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folate in erythrocytes
Reference values:
- Red Cell Folate: 110-700 ng/mL
Clinical significance:
Also see vitamin B12/folate measurement
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.
Decreases:
- folate deficiency
Principle:
Also see vitamin B12/folate measurement
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.
Specimen: - see vitamin B12/folate measurement
Related
erythrocyte; red blood cell (RBC)
folate in serum/plasma
folic acid; folate; vitamin B9
General
folate measurement
References
- Mini Panel of 2 tests: Folate, RBC . Hematocrit (client supplied)
Laboratory Test Directory ARUP: 70385