E72.21 ICD-10-CM Code: Argininemia
E72.21 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Metabolic disorders (E70-E88)
E72.21
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceArgininemia
Argininemia is a rare genetic disorder where the body cannot properly break down the amino acid arginine, causing it to build up to harmful levels in the blood and urine. This buildup can lead to neurological problems, developmental delays, and other serious health complications.
Buddy Insight
Argininemia (arginase deficiency) is a urea cycle disorder where deficiency of the enzyme arginase causes accumulation of arginine in blood and cerebrospinal fluid.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
MappedHCC 43
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for E72.21 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for E72.21 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for E72.21 in this effective period.
Excludes 1
Official- disorders of ornithine metabolism (E72.4)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for E72.21 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for E72.21 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for E72.21 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 E72.21 an HCC code?
E72.21 is not in the CMS-HCC V28 or V24 community payment model. E72.21 has a separate mapping under the CMS-HCC ESRD model (HCC 23 (Other Significant Endocrine and Metabolic Disorders)) and the Part D RxHCC model (HCC 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders)); the applicable result needs member context. E72.21 also appears in the HHS-HCC commercial risk model (HCC 028 (HHS-HCC 028 child, RAF varies by metal level)), where the result depends on member context and is not a Medicare Advantage payment mapping.
- Code
- E72.21
- Description
- Argininemia
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
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 E72.21 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT Criteria for E72.21
For E72.21 to 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 E72.21 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
E72.21 is the ICD-10-CM diagnosis code for argininemia. Argininemia is a rare genetic disorder where the body cannot properly break down the amino acid arginine, causing it to build up to harmful levels in the blood and urine. This buildup can lead to neurological problems, developmental delays, and other serious health complications. E72.21 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering metabolic disorders (e70-e88).
E72.21 has no mapping under the CMS-HCC V28 or V24 community payment models. E72.21 has a separate mapping under the CMS-HCC ESRD model (HCC 23 (Other Significant Endocrine and Metabolic Disorders)) and the Part D RxHCC model (HCC 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders)); the applicable result needs member context. E72.21 also appears in the HHS-HCC commercial risk model (HCC 028 (HHS-HCC 028 child, RAF varies by metal level)), where the result depends on member context and is not a Medicare Advantage payment mapping. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.
Argininemia is a metabolic disorder requiring documentation of the specific type and any associated complications (such as hyperammonemia, seizures, or developmental delay) for complete coding.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for E72.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Argininemia is a metabolic disorder requiring documentation of the specific type and any associated complications (such as hyperammonemia, seizures, or developmental delay) for complete coding
- •This condition is typically lifelong and should be coded as a principal diagnosis when it is the primary reason for the encounter; look for related codes for complications or management of the condition
Clinical Significance
Argininemia (arginase deficiency) is a urea cycle disorder where deficiency of the enzyme arginase causes accumulation of arginine in blood and cerebrospinal fluid. Unlike other urea cycle disorders, argininemia typically presents insidiously in childhood (age 2-4) with progressive spastic diplegia, seizures, and intellectual decline rather than acute hyperammonemic crises. Hyperammonemia when it occurs is usually milder than in other urea cycle disorders.
Documentation Requirements
- ✓Document elevated plasma arginine levels, arginase enzyme activity, genetic testing for ARG1 mutations, neurological assessment including spasticity evaluation, developmental milestones, ammonia levels, and treatment regimen (low-protein diet with essential amino acid supplementation, nitrogen scavenger therapy if needed).
- ✓Record spasticity management plan.
Commonly Confused Codes
- •E72.22 (Arginosuccinic aciduria) which involves a different urea cycle enzyme
- •E72.23 (Citrullinemia) for argininosuccinate synthetase deficiency
- •E72.20 (Disorder of urea cycle metabolism, unspecified) which lacks specificity
- •G80.1 (Spastic diplegic cerebral palsy) when the metabolic basis is missed.