Diphtheria – Serology

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

Testing Indications

Testing for Diphtheria is not done for immunity/acute diagnosis/pre-vaccination screening and is only available only for the rare event of an adverse reaction to Diphtheria vaccine or the possibility of humoral immunodeficiency in the patient. This must be indicated on the test requisition in order for testing to be performed.

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

Diptheria serology

Whole blood or Serum

5.0 ml blood or 1.0 ml or serum

Blood, clotted - vacutainer tubes (SST)

Submission and Collection Notes


Indicate on the General Test Requisition Form if testing is required due adverse reaction to Diphtheria vaccine, or humoral immunodeficiency in the patient. This must be indicated on the test requisition in order for testing to be performed.


Serum samples should not be heat-inactivated, as this may give false positive results.


The results may be used to aid diagnosis of immunodeficiency. Results must be confirmed by clinical findings and other serological tests.

The results obtained from this assay are not diagnostic proof of protection/immunity against Diphtheria or the presence/absence of immunodeficiency.

Haemolysed, icteric, lipemic or microbially contaminated sera or plasma are not appropriate for testing and will be rejected.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Special Instructions

Instructions for using SST tubes are found in the document titled:LAB-SD-008, Blood Collection Using Serum Separator Tubes.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Diphtheria serology testing is performed once per month.

Turnaround time is up to 28 days from receipt by PHO laboratory.

Test Methods

Diphtheria serology testing for Anti-Diphtheria Toxoid IgG is by the Enzyme Immunoassay (EIA) method.


Results are reported to the ordering physician or health care provider as indicated on the requisition.

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Updated 20 July 2020