Vitamin B 12 Deficiency Presenting as Failure to Thrive, Regression of Milestones, and Severe Hemolytic Anemia in an Infant: A Case Report

Abstract

Vitamin B12 is essential for DNA synthesis and is necessary for the development of the central nervous system. Vitamin B12 deficiency occurs in babies who are exclusively breast-fed by mothers with insufficient stores of vitamin B12. In vitamin B12 deficiency, the clinical features are mainly hematological and neurological. Megaloblastic anemia is the characteristic feature of vitamin B12 insufficiency. Rare haematological manifestations include pancytopenia and hemolytic anemia. The other clinical spectrum of vitamin B12 deficiency comprises vomiting, lethargy, failure to thrive, hypotonia, and retrogression of developmental milestones. We reported a 7-month-old infant with vitamin B12 deficiency who presented with loss of weight and regression of social smile since one month of age. Her weight, length, and head circumference were in the less than 3^rd centile range according to the World Health Organisation (WHO) growth chart. She had severe pallor, hyperpigmentation of palms, soles, and knuckles, brownish depigmented brown sparse hair, and hepato-splenomegaly of 4 cm each. The laboratory results revealed Hb of 3.5gm/dl, Mean Corpuscular Volume (MCV) of 99fl, thrombocytopenia, normal ferritin levels, and peripheral smear showed polychromatophils, 19 nucleated Red Blood Cell (RBCs)/100White Blood Cells (WBCs), macrocytes, leucocytes shift to the left with 21% hypersegmented neutrophils, suggestive of hemolytic anemia. Vitamin B12 levels were 146pg/ml [N=200-900 pg/ml]. The baby started smiling 2 days after the vitamin B12 injection, gained 700 g during the follow-up of 3 months, and the pigmentation disappeared from the palms and soles.