RT Book, Section A1 Zehnder, James L. A2 Katzung, Bertram G. A2 Vanderah, Todd W. SR Print(0) ID 1176466754 T1 Agents Used in Cytopenias; Hematopoietic Growth Factors T2 Basic & Clinical Pharmacology, 15e YR 2021 FD 2021 PB McGraw-Hill PP New York, NY SN 9781260452310 LK accessmedicine.mhmedical.com/content.aspx?aid=1176466754 RD 2024/03/28 AB CASE STUDYA 25-year-old woman who has been on a strict vegan diet for the past 2 years presents with increasing numbness and paresthesias in her extremities, generalized weakness, a sore tongue, and gastrointestinal discomfort*. Physical examination reveals a pale woman with diminished vibration sensation, diminished spinal reflexes, and extensor plantar reflexes (Babinski sign). Examination of her oral cavity reveals atrophic glossitis, in which the tongue appears deep red in color and abnormally smooth and shiny due to atrophy of the lingual papillae. Laboratory testing reveals a macrocytic anemia based on a hematocrit of 30% (normal for women, 37–48%), a hemoglobin concentration of 9.4 g/dL, an erythrocyte mean cell volume (MCV) of 123 fL (normal, 84–99 fL), an erythrocyte mean cell hemoglobin concentration (MCHC) of 34% (normal, 31–36%), and a low reticulocyte count. Further laboratory testing reveals a normal serum folate concentration and a serum vitamin B12 (cobalamin) concentration of 98 pg/mL (normal, 250–1100 pg/mL). Once megaloblastic anemia was identified, why was it important to measure serum concentrations of both folic acid and cobalamin? Should this patient be treated with oral or parenteral vitamin B12?