Billing code 78121: Red cell massMedicare rate & RVUs in Georgia
Reports a nuclear medicine study that determines circulating red cell mass using multiple measurements, often during evaluation of erythrocytosis.
Medicare pays $88.62–$99.27 for 78121 in the office in Georgia, from Rest Of Georgia to Atlanta. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
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 in Georgia
| Payment locality | Office | Facility |
|---|---|---|
| Atlanta | $99.27 | Unavailable |
| Rest Of Georgia | $88.62 | Unavailable |
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
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
| Rule | CMS value | What it means |
|---|---|---|
| Global period | XXX | The global surgery concept doesn’t apply. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 1 | Diagnostic 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
78121-26 · Professional component
$14.70
Pays only the interpretation and report.
78121 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 78120Red cell mass
- Both report red cell mass testing. Choose 78121 for multiple determinations and 78120 for a single determination.
- 78122Blood volume test
- 78122 reports total blood-volume determination; 78121 reports multiple determinations of red cell mass specifically.
- 78111Plasma volume
- 78111 measures plasma volume through multiple determinations, while 78121 measures red cell mass through multiple determinations.
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
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