Vitamin D deficiency of a group - 15 pcnt to 48 pcnt (depends on tester used)

Harmonization of serum 25-hydroxycalciferol assay results from high-performance liquid chromatography, enzyme immunoassay, radioimmunoassay, and immunochemiluminescence systems: A multicenter study

Different results by 5 types of testers on 275 blood samples

    Roche reads 9 ng too high if take 10 mg of Biotin daily for a week

J Clin Lab Anal. 2017 Nov;31(6). doi: 10.1002/jcla.22117. Epub 2017 Feb 7.

Nikooyeh B1, Samiee SM2, Farzami MR2, Alavimajd H3, Zahedirad M1, Kalayi A1, Shariatzadeh N1, Boroumand N3, Golshekan E2, Gholamian Y2, Neyestani TR1.

1. Tests for Vitamin D category listing has items* This problem along with other problems with vitamin D testers have been documented by many studies * Greatly improved Vitamin D testing repeatability – May 2020* Problems with Vitamin D Testing – chapter – Aug 2019* How to compare Vitamin D measurements from multiple studies – July 2021* Big differences (~10 ng) in vitamin D test results, even when using the same type of tester – Aug 2015* * Huge differences in % deficient (< 30ng) depending on the tester used** * * * *Note: A, B, and C unable to detect/measure < 13 nmol (5 ng) * * 4 popular vitamin D testers gave very different results (no surprise) – June 2021* Percent who are Vitamin D Deficient: 6, 9, or 22 – depends on testing system – Oct 2014* No vitamin D test needed before supplementing (typically) – April 2014* Vitamin D tester falsely said half of hemodialysis patients had less than 30 ng – Jan 2013* Vitamin D measurements vary from the same blood sample – March 20141090 tests of the same blood sample on the same type of tester

BACKGROUND:

Remarkable disagreement among different systems of 25-hydroxy vitamin D 25(OH)D assay makes decision making for both clinical and community interventions very difficult. This study aimed to harmonize the results obtained from different 25(OH)D assay systems.

METHODS:

A total of 275 serum samples were analyzed for 25(OH)D using DIAsource-enzyme immunoassay (EIA), DIAsource-radioimmunoassay (RIA), Roche-electrochemiluminescence (ECL), Diasorin-chemiluminescent immunoassay (CLIA), and high-performance liquid chromatography (HPLC), as the reference method. Serum intact parathyroid hormone (iPTH) was also measured in all samples. Between-system agreement and harmonization were evaluated using Bland-Altman analysis, receiver operating characteristic (ROC), and regression analysis.

RESULTS:

Mean serum 25(OH)D concentrations and frequency distribution of vitamin D status showed a significant difference among the studied systems (P<.001 for both). Serum 25(OH)D assay results from all systems correlated with those from HPLC. As compared with HPLC, ECL showed a positive bias (+3.8 nmol/L), whereas CLIA had a negative bias (-11.9 nmol/L). Both EIA and RIA showed a more or less similar positive bias (8.0 and 8.1 nmol/L, respectively). Using serum iPTH-based 25(OH)D cutoff points, only ECL results became comparable to and without significant difference with HPLC. However, when system-specific cutoffs were defined based on HPLC results using regression equations, mean 25(OH)D and frequency distribution of vitamin D status were more harmonized compared with the other methods.

CONCLUSION:

Our findings showed that with adjustment of circulating 25(OH)D based on HPLC, frequency distribution of vitamin D status, as judged by different methods, can be well harmonized with no statistically significant inter-system difference.

PMID: 28169461 DOI: 10.1002/jcla.22117