Imerslund-Grasbeck syndrome in a 5-year-old Iranian boy.

Imerslund-Grasbeck syndrome (IGS) is a rare syndrome characterized by clinical symptoms and signs of Vitamin B12 deficiency and proteinuria. Our patient was a 5-year-old boy with pallor, lack of appetite, and low weight gain. Laboratory studies showed severe macrocytic anemia, normal reticulocyte count, negative direct coombs test, normal osmotic fragility, and autohemolysis test. He has had intermittent proteinuria since 3 years ago despite normal creatinine level and absence of hematuria or hypertension. Finally, based on low level of serum B12 vitamin and normal folate level accompanied by asymptomatic proteinuria, the diagnosis of IGS was made. Furthermore, his sister has had laboratory abnormalities without any symptoms. IGS responded to B12 replacement therapy dramatically but intermittent proteinuria persisted even after appropriate therapy.