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Test ID: RBC Folate
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RBC Folate
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Useful For
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For diagnosis of folate deficiency, monitoring of folate therapy, evaluating megalobalstic and macrocytic anemia.
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Method name and description
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Electrochemiluminescence immunoassay (ECLIA): Competition principle
Measurement of antigen or antibody based on the change in electrochemiluminescence (ECL) signal before and after immunoreaction. Results are determined automatically by the software by comparing the electrochemiluminescence signal obtained from the reaction product of the sample with the signal of the cutoff value previously obtained by calibration.
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Clinical information
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Nutritional and macrocytic anemias can be caused by a deficiency of folate. This deficiency can result from diets devoid of raw fruits, vegetables or other foods rich in folic acid, as may be the case with chronic alcoholics, drug addicts, the elderly or persons of low socioeconomic status, etc. In addition, low serum folate during pregnancy has been associated with neural tube defects in the fetus. Dietary deficiency and malabsorption are the major causes of folate deficiency in humans. Folate is necessary for normal metabolism, DNA synthesis and red blood cell regeneration. Untreated deficiencies may lead to megaloblastic anemia.
Since a deficiency of either vitamin B12 or folate can cause megaloblastic anemia, it is advisable to determine the concentration of both vitamin B12 and folate in order to properly diagnose the etiology of anemia. For diagnosis of folate deficiency, it is recommended to perform determinations not only in serum but also in erythrocytes. More than 95 % of folate occurs in the red blood cells. The folate concentration in erythrocytes more truly reflects the overall folate concentration in the tissue. Radio assays were first reported for folate in 1973.
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Specimen type / Specimen volume / Specimen container
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Specimen type: Whole blood
Minimum volume of sample: 4 mL
Hemolysate: K2‑EDTA and K3‑EDTA tube
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Collection instructions / Special Precautions / Timing of collection
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Collect blood by standard venipuncture techniques as per specimen requirements. When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer
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Storage and transport instructions
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Storage: 2 hours at 20 – 25°C
24 hours at 2 – 8°C;
1 month at ‑20 °C
Transport: 2-25°C
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Specimen Rejection Criteria
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Wrong collection container, insufficient and clotted sample.
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Biological reference intervals and clinical decision values
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Factors affecting test performance and result interpretation
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It is contraindicated to measure samples of patients receiving therapy with certain pharmaceuticals, e.g. methotrexate or leucovorin, because of the cross-reactivity of folate binding protein with these compounds.
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Turnaround time / Days and times test performed / Specimen retention time
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Daily (24/7)
Turn-around time:
Routine: One working day
Specimen Retention: 4 days
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