Clinical and Hematological Characteristics of Vitamin B12 Deficiency and Evaluation of the Therapeutic Response to Vitamin B12 Supplementation

Background Vitamin B12 deficiency, or cobalamin deficiency, is common among populations with low consumption of animal-based products, mainly in India, due to religious and socioeconomic factors, which significantly increase the deficiency rate. The condition has been characterized by a wide range of clinical and hematological symptoms, mainly affecting the blood and nervous system. This study aims to assess the clinical and hematological characteristics of patients with vitamin B12 deficiency and assess the therapeutic response to supplementation with vitamin B12. Methodology This two-year, in-hospital study was conducted at K. J. Somaiya Medical College and Hospital. The study involved 180 patients aged between 18 and 70 years with hemoglobin below 13 g/dL for males, less than 12 g/dL for females, and serum vitamin B12 levels below 250 pg/mL. Data on demographic and clinical characteristics of the patients, along with hematological parameters, including complete blood count, peripheral smear, reticulocyte count, and bone marrow examination, were collected. Each patient received six intramuscular injections per week of 1,000 µg of vitamin B12. The hematological parameters were measured at different follow-up intervals, and the therapeutic response was measured using the one-way analysis of variance. We employed Pearson's correlation coefficient to investigate the relationship between the severity of anemia and vitamin B12 level. Results The study showed a higher prevalence of male patients, accounting for 105 (58.3%) of the sample, with the majority of patients aged between 46 and 60 years, totaling 70 (38.9%). Common comorbidities included hypertension in 60 (33.3%) and diabetes in 45 (25%) patients. The most frequently reported symptom was fatigue, present in 120 (66.7%) patients, followed by neurological symptoms such as tingling and numbness in the extremities reported by 98 (54.4%) patients. Baseline hematological assessments indicated macrocytic anemia, with a mean hemoglobin level of 9.7 g/dL and an elevated mean corpuscular volume (MCV) of 104.7 fL. At the end of six weeks of vitamin B12 therapy, there were notable improvements, with hemoglobin levels rising to 12.6 g/dL, MCV decreasing to 91.3 fL, and reticulocyte count increasing to 2.1%. A strong positive correlation was observed between hemoglobin levels and serum vitamin B12 concentrations (r = 0.75, p < 0.001). Conclusions Vitamin B12 deficiency leads to clinical and hematological abnormalities, including macrocytic anemia and neurological symptoms. This study demonstrates that vitamin B12 supplementation effectively reverses these abnormalities, improving both hematological and neurological outcomes. Given the prevalence of deficiency, routine screening and supplementation are recommended, particularly for at-risk populations such as vegetarians and older adults. Further research is needed to assess the long-term effects of supplementation, particularly its potential role in reducing cardiovascular risk in individuals with vitamin B12 deficiency.