Electrophoresis, Protein, Urine
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urine proteins can be grouped into 5 fractions by protein electrophoresis:
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.
Monitoring patients with monoclonal gammopathies
Urine protein electrophoresis alone is not considered an adequate screening for monoclonal gammopathies
A characteristic monoclonal band (M-spike) is often found in the urine of patients with multiple myeloma (MM). The initial identification of an M-spike or an area of restricted migration should be followed by MPSU / Monoclonal Protein Study, Urine that includes immunofixation to identify the immunoglobulin heavy chain and/or light chain. Immunoglobulin heavy chain fragments as well as free light chains may be seen in the urine of patients with monoclonal gammopathies.
The presence of a monoclonal light chain M-spike of >1 g/24 hours is consistent with a diagnosis of MM or macroglobulinemia.
The presence of a small amount of monoclonal light chain and proteinuria (total protein >3 g/24 hours) which is predominantly albumin is consistent with amyloidosis (AL) or light chain deposition disease (LCDD). Because patients with AL and LCDD may have elevated urinary protein without an identifiable M-spike, urine protein electrophoresis is not considered an adequate "screen" for the disorder. MPSU / Monoclonal Protein Study, Urine that includes immunofixation should be performed if the clinical suspicion is high.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Patients suspected of having a monoclonal gammopathy may have a normal urine protein electrophoretic pattern, and these patients should have immunofixation (MPSU / Monoclonal Protein Study, Urine) performed. Monoclonal gammopathies are rarely seen in patients <30 years of age.
Hemolysis may cause a discrete band on protein electrophoresis, which will be negative on immunofixation.
Penicillin may split the albumin band.
Radiographic agents may produce an uninterpretable pattern.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
> or =18 years: <102 mg/24 hours
Reference values have not been established for patients that are <18 years of age.
If protein concentration is abnormal, the following fractions, if present, will be reported as a percent of the protein, total.
Reference value applies to 24-hour collection. Specimens collected for periods other than 24 hours will be reported in concentration units.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Kyle, RA, Katzmann, JA, Lust, JA, Dispenzieri A: Clinical indications and applications of electrophoresis and immunofixation. In Manual of Clinical Laboratory Immunology. Sixth edition Edited by NR Rose, RG Hamilton, B Detrick: Washington, DC. ASM Press, 2002, pp 66-67
2. Kyle, RA, Katzmann, JA, Lust, JA, Dispernzieri, A: Immunochemical characterization of immunoglobulins. In Manual of Clinical Laboratory Immunology. Sixth edition, Edited by NR Rose, RG Hamilton, B Detrick. Washington, DC. ASM Press, 2002, pp 71-91