Folic Acid
Sample: Serum . Avoid exposure to light. Stable 24 hours at 4°C or longer if frozen.
Schedule: Daily
Units: ng/mL (Convertion factor 1ng/mL = 2.204 nmoL/L)
Range: Serum : 3 - 19 ng/mL RBC : 93 - 641 ng/mL Whole Blood : 43 - 295 ng/mL
Remarks:
Folic Acid ( Serum and RBC ) In Serum: Folic acid test is used for the detection of folate deficiency, for monitoring therapy with folate, in the evaluation of megaloblastic and macrocytic anaemia, for evaluating alcoholic patients and those with prior jejunoileal bypass for morbid obesity or those with intestinal blind-loop syndrome. Folic acid levels in blood may be decreased in patients taking oral contraceptives. Usually Folic acid concentration in serum is measured together with Vitamin B12 levels. Serum levels are affected by present dietary intake. Drugs that are folate antagonists, such as methotrexate and pentamidine, may induce a deficiency state. Some drugs, such as oral contraceptives, phenytoin, and ethanol impair absorption of folate. Chronic use of antacids by patients with diets marginal in folate has been considered as a cause of folic acid deficiency. Levels are commonly high in patients with Vitamin B12 deficiency since this vitamin is needed to allow incorporation of folate into tissue cells. Folate (folic acid) deficiency is present in some 33% of pregnant women, many alcoholics, patients with a wide variety of malabsorption syndromes including celiac disease, sprue, Crohns disease, and jejunal/ileal bypass procedure.
Folic Acid in RBC (RBC Folate) The megaloblastic anaemia of folate deficiency is usually associated with red cell folate levels <100 ng/mL RBCs.. This test is used for detection of Folate deficiency. Since serum folate values fluctuate significantly with diet, measurement of red blood cell folate is a better measure of tissue folate stores. It is widespread practice to measure serum and red cell folate with Vitamin B12 levels.
