What is ICD-10 code E79.9?

E79.9 is the ICD-10-CM diagnosis code for Disorder of purine and pyrimidine metabolism, unspecified. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E79.9 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E79.9 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. E79.9 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. E79.9 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.

Which HCC does E79.9 map to under V28?

E79.9 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

What does E79.9 pay in RAF?

E79.9 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

What is the V28 vs V24 difference for E79.9?

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. E79.9 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 documentation supports E79.9?

Use this code only when the specific purine or pyrimidine metabolism disorder cannot be determined; always attempt to obtain more specific documentation from the provider before defaulting to the unspecified code Review the patient's lab results and clinical presentation for clues about which specific disorder may be present (such as gout, hyperuricemia, or other named conditions) to support more specific coding Because E79.9 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. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM E79.9: Disorder of purine

E79.9 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · free HCC coding tools

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Code lookupE79.9Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E79.9

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

Disorder of purine and pyrimidine metabolism, unspecified

This code describes a problem with how the body breaks down or uses purines and pyrimidines, which are building blocks of DNA and RNA, but the specific type of disorder is not identified. It's used when a metabolic disorder affecting these substances is present but not further specified.

Buddy Insight

Disorder of purine and pyrimidine metabolism, unspecified is used when a purine or pyrimidine metabolic disorder is confirmed but the specific condition has not been documented.

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 29

HHS-HCC 29

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

E79Disorders of purine and pyrimidine metabolism

E79.9Disorder of purine and pyrimidine metabolism, unspecified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E79.9 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E79.9 in this effective period.

Related Child Codes

Official

E79.0Hyperuricemia without signs of inflammatory arthritis and tophaceous disease

E79.1Lesch-Nyhan syndrome

E79.2Myoadenylate deaminase deficiency

E79.8Other disorders of purine and pyrimidine metabolism

Includes

Official

ICD-10-CM does not list Includes notes for E79.9 in this effective period.

Excludes 1

Official

Ataxia-telangiectasia (Q87.19)
Bloom's syndrome (Q82.8)
Cockayne's syndrome (Q87.19)
calculus of kidney (N20.0)
combined immunodeficiency disorders (D81.-)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E79.9 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E79.9 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E79.9 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation confirming a purine or pyrimidine metabolism disorder

Abnormal purine or pyrimidine metabolites in blood or urine

Clinical symptoms attributed to the metabolic disorder

Reason for lack of specificity (workup pending, inconclusive results)

MEAT Support

HCC Buddy guidance

Provider documentation confirming a purine or pyrimidine metabolism disorder

Abnormal purine or pyrimidine metabolites in blood or urine

Clinical symptoms attributed to the metabolic disorder

Reason for lack of specificity (workup pending, inconclusive results)

Audit Caution

HCC Buddy guidance

Using this unspecified code when specific test results in the record would support a named disorder

Not querying the provider when uric acid levels, xanthine levels, or other metabolite abnormalities are documented

Confusing gout (a clinical disease) with a purine metabolism disorder (the underlying metabolic pathway defect)

Failing to investigate DPD deficiency in patients with severe fluoropyrimidine toxicity

Common Mistakes

HCC Buddy guidance

E79.0 — Hyperuricemia without gout: more specific when elevated uric acid is the finding

E79.1 — Lesch-Nyhan syndrome: use when complete HPRT deficiency with neurological features is confirmed

E79.89 — Other specified disorders: use when a specific disorder is named but lacks its own code

M10.9 — Gout, unspecified: for urate crystal arthropathy, a different clinical entity

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 E79.9 an HCC code?

Yes. E79.9 maps to Other Significant Endocrine and Metabolic Disorders under the V24 model but is not retained in V28.

Code: E79.9
Description: Disorder of purine and pyrimidine metabolism, unspecified
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 E79.9 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E79.9

For E79.9 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 E79.9 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E79.9 is the ICD-10-CM diagnosis code for disorder of purine and pyrimidine metabolism, unspecified. This code describes a problem with how the body breaks down or uses purines and pyrimidines, which are building blocks of DNA and RNA, but the specific type of disorder is not identified. It's used when a metabolic disorder affecting these substances is present but not further specified. E79.9 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, E79.9 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.

Use this code only when the specific purine or pyrimidine metabolism disorder cannot be determined; always attempt to obtain more specific documentation from the provider before defaulting to the unspecified code. Because E79.9 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 E79.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when the specific purine or pyrimidine metabolism disorder cannot be determined; always attempt to obtain more specific documentation from the provider before defaulting to the unspecified code
•Review the patient's lab results and clinical presentation for clues about which specific disorder may be present (such as gout, hyperuricemia, or other named conditions) to support more specific coding

Clinical Significance

Disorder of purine and pyrimidine metabolism, unspecified is used when a purine or pyrimidine metabolic disorder is confirmed but the specific condition has not been documented. This code signals incomplete diagnostic workup and should prompt queries for specificity, particularly since some purine/pyrimidine disorders have specific treatments and important drug interaction implications.

Documentation Requirements

✓Provider documentation confirming a purine or pyrimidine metabolism disorder
✓Abnormal purine or pyrimidine metabolites in blood or urine
✓Clinical symptoms attributed to the metabolic disorder
✓Reason for lack of specificity (workup pending, inconclusive results)
✓Plan for further diagnostic evaluation

Commonly Confused Codes

•E79.0: Hyperuricemia without gout: more specific when elevated uric acid is the finding
•E79.1: Lesch-Nyhan syndrome: use when complete HPRT deficiency with neurological features is confirmed
•E79.89: Other specified disorders: use when a specific disorder is named but lacks its own code
•M10.9: Gout, unspecified: for urate crystal arthropathy, a different clinical entity