Background. Nutritional vitamin B12 (VB ₁₂ ) deficiency is characterized by anemia, the inability to gain weight, delay or decline in development. Children of mothers with VB ₁₂ deficiency have a risk of nutritional VB ₁₂ deficiency. Prevention and early treatment are necessary to prevent irreversible neurological damage. We aimed to conduct a retrospective study to understand the characteristics of patients with VB ₁₂ deficiency.

Methods. Our study included patients admitted to Başkent University Faculty of Medicine Pediatric Hematology outpatient clinic between January 2015 - February 2020 for VB ₁₂ deficiency. Their clinical and laboratory characteristics were retrospectively examined through the hospital automation system.

Results. Vitamin B12 deficiency was detected in 129 of the 3198 patients; 100 of them were followed regularly. The mean age at admission of our patients was 10 ± 12 months (1 month - 7.5 years); 98% of these children were aged 0-2 years. The mean VB ₁₂ level of our patients was 171.63 ± 51.2 pg/ml (83 - 273), mean hemoglobin 11.2 ± 1.37 g/dl (6.3 - 13.9), mean MCV 74.5± 9.1 fl (54-106.5) and mean iron level was 54 ±23 μg/dl (18 - 94). At the end of one month of loading therapy (oral or intramuscular, IM), the average VB ₁₂ level was 769 ± 537 pg/ml (post loading). One month after the loading therapy (pre-maintenance) the average VB ₁₂ level was 426 ±156 pg/ml. In seven cases who received IM therapy, the loading treatment was performed for the second time. The mean VB ₁₂ level of the mothers of 85 cases was 174±127 pg/ml (134 - 650). VB ₁₂ deficiency was detected in 55% of mothers, VB ₁₂ level being between 200 - 300 pg/ml in 76%, and below 200 pg/ml in the 24%. The family members of 35% of our patients (including parents) had VB ₁₂ deficiency.

Conclusions. In our country, routine screening of VB ₁₂ levels in infants is not performed; however, its early diagnosis and treatment can prevent many adverse effects mainly on the central nervous system. The fact that 98% of patients were 0-2 years old indicates that its deficiency may be quite high in the young age, and routine screening of this age group for VB ₁₂ deficiency and further studies for prophylaxis may be needed.

Keywords: infancy, maternal vitamin B, nutritional vitamin B, vitamin B