folate in erythrocytes

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Reference interval

In the erythrocyte folate procedure, the sample is first diluted 1:1 with ascorbic acid in water & incubated for 90 minutes. The ascorbic acid stabilizes the folate liberated from erythrocytes. The 90 minute incubation is necessary for hemolysis of erythrocytes & allows the endogenous folate conjugases to hydrolyze the conjugated pteroylpolyglutamates to pteroylmonoglutamates prior to assay. The sample is further diluted 1:2 with protein diluent. The concentration of protein in this diluent is 2 times that found in the standards. The resulting diluted hemolysate thus contains a protein concentration & matrix similar to that used in the standards.

Red cell folate concentration shows a much better correlation with the presence of megaloblastic changes than serum levels & is unaffected by short term dietary changes. However erythrocyte folate levels may be normal in megaloblastic state due to folate lack when anemia is slight or absent. Also, low erythrocyte folate levels have been observed in approximately 1/2 of patients with primary cobalamin deficiency. Therefore it is necessary to measure the serum Vitamin B12 level along with the red cell folate level.

↑ Mini Panel of 2 tests: Folate, RBC . Hematocrit (client supplied) Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0070385.jsp