0009-9120(17)30670-7.
PMID: 29074091

Study population: acute dyspnea patients (n=314)
Sample type:
“Circulating FGF23 concentrations provide incremental prognostic information to established risk indices in patients with acute dyspnea, but do not improve diagnostic accuracy over NT-proBNP measurements.”

Sex and Iron Modify Fibroblast Growth Factor 23 (FGF23) Concentration in 1-Year-Old Children.
Elisa Holmlund-Suila Maria Enlund-Cerullo Saara Valkama Helena Hauta-alus Jenni Rosendahl Otto Helve Timo Hytinantti Heli Viljakainen Sture Andersson Outi Mäkitie.
J Clin Endocrinol Metab. 2017 Dec 1;102(12):4526-4533.
PMID: 29029193

Study population: healthy term infants (n=721)
Sample type: Serum
Conclusion: “At 1 year of age, FGF23 status was different in girls and boys, with intact FGF23 concentrations higher in girls. […] The iron concentration was positively associated with intact FGF23 and was the strongest modifier of intact FGF23 […]. The association between iron and C-terminal FGF23 was inversely related […]”

Fibroblast Growth-factor 23 and Calcium-binding Proteins are not Associated with Chronic Itch in Patients on Haemodialysis
Thomas Mettang, Kevin Kunzmann, Heinz-Jürgen Roth and Elke Weisshaar
Acta Derm Venereol 2017; 97: 381–382
PMID: 27671605

Study population: haemodialysis patients with a chronic itch (CI, n=18), controls (n=18)
Sample type: Serum
Conclusion: “Serum levels of hsCRP of Fetuin A and MGP were significantly higher in patients with CI, but no significant differences were found between the 2 groups in serum-calcium, serum-phosphate, 25[OHD3 and FGF23.”

FGF23 and vitamin D metabolism in chronic kidney disease – mineral bone disorder.
Isabelle Piec, Allison Chipchase, Holly Nicholls, Christopher Washbourne, Jonathan Tang & William D. Fraser.
Bone Abstracts (2016) 5 P469.

Study population: CKD patient (n=74) and non-CKD controls (n=79)
Sample type: Serum
Conclusion: “cFGF23 is raised in patients with CKD as a compensatory response to hyperphosphatemia or phosphate overload. Due to 25(OH)D deficiency, patients with CKD develop secondary hyperparathyroidism which exacerbates bone loss bone disease. 24-hydroxylase, enzyme responsible for the catabolism of both 25(OH)D and 1,25(OH)2D, is rapidly induced by 1,25(OH)2D and FGF-23 and suppressed by parathyroid hormone (PTH). In CKD, net effects of declining renal function and rising FGF23 and PTH concentrations on vitamin D catabolism are not clear. We observed that 24,25(OH)2D3 concentrations are further suppressed in CKD patient with vitamin D deficiency, suggesting metabolism favours the production of biologically active 1,25(OH)2D.”

Serum FGF23 levels may not be associated with serum phosphate and 1,25-dihydroxyvitamin D levels in patients with Fanconi syndrome-induced hypophosphatemia
Shunsuke Goto, Hideki Fujii, Keiji Kono, Kentaro Watanabe, Kentaro Nakai and Shinichi Nishi
Clinical Kidney Journal, 2016, 9(5): 677–681
PMCID: PMC5036911

Study population: patients with Fanconi syndrome (n=4)
Sample type: Serum
“Serum intact and C-terminal FGF23 levels were extremely low. Although serum phosphate and 1,25-dihydroxyvitamin D levels improved to or above the normal range within 1 year of treatment with oral phosphate and
1,25-dihydroxyvitamin D, serum FGF23 levels remained low. Serum FGF23 levels in patients with Fanconi syndrome might be regulated by novel factors other than serum phosphate and 1,25-dihydroxyvitamin D levels.”

Isabelle Piec, Allison Chipchase, Holly Nicholls, Christopher Washbourne, Jonathan Tang, and William D. Fraser
Nephrol. Dial. Transplant., May 2016; 31: i460.

Study population: patients with primary hyperparathyroidism (n=89), healthy controls (n=45)
Sample type: Serum
Conclusion: “In CKD, net effects of declining renal function and rising FGF23 and PTH concentrations on vitamin D catabolism are not clear.”


Back to top