Clinical Use:
Background: Megaloblastic anaemia can be suspected from the presence in a blood film of macrocytes, ovalocytes and hypersegmented neutrophils (those with >5 lobes). However the first indication in many cases is a raised MCV, often without an associated anaemia. A reduction in serum folate occurs with a reduction in folate intake or with a negative folate balance and may be low without significant body reduction. The red cell folate concentration shows better correlation with megaloblastic changes, although it is not a specific sign of folate deficiency.

It can also be low in up to 50% of patients with severe B12 deficiency due to the requirement for B12 in the provision of tetrahydrofolate (THF). The red cell folate may be normal despite folate deficiency when there is reticulocytosis, following a recent blood transfusion or when anaemia is absent.

Red Cell Folate levels remain relatively constant throughout the life of a red cell. Serum folate is more prone to variation and can be affected by the patient’s diet immediately prior to blood being taken, alcohol, trauma and other factors. Measuring red cell folate is done to see if the patient’s low serum folate has been reduced for some time. Red Cell Folate is not stable for long periods of time and needs to be treated with ascorbic acid and frozen prior to use (see Red Cell Lysate sop).

Reference Ranges: 280 – 790 ug/L
Associated Diseases:
Patient Preparation:
Specimen Requirements: Sample type:

  • Whole blood collected into EDTA tube.
    • The patient must not have been transfused within 3 months of the sample, as the red cell folate result will be that of the transfused blood.
    • If in doubt ask a senior member of staff or a Consultant Haematologist.

Sample identification:

  • Three patient identifiers from
    • Name
    • D.O.B.
    • Address
    • N.H.S. number
    • Unit Number

    should match on the specimen and request form. This check may be performed prior to centrifugation by the Central Sort department.

Turnaround Time: 24 hours
Additional Information:
Referred Test: