A 10-month-old male child presented with a one-day history of fever. The child was noted to be pale and lethargic. A full blood count was performed and the following results were noted:
Hb 40 g/L, MCV 99 fL (normal range for age 70-83 fL), WCC 9.5 x 109/L and platelet count 42 x 109/L
The blood film showed the presence of oval macrocytes, hypersegmented neutrophils and circulating megaloblasts.
Further investigations revealed a low serum folate of 2.1 nmol/L (NR 5.5-33.3) and a low vitamin B12 level of 103 pmol/L (NR 109-646). Iron studies were within normal limits.
A diagnosis of megaloblastic anaemia secondary to nutritional folate and vitamin B12 deficiency was made.
Oval macrocytes / hypersegmented neutrophil
Circulating megaloblast
Megaloblastic anaemia in children is usually due to a lack of vitamin B12 and/or folic acid either through poor diet, increased cell turnover or malabsorption. Vitamin B12 and folic acid are prerequisites for DNA synthesis and thus the production of normocytic haematopoiesis. In their absence, the peripheral blood is characterised by the presence of oval macrocytes, teardrop poikilocytes and hypersegmented neutrophils. Basophilic stippling and Howell Jolly bodies may also be present. The mean cell volume in this child is raised for age.
The bone marrow is hypercellular with increased numbers of megaloblasts which show asynchrony of nuclear and cytoplasmic maturation. The nuclei maintain a primitive, open chromatin pattern while the cytoplasm matures normally. Giant metamyelocytes and hypersegmented neutrophils are also present. The megakaryocytes show hypersegmented nuclei with an open chromatin pattern. Megaloblastic anaemia due to inadequate dietary intake may coexist with iron deficiency.
Vitamin B12 deficiency in infancy may lead to irreversible neurological damage. Iron deficiency, often seen more commonly in this age group, can also result in less severe, but similarly irreversible neurological damage. Iron deficiency is usually secondary to excessive cow’s milk and inadequate ingestion of solids.
Further discussion with this child’s parents revealed that the child was breast fed for the first 2 weeks of life and was then fed a homemade formula of barley water, corn syrup and goat’s milk. At the time of presentation, the child had not started on solids. Goats’ milk is sometimes substituted for cows’ milk, as it is less allergenic than cows’ milk. Compared with breast milk, goat’s milk has a very low concentration of vitamin B12, folic acid and iron.
This child was transfused and given oral folate and vitamin B12 injections. His fever was treated with antibiotics. At 5 months post presentation, he remains well.