PT  - JOURNAL ARTICLE
AU  - Sadat-Ali, Mir
AU  - Al-Elq, Abdulmohsen H.
AU  - Al-Shaikh, Iman H.
AU  - Al-Turki, Haifa A.
AU  - Al-Ali, Amein K.
AU  - Al-Othman, Abdallah A.
TI  - Assessment of low vitamin D among Saudi Arabians. Did we overshoot the runway?
DP  - 2014 Oct 01
TA  - Saudi Medical Journal
PG  - 1243--1249
VI  - 35
IP  - 10
4099  - http://smj.org.sa/content/35/10/1243.short
4100  - http://smj.org.sa/content/35/10/1243.full
SO  - Saudi Med J2014 Oct 01; 35
AB  - OBJECTIVES: To compare the performance of 3 commonly used 25-hydroxyvitamin D (25-OHD) assays among a sample of the Saudi population.METHODS: This cross-sectional study was carried out between January 2011 and December 2012 at King Fahd Hospital of the University, Al-Khobar, Saudi Arabia. After informed consent, blood samples for measurement of 25-OHD level was extracted from 200 adults. The vitamin D level of each individual were determined using chemiluminescence immunoassay (CLIA), radio-immuno assay (RIA), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. Assays were also compared through commonly used cut-points for classification of vitamin D deficiency. Bias between assays was evaluated using Bland-Altman plots.RESULTS: The average age of patients was 45.7+/-16.1 years. A significant difference between the assays was found. The mean 25-OHD levels were highest for the LC-MS/MS (21.65 ng/mL, 95% CI 19.74-23.56), intermediate for RIA (16.607 ng/mL, 95% CI 14.87-18.32), and lowest for CLIA method (13.864 ng/mL, 95% CI 12.109-15.618). Using 30 ng/mL as a cutoff value, only 6% was found to have normal levels of 25-OHD using CLIA, 9% using RIA, and 22% using LC-MS/MS.CONCLUSION: Levels of 25-OHD and the prevalence of vitamin D deficiency are dependent on the assay used. The reported high prevalence of hypovitaminosis D among the Saudi population can be partially explained by the use of assays that underestimate vitamin D levels.