84166 Protein e-phoresis/urine/csf
Also known as: urine protein electrophoresis, CSF protein electrophoresis, UPEP
Electrophoresis of proteins in urine and/or cerebrospinal fluid separating and identifying protein fractions.
In Plain Language
urine/spinal fluid protein test
Clinical Context
Identifies abnormal proteins in urine (Bence Jones proteins in myeloma) or CNS fluid; detects monoclonal components and inflammatory patterns.
RVU Breakdown
| Work RVU | 0.37 |
| Total RVU | 0.37 |
Est. Medicare Payment
National estimate based on 2026 CMS PFS Conversion Factor ($33.40). Actual payment varies by locality (GPCI adjustment).
Billing & Documentation
Lab and pathology codes require an order from the treating provider with clinical indication. For molecular pathology and genetic testing, document the specific analytes tested and clinical rationale.
How This Code Compares
With a work RVU of 0.37, this code ranks in the 29th percentile among Pathology & Lab codes — 1.8x below the median (0.68). The highest wRVU in this category is 2.78.
Specialties
Frequently Asked Questions
What is CPT code 84166?
CPT 84166 (Protein e-phoresis/urine/csf) is a Pathology & Lab code. Electrophoresis of proteins in urine and/or cerebrospinal fluid separating and identifying protein fractions.
Who uses CPT code 84166?
CPT 84166 is used by Clinical Chemistry, Nephrology, Laboratory Medicine. Identifies abnormal proteins in urine (Bence Jones proteins in myeloma) or CNS fluid; detects monoclonal components and inflammatory patterns.
When is CPT 84166 used?
Identifies abnormal proteins in urine (Bence Jones proteins in myeloma) or CNS fluid; detects monoclonal components and inflammatory patterns.
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CPT® is a registered trademark of the American Medical Association. Data sourced from CMS Physician Fee Schedule RVU26A. Descriptions, synonyms, and clinical context are original content by RVU Edge.