Four automated 25-OH total vitamin D immunoassays and commercial liquid chromatography tandem-mass spectrometry in Finnish population
Comparative Study Clin Lab . 2013;59(3-4):397-405. doi: 10.7754/clin.lab.2012.120527.
Marja-Kaisa Koivula 1, Nina Matinlassi, Päivi Laitinen, Juha Risteli
Worst case differences for 8 Finns
- In adddition, there are differences between tests made on the same brand of tester and even the identical tester
- VitaminDWiki concluded years ago that +- 5 nanograms difference in test results had no significance.
- Sometimes there can be a 40 nanogram difference between testers for the same blood sample
Tests for Vitamin D contains the following overview/opinion
- Fact: Many countries no longer pay for more than 1 (some not pay for even a single Vit D test)
They feel that Vit D testing is not needed except for a few conditions (Rickets, etc) Japan is an exception
- Fact: Vit D tests are not very accurate
The best lab tests have accuracies and repeatabilities of +-5 ng
Many lab tests have accuracies and repeatabilities of +- 10 ng - or worse
Vitamin D deficiency of a group - 15% to 48%
- Fact: Low-cost office/home Vit D tests are available around the world (not US as of 2018)
Low-cost 35 ng Y/N test by Nanospeed
Low-cost Vitamin D testers (about 13 dollars in quantity) – Feb 2018 Nanospeed
Quick, free, self test for deficiency
- Fact: 3 major Vit D gene problems are not noticed by Vit D tests
~ 20% of people have poor Vit D genes
Hint that Vit D not getting to cells: Vit D related diseases run in your family
Another hint - you have one of the 40 diseases which are 2X more likely if have poor genes
- Fact: A Vit D test will rarely (<1 in 1000) indicate that you are getting too much
- Opinion: If only getting a single test, wait till after supplementing with Vit D
3 months after starting a maintenance dose or 4 weeks after a loading dose
- Percent who are Vitamin D Deficient: 6, 9, or 22 – depends on testing system – Oct 2014
- Technical comparison of vitamin D testers – July 2013
- Vitamin D tester falsely said half of hemodialysis patients had less than 30 ng – Jan 2013
- Low cost vitamin D Blood Tests
- Problems with Vitamin D Testing – chapter – Aug 2019
Vitamin D measurements vary with the same sample of blood – March 2014 has the following
Background: Comparing four fully automated 25-OH-D immunoassays to a commercially available liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with human serum samples from Finnish population.
Methods: 400 samples were analyzed with the Liaison Total Vitamin D, the IDS-iSYS 25-Hydroxy Vitamin D, the ARCHITECT 25-OH Vitamin D, the ADVIA Centaur Vitamin D Total, and a commercially available LC-MS/MS 25-OH D (PerkinElmer) method.
Results: The Liaison method mean value (95% confidence intervals) was 65.6 nmol/L (62.6 - 68.6); the IDS-iSYS mean was 70.3 nmol/L (67.4 - 73.1); the ARCHITECT mean was 69.0 nmol/L (65.5 - 72.5); ADVIA Centaur mean was 71.6 nmol/L (68.9 - 74.3), and the LC-MS/MS mean was 82.8 nmol/L (79.4 - 86.2). The regression coefficients (r) between the LC-MS/MS and immunoassays were 0.650 for Liaison, 0.757 for IDS-iSYS, 0.721 for ARCHITECT and 0.684 for ADVIA Centaur. With the Passing-Bablok analysis, none of the immunoassays gave results equivalent to LC-MS/MS. Two of the four automated 25-OH-vitamin D assays (IDS-iSYS, ADVIA Centaur) were overall in good clinical agreement with LC-MS/MS, even though the results obtained with all compared methods were not equivalent.
Conclusions: In conclusion, in routine clinical laboratory both immunoassays and LC-MS/MS are useful for measuring 25-OH-vitamin D provided that these methods are correctly standardized and especially sample pretreatment is carefully performed.