Protein Electrophoresis, Random Urine With Reflex to IFE, Random Urine
| Protein Electrophoresis, Random Urine With Reflex to IFE, Random Urine | | | |
| Number | | 003715 |
CPT | | 84156; 84166 |
| Synonyms | | Electrophoresis, Protein, Random Urine With Reflex to IFE, Urine ; Urine Electrophoresis, Random Urine With Reflex to IFE, Urine ; Urine Protein Electrophoresis, Random Urine With Reflex to IFE, Urine |
| Test Includes | | Random urine protein electrophoresis with automatic reflex to urine immunofixation (IFE) at additional charge if M-spike is present. |
| Special Instructions | | For 24-hour urine specimens, order test 123018. |
| Specimen | | Urine (random) |
| Volume | | 20 mL aliquot |
| Minimum Volume | | 5 mL aliquot |
| Container | | Plastic urine container, no preservative |
| Collection | | Collect first morning urine; mix well. |
| Storage Instructions | | Refrigerate at 2°C to 8°C. |
| Causes for Rejection | | Preservative added |
| Use | | Work up myeloma, macroglobulinemia of Waldenström, lymphoma, amyloidosis; differentiate between normal renal function, glomerular proteinuria, and tubular proteinuria. Increased glomerular permeability leads to higher concentrations of large proteins in the glomerular filtrate. Diminished tubular reabsorptive capacity results in a marked increase in urinary excretion of low molecular weight problems. |
| Limitations | | May not detect pathologic light chains due to insufficient sensitivity. Should be followed with immunoelectrophoretic or immunofixation study performed on concentrated urine. Optimal specimen when looking for a free monoclonal light chain (Bence Jones protein) is a 24-hour collection. |
| Methodology | | Electrophoresis on agarose media |
| Additional Information | | A serum protein electrophoresis should be reviewed concurrently if one has not been recently studied. In nonselective glomerular proteinuria, the urine electrophoretic pattern is often a nonspecific one which may be called “mirror image” to that of the serum. Contamination of the urine with blood can give a similar pattern. With selective glomerular permeability, albumin, alpha1 proteins, and transferrin are the predominant proteins identified on the urine protein electrophoresis, with a relative absence of heavier molecular weight proteins (ie, alpha2 macroglobulin and immunoglobulins). With tubular proteinuria, low molecular weight proteins (alpha2 macroglobulin) are predominant, with trace amounts of albumin. So called “overflow proteinuria” occurs when low molecular weight proteins are filtered through the glomerulus in increased amounts. |
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