Albertine Donker

General Introduction 11 1 GENERAL INTRODUCTION From childhood to adulthood, anemia is a very common clinical condition. Worldwide, anaemia affects approximately 1.62 billion people, which corresponds to 24.8% of the population. 1 Therefore, both primary care and academic doctors, involved in either pediatric or adult mecidine, are consulted for anemia very often. Despite the multiple causes of anemia, in many patients evaluation is straightforward and reveals a specific diagnosis. A standard diagnostic approach is to classify anemia as microcytic (mean corpuscular volume (MCV) <80 fL), normocytic, or macrocytic (MCV >98 fL). The majority of anemias are microcytic. 1 Microcytic anemias are primarily caused by iron deficiency (ID). Although the proportion may vary among population groups and in different areas according to the local conditions, it is generally assumed that 50% of the cases of anaemia worldwide are due to ID as a consequence of nutritional deficits, gastro-intestinal or gynecological blood loss or iron malabsorption. 2-5 Furthermore, hemoglobinopathies, especially thalassemia syndromes, need to be considered as a cause of microcytic anemias within specific populations. 1 In some patients the microcytic anemias cannot be explained by ID or a hemoglobinopathy. In those cases a genetic disorder of iron metabolism or heme synthesis due to defects in genes involved in these processes might be the cause of the microcytic anemia. 6-9 It is a diagnostic challenge for the clinician to distinguish these rare disorders from the far more common afore-mentioned conditions. Missing a microcytic anemia due to a genetic disorder of iron metabolism or heme synthesis may result in an unnecessarily long diagnostic process and ineffective, or even harmful treatments. Moreover, in some genetic anemias, such as the sideroblastic anemias, iron overload (IO) is of greater clinical consequence than the anemia itself since unrecognized tissue iron loading might lead to severe morbidity and even mortality. 8,10 Apart from diagnostic flowcharts that facilitate clinicians to accurately and timely diagnose these genetic microcytic anemias, treatment protocols are required for the different disorders in order to reduce the disease burden for the individual patient and to avoid lifelong sequelae of ID or IO.