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

In Merced, CA, Medicare pays $105.14 for 78121 in the office.

Check a contract rate as a % of Medicare · 78121 nationwide

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

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.

How Merced, CA compares for 78121

Across 109 of 109 payment localities, the office rate for 78121 runs from $84.66 in Arkansas to $135.69 in San Benito County, CA. Merced, CA pays $105.14. The RVUs are the same everywhere; the geographic indexes change the dollars.

Every other payment area

78121 rates by state

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

See 78121 in every payment locality

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.

Payment rules and modifiers for 78121

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

What modifiers do to the payment

When to use modifier 26

Codes related to 78121

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

How 78121 has changed in Merced, CA

Price 78121 for an earlier date of service

Where the Merced, CA rate applies

Merced, CA is a Medicare payment area, not a city. Our Census mapping connects it to 24 cities and communities in California. Some span more than one payment area; confirm with the service ZIP.

• Merced
• Atwater
• Ballico
• Bear Creek
• Cressey
• Delhi
• Dos Palos
• Dos Palos Y

Browse all communities in California

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

Open CMS sourceHow we calculate rates