Anemias beyond B12 and iron deficiency: the buzz about other B's, elementary, and nonelementary problems.

The term "unexplained anemia" appears frequently in a request for a hematology consultation. Although most anemia consultations are fairly routine, they occasionally represent challenging problems that require an amalgam of experience, insight, and a modicum of "out-of-the-box" thinking. Problem anemia cases and pitfalls in their recognition can arise for one of several reasons that are discussed in the cases presented herein. "Anemias beyond B12 and iron deficiency" covers a vast domain of everything that lies beyond the commonly encountered anemias caused by simple deficiencies of 2 currently major hematologically relevant micronutrients. However, even these deficiencies may be obscured when they coexist or are not considered because of misleading distractions. They may also be mistakenly identified when other less common nutrient deficiencies occur. I present herein case examples of such situations: a young patient with pancytopenia and schistocytes who was responsive to plasmapheresis, but in whom pernicious anemia was not suspected because of ethnicity and age; a bicytopenic patient with anemia and myelodysplastic features caused by copper deficiency after gastric reduction surgery; and a patient with BM hypoplasia and a dimorphic blood smear who was found to have paroxysmal nocturnal hemoglobinuria. These "pearls" represent but 3 examples of the many varieties of problems in anemia diagnosis and are used to illustrate potential pitfalls and how to avoid them.