Erythrocyte Creatine Levels in Anemia

The autom ated diacetyl-l-napthol procedure was found to be a simple and relatively quick m ethod for the determ ination of erythrocyte creatine (EC), exhibiting both better precision and greater sensitivity than reticulocyte counting. A reference range of 1.8 to 5.0 mg per dl (mean, 3.0 ± 0.9 mg per dl) was established by m easuring EC levels in 81 normal adults varying in ages from 20 to 47 years of age. Normal creatine values displayed a slight sex dependency, with females exhibiting som ewhat higher levels than males. In evaluating the relative usefulness of EC versus reticulocyte counting in the assessm ent of anemia, both parameters w ere m easured and compared in 41 patients with various hemolytic and nonhem olytic anemias. A direct rela­ tionship was noted betw een the two param eters (p < 0.0001); however, the actual data correlation was only fair (r = 0.49). In a serial study of an irondeficiency anemic patient responding to iron adm inistration, erythrocyte creatine levels were found to rise more slowly than the reticulocyte count and to rem ain elevated after the reticulocyte count had returned to normal.