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Test Code RMPU Monoclonal Protein Studies, Random, Urine


Ordering Guidance


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.



Shipping Instructions


Refrigerate specimen during collection and send refrigerated.



Specimen Required


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.


Useful For

Identifying monoclonal gammopathies using random urine specimens

Profile Information

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

Testing Algorithm

The following algorithms are available:

-Amyloidosis: Laboratory Approach to Diagnosis

-Multiple Myeloma: Laboratory Screening

Method Name

MPTRU: Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS)

RPEU: Agarose Gel Electrophoresis

RPTU2: Turbidimetry/Enzymatic Colorimetric Assay

Reporting Name

M-protein Studies, Random, U

Specimen Type

Urine

Specimen Minimum Volume

30 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days
  Frozen  5 days
  Ambient  24 hours

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

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

-Multiple Myeloma: Laboratory Screening

Reference Values

CREATININE:

≥18 years old: 16-326 mg/dL

Reference values have not been established for patients younger than 18 years of age.

 

PROTEIN/CREATINE RATIO:

≥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

Interpretation

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.

Cautions

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.

Method Description

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)

Day(s) Performed

Monday through Friday

Report Available

4 to 6 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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.

CPT Code Information

84156

82570

84166

0077U

LOINC Code Information

Test ID Test Order Name Order LOINC Value
RMPU M-protein Studies, Random, U 101909-0

 

Result ID Test Result Name Result LOINC Value
607975 Albumin 6942-7
617119 M-protein Isotype MS, Random, U In Process
PTCN1 Protein, Total, Random, U 2888-6
617120 Flag M-protein Isotype MS, Random, U No LOINC Needed
CRTR1 Creatinine, Random, U 2161-8
607976 Alpha-1 globulin 9734-5
607977 Alpha-2 globulin 38190-5
PCRT1 Protein/Creatinine Ratio 2890-2
607978 Beta globulin 9744-4
607979 Gamma globulin 9745-1
33044 A/G Ratio 44293-9
33045 M spike 40661-1
33046 M spike 40661-1
33047 Impression 49299-1