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E74.04 ICD-10-CM Code: McArdle disease

E74.04 maps to CMS-HCC V28 50. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

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Code lookupE74.04

FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Metabolic disorders (E70-E88)

E74.04

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

McArdle disease

A rare inherited disorder affecting muscles where the body cannot break down muscle glycogen, causing severe muscle pain and weakness during exercise.

Buddy the Bee presenting code insight

Buddy Insight

McArdle disease (Glycogen Storage Disease Type V) is caused by muscle glycogen phosphorylase deficiency, making patients unable to use glycogen for energy during exercise.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 50

Coefficient HCC 50: 0.648 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 027

Code-level coefficient reference

ESRD/PACE

HCC 23

Code-level coefficient reference

RXHCC

HCC 43

Code-level coefficient reference

Code Book Path

Official
E74Other disorders of carbohydrate metabolismE74.0Glycogen storage diseaseE74.04McArdle disease

Inclusion Terms

Official
  • Type V glycogen storage disease

Excludes 2

Official
  • Ehlers-Danlos syndromes (Q79.6-)Inherited from E70-E88

Related Codes

Official
E74.00Glycogen storage disease, unspecifiedE74.01von Gierke diseaseE74.02Pompe diseaseE74.03Cori diseaseE74.05Lysosome-associated membrane protein 2 [LAMP2] deficiency

Includes

Official

No Includes notes are included in this display for E74.04. Check the code and parent instructions in the Code Book.

Excludes 1

Official
  • transitory endocrine and metabolic disorders specific to newborn (P70-P74)Inherited from E00-E89, E70-E88, E74
  • androgen insensitivity syndrome (E34.5-)Inherited from E00-E89, E70-E88, E74
  • congenital adrenal hyperplasia (E25.0)Inherited from E00-E89, E70-E88, E74
  • hemolytic anemias attributable to enzyme disorders (D55.-)Inherited from E00-E89, E70-E88, E74
  • Marfan syndrome (Q87.4-)Inherited from E00-E89, E70-E88, E74
  • 5-alpha-reductase deficiency (E29.1)Inherited from E00-E89, E70-E88, E74
  • diabetes mellitus (E08-E13)Inherited from E00-E89, E70-E88, E74
  • hypoglycemia NOS (E16.2)Inherited from E00-E89, E70-E88, E74
  • increased secretion of glucagon (E16.3)Inherited from E00-E89, E70-E88, E74
  • mucopolysaccharidosis (E76.0-E76.3)Inherited from E00-E89, E70-E88, E74

Code First

Official

No Code First sequencing instructions are included in this display for E74.04. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for E74.04. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for E74.04. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
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

MEAT Support

HCC Buddy guidance
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

Audit Caution

HCC Buddy guidance
Coding only the rhabdomyolysis or exercise intolerance without identifying the underlying McArdle disease
Confusing McArdle disease with other metabolic myopathies or exertional rhabdomyolysis from other causes
Failing to code acute kidney injury as a complication when myoglobinuria-induced renal damage occurs
Using a nonspecific myopathy code when the genetic diagnosis is documented

Common Mistakes

HCC Buddy guidance
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

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is E74.04 an HCC code?

Yes. E74.04 (McArdle disease) maps to HCC 50, Amyloidosis, Porphyria, and Other Specified Metabolic Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.648. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: E74.04 is billable and maps to V28 HCC 50, Amyloidosis, Porphyria, and Other Specified Metabolic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
E74.04
Description
McArdle disease
HCC (V28)
HCC 50 — Amyloidosis, Porphyria, and Other Specified Metabolic Disorders
RAF reference coefficient
0.648
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 50, Amyloidosis, Porphyria, and Other Specified Metabolic Disorders
0.648
ESRDHCC 23, Other Significant Endocrine and Metabolic Disorders
Not separately weighted
RxHCCHCC 43, Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work E74.04 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for E74.04

For E74.04, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • 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

Coder workflow notes

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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 source-labeled community, non-dual, aged reference coefficient of 0.648. No V24 mapping is shown for E74.04; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Also known as muscle phosphorylase deficiency; document exercise intolerance and myoglobinuria (dark urine after exercise). For E74.04, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, 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

Child Codes

E74.00Glycogen storage disease, unspecified
HCC 50
E74.01von Gierke disease
HCC 50
E74.02Pompe disease
HCC 49
E74.03Cori disease
HCC 50
E74.04McArdle disease
HCC 50
E74.05Lysosome-associated membrane protein 2 [LAMP2] deficiency
HCC 50
E74.09Other glycogen storage disease
HCC 50

Code Hierarchy

└E74Other disorders of carbohydrate metabolism└E74.0Glycogen storage disease└E74.04McArdle disease
└E74.04McArdle disease

Also searched as

  • E74 04
  • E7404

For E74.04, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

E74.04 maps to CMS-HCC V28 category 50, Amyloidosis, Porphyria, and Other Specified Metabolic Disorders. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for E74.04. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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Open E74.04 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

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