Suprava Patel, Puja Dhupar and Ashok Bhattar
Background: Nutritional deficiency, especially B12 deficiency is quite common in India. The manifestation can range from anemia usually megaloblastic anemia as an early indicator to neurological sequel that develops later. Evaluation of Mean Corpuscular Volume (MCV) as a screening parameter has been highly unreliable and misleading. This has resulted in delayed diagnosis with irreversible changes.
Aim: Our study aimed at evaluating the sensitivity, specificity and diagnostic accuracy of MCV in delineating vitamin B12 deficiency.
Methods: The study population consisted of 501 adolescent girls aged 10 to 18 years going to schools in the rural areas of the district. Pre-designed proforma comprising of required demographic profile and detail history were filled-up. The cut off value used for serum B12 was 200 pg/ml and that of MCV was 100 fL.
Findings: The prevalence of vitamin B12 deficiency in rural areas was found to be 58.58% in adolescent school going girls. The B12 deficient population depicted significant association with vegetarian diet (p<0.001) and BMI (p=0.005). The sensitivity and specificity of MCV to screen out B12 deficiency were calculated to be 10.14% and 92.82% respectively. Accuracy of MCV as an indicator for B12 deficiency was estimated to be 45.05%. From all the above data, the percentage of subjects missed to be diagnosed for B12 deficiency of all deficient subjects was calculated to be 89.86%.
Conclusion: The study revealed that almost every alternate adolescent girl was found to be B12 deficient. Raised MCV was found in only 1% cases and the sensitivity was very low. Hence, MCV should not be the screening criteria for B12 deficiency which might be misleading.
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