Propranolol benefits infantile tremor syndrome after initiating vitamin B12 therapy: Case Study

Children with vitamin B12 deficiency can present with anaemia, pancytopenia, failure to thrive, hypotonia and developmental delays and/or regression. Vitamin B12 deficiency can be seen in infants who are exclusively breastfed by mothers who are vegetarian or who are themselves vitamin B12 deficient. Investigations in children with vitamin B12 deficiency can reveal macrocytic anaemia, leukopenia, thrombocytopenia, high serum homocysteine levels and high lactate dehydrogenase (LDH) levels. Peripheral blood smears may show macrocytic hypochromic oval erythrocytes, anisocytosis, poikilocytosis, and hyper-segmentation of neutrophils. Furthermore, head imaging may reveal cerebral atrophy and delayed myelination patterns for age. Early recognition and treatment of vitamin B12 deficiency can lead to significant improvement in terms of neurodevelopment and prevent long term neurological consequence

A previously healthy 13-month-old girl was referred to a tertiary pediatric care centre for further investigations and management of her pancytopenia. She was initially seen by a general paediatrician in the community for concerns of a 2-month history of tiredness, decreased appetite and failure to thrive. Further investigations revealed that her anaemia was macrocytic: her MCV was 107.4 fL (range 79–97 fL). She was diagnosed with infantile tremor syndrome (ITS), which was likely triggered by her vitamin B12 treatment, as described in the literature. She also had undetectable vitamin B12 levels (<100 pg/mL, normal range 160–950 pg/mL), as well as high lactate dehydrogenase (LDH) levels (>4,300 U/L, normal range 373–618 U/L). Her reticulocyte count was also inappropriately within the normal range (61 × 103/μL, normal range 19–73 × 103/μL) given her significant anaemia. Her other nutrients including iron and folic acid were within normal range. Immunoglobulin levels were not measured.