PURPOSE: Folate levels are routinely ordered in the evaluation of macrocytosis with or without frank anemia, yet the value of these tests is questionable. We evaluated the clinical utility of folate testing in routine clinical practice.

SUBJECTS AND METHODS: We conducted a retrospective review of all serum and erythrocyte folate assays performed over a one-year period at three hospitals. We determined the frequency of low values, then reviewed the medical records of all patients with low values to determine whether low folate levels changed clinician behavior. We also performed a cost analysis to determine the cost of testing per case in which behavior changed.

RESULTS: Only 2.3% of the 2,998 folate levels obtained during the study period were low. The low levels were noted in the record in 53% of cases, and folic acid was prescribed or continued at discharge in only 24%. The cost analysis showed that nearly $10,000 was spent in folate testing per patient in which behavior changed.

CONCLUSIONS: Folate values were rarely low in the population tested, and low values infrequently led to a change in clinician behavior. Given the limited clinical value of folate tests, we propose that, in cases of macrocytosis with or without anemia, to minimize cost and prevent missed cases of true folate deficiency, empirical supplementation with folic acid should be used in place of testing for deficiency.