Identifying monoclonal gammopathies using random urine specimens
Test Id | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
MPTRU | M-protein Mass-Fix, Random, U | No | Yes |
RPEU | Protein Electrophoresis, Random, U | No | Yes |
RPTU2 | Protein/Creatinine Ratio, Random, U | Yes, (RPTU1) | Yes |
MPTRU: Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS)
RPEU: Agarose Gel Electrophoresis
RPTU2: Turbidimetry/Enzymatic Colorimetric Assay
Mass-Fix
Mass Fix
MassFix
Bence Jones Urine
Heavy Chains Urine
Immunoelectrophoresis, Urine
Immunofixation Electrophoresis (IFE)
Immunofixation, Urine
Kappa Chains Urine
Lambda Chains Urine
Light Chains Urine
Paraprotein
Special Protein Studies, Urine
Urine
The use of a random urine specimen is sufficient for identifying the presence or absence of monoclonal proteins, but a 24-hour specimen is preferred for quantitating and monitoring the abnormality. See SMPU / Monoclonal Protein Studies, 24 Hour, Urine.
Refrigerate specimen during collection and send refrigerated.
Supplies: Urine Container, 60 mL (T313)
Submission Container/Tube: Plastic, 60-mL urine bottle
Specimen Volume: 50 mL
Collection Instructions:
1. Collect a random urine specimen.
2. Aliquot between 30 mL and 50 mL of urine into a plastic, 60-mL urine bottle.
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.
30 mL
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Urine | Refrigerated (preferred) | 14 days | |
Frozen | 5 days | ||
Ambient | 24 hours |
Identifying monoclonal gammopathies using random urine specimens
Urine proteins can be grouped into 5 fractions by protein electrophoresis:
-Albumin
-Alpha-1
-Alpha-2
-Beta-globulin
-Gamma globulin
One or more quantifiable monoclonal proteins may be present and reported as M spike.
The urine total protein concentration, the electrophoretic pattern, and the presence of a monoclonal immunoglobulin light chain may be characteristic of monoclonal gammopathies such as multiple myeloma, primary systemic amyloidosis, and light-chain deposition disease.
The following algorithms are available:
-Amyloidosis: Laboratory Approach to Diagnosis
CREATININE:
> or =18 years old: 16-326 mg/dL
Reference values have not been established for patients younger than 18 years of age.
PROTEIN/CREATINE RATIO:
> or =18 years: <0.18 mg/mg creatinine
Reference values have not been established for patients younger than 18 years of age.
ELECTROPHORESIS, PROTEIN:
The following fractions, if present, will be reported as mg/dL:
Albumin
Alpha-1 globulin
Alpha-2 globulin
Beta globulin
Gamma globulin
No reference values apply to random urines.
MASS-FIX M-PROTEIN ISOTYPE:
M-protein Isotype MS:
No monoclonal protein detected
Flag M-protein Isotype MS:
Negative
The presence of a monoclonal immunoglobulin light chain in the urine is seen in multiple myeloma, macroglobulinemia, primary systemic amyloidosis and light-chain deposition disease, monoclonal gammopathy of undetermined significance, and idiopathic Bence-Jones proteinuria. The presence of a monoclonal light chain can produce renal insufficiency, may be deposited as amyloid fibrils, may damage the proximal tubes producing Fanconi syndrome, or light chains may deposit in the glomerulus and cause light-chain deposition disease.
Heavy-chain fragments as well as light chains may be seen in the urine of patients with multiple myeloma or amyloidosis.
Monoclonal gammopathies are rarely seen in patients younger than 30 years of age.
Hemolysis may cause a discrete band on protein electrophoresis, which will be negative on isotyping.
Penicillin may split the albumin band.
Radiographic agents may produce an uninterpretable pattern.
1. Abraham RS, Barnidge DR: Protein analysis in the clinical immunology laboratory. In: Detrick B, Hamilton RG, Schmitz JL, eds. Molecular and Clinical Laboratory Immunology. 8th ed. Wiley; 2016:chap 4
2. Sykes E, Posey Y: Immunochemical characterization of immunoglobulins in serum, urine, and cerebrospinal fluid. In: Detrick B, Hamilton RG, Schmitz JL, eds. Molecular and Clinical Laboratory Immunology. 8th ed. Wiley; 2016:chap 9
Protein:
The sample is preincubated in an alkaline solution containing EDTA, which denatures the protein and eliminates interference from magnesium ions. Benzethonium chloride is then added, producing turbidity.(Package insert: Total Protein Urine/CSF. Roche Diagnostics; V13.0, 11/2018)
Creatinine:
The enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus v2. Roche Diagnostics; V15.0, 03/2019)
Electrophoresis:
Urine proteins are separated in an electric field according to their size, shape, and electric charge (Helena SPIFE Touch). The separation is performed on agarose gels. The proteins are visualized by staining with acid blue and the intensity of staining is quantitated by densitometry (Helena Quick Scan Touch). Multiplying by the urine protein concentration converts the percentage of protein in each fraction into urine concentration.(Instruction manual: SPIFE Touch. Helena Laboratories, Corp; 11/2016; package insert: SPIFE Touch SPE Pro 277. Helena Laboratories, Corp; 06/2018; Keren DF, Humphrey RL: Clinical indications and applications for serum and urine protein electrophoresis and immunofixation. In: Detrick B, Hamilton RG, Schmitz JL, eds. Molecular and Clinical Laboratory Immunology. 8th ed. Wiley; 2016:chap 8)
Mass-Fix:
M-protein isotype by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is performed with immunoaffinity purification followed by MALDI-TOF MS analysis. For the immunoaffinity purification, patient sample is applied to 5 separate immunoaffinity resins (CaptureSelect, Life Sciences) specific to immunoglobulin G, A, M, K, and L. Unbound protein is washed away and the isolated immunoglobulins are to separate the heavy and light chains subunits to be analyzed via MALDI-TOF MS. The 5 separate spectra from each patient immunopurification are overlaid and investigated for an overabundance of immunoglobulin and immunoglobulin light chain.(Milani P, Murray DL, Barnidge DR, et al: The utility of MASS-FIX to detect and monitor monoclonal proteins in the clinic. Am J Hematol. 2017 Aug;92(8):772-779. doi: 10.1002/ajh.24772)
Monday through Friday
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.
84156
82570
84166
0077U
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
RMPU | M-protein Studies, Random, U | 101909-0 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
33044 | A/G Ratio | 44293-9 |
33045 | M spike | 40661-1 |
33046 | M spike | 40661-1 |
33047 | Impression | 49299-1 |
607975 | Albumin | 6942-7 |
607976 | Alpha-1 globulin | 9734-5 |
607977 | Alpha-2 globulin | 38190-5 |
607978 | Beta globulin | 9744-4 |
607979 | Gamma globulin | 9745-1 |
617119 | M-protein Isotype MS, Random, U | In Process |
617120 | Flag M-protein Isotype MS, Random, U | No LOINC Needed |
CRTR1 | Creatinine, Random, U | 2161-8 |
PCRT1 | Protein/Creatinine Ratio | 2890-2 |
PTCN1 | Protein, Total, Random, U | 2888-6 |
Change Type | Effective Date |
---|---|
New Test | 2023-05-16 |