Puzzling cases of pediatric microcytosis

Iron deficiency anemia is a common diagnosis in the pediatric age group and often attributed to poor diet, excessive milk intake, or blood loss. The following case report presents challenging clinical situations that were puzzling and prompted further work up, because of poor or partial response to treatment with oral and IV iron. For two of our cases, genetic testing identified rare disorders of iron metabolism, while chronic blood loss resulted in refractory iron deficiency in the third case and genetic testing revealed carrier status for erythropoietic protoporphyria. This is a retrospective chart review at a single tertiary care children's hospital. Clinical and laboratory data from three pediatric patients with refractory microcytosis were assessed. These cases illustrate that patients with suspected iron deficiency anemia that are unresponsive or partially responsive may need further genetic testing to evaluate for rare iron metabolism disorders that should be in the differential diagnosis such as tRNA nucleotidyl transferase 1 (TRNT1) gene defect, iron refractory iron deficiency anemia (IRIDA), due to TMPRSS6 gene defect), and erythropoietic protoporphyria.