Table 1.

Characteristics of commercially available assays to measure FGF23 according to the package insert of the manufacturers and independently published assay variation

Name of the assay	Manufacturer	IVD/RUO	Automated	Detection	Antibodies	Detection limit	Highest measurable value	Sample volume	Sample recommended	Intra-assay CV	Inter-assay CV	Intra assay CV (literature)	Inter assay CV (literature)
Intact FGF 23 assays
Human FGF-23 intact	Quidel-Immutopics, San Clemente, California	RUO	NO	2 steps ELISA (HRP)	1 murine monoclonal antibody and 1 affinity purified goat polyclonal antibody	1.5 pg/mL	660 pg/mL	50 µL	Plasma, cell culture	< 4.1%	< 9.1%	< 6% [35], < 10% [27]	First generation: 22–61% [35]; 14–40%[69] Second generation: 5.2% [43], 25.5% at 31.6 ng/mL and 6.2% at 155.6 ng/mL[31], 6.9–19.2% [30]
FGF-23	Kainos, Tokyo, Japan	RUO	NO	2 steps ELISA (HRP)	2 murine monoclonal antibodies	3 pg/mL	800 pg/mL	50 µL	Serum is recommended. heparin and EDTA plasma may be used	< 3%	< 3.8%	< 10% [35], < 10%[27]	< 14% with manual washing step [35]
Human FGF-23	Merck Millipore, Burlington, MA, USA	RUO	NO	2 steps ELISA (HRP)	2 goat polyclonal antibodies	9.9 pg/mL	2400 pg/mL	50 µL	None recommended. Serum, plasma, adipocyte extract, cell culture	< 11%	< 11%	15% at 18 pg/mL [27]
Intact FGF23	Biomedica Medizinprodukte, Vienna, Austria	CE IVD	NO	1 step ELISA (HRP)	1 monoclonal recombinant anti-human GGF23 antibody and 1 monoclonal mouse anti-human FGF23 antibody	5.4 pg/mL	1600 pg/mL	50 µL	None recommended Plasma (EDTA, citrate, heparın), serum, urine, cell culture supernatant	< 6%	< 8%
MedFrontier intact FGF23	Minaris Medical, Tokyo, Japan	RUO	NO	CLEIA	2 mouse monoclonal antibodies	10 pg/mL	3000 pg/mL	20 µL	Serum	< 5%	< 5%
FGF23	USCN (Wuhan, China)	RUO	NO	ELISA (HRP)	“Antibodies specific to FGF23”	15.6 pg/mL	1000 pg/mL	100 µL	Serum, plasma, tissue homogenates, cell lysates, cell culture supernates and other biological fluids	< 10%	< 12%
Human FGF-23	Avira Bioscience, Santa Clara, CA, USA	RUO	NO	2 steps ELISA (HRP)	“recombinant human FGF-23 and antibodies raised against this protein”	15 pg/mL	2000 pg/mL	100 µL	More recommended. Serum, EDTA plasma	< 8%	< 12%
Human FGF23	LSBio, Seattle, WA, USA	RUO	NO	2 steps ELISA (HRP)	No information provided	15.6 pg/mL	1000 pg/mL	100 µL	None recommended. Serum, plasma	< 4%	< 6.4%
LIAISON® FGF 23	DiaSorin, Saluggia, Italy	CE IVD	YES	CLIA	3 monoclonal antibodies, 1 directed against the N-terminal portion of iFGF23, another, labeled with fluoresceine, directed against the C-terminal portion, and the 3rd one, bound with isoluminol, directed against fluoresceine	5 pg/mL	5000 pg/mL	150 µL	EDTA plasma	< 4%	< 8%		< 2.5% at 50 and 242 pg/mL) [31], 5.8–7.1% [30]
CL-JACK FGF23	Minaris Medical, Tokyo, Japan	IVD Japan*	YES*	CLEIA*	2 mouse monoclonal antibodies*	5 pg/mL*	10,000 pg/mL*	10 µL*	Serum*	< 10%*			< 3.5%[33]
C-terminal FGF 23 assays
MicroVue Human FGF-23 (C-term)	Quidel- Immutopics, San Clemente, California	RUO	NO	2 steps ELISA (HRP)	Two affinity purified goat polyclonal antibodies	1.5 RU/mL	1400 RU/mL	100 µL	Plasma or cell culture media	< 2.4%	< 4.7%	< 5%[35], < 10% [27]	First generation: < 16%[35], ~ 10% [69] Second generation: 7.2% [43]
FGF23 (C-terminal)	Biomedica Medizinprodukte, Vienna, Austria	CE IVD	NO	1 step ELISA (HRP)	1 polyclonal rabbit anti-human FGF23 and 1anti-human FGF23 antibody	0.08 pmol/ (0.6 pg/mL)	20 pmol/L (150.4 pg/mL)	50 µL	Serum, EDTA plasma, citrate plasma, heparin plasma	< 10%	< 12%
Human FGF 23 C-terminal peptide	Avira Bioscience, Santa Clara, California	RUO	NO	2 steps ELISA (HRP)		15 pg/mL	16,000 pg/mL	100 µL	More recommended. Serum, EDTA plasma	< 8%	< 12%

CLIA chemiluminescence immunoassay, CE IVD European Mark for In Vitro Diagnostic use in Diagnostic, RUO For research use only, not to be used for diagnostic purposes, ELISA Enzyme-Linked Immunosorbent Assay, HRP Horseradish peroxidase, CLEIA Chemiluminescence enzyme immunoassay, NP not provided, CV coefficient of variation

*Information only available in Japanese and freely translated