Aim and objectives: To compare and evaluate the effect of sample type on vitamin D concentration in order to avoid multiple sample collection. Materials and methods: The study was conducted in a tertiary care hospital on 40 adult subjects whose samples were for both serum vitamin D and plasma parathyroid hormone (PTH). Leftover plasma sample was utilized for vitamin D analysis. Samples were analyzed on Advia Centaur XP from Siemens Healthineers. Bland–Altman analysis and regression equation were derived to evaluate the extent of agreement and conversion between sample types. Results and conclusion: Serum vitamin D is higher than plasma vitamin D (by 6.5 ng/mL), and it is more pronounced in samples with vitamin D greater than 20 ng/mL. Clinical significance: It is important that lab and clinicians should be aware of the comparably large preanalytical bias introduced by changing between serum and EDTA plasma sample for vitamin D analysis. This would impact patients who are serially monitored for vitamin D supplementation.
Van Schoor NM, Lips P. Worldwide vitamin D status. Best Pract Res Clin Endocrinol Metab 2011;25(4):671–680. DOI: 10.1016/j.beem.2011.06.007.
Mithal A, Wahl DA, Bonjour JP, et al. Global vitamin D status and determinants of hypovitaminosis D. Osteoporos Int 2009;20(11): 1807–1820. DOI: 10.1007/s00198-009-0954-6.
Van der Meer IM, Middelkoop BJ, Boeke AJ, et al. Prevalence of vitamin D deficiency among Turkish, Moroccan, Indian and Sub-Sahara African populations in Europe and their countries of origin: an overview. Osteoporos Int 2011;22(4):1009–1021. DOI: 10.1007/s00198-010-1279-1.
Ramakrishnan S, Bhansali A, Bhadada SK, et al. Vitamin D status and its seasonal variability in healthy young adults in an asian indian urban population. Endocr Pract 2011;17(2):185–191. DOI: 10.4158/EP10155.OR.
Marwaha RK, Tandon N, Garg MK, et al. Vitamin D status in healthy indians aged 50 years and above. J Assoc Physicians India 2011;59:706–709.
Institute of medicine (US) committee to review dietary reference intakes for vitamin D and calcium. In: Ross AC, Taylor CL, Yaktine AL. Dietary Reference Intakes for calcium and vitamin D. Washington (DC): National Academic Press (US); 2011. Available from: https://www.ncbi.nlm.nih.gov/books/NBK56070/doi:10.17226/13050.
Ritu G, Gupta A. Vitamin D deficiency in India: prevalence, causalities and interventions. Nutrients 2014;6(2):729–775. DOI: 10.3390/nu6020729.
Yu CL, Falk RT, Kimlin MG, et al. The impact of delayed blood centrifuging, choice of collection tube and type of assay on 25-hydroxyvitamin D concentration. Cancer Causes Control 2010;21(4):643–648. DOI: 10.1007/s10552-009-9485-x.
Colak A, Toprak B, Dogan N, et al. Effect of sample type, centrifugation and storage conditions on vitamin D concentration. Biochemica Medica 2013;23(3):321–325. DOI: 10.11613/BM.2013.039.
Holmes EW, Garbincius J, McKenna KM. Analytical variability among methods for the measurement of 25-hydroxyvitamin D. Still adding to the noise. Am J Clin Pathol 2013;140(4):550–560. DOI: 10.1309/AJCPU2SKW1TFKSWY.
Oddoze C, Lombard E, Portugal H. Stability study of 81 analytes in human whole blood, in serum and in plasma. Clinical Biochemistry 2012;45(6):464–469. DOI: 10.1016/j.clinbiochem.2012.01.012.
Rezayi M, Ghayour-Mobarhan M, Sany SBT, et al. A comparison of analytical methods for measuring concentrations of 25-hydroxy vitamin D in biological samples. Anal Methods 2018;10:5599–5612. DOI: 10.1039/C8AY02146E.
Ricos C, Alvarez V, Cava F, et al. Current databases on biologic variation:pros, cons and progress. Scand J Clin Lab Invest 1999;59(7):491–500. DOI: 10.1080/00365519950185229.