What is a Urine Protein Electrophoresis (UPEP) test?
Urine Protein Electrophoresis (UPEP) is a laboratory test that separates and measures different types of proteins found in urine.
Normally, only a small amount of protein passes into the urine. UPEP helps determine which proteins are present and in what pattern, which can provide information about kidney function and certain blood or plasma-cell disorders.
What is it used for?
UPEP may be used to:
Investigate unexplained protein in the urine (proteinuria)
Help evaluate kidney disease
Detect abnormal proteins such as monoclonal proteins (M-proteins)
Support the investigation of multiple myeloma and other plasma-cell disorders
Help identify whether urinary protein loss is mainly glomerular or tubular
Monitor certain disorders that produce abnormal immunoglobulins
UPEP is often performed together with serum protein electrophoresis (SPEP) and, when indicated, immunofixation electrophoresis (IFE).
Why do I need a Urine Protein Electrophoresis test?
Your healthcare provider may request UPEP if you have:
Persistent or unexplained proteinuria
Abnormal kidney function
Unexplained anemia or bone abnormalities
High total protein or abnormal protein results in blood
Suspected monoclonal gammopathy or multiple myeloma
A previously detected abnormal protein that needs monitoring
What happens during the test?
A urine sample is collected and sent to the laboratory.
Depending on the laboratory's protocol, UPEP may be performed on:
A 24-hour urine collection, which allows measurement of total protein excretion and protein distribution, or
A random urine sample, particularly for screening or when combined with other urine protein measurements.
In the laboratory, proteins are separated according to their electrical properties, producing an electrophoretic pattern. The major protein fractions can then be assessed.
Will I need to do anything to prepare for the test?
Usually, no special preparation such as fasting is required.
If a 24-hour urine collection is requested, it is important to:
Start the collection at the instructed time.
Discard the first urine at the start time.
Collect all urine for the next 24 hours.
Include the final urine specimen at the end of the collection period.
Keep the container stored as instructed, usually refrigerated or appropriately cooled.
An incomplete collection can make the results difficult to interpret.
Are there any risks to the test?
There are no significant risks associated with collecting urine.
If a 24-hour collection is required, the main concern is accidentally missing one or more urine specimens.
What do the results mean?
UPEP evaluates the amount and pattern of proteins present in urine.
Normally, urinary protein is predominantly albumin, with smaller amounts of other proteins.
Increased urinary protein
An increased amount of protein may occur with:
Glomerular kidney disease
Diabetic kidney disease
Hypertension-related kidney disease
Tubular disorders
Inflammation or infection of the urinary tract
Some plasma-cell disorders
The pattern of protein excretion can be particularly useful in determining the possible source of the protein.
Monoclonal protein detected
A distinct or restricted protein band may suggest the presence of a monoclonal protein.
This can occur in conditions such as:
Multiple myeloma
Monoclonal gammopathy of undetermined significance (MGUS)
Other plasma-cell or B-cell disorders
However, UPEP alone does not establish a diagnosis. Additional testing, particularly urine immunofixation, may be more sensitive for identifying and characterizing small monoclonal proteins.
Important note
UPEP should generally be interpreted together with the patient's clinical findings and other laboratory tests, such as:
Urine total protein
Urine albumin/creatinine ratio (ACR)
Serum protein electrophoresis (SPEP)
Serum and urine immunofixation
Serum free light chains
Creatinine and eGFR
Complete blood count and other tests when plasma-cell disorders are suspected
A negative UPEP does not necessarily exclude a monoclonal protein, particularly when the amount is small.
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