Discriminant Functions in the Diagnosis of Vitamin B12 Deficiency Anemia, the Value of RDW-SD: An Analytical Study
Journal Title: National Journal of Laboratory Medicine - Year 2017, Vol 6, Issue 1
Abstract
Introduction: Mean Corpuscular Volume (MCV) has been proposed as the most sensitive hematological indicator of vitamin B12 / folate deficiencies and it tends to increase in these patients even before hemoglobin levels decrease significantly. Also, there are reasonable questions as to whether discriminant functions are sufficiently accurate to warrant not ordering serum B12/folate levels and other standard tests to detect vitamin B12/folate deficiency. Aim: This study was done to evaluate the discriminant functions MCV (Mean Corpuscular Volume), RDW-CV (Red Cell Distribution Width-Co-efficient of variation) and RDW-SD (Red Cell Distribution Width-Standard Deviation) for their ability to detect vitamin B12 deficiency and related anemia in 100 cases. We were especially interested in determining the value of a recently introduced discriminant function, RDW-SD versus RDW-CV, since so far all the attention is being given to MCV as the earliest hematologic indicator of vitamin B12 deficiency. Materials and Methods: This was a retrospective analytical study. Total 100 patients with serum levels of vitamin B12<200 pg/mL, by Electrochemiluminescence assay (Cobas e 601, Roche diagnostics, North America) and who were evaluated for complete blood count and peripheral smear with normal serum iron profile. The hematological parameters such as hemoglobin, MCV, RDW-CV and RDW-SD were estimated by automated analyzer Sysmex XN-1000 (Sysmex America, Inc. in Lincolnshire, Illinois). Pearsons correlation was applied for calculating the correlation of hematological parameters. The p-value of less than 0.05 was considered statistically significant. Results: Out of 100 cases of vitamin B12 deficiency, elevated RDW-SD, RDW-CV and MCV were seen in 90%, 72% and 64% cases respectively. RDW –SD showed a strong negative correlation with serum vitamin B12 levels (p-value= 0.029) which is statistically significant (p<0.05). Whereas, RDW-CV showed a weak negative correlation with serum Vitamin B12 levels with a statistically insignificant p-value of 0.58 (p>0.05). RDW-SD, RDW-CV and MCV showed a sensitivity of 95%, 81% and 69.1% respectively for detection of anemia. Conclusion: RDW-SD is a useful discriminant function in conditions where MCV may be normal despite vitamin B12 deficiency. Standard blood reports for clinical use should include the RDW-CV and RDW-SD, in addition to MCV in diagnosis of suspected vitamin B12 deficiency
Authors and Affiliations
Rajalakshmi Birur Rajashekar, Sapna Patel, Praveen Kulkarni
Keywords
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- EP ID EP375862
- DOI 10.7860/NJLM/2017/24716:2185
- Views 131
- Downloads 0
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