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Test Code USTEKSO Ustekinumab Quantitation with Antibodies, Serum

Additional Codes

Mayo Test Code: USTEK


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL Serum

Collection Instructions:

1. Draw blood immediately before the next dose of drug administration (trough level).

2. Centrifuge and aliquot serum into a plastic vial.


Forms

If not ordering electronically, complete, print, and send 1 of the following with the specimen:

-Gastroenterology and Hepatology Test Request (T728)

-Therapeutics Test Request (T831)

Useful For

Evaluating patients for loss of response, partial response on initiation of therapy, autoimmune or hypersensitivity reactions, primary nonresponse, reintroduction after drug holiday, endoscopic/computed tomography enterography recurrence (in inflammatory bowel disease) and acute infusion reactions using trough level specimens

 

This test does not differentiate between the originator and biosimilar products.

Profile Information

Test ID Reporting Name Available Separately Always Performed
USQN Ustekinumab QN, S No Yes
USTAB Ustekinumab Ab, S No Yes

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

Ustekinumab QN with Antibodies, S

Specimen Type

Serum

Specimen Minimum Volume

Serum: 0.35 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK
Heat-inactivated specimen Reject

Reference Values

USTEKINUMAB QUANTITATION:

Limit of quantitation is 0.3 mcg/mL

 

For maintenance stages:

Concentrations ≥1.0 mcg/mL are associated with clinical response and clinical remission

Concentrations ≥4.5 mcg/mL are associated with mucosal healing

 

USTEKINUMAB ANTIBODIES:

Limit of quantitation is 10 AU/mL

Absent: <10 AU/mL

Present: ≥10 AU/mL

Cautions

This test measures free ustekinumab (UTK) and free antibodies to ustekinumab (ATU). This test does not measure UTK bound to ATU (immunocomplexes).

 

Presence of UTK at concentrations greater than 1 mcg/mL may impair detection of ATU, as the ATU assay is not drug tolerant.

 

Elevated rheumatoid factor (RF) may falsely increase results of ATU. During validation studies, negative ATU samples remained negative and positive ATU samples remained positive; however, the quantitative result differed by more than 20% when compared to the non-RF spiked original samples. If patients are positive for RF, clinical correlation is recommended for ATU test interpretation.

 

While the immunogenicity rates between reference product and biosimilars are similar, there could be epitope differences in the anti-drug-antibodies for each formulation.

 

These assays are designed to quantify ustekinumab and detect anti-drug antibodies specific to it, regardless of formulation. It is suitable for testing both the reference product and all US Food and Drug Administration and European Medicines Agency-approved biosimilars. The assays do not differentiate between the originator and biosimilar products.

Day(s) Performed

Monday, Thursday

Report Available

2 to 6 days

Specimen Retention Time

14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80299

83520

LOINC Code Information

Test ID Test Order Name Order LOINC Value
USTEK Ustekinumab QN with Antibodies, S In Process

 

Result ID Test Result Name Result LOINC Value
USQN Ustekinumab QN, S 87408-1
USTAB Ustekinumab Ab, S 87409-9