Cross-reactivity of 25-hydroxyvitamin D2 in ADVIA centaur vitamin D assay

A. Fortunato; E. Cavalier

Background: Vitamin D3 is the common supplemented form, vitamin D2 is often provided as prescribed supplement in many countries, such as the USA. In these countries, measuring 25(OH)D in patients treated with vitamin D2 using an assay that measures 25(OH)D2 poorly may confound clinical care. Recently, the ADVIA Centaur vitamin D assay has been commercialized for use in the clinical laboratory. We evaluated the assay’s ability of measuring both 25(OH)D2 and 25(OH)D3 and compared the results to established automated and a LC-MS/MS method.

Methods: Adult volunteers, who gave informed consent, took orally 3000 IU vitamin D3 [D3], 3000 IU vitamin D2 [D2], or 1500 IU vitamin D2 plus 1500 IU vitamin D3 [D3+D2] daily for 3 months. Blood was obtained, processed, divided into aliquots, and stored at −20 °C until measurement. The Total 25(OH)D levels were measured with LC–MS/MS, DiaSorin Liaison, IDS-iSYS, and the Siemens ADVIA Centaur Total vitamin D immunoassays (Old and New calibration).

Results: In no supplementation subjects (n=10), the immunoassay values were similar to the LC/MS–MS. In D3 (n=9), the immunoassays were higher than LC/MS–MS. In D2 (n=8), Liaison (Mean + SD) (31.3+8.3) and IDS- iSYS (31.6+7.2) were similar to LC-MS/MS (35.3+8.8). The Centaur (Old and New) produced higher values: 52.7+21.1 ng/ml and 51.4+19.9 ng/ml. In D3+D2 group (n=3), we obtained 81.1+39.8 ng/ml (Centaur Old), 75.8+32.6 ng/ml (Centaur New). The LC–MS/MS, Liaison, and IDS-iSYS were: 52.1+13.0, 50.7+11.1, and 56.7+16.7, respectively.

Conclusions: The IDS-iSYS and Liaison 25-OH vitamin D results confirmed their D3 and D2 co-specificity. The elevated results in D2 and D3+D2 supplemented subjects suggested the Centaur method might significantly overestimated 25(OH)D level in patients treated with vitamin D2.

Table 1 Total 25(OH) D Level (ng/ml)
	Vitamin D supplementation type
	Vitamin D2			Vitamin D3			Vitamin D2 and Vitamin D3			None
25(OH)D Method	N	Mean	S.D	N	Mean	S.D	N	Mean	S.D	N	Mean	S.D
LCMS/MS	8	35.3	8.8	9	48.2	13.3	3	52.1	13.0	10	21.0	11.1
Liaison	8	31.6	7.2	9	60.8	18.8	3	50.7	11.1	10	22.0	10.3
IDS-iSYS	8	31.3	8.3	9	54.8	19.2	3	56.7	16.7	10	20.1	10.6
Centaur Old	8	52.7	21.1	9	59.4	20.2	3	81.1	39.8	10	21.2	9.1
Centaur New	8	51.4	19.9	9	62.3	20.9	3	75.8	32.6	10	21.2	8.8

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Endocrine Abstracts

P242