IGHE and hereditary elliptocytosis: The workup should also include basal tryptase determination (suggestive of mastocytosis or clonal HE/HES), vitamin B12 (elevated B12 and tryptase are suggestive of clonal eosinophilia), plasma protein electrophoresis (polyclonal hypergammaglobulinemia is suggestive of IgG4-related disease, angioimmunoblastic T-cell lymphoma or chronic parasitic infection) and total IgE (although the specificity is limited, elevated levels suggest reactive eosinophilia).