Monoclonal Protein Screen, Random, Urine
Use
This test is useful for identifying monoclonal gammopathies using random urine specimens. The presence of monoclonal immunoglobulin light chains or quantifiable M-spikes can indicate conditions such as multiple myeloma, primary systemic amyloidosis, light‑chain deposition disease, monoclonal gammopathy of undetermined significance, and idiopathic Bence‑Jones proteinuria. Analysis includes evaluation of urine total protein concentration, electrophoretic pattern, and M‑protein isotype. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/616915?utm_source=openai))
Special Instructions
Profile includes MPTRU (M‑protein Mass‑Fix, Random, U) always performed, and RPTU2 (Protein/Creatinine Ratio, Random, U) always performed (available separately). Reflex test RPEU (Protein Electrophoresis, Random, U) may be performed at additional charge if MASSFIX is positive. Collect random urine aliquot of 30–50 mL into 60 mL plastic urine bottle and refrigerate. Submit refrigerated specimens. If not ordering electronically, use Renal Diagnostics Test Request (T830). ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/616915?utm_source=openai))
Limitations
A random urine specimen is sufficient for screening the presence/absence of monoclonal proteins, but a 24‑hour urine is preferred for quantitation and monitoring. Urine M‑protein MASSFIX alone is not considered adequate screening; reflex to protein electrophoresis is needed if positive. No FDA clearance; developed under CLIA. Hemolysis, radiographic agents, or penicillin can interfere with electrophoresis interpretation. Monoclonal gammopathies are rare in patients <30 years old. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/616915?utm_source=openai))
Methodology
Mass Spectrometry (MALDI-TOF)
Biomarkers
LOINC Codes
- In Process
- In Process
- No LOINC Needed
- 2161-8
- 2890-2
- 2888-6
Result Turnaround Time
4-6 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
50 mL
Minimum Volume
30 mL
Container
Plastic, 60‑mL urine bottle
Collection Instructions
Collect random urine specimen; aliquot between 30 mL and 50 mL into plastic, 60 mL urine bottle and refrigerate.
Causes for Rejection
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Ambient: 24 hours |
| Refrigerated | Refrigerated (preferred): 14 days |
| Frozen | Frozen: 5 days |