Haematology

Name

Alternative name/Profile

Department

Investigation

Specimen type

Sample type

Sample container & volume

Frequency of analysis

Turnaround time

Availability

Notes

Total B12 assay now performed on Abbott Alinity i platform  as of 10th September 2024. Note new reference range.

Patient must be fasting for a minimum of 12hrs

(Queries to Haematinics Laboratory on 01-4162012)

See GP External Request Form for B12 and Folate. This form must be filled in completely. When requesting blood tests for patients, place all extra forms (e.g. for B12/Folate and Vit D) and necessary samples in the same bag to allow easier processing of patient samples on receipt in laboratory.

All forms may be found here:

https://www.stjames.ie/services/laboratorymedicinelabmed/policiesandguidelines/gpexternalrequestforms/

Haematinics Demand Management Guidelines:

1) Patients on parenteral vitamin B12 or oral folic acid replacement therapy should not have further vitamin B12 or folic acid measurements performed unless blood counts or neurological symptoms fail to improve.

2) Repeating normal vitamin B12 levels is rarely indicated within 6 months of testing.

3) Repeating normal folate levels is rarely indicated within 3 months of testing.

4) Clinical details are required for all vitamin B12 and folate requests. Compliance will be monitored by periodical auditing.

Limitations of this Assay:

• Results should be used in conjunction with other data e.g. symptoms, results of other tests, and clinical impressions.
• The diagnosis of B12 deficiency cannot be solely based on total serum B12 levels. Further testing of folic acid, intrinsic factor blocking antibodies (IFA), holotranscobalamin, homocysteine, and/or methyl malonic acid is suggested for symptomatic patients with haematological or neurological abnormalities.

• Haemolysed samples are not suitable for analysis. 

• Heterophilic antibodies and rheumatoid factor (RF) in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this interference, and anomalous values may be observed. Additional information may be required for diagnosis.

Related links

Reference range

New normal reference range:

211-760 ng/l

Last updated

Tue, 11 Nov 2025 12:52:55 GMT