Billing code 88319: Enzyme histochemistryMedicare rate & RVUs in Washington
Reports enzyme histochemical analysis of a tissue specimen, often in muscle biopsy workups where demonstrating enzyme activity helps characterize a disorder.
Medicare pays $137.94–$158.40 for 88319 in the office in Washington, from Rest Of Washington to Seattle (King Cnty). 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 88319 covers
Enzyme histochemistry uses stains to demonstrate enzyme activity in tissue, supporting evaluation of suspected metabolic or neuromuscular disease. A common setting is a muscle biopsy workup, where a pathology laboratory processes tissue and a pathologist interprets the staining pattern. The service is reported for each specimen analyzed, rather than for each individual stain applied to that specimen.
Select the code when the documented work specifically evaluates tissue enzyme activity. The pathology report and laboratory record should identify the specimen and findings that support the enzyme study. Medicare recognizes professional and technical components: modifier 26 identifies the interpretation, modifier TC identifies the laboratory work, and billing without either modifier represents the global service.
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 88319 pays more and less in Washington
| Payment locality | Office | Facility |
|---|---|---|
| Rest Of Washington | $137.94 | Unavailable |
| Seattle (King Cnty) | $158.40 | Unavailable |
How the 88319 rate is calculated
Each of 88319’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 · 88319
RVUs × geographic indexes × conversion factor
Work0.52
0.52 RVUs× 1.000 GPCI
Practice expense3.40
3.40 RVUs× 1.000 GPCI
Malpractice0.03
0.03 RVUs× 1.000 GPCI
Adjusted RVUs
3.9500
Conversion factor
$33.4009
Medicare rate
$131.93
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 88319
The CMS indicators that decide how 88319 is paid alongside other services.
CMS payment indicators · 88319
Enzyme histochemistry
| 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
88319 without 26 · national office
$131.93
Enzyme histochemistry
88319-26 · Professional component
$25.38
Pays only the interpretation and report.
88319 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 88312Special stain
- 88312 represents its designated special-stain group, including stains used to identify microorganisms. Use 88319 when the study demonstrates enzyme activity in tissue.
- 88313Special stain
- 88313 covers a different designated special-stain group. The distinction is the stain type and purpose, not simply the number of stains performed.
- 88314Histochemical stain
- 88314 is for histochemical staining on frozen sections. Code 88319 is selected for enzyme histochemistry by specimen.
- 88342Antibody stain
- 88342 reports immunohistochemistry using an antibody. Choose 88319 when the tissue study demonstrates enzyme activity instead.
88319 billing questions
Is 88319 reported per stain or per specimen?
Report it per specimen analyzed. Multiple enzyme stains on the same specimen do not, by themselves, establish multiple units.
When should 88319 be chosen over 88312 or 88313?
Use 88319 for tissue enzyme histochemistry. Codes 88312 and 88313 cover other special-stain groups, so choose according to the type of stain performed.
How are the professional and technical services reported?
Use modifier 26 for the pathologist’s interpretation and modifier TC for the laboratory work. Without either modifier, the claim represents the global service.
What documentation supports reporting 88319?
The record should identify the tissue specimen and document enzyme histochemical analysis and the resulting interpretation. A general tissue examination alone does not establish this service.
Can 88319 be reported with a surgical pathology examination?
It may be reported with a surgical pathology examination when enzyme histochemistry is separately performed and documented for the specimen. The pathology record should support both services.
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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