Gamma Glutamyl Transferase — NCD 153 | CMS Coverage Update

TL;DR: The Centers for Medicare & Medicaid Services modified NCD 153, the national coverage determination governing Gamma Glutamyl Transferase (GGT) testing, effective March 7, 2026. Here's what billing teams need to know.

The CMS GGT coverage policy under NCD 153 Medicare defines when this liver enzyme test is covered, when it isn't, and—critically—when repeating the test will get your claim denied. This policy does not list specific CPT or HCPCS codes in the current document, so your billing team will need to cross-reference your charge master for the applicable lab codes. If GGT testing is part of your lab billing volume, read this before your next billing cycle.

Quick-Reference Table

CMS Gamma Glutamyl Transferase Coverage Criteria and Medical Necessity Requirements 2026

The CMS GGT coverage policy under NCD 153 covers Gamma Glutamyl Transferase testing in seven specific clinical situations. Every one of them ties to hepatobiliary function. Get used to thinking about this test that way — if the order isn't about the liver or biliary tract, Medicare probably won't pay for it.

Here are the seven covered indications under NCD 153:

That last one is where GGT billing gets interesting. GGT is uniquely suited to isolate liver-origin alkaline phosphatase from bone or placental sources. If your ordering provider is using GGT to sort out an unexplained alkaline phosphatase elevation, document that clinical question clearly. That documentation supports medical necessity for the claim.

Medical necessity under this coverage policy depends entirely on which indication the ordering physician documents. Vague orders like "liver function panel" without a clear clinical context are a claim denial waiting to happen.

This policy doesn't mention prior authorization requirements for GGT testing. That tracks — this is a lab test ordered in the course of clinical management, not a scheduled procedure. But lack of prior authorization requirements doesn't mean documentation is optional. Medicare still requires medical necessity to be established in the medical record.

For reimbursement purposes, your MAC may have additional local coverage determination (LCD) policies that layer on top of NCD 153. Check with your Medicare Administrative Contractor if you're seeing unexpected denials — especially if you're billing high volumes of GGT tests for patients who don't clearly fall into one of the seven covered indications.

CMS GGT Testing Exclusions and Non-Covered Indications

NCD 153 doesn't use the word "excluded" — but it defines four situations where GGT testing is generally not necessary. These are your denial triggers. Know them.

Limitation 1: Normal result after monitoring non-hepatobiliary disease. If you ordered GGT to monitor liver dysfunction secondary to a non-hepatobiliary disease, got a normal result, and nothing has changed in the patient's signs, symptoms, or treatment plan — don't repeat it. Medicare won't pay for it unless new indications appear.

This one catches people. A provider monitoring a lupus patient for liver involvement gets a normal GGT. The patient's condition is stable. Ordering a follow-up GGT three months later, with no new symptoms, is a problem. Document any new indications clearly if you do repeat the test.

Limitation 2: GGT is the only abnormal liver enzyme. If GGT is elevated but every other liver enzyme is normal, NCD 153 says it's generally not necessary to pursue further GGT evaluation for liver disease under that specific indication. An isolated GGT elevation in the absence of other findings doesn't automatically justify serial testing.

Limitation 3: Frequency cap for source differentiation. When GGT is being used to determine whether abnormal enzyme tests reflect liver abnormality rather than other tissue sources, you generally can't repeat it more than once per week. One test per week is the outer limit for this indication.

Limitation 4: Monitoring known liver disease. GGT is extremely sensitive — so sensitive that it's actually not useful for monitoring patients with known liver disease. An elevated GGT in a patient with established cirrhosis, for example, tells you almost nothing actionable. NCD 153 explicitly calls this out. Don't bill repeated GGT tests for monitoring purposes in confirmed liver disease cases. Medicare won't consider them medically necessary.

The real issue here is frequency. CMS isn't saying GGT is rarely covered — it's saying that repeating GGT without a clear, documented clinical reason is where claims fall apart. Your billing guidelines should flag repeat GGT orders for the same patient within short intervals and trigger a documentation review before the claim goes out.

Coverage Indications at a Glance

CMS GGT Billing Guidelines and Action Items 2026

GGT billing billing under NCD 153 is straightforward — until it isn't. Here's what your team should do before March 7, 2026, and after.

CPT, HCPCS, and ICD-10 Codes for GGT Under NCD 153

The current NCD 153 policy document does not list specific CPT, HCPCS, or ICD-10-CM codes. This is not unusual for older NCD frameworks — the code-level detail is often maintained at the MAC or LCD level rather than in the national determination itself.

What this means for your billing team: You cannot rely on NCD 153 alone to build your charge capture or claim edits for GGT billing. You need to:

• Identify the CPT code(s) your lab uses for GGT testing. Check your charge description master.
• Confirm which ICD-10-CM codes your MACs require for each of the seven covered indications.
• Check for any active LCD from your regional Medicare Administrative Contractor that references NCD 153 and specifies code-level requirements.

If your compliance officer or billing consultant isn't already tracking MAC-level guidance alongside this NCD, now is the time to set that up. The national coverage determination tells you the rules. Your MAC tells you how to bill them.