Gamma Glutamyl Transferase — NCD 153 | CMS Coverage Update

CMS Modified NCD 153 for Gamma Glutamyl Transferase (GGT), effective March 7, 2026. Here's what billing teams need to know.

The Centers for Medicare & Medicaid Services updated its coverage policy for Gamma Glutamyl Transferase (GGT) testing under NCD 153 in the Medicare National Coverage Determinations system. This policy governs when GGT lab tests are covered as medically necessary under Medicare's Diagnostic Laboratory Tests benefit category. NCD 153 in the CMS Medicare system does not list specific CPT or HCPCS codes — which creates real documentation risk for billing teams who assume any GGT order is automatically covered.

Quick-Reference Table

CMS Gamma Glutamyl Transferase Coverage Criteria and Medical Necessity Requirements 2026

The CMS GGT coverage policy is clinically specific. Not every GGT order qualifies. CMS ties medical necessity directly to the clinical reason the test was ordered — and that reason has to match one of the covered indications in NCD 153.

GGT billing is covered when it provides information about known or suspected hepatobiliary disease. That includes testing following chronic alcohol or drug ingestion, exposure to hepatotoxins, use of medications with known liver toxicity risk (such as statins, barbiturates, phenytoin, cimetidine, and carbamazepine), and following infections like viral hepatitis, amoebiasis, tuberculosis, and psittacosis.

Coverage also extends to assessing liver injury or function after a diagnosis of primary or secondary malignant neoplasms. If your oncology or hematology team orders GGT for a patient with known cancer, that's a covered use. Same goes for liver function assessment in a wide range of systemic diseases — diabetes mellitus, malnutrition, iron and mineral metabolism disorders, sarcoidosis, amyloidosis, lupus, and hypertension all qualify.

GI and pancreatic disease contexts are covered too. If a patient has gastrointestinal or pancreatic disease and GGT is ordered to assess liver function, that's within the policy. Post-liver transplant monitoring is also explicitly covered — this is one of the cleaner indications in the policy, and transplant teams should document it accordingly.

The seventh covered indication is the one that generates the most confusion: differentiating sources of elevated alkaline phosphatase. GGT is a useful tool here because elevated alkaline phosphatase can come from bone, liver, or placental sources. A high GGT alongside high alkaline phosphatase points toward a hepatic origin. Note that a normal GGT does not fully rule out liver disease — the policy says so explicitly.

NCD 153 does not mention prior authorization as a requirement for GGT testing. But that doesn't mean your Medicare Administrative Contractor won't have additional local coverage determination rules. Check with your MAC before assuming national coverage automatically applies to your region.

CMS GGT Exclusions and Non-Covered Indications 2026

The limitations in NCD 153 are where claims get denied. CMS is specific about when repeat GGT testing is not medically necessary, and these are the rules your ordering providers need to understand before the effective date of March 7, 2026.

Repeat testing after a normal result. When GGT is used to assess liver dysfunction secondary to an existing non-hepatobiliary disease — and there's no change in signs, symptoms, or treatment — repeating the test after a normal result is generally not covered. CMS position: you got a normal result, nothing changed, you don't need another one.

Isolated GGT elevation. If GGT is the only elevated liver enzyme, CMS says further evaluation for liver disease based on that finding alone is generally not necessary. This matters for billing. If a provider orders a follow-up workup because GGT was elevated but all other liver enzymes were normal, those downstream tests are at risk.

Frequency limits on source-differentiation testing. When GGT is ordered to determine whether other abnormal enzyme tests reflect liver abnormality rather than other tissue involvement, CMS limits coverage to generally no more than one test per week. If your lab bills multiple GGT tests in a single week for this indication, expect scrutiny.

Known liver disease monitoring. This one is counterintuitive. Because GGT is extremely sensitive to cytochrome oxidase induction and cell membrane permeability changes, CMS says it's generally not useful for monitoring patients with known, established liver disease. Ordering GGT repeatedly for active liver disease management is not a covered use under NCD 153. This limitation catches practices off guard — particularly hepatology and gastroenterology teams who reflexively include GGT in routine liver panels.

Coverage Indications at a Glance

CMS GGT Billing Guidelines and Action Items 2026

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

The policy data provided for NCD 153 does not list specific CPT or HCPCS codes. CMS did not enumerate procedure codes in this version of the policy.

This is meaningful for billing teams. Coverage under NCD 153 is determined by medical necessity criteria and clinical indication — not by code-level inclusion or exclusion lists. Your GGT claims will be evaluated against the indications and limitations described in the policy, driven by the diagnosis codes submitted.

That means your ICD-10-CM coding carries the full weight of medical necessity justification for every GGT claim. If you're not sure which diagnosis codes are appropriate for your patient population, talk to your compliance officer or billing consultant before the effective date.

If your MAC has published a local coverage determination for laboratory testing that includes GGT, that LCD will specify the applicable CPT codes and covered diagnosis codes for your region. Pull that LCD and cross-reference it with NCD 153.