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Test Code MALDO M-Protein Isotype, Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry, Serum

Specimen Required

Patient Preparation: Fasting 12 hours preferred but not required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Useful For

Aiding in the diagnosis of monoclonal gammopathies, when used in conjunction with free light chain studies


This test alone is not considered an adequate screen for monoclonal gammopathies.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IGD Immunoglobulin D (IgD), S Yes No
IMMG Immunoglobulins IgG,A,M, S Yes No
FLCP Immunoglobulin Free Light Chains, S Yes No
IMFX Immunofixation Yes, (IMFXO) No
IGE Immunoglobulin E (IgE), S Yes No

Testing Algorithm

This test includes M-protein isotyping. If a light chain is identified without a corresponding heavy chain during initial testing, immunofixation with IgD and IgE antisera will be performed at an additional charge.

Method Name

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

Reporting Name

M-Protein Isotype Only, S

Specimen Type


Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  14 days
  Ambient  7 days

Reference Values

Negative: No monoclonal protein detected.

Day(s) and Time(s) Performed

Monday through Friday

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. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
MALDO M-Protein Isotype Only, S 90990-3


Result ID Test Result Name Result LOINC Value
606982 M-protein Isotype Flag, S 94400-9
606590 M-Protein Isotype MALDI-TOF MS 90990-3