E74.04
BillableMcArdle disease
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E74.04 an HCC code?
Yes. E74.04 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 E74.04
For E74.04to 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 E74.04 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E74.04 is the ICD-10-CM diagnosis code for mcardle disease. A rare inherited disorder affecting muscles where the body cannot break down muscle glycogen, causing severe muscle pain and weakness during exercise. E74.04 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, E74.04 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, E74.04 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.
Also known as muscle phosphorylase deficiency; document exercise intolerance and myoglobinuria (dark urine after exercise). Because E74.04 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 E74.04 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Also known as muscle phosphorylase deficiency; document exercise intolerance and myoglobinuria (dark urine after exercise)
- •Distinguish from other glycogen storage diseases by the primary muscle involvement rather than liver involvement
Clinical Significance
McArdle disease (Glycogen Storage Disease Type V) is caused by muscle glycogen phosphorylase deficiency, making patients unable to use glycogen for energy during exercise. This results in exercise intolerance, muscle cramps, myoglobinuria (which can cause acute kidney injury), and a characteristic 'second wind' phenomenon. Unlike liver-predominant GSDs, McArdle primarily affects skeletal muscle function.
Documentation Requirements
- ✓Confirmed diagnosis of McArdle disease or GSD Type V
- ✓Muscle biopsy results or myophosphorylase enzyme assay, or genetic PYGM testing
- ✓Documentation of exercise intolerance and muscle symptoms
- ✓History of myoglobinuria or rhabdomyolysis episodes
- ✓Renal function assessment if myoglobinuria has occurred
- ✓Activity modification and dietary management plan
Commonly Confused Codes
- •E74.02 — Pompe disease (Type II): also causes muscle weakness but involves acid maltase, not phosphorylase
- •E74.03 — Cori disease (Type III): affects both liver and muscle, different enzyme
- •E74.00 — Glycogen storage disease, unspecified: do not use when McArdle is confirmed
- •M62.82 — Rhabdomyolysis: a complication of McArdle disease, not the primary diagnosis
- •G72.9 — Myopathy, unspecified: the metabolic cause should be coded as primary