What is ICD-10 code E72.22?

E72.22 is the ICD-10-CM diagnosis code for Arginosuccinic aciduria. A rare genetic disorder where the body cannot properly break down the amino acid arginine, causing accumulation of arginosuccinic acid. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E72.22 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E72.22 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. E72.22 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. E72.22 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for E72.22?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. E72.22 was a payment HCC under V24 (Other Significant Endocrine and Metabolic Disorders) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting E72.22?

This is one of the more common urea cycle disorders; document any neurological complications or developmental delays Monitor ammonia levels as part of ongoing management; document treatment with arginine or other therapies Because E72.22 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM E72.22: Arginosuccinic aciduria

ICD-10-CM Code View

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Code lookupE72.22Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E72.22

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

Arginosuccinic aciduria

A rare genetic disorder where the body cannot properly break down the amino acid arginine, causing accumulation of arginosuccinic acid.

Buddy Insight

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Mapped

HCC 23

Other Significant Endocrine a...

RAF 0.194

ACA/HHS

Mapped

HCC 28

HHS-HCC 28

Varies by metal level

ESRD/PACE

Mapped

HCC 23

Other Significant Endocrine a...

RAF 0.036

RXHCC

Mapped

HCC 43

Other Significant Endocrine a...

RAF 0.063

Code Book Path

Official

E72Other disorders of amino-acid metabolism

E72.2Disorders of urea cycle metabolism

E72.22Arginosuccinic aciduria

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E72.22 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E72.22 in this effective period.

Related Child Codes

Official

E72.20Disorder of urea cycle metabolism, unspecified

E72.21Argininemia

E72.23Citrullinemia

E72.29Other disorders of urea cycle metabolism

Includes

Official

ICD-10-CM does not list Includes notes for E72.22 in this effective period.

Excludes 1

Official

disorders of ornithine metabolism (E72.4)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E72.22 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E72.22 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E72.22 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Document plasma argininosuccinic acid levels, ammonia levels, ASL gene mutation analysis, hepatic function including assessment for fibrosis, hair examination for trichorrhexis nodosa, developmental assessment, and dietary management plan.

Record arginine supplementation dosage and nitrogen scavenger therapy use.

MEAT Support

HCC Buddy guidance

Record arginine supplementation dosage and nitrogen scavenger therapy use.

Audit Caution

HCC Buddy guidance

Trichorrhexis nodosa (brittle hair) is a clinical clue unique to arginosuccinic aciduria among urea cycle disorders.

When present, it should prompt metabolic workup.

Ensure hepatic complications are coded in addition to the underlying metabolic disorder.

Common Mistakes

HCC Buddy guidance

E72.21 (Argininemia) for arginase deficiency

E72.23 (Citrullinemia) for argininosuccinate synthetase deficiency

E72.20 (Disorder of urea cycle metabolism, unspecified) which lacks specificity

K74.6 (Other and unspecified cirrhosis of liver) when hepatic disease is coded without the underlying metabolic cause.

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 E72.22 an HCC code?

Yes. E72.22 maps to Other Significant Endocrine and Metabolic Disorders under the V24 model but is not retained in V28.

Code: E72.22
Description: Arginosuccinic aciduria
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

V24HCC 23, Other Significant Endocrine and Metabolic Disorders

0.194

ESRDHCC 23, Other Significant Endocrine and Metabolic Disorders

0.036

RxHCCHCC 43, Other Significant Endocrine and Metabolic Disorders

0.063

Each model's RAF is its CMS base weight for that model's standard population, so 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 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.

Work E72.22 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E72.22

For E72.22 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 E72.22 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E72.22 is the ICD-10-CM diagnosis code for arginosuccinic aciduria. A rare genetic disorder where the body cannot properly break down the amino acid arginine, causing accumulation of arginosuccinic acid. E72.22 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 older CMS-HCC V24 model, E72.22 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 one of the more common urea cycle disorders; document any neurological complications or developmental delays. Because E72.22 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 E72.22 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is one of the more common urea cycle disorders; document any neurological complications or developmental delays
•Monitor ammonia levels as part of ongoing management; document treatment with arginine or other therapies

Clinical Significance

Arginosuccinic aciduria (argininosuccinate lyase deficiency) is the second most common urea cycle disorder, characterized by accumulation of argininosuccinic acid in blood, urine, and cerebrospinal fluid. Patients present with neonatal-onset or late-onset hyperammonemia, but uniquely among urea cycle disorders, also frequently develop chronic hepatic disease with fibrosis and trichorrhexis nodosa (brittle, fragile hair). Long-term management requires dietary protein restriction and arginine supplementation.

Documentation Requirements

✓Document plasma argininosuccinic acid levels, ammonia levels, ASL gene mutation analysis, hepatic function including assessment for fibrosis, hair examination for trichorrhexis nodosa, developmental assessment, and dietary management plan.
✓Record arginine supplementation dosage and nitrogen scavenger therapy use.

Commonly Confused Codes

•E72.21 (Argininemia) for arginase deficiency
•E72.23 (Citrullinemia) for argininosuccinate synthetase deficiency
•E72.20 (Disorder of urea cycle metabolism, unspecified) which lacks specificity
•K74.6 (Other and unspecified cirrhosis of liver) when hepatic disease is coded without the underlying metabolic cause.