E74.00
BillableGlycogen storage disease, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E74.00 an HCC code?
Yes. E74.00 maps to Amyloidosis, Porphyria, and Other Specified Metabolic Disorders under the CMS-HCC V28 risk adjustment model (and Other Significant Endocrine and Metabolic Disorders under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for E74.00
For E74.00to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed E74.00 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E74.00 is the ICD-10-CM diagnosis code for glycogen storage disease, unspecified. A rare inherited disorder where the body cannot properly store or break down glycogen (a form of stored sugar), but the specific type is not identified. E74.00 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering metabolic disorders (e70-e88).
Under the CMS-HCC V28 risk adjustment model, E74.00 maps to Amyloidosis, Porphyria, and Other Specified Metabolic Disorders (HCC 50) with a community, non-dual, aged base RAF weight of 0.648. Under the older CMS-HCC V24 model, E74.00 maps to Other Significant Endocrine and Metabolic Disorders (HCC 23) with a community, non-dual, aged base RAF weight of 0.194. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This is an unspecified code; always attempt to identify the specific glycogen storage disease type (E74.01-E74.09) from clinical findings or genetic testing. Because E74.00 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E74.00 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Glycogen storage disease, unspecified, indicates a diagnosed glycogen storage disorder where the specific type has not been identified. Glycogen storage diseases are a family of inherited conditions affecting glycogen synthesis or breakdown, causing organ damage to the liver, muscles, or heart. This unspecified code should prompt further diagnostic workup to identify the specific type, which is critical for treatment planning.
Documentation Requirements
- ✓Provider diagnosis of glycogen storage disease
- ✓Laboratory findings such as hypoglycemia, lactic acidosis, or elevated liver enzymes
- ✓Tissue biopsy results or enzyme assay findings if performed
- ✓Clinical findings such as hepatomegaly, muscle weakness, or cardiomyopathy
- ✓Plan for genetic testing or further workup to determine the specific type
Commonly Confused Codes
- •E74.01 — von Gierke disease (Type I): specific GSD with glucose-6-phosphatase deficiency
- •E74.02 — Pompe disease (Type II): specific GSD with acid maltase deficiency
- •E74.03 — Cori disease (Type III): specific GSD with debranching enzyme deficiency
- •E74.04 — McArdle disease (Type V): specific GSD with muscle phosphorylase deficiency
- •E74.09 — Other glycogen storage disease: for specified types not individually coded