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Test Code GUSAP Guselkumab Quantitation with Antibodies, Serum


Specimen Required


Patient Preparation: For 12 hours before specimen collection, patient should not take multivitamins or dietary supplements (eg, hair, skin, and nail supplements) containing biotin (vitamin B7).

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1.1 mL serum

Collection Instructions:

1. Draw blood immediately before next scheduled dose (trough specimen).

2. Within 2 hours of collection, centrifuge, and aliquot serum into a plastic vial.


Useful For

Evaluation of patients with limited primary (initial) response to or secondary loss of response to guselkumab.

Profile Information

Test ID Reporting Name Available Separately Always Performed
GUS Guselkumab, S Yes Yes
GUSAB Guselkumab Ab, S No Yes

Method Name

GUS: Liquid Chromatography Mass Spectrometry (LC-MS)

GUSAB: Electrochemiluminescent Bridging Immunoassay (ECLIA)

Reporting Name

Guselkumab QN with Antibodies, S

Specimen Type

Serum

Specimen Minimum Volume

Serum: 0.75 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  24 hours

Reject Due To

Gross hemolysis OK
Gross lipemia Reject
Gross icterus OK
Heat-treated specimens Reject

Reference Values

GUSELKUMAB QUANTITATION:

Guselkumab lower limit of quantitation = 0.5 mcg/mL

 

ANTIBODIES TO GUSELKUMAB:

<9.8 ng/mL

Interpretation

The presence of detectable anti-guselkumab antibodies may be associated with increased guselkumab clearance and lower circulating concentrations of guselkumab in serum. Low trough concentrations of guselkumab may be correlated with loss of response to the drug.

Day(s) Performed

Weekly

Report Available

2 to 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

80299

83520

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GUSAP Guselkumab QN with Antibodies, S In Process

 

Result ID Test Result Name Result LOINC Value
622837 Guselkumab, S In Process
623122 Guselkumab Ab, S In Process
623291 GUSAB Interpretation 77202-0