Sir,This is in reference to the article, “A Study of Clinical Profile of Vitamin B12 Deficiency with Special Reference to Dermatologic Manifestations in a Tertiary Care Hospital in Sub-Himalayan Bengal” published in Indian J Dermatol 2015;60:419.[1]The authors have done a commendable job to know the clinical profile of Vitamin B12 deficiency in this region and to find out if there is any relationship between dermatologic manifestations with Vitamin B12 deficiency.However, I have a few concerns regarding the methodology being adopted in the present study.The authors have titled their study as Clinical Profile of “Vitamin B12 Deficiency.”In the material and methods, the authors have written that the inclusion criteria for the study were symptomatic anemiapatients requiring hospital admission with one or more laboratory investigations which were mean corpuscular volume (MCV), hemoglobin, white blood cells count, and platelet count.The diagnostic criterion for Vitamin B12 deficiency has not been taken robustly. The authors have based the diagnosis of Vitamin B12 deficiency on MCV only, but MCV is altered in a number of conditions and is not diagnostic of Vitamin B12 deficiency. Serum B12 levels are usually advised by clinicians (as the authors have later mentioned in their results) but even total serum Vitamin B12 is a late, relatively insensitive and unspecific biomarker of deficiency.Holotranscobalamin (holoTC), also known as active B12, is the earliest laboratory parameter for B12 deficiency, while methylmalonic acid (MMA) is a functional B12 marker that will increase when the B12 stores are depleted. Isolated lowering of holoTC shows B12 depletion (negative B12 balance), while lowered holoTC plus elevated MMA and homocysteine indicates a metabolically manifest B12 deficiency, although there still may be no clinical symptoms.[2]Further, the authors mentioned to have excluded those already on Vitamin B12 supplementations. It seems unjustifiable to exclude the patients on Vitamin B12 supplementations as a hematologic response to Vitamin B12 supplementation is not predictable.[3] The readers would have been benefitted, if the authors had cleared on the duration for which the patients were taking Vitamin B12 supplements and they should also have done the serum B12 levels in these patients, if not the above-mentioned tests.Further the authors have stated this study to be the prospective observational study but as is clear from the methodology adopted later, this is a basic cross-sectional study (prevalence study) as it is an observational study in which exposure and disease are determined at the same point in time in a given population whereas the hallmark of the prospective study is the follow-up of patients which is not done in the present study.