Abnormal lymphocyte deoxyuridine suppression test: A reliable indicator of decreased lymphocyte folate levels

Abstract

AbstractThe deoxyuridine (dU) suppression test measures the availability of folate and, indirectly, vitamin B12 in de novo thymidine synthesis and is of established value in defining biochemical megaloblastosis in bone marrow cells. Recent studies have suggested that the application of this test to DNA synthesis in transformed lymphocytes may be valuable in defining nutrient deficiency that is subtle, masked, or present in some cell lines but not in others. This use of the test has not been fully accepted because lymphocyte folate and B12 levels had not been simultaneously measured prior to the current study. In this study, vitamin availability for the dU suppression test was closely correlated with folate levels in radioassay and less well correlated with vitamin B12 levels in the cell. The folate levels varied widely when dU suppression was efficient but were uniformly low in subjects with ineffective dU suppression. These studies validate the use of the lymphocyte dU suppression test as a means of detecting folate deficiency in this cell line.