After many decades of study, sprue, pernicious anemia, and the other related anemias have come to be accepted as being closely related by distinct clinical syndromes. They have in common a macrocytic anemia. The occurrence of Addisonian pernicious anemia is more frequent in the temperate zones while the incidence of sprue is higher in the tropics. In any large clinic one sees patients who have clearcut clinical syndromes on which all observers agree as to diagnosis. There are always a few cases, however, about which observers have differences of opinion or are unable to make up their minds. Such cases we classify as indeterminate.
In classifying the macrocytic anemias it is important to do repeated gastric analyses. In Addisonian pernicious anemia there is no free hydrochloric acid even after histamine stimulation. In other types of macrocytic anemia free hydrochloric acid is usually present. Sprue is characterized by acid steatorrhea.