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HelpOrderable Name 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 |
Testing Algorithm
For more information see Ulcerative Colitis and Crohn Disease Therapeutic Drug Monitoring Algorithm.
Special Instructions
Method Name
GUS: Liquid Chromatography Mass Spectrometry (LC-MS)
GUSAB: Electrochemiluminescent Bridging Immunoassay (ECLIA)
Specimen Type
SerumSpecimen 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
Day(s) Performed
Weekly
Report Available
2 to 9 daysCPT Code Information
80299
83520