Clinical utility of folic acid testing for patients with anemia or dementia

BACKGROUND: Serum folic acid tests are routinely ordered by physicians for evaluating anemia and sometimes ordered for evaluating dementia and altered mental status. OBJECTIVE: To determine the utility of routine folic acid testing for patients with anemia or dementia/altered mental status in the era of folic acid fortification. DESIGN: Retrospective analysis of consecutive folic acid tests performed on adults over a 4-month period; chart review of patients without anemia. MEASUREMENTS AND MAIN RESULTS: Serum folic acid level, mean corpuscular volume (MCV), and hematocrit. We reviewed 1,007 folic acid tests performed on 980 patients. The average age was 63.8 years, and 62% of the tests were from outpatient facilities. Only 4 (0.4%) patients had folic acid levels <3 ng/mL, while 10 (1%) patients had levels of 3-4 ng/mL (borderline). Thirty-five percent of the folic acid tests were performed on patients who were not anemic; most of these were ordered to evaluate dementia or altered mental status and folic acid level was normal in all these patients. Only 7% of the patients tested had a macrocytic anemia; these patients were more likely than those without macrocytic anemia to have low folic acid levels (2.8% vs 0.4%, p < .03). CONCLUSION: Low serum folic acid levels were rarely detected in a series of patients being evaluated for anemia, dementia, or altered mental status. The test should be reserved for patients with macrocytic anemia and those at high risk for folic acid deficiency.