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Test ID: Folate Serum
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Folate Serum
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Useful For
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AId in diagnosis of one cause of anemia (megaloblastic anemia) or neuropathy; to evaluate nutritional status and to monitor the effectiveness of treatment for folate deficiency.
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Method name and description
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Electrochemiluminescence immunoassay (ECLIA): Competition principle
Electrochemiluminescence immunoassay (ECLIA) intended for use on the cobas e 801 immunoassay analyzer. The Folate assay is based on competition principle. Patient specimen,with the folate pretreatment reagents 1 and 2, bound folate is released from endogenous folate binding proteins. By incubating the pretreated sample with the ruthenium labeled folate binding protein, a folate complex is formed, the amount of which is dependent upon the analyte concentration in the sample. After addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell II M. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier. Results are determined via a calibration curve which is instrument specifically generated by 2‑point calibration and a master curve.
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Clinical information
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Folate deficiency can be caused by decreased nutritional intake, poor absorption of ingested folate in the intestine or increased demand of folate, for example during physical activity or pregnancy. Deficiency of folate can also be a result of liver diseases or impaired folate metabolism due to genetic defects or drug interactions. A clinical manifestation of both folate and vitamin B12 deficiency is the so called megaloblastic (macrocytic) anemia: due to the affected DNA synthesis and cell maturation, especially involving the cells of erythropoiesis, the total count of erythrocytes is significantly reduced. Because vitamin B12 and folate are closely interrelated in the cellular one‑carbon unit metabolism, it is advisable to determine both parameters simultaneously in patients with the relevant symptoms of vitamin deficiency.
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Specimen type / Specimen volume / Specimen container
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Specimen type: Serum, Plasma
Minimum volume of sample: 1 mL
Serum: Plain tube (red or yellow top)
Plasma: Li‑heparin, 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.
Preferably patient should be fasting.
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Storage and transport instructions
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Storage: 2 hours at 20 – 25°C
48 hours at 2 – 8°C;
28 days at ‑20 °C (± 5 °C)
Transport: 2-25°C
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Specimen Rejection Criteria
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Grossly hemolyzed, icteric and lipemic samples, wrong collection container, insufficient sample and heat‑inactivated samples.
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Biological reference intervals and clinical decision values
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Age
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Reference interval (nmol/L)
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From
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To
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From
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To
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0 Minutes
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11 Years
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20
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85
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11 Years
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19 years
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11
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62
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19 years
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59 years
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10
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70
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59 years
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150 years
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13
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104
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Factors affecting test performance and result interpretation
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Hemolysis may significantly increase folate values due to high concentrations of folate in red blood cells. Therefore, hemolyzed samples are not suitable for use in this assay.
Samples with extremely high total protein concentrations (e.g. patients suffering from Waldenström’s macroglobulinemia) are not suitable for use in this assay, since they may lead to the formation of protein gel in the assay cup. Processing protein gel may cause a run abort. The critical protein concentration is dependent upon the individual sample composition.
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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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