Ustekinumab Quantitation with Antibodies, Serum
Test Overview
Clinical Utility
Evaluation of loss of response to therapy.
Quantification of ustekinumab in human serum.
Trough level quantitation for evaluation of patients treated with ustekinumab.
Detection of antibodies to ustekinumab in human serum.
Method
Enzyme-linked immunosorbent assay (ELISA)
Method Description
Ustekinumab (UTK) quantitation and anti-ustekinumab antibody measurements are performed using enzyme-linked immunosorbent assay. Microwell strips are pre-coated with UTK or anti-UTK antibody . Calibrators, controls, and patient samples are added to separate wells, allowing either UTK or antibodies to ustekinumab (ATUs) to bind to immobilized antigen. Unbound sample is washed away, and a second horseradish peroxidase-labeled anti-UTK or UTK (conjugate) is added to each well. A second incubation step allows the conjugate to bind to the UTK or ATU that has become attached to the microwells. After washing away the excess of unbound conjugate, the remaining enzyme activity is determined by adding a substrate and measuring the intensity of the color that develops in a spectrophotometer. The signal obtained is proportional to the amount of UTK or ATUs in the patient sample.
Result Included
Ustekinumab; Ustekinumab Antibodies
Aliases/Synonyms
Stelara; Stelara antibodies
Specimen
Specimen Type
SerumContainers
Preferred Containers
Gold top (clot activator & gel)
Acceptable Containers
Red top (no additive)
Volume
Sample Volume
0.5 mL
Minimum Volume
0.35 mL
Patient Preparation
Collect specimen immediately before the next dose of drug administration (trough level).
Collection & Handling
Handling Information
Store and send cold or frozen.
Stability
| Refrigerated | Frozen |
|---|---|
| 21 days | 21 days |
Rejection Criteria
| Criteria | Specification |
|---|---|
| Specimen | Heat Inactivated |
Performance & Interpretation
Turnaround Time
9 days
Results
-
Ustekinumab quantificationmcg/mLIn inflammatory bowel disease, at post-induction measurement (week 8), concentrations above 3.5 mcg/mL are associated with good outcomes.
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 AntibodiesAU/mLAbsent: <10
Present: ≥ 10
Referral Location
Out-of-Country
Interface & Setup
HL7 Interface Codes
| Order Code | Result Name | Result Codes | Units |
|---|---|---|---|
| USQA S | Ustekinumab QN, S | 65235 | mcg/mL |
| Ustekinumab Ab, S | 65236 | AU/mL |
Test Version
Last Updated
2025-11-19