CPT 84165Laboratory

Protein e-phoresis serum

CPT code 84165 covers a laboratory test that separates proteins in your blood serum using an electrical current to identify abnormal protein patterns. This test helps diagnose conditions like multiple myeloma, liver disease, kidney problems, and immune system disorders.

Showing rates for

National Average

Base Medicare rate

$17.14

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

0.37

PE RVU (NF)

0.15

MP RVU

0.01

Total RVU

0.53

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

Loading bundling edits…

Billing tips

Link to specific ICD-10 codes indicating medical necessity (D89.9 for disorder involving immune mechanism, R77.9 for abnormal serum protein, C90.00 for multiple myeloma evaluation) rather than screening codes
Impact: Prevents denial for lack of medical necessity; increases first-pass claim acceptance rate by 40-60% for this test
Do not bill 84165 with 84166 (immunoelectrophoresis) or 86334/86335 (immunofixation) on the same date without clear documentation of distinct medical necessity for each test
Impact: Avoids bundling denials and downcoding; prevents loss of $17.14 reimbursement per test when inappropriately bundled
Bill only once per specimen collection date unless repeat testing is medically necessary and documented; use modifier 91 for same-day repeats with documented clinical rationale
Impact: Prevents automatic denial of duplicate claims; allows recovery of additional $17.14 when legitimately repeated
Verify that referring physician's NPI and ordering documentation are complete before claim submission, as laboratory tests face high scrutiny in prepayment audits
Impact: Reduces claim rejection rate by 25-35%; incomplete ordering information is a top denial reason for laboratory claims
When billing for Medicare patients, ensure test is ordered for accepted indications; routine screening in asymptomatic patients without risk factors will be denied
Impact: Prevents non-coverage denials; Medicare LCD policies vary by MAC and may limit coverage to specific diagnosis codes
For reference laboratory arrangements, clarify financial responsibility and modifier 90 requirements based on your billing arrangement to avoid duplicate billing

Live Field Datano reports yet

Real billers contribute denial patterns and appeal strategies for this code. Once 5+ reports come in, you’ll see live aggregated data here — the only place this exists, free.

Working with CPT 84165?

Get the free Revenue Protection Toolkit — the denial triggers, modifier pitfalls, and bundling conflicts that quietly cost you reimbursement. Instant download.

Help build the field knowledge

MedPayIQ gets smarter as billers contribute. If you've had this code denied, share what happened so others learn from it. Anonymous, no patient info.

Related actions

Frequently asked questions

What is the 2025 Medicare reimbursement rate for CPT code 84165?

The 2025 Medicare national average non-facility reimbursement rate for CPT 84165 (protein electrophoresis serum) is $17.14. The facility rate is also $17.14. This is based on a total RVU of 0.53 (Work RVU: 0.37, PE RVU: 0.15, MP RVU: 0.01) multiplied by the 2025 conversion factor of 32.3465.

How often can CPT 84165 be billed for the same patient?

CPT 84165 can typically be billed once per medical encounter or specimen collection. For same-day repeat testing, modifier 91 must be appended with documentation of clinical necessity for the repeat test. Frequency limitations vary by payer; Medicare generally requires documented medical necessity for tests repeated within 30-60 days, such as monitoring treatment response in diagnosed conditions or evaluating acute clinical changes.

What diagnosis codes support medical necessity for CPT 84165?

Common diagnosis codes supporting 84165 include: C90.00-C90.02 (multiple myeloma), D89.9 (disorder involving immune mechanism), R77.2 (abnormal immunoglobulins), R77.9 (other abnormalities of plasma proteins), K70-K77 (liver diseases), N00-N08 (glomerular diseases), and codes for amyloidosis, Waldenström macroglobulinemia, or unexplained symptoms suggesting protein disorders. Routine screening codes without supporting clinical findings typically result in denial.

Can CPT 84165 be billed with immunofixation (86334/86335) on the same date?

Yes, but documentation must support medical necessity for both tests. Typically, 84165 (protein electrophoresis) is performed first as a screening test; if an abnormal protein pattern is detected, reflex testing with immunofixation (86334/86335) identifies the specific immunoglobulin type. Document the sequential nature of testing and abnormal findings from 84165 that triggered the immunofixation. Without proper documentation, payers may bundle or deny one of the tests.

What is the difference between CPT 84165 and 84166?

CPT 84165 is protein electrophoresis of serum, which separates total serum proteins into fractions (albumin and globulins). CPT 84166 is immunoelectrophoresis, a more specialized technique that identifies specific immunoglobulins using antibody reactions. Code 84166 is less commonly performed and has been largely replaced by immunofixation (86334/86335). These are distinct tests and should not be billed together without clear documentation of separate medical necessity.

Do I need modifier 91 when billing 84165 twice on the same day?

Yes, modifier 91 is required when billing 84165 more than once on the same date of service for the same patient to obtain subsequent reportable test results. Without modifier 91, the duplicate claim will be automatically denied as a duplicate service. Documentation must clearly state the clinical reason for repeat testing (not simply quality control or confirmation of results, but actual clinical need for additional information).

Is CPT 84165 covered by Medicare for routine screening?

No, Medicare does not typically cover CPT 84165 for routine screening in asymptomatic patients without risk factors or clinical indicators. Coverage requires documented medical necessity such as abnormal findings on prior tests, signs or symptoms consistent with protein disorders, monitoring diagnosed conditions, or evaluation of specific disease states. Local Coverage Determinations (LCDs) vary by Medicare Administrative Contractor (MAC), so verify your specific MAC's coverage policy.