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CPT code 78121: Red cell mass, multiple determinations2026 Medicare rate & RVUs

Reports a nuclear medicine study that determines circulating red cell mass using multiple measurements, often during evaluation of erythrocytosis.

CMS RVU26DEffective Oct 1, 2026109 payment localities219 Medicare services in 2024

Medicare pays $97.53 for 78121 nationally in the office. Local office rates run $84.66–$135.69.

Medicare rate · 78121

Red cell mass, multiple determinations

Office or facility?

Work RVUs
0.31
Total RVUs
2.92
Global days
XXX

National rate · 2026

$97.53

Office setting, before claim adjustments.

See every locality for 78121 →Billed by an NP, PA or therapist? →

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

Your location

Medicare pays by the payment locality where the service is performed.

On this page 10 sections
  1. Medicare rate
  2. What 78121 covers
  3. By payment locality
  4. Rate map
  5. How it’s calculated
  6. Payment rules
  7. Similar codes
  8. Related codes
  9. Billing questions
  10. Sources

What 78121 covers

This study measures the amount of red blood cells circulating in the patient’s body. It commonly involves labeling the patient’s red cells, returning them to circulation, and obtaining multiple measurements from blood samples. Nuclear medicine staff perform the technical work, and a qualified physician interprets the results. The test may help evaluate whether an elevated red cell count reflects increased red cell mass or another cause, such as reduced plasma volume.

Select this code when the performed study includes multiple red cell mass determinations; use the single-determination code when only one is performed. Documentation should identify the study performed, its multiple measurements, and the physician’s interpretation. CMS recognizes professional and technical components: modifier 26 identifies interpretation, modifier TC identifies equipment and staff, and billing without either modifier represents the global service. Modifiers 26 and TC are separately priced.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where 78121 pays more and less

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 payment localities

$84.66 to $135.69

$84.66$110.17$135.69
One dot per payment locality, office / nonfacility. Hover a dot to see the locality; select it to open that rate.

109 of 109 payment localities

78121 office and facility rates by payment locality
Payment localityOfficeFacility
Alabama$86.12Unavailable
Alaska$107.52Unavailable
Arizona$94.64Unavailable
Arkansas$84.66Unavailable
Atlanta, GA$99.27Unavailable
Austin, TX$102.32Unavailable
Bakersfield, CA$105.28Unavailable
Baltimore area, MD$104.33Unavailable
Beaumont, TX$89.72Unavailable
Brazoria, TX$96.48Unavailable

78121 rates by state

Office rate range in each state. Select a state to see its payment localities.

MEWIVTNHMTNDMNMINYMARIWAIDWYSDIAILINOHPANJCTORNVUTCONEMOKYWVVAMDDECAAZNMKSOKARTNNCSCDCTXLAMSALGAFLAKHI

Explore a state

Local rates. Clear comparisons.

Hover or focus a tile to see its rate range. Select it to open the state’s fee schedule.

$84.66

$120.41

Color shows the midpoint of each state’s locality range.

View every state and territory as a table
78121 office rate range by state
State / territoryOffice rate rangeLocalities
AK$107.521
AL$86.121
AR$84.661
AZ$94.641
CA$105.14–$135.6929
CO$102.761
CT$104.671
DC$113.501
DE$96.391
FL$94.61–$103.593
GA$88.62–$99.272
GU$108.541
HI$108.541
IA$89.261
ID$89.811
IL$91.03–$101.204
IN$90.431
KS$88.491
KY$87.901
LA$87.63–$92.712
MA$101.89–$114.362
MD$98.52–$113.503
ME$90.06–$96.142
MI$90.31–$95.682
MN$98.831
MO$85.69–$93.433
MS$85.211
MT$97.531
NC$91.201
ND$96.541
NE$89.911
NH$100.831
NJ$105.97–$111.982
NM$90.771
NV$97.341
NY$92.76–$115.795
OH$90.101
OK$88.011
OR$96.69–$106.762
PA$90.43–$101.552
PR$98.451
RI$100.371
SC$90.781
SD$96.421
TN$88.981
TX$89.72–$102.328
UT$92.231
VA$95.59–$113.502
VI$98.451
VT$95.851
WA$101.80–$117.152
WI$92.781
WV$87.051
WY$97.101

How the 78121 rate is calculated

Each of 78121’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

How the rate is built · 78121

RVUs × geographic indexes × conversion factor

Office or facility?

Work0.31

0.31 RVUs× 1.000 GPCI

Practice expense2.56

2.56 RVUs× 1.000 GPCI

Malpractice0.05

0.05 RVUs× 1.000 GPCI

Adjusted RVUs

2.9200

Conversion factor

$33.4009

Medicare rate

$97.53

Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.

Payment rules and modifiers for 78121

The CMS indicators that decide how 78121 is paid alongside other services.

CMS payment indicators · 78121

Red cell mass, multiple determinations

RuleCMS valueWhat it means
Global periodXXXThe global surgery concept doesn’t apply.
Multiple procedures0No multiple-procedure reduction.
Bilateral (modifier 50)0The 150% bilateral adjustment doesn’t apply.
Assistant at surgery (80/81/82/AS)0Not paid without supporting documentation.
Co-surgeons (62)0Not permitted.
Team surgery (66)0Not permitted.
Professional/technical1Diagnostic test with separate professional (26) and technical (TC) components.

What modifiers do to the payment

Modifier 26 · payment effect

With and without the modifier

78121 without 26 · national office

$97.53

Red cell mass, multiple determinations

78121-26 · Professional component

$14.70

Pays only the interpretation and report.

When to use modifier 26

78121 compared with similar codes

Compare codes · National

4 codes, side by side

Office or facility?

  • 78121

    Red cell mass, multiple determinations0.31 wRVU

    $97.53

  • 78120

    Red cell mass, single determination0.22 wRVU

    $72.48−$25.05

  • 78122

    Blood volume test, whole blood determination0.44 wRVU

    $101.20+$3.67

  • 78111

    Plasma volume, multiple sampling0.21 wRVU

    $96.86−$0.67

How to choose

78120Red cell massSingle determination
Both report red cell mass testing. Choose 78121 for multiple determinations and 78120 for a single determination.
78122Blood volume testWhole blood determination
78122 reports total blood-volume determination; 78121 reports multiple determinations of red cell mass specifically.
78111Plasma volumeMultiple sampling
78111 measures plasma volume through multiple determinations, while 78121 measures red cell mass through multiple determinations.

Codes related to 78121

Related codes aren’t interchangeable: bill the code that matches the service performed.

Codes related to 78121
CodeHow it relatesNational office range
Same family
78120Red cell mass, single determinationRed cell mass study with a single determination rather than multiple determinations.$62.72–$100.56
Often billed with
78111Plasma volume, multiple samplingMultiple plasma-volume determinations may accompany red cell mass testing in a blood-volume assessment.$83.62–$135.83
Used instead
78122Blood volume test, whole blood determinationDetermines total blood volume rather than reporting red cell mass alone.$88.32–$139.24
78130Red-cell survival, erythrocyte lifespanEvaluates red cell survival over time rather than measuring circulating red cell mass.$111.00–$174.36

78121 billing questions

When should 78121 be chosen instead of 78120?

Use 78121 when the red cell mass study involves multiple determinations. Use 78120 when the study involves a single determination.

Does “multiple” mean the test was repeated on another date?

It refers to multiple determinations in the performed study, not simply a later repeat of the test. The record should support that the study included multiple measurements.

How should the professional and technical portions be billed?

Report modifier 26 for the physician’s interpretation or modifier TC for the technical service. Without either modifier, the claim represents the global service.

Can plasma volume testing be reported with this study?

A plasma volume determination is a separate measurement from red cell mass and may be performed as part of a blood-volume assessment. The record should support each service reported.

What documentation supports 78121?

Document the red cell mass study, the multiple determinations performed, and the physician’s interpretation. The technical record should support the equipment and staff services when the TC portion is billed.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Show the CMS file lines behind this rate
RVUs for 78121PPRRVU2026_Oct_nonQPP.csv, line 9,233 (RVU26D)

Open CMS sourceHow we calculate rates

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