What is ICD-10 code E72.3?

E72.3 is the ICD-10-CM diagnosis code for Disorders of lysine and hydroxylysine metabolism. Metabolic disorders affecting how the body processes lysine and hydroxylysine, two important amino acids. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E72.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E72.3 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. E72.3 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. E72.3 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 E72.3?

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. E72.3 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 E72.3?

This category includes conditions like hyperlysinemia and saccharopinuria; document the specific disorder if known These are rare disorders; ensure documentation supports the diagnosis and any associated symptoms Because E72.3 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.

E72.3: Disorders of lysine and hydroxylysine metabolism — ICD-10 | Other Significant Endocrine

ICD-10-CM Code View

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Code lookupE72.3Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E72.3

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

Disorders of lysine and hydroxylysine metabolism

Metabolic disorders affecting how the body processes lysine and hydroxylysine, two important amino acids.

Buddy Insight

Disorders of lysine and hydroxylysine metabolism are rare inborn errors affecting amino acid catabolism that can lead to intellectual disability, seizures, and metabolic crises.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 23

Other Significant Endocrine a...

RAF 0.194

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 23

Other Significant Endocrine a...

RAF 0.0

RXHCC

Mapped

HCC 43

Other Significant Endocrine a...

RAF 0.0

Code Trumping

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Code Book Path

Official

E72Other disorders of amino-acid metabolism

E72.3Disorders of lysine and hydroxylysine metabolism

Inclusion Terms

Official

Glutaric aciduria NOS
Glutaric aciduria (type I)
Hydroxylysinemia
Hyperlysinemia

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E72.3 in this effective period.

Related Child Codes

Official

E72.0Disorders of amino-acid transport

E72.1Disorders of sulfur-bearing amino-acid metabolism

E72.2Disorders of urea cycle metabolism

E72.4Disorders of ornithine metabolism

E72.5Disorders of glycine metabolism

Includes

Official

ICD-10-CM does not list Includes notes for E72.3 in this effective period.

Excludes 1

Official

glutaric aciduria type II (E71.313)
Refsum's disease (G60.1)
Zellweger syndrome (E71.510)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E72.3 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E72.3 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E72.3 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Specific disorder of lysine/hydroxylysine metabolism identified (e.g., hyperlysinemia, saccharopinuria, glutaric aciduria type I)

Biochemical confirmation via plasma amino acid analysis or urine organic acid testing

Genetic testing results if available

Current treatment regimen including dietary restrictions and supplements

MEAT Support

HCC Buddy guidance

Specific disorder of lysine/hydroxylysine metabolism identified (e.g., hyperlysinemia, saccharopinuria, glutaric aciduria type I)

Biochemical confirmation via plasma amino acid analysis or urine organic acid testing

Genetic testing results if available

Current treatment regimen including dietary restrictions and supplements

Audit Caution

HCC Buddy guidance

Confusing lysine metabolism disorders with other amino acid metabolism disorders that have more specific codes

Using this code for glutaric aciduria type I, which may be better captured under E72.3 but requires careful documentation review

Failing to document the specific lysine disorder when the diagnosis is known

Not coding associated neurological complications as secondary diagnoses

Common Mistakes

HCC Buddy guidance

E72.89 — Other specified disorders of amino-acid metabolism: use for amino acid disorders not classified in E72.0-E72.8

E72.9 — Disorder of amino-acid metabolism, unspecified: non-specific code when the exact disorder is unknown

E71.310-E71.318 — Disorders of fatty-acid oxidation: separate metabolic pathway, not amino acid metabolism

E72.4 — Disorders of ornithine metabolism: different amino acid pathway

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is E72.3 an HCC code?

Yes. E72.3 maps to Other Significant Endocrine and Metabolic Disorders under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 23, Other Significant Endocrine and Metabolic Disorders

0.194

ESRDHCC 23, Other Significant Endocrine and Metabolic Disorders

0.000

RxHCCHCC 43, Other Significant Endocrine and Metabolic Disorders

0.000

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.

Work E72.3 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E72.3

For E72.3to 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 E72.3 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E72.3 is the ICD-10-CM diagnosis code for disorders of lysine and hydroxylysine metabolism. Metabolic disorders affecting how the body processes lysine and hydroxylysine, two important amino acids. E72.3 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, E72.3 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 category includes conditions like hyperlysinemia and saccharopinuria; document the specific disorder if known. Because E72.3 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 E72.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This category includes conditions like hyperlysinemia and saccharopinuria; document the specific disorder if known
•These are rare disorders; ensure documentation supports the diagnosis and any associated symptoms

Clinical Significance

Disorders of lysine and hydroxylysine metabolism are rare inborn errors affecting amino acid catabolism that can lead to intellectual disability, seizures, and metabolic crises. These conditions, including hyperlysinemia and saccharopinuria, require ongoing metabolic management and carry significant morbidity risk. Accurate coding ensures appropriate risk adjustment for the complex care these patients require.

Documentation Requirements

✓Specific disorder of lysine/hydroxylysine metabolism identified (e.g., hyperlysinemia, saccharopinuria, glutaric aciduria type I)
✓Biochemical confirmation via plasma amino acid analysis or urine organic acid testing
✓Genetic testing results if available
✓Current treatment regimen including dietary restrictions and supplements
✓Documentation of associated complications such as developmental delay or seizures

Excludes 1, Do NOT code together

glutaric aciduria type II (E71.313)
Refsum's disease (G60.1)
Zellweger syndrome (E71.510)

Commonly Confused Codes

•E72.89: Other specified disorders of amino-acid metabolism: use for amino acid disorders not classified in E72.0-E72.8
•E72.9: Disorder of amino-acid metabolism, unspecified: non-specific code when the exact disorder is unknown
•E71.310-E71.318: Disorders of fatty-acid oxidation: separate metabolic pathway, not amino acid metabolism
•E72.4: Disorders of ornithine metabolism: different amino acid pathway