Clinical Information

Patients with combined folate and iron deficiencies may not demonstrate the erythrocyte macrocytosis typical of folate deficiency anemia. In these patients, however, the red cell distribution width will typically be elevated. Recent folic acid administration or dietary folate intake could result in normal or elevated values and possibly mask an underlying folate deficiency. Hemolysis significantly increases folate values in serum due to the high folate concentrations found in red blood cells. Methotrexate and leucovorin interfere with folate measurement because these drugs cross-react with folate binding proteins.