2027 ICD-10-CM Diagnosis Code E79.9Disorder of purine and pyrimidine metabolism, unspecified
ICD-10-CM Codes›E00–E89›E70-E88›E79
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
E79.9 is a billable ICD-10-CM diagnosis code for disorder of purine and pyrimidine metabolism, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 642. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 35 closely related codes. Coders also document this condition as disorder of purine and pyrimidine metabolism. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified nutritional and metabolic disorders.
E79.9 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 23 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 23, ESRD (V21) category 23, ESRD (V24) category 23, and RxHCC Part D (V08) category 43 for payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
E79.9 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Disorder of purine and pyrimidine metabolism
- Disorder of purine metabolism
- Disorder of pyrimidine metabolism
- Gout secondary to enzyme defect
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to E79.9: its own notes plus those printed at E79, block E70-E88, and Chapter 4. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- Ehlers-Danlos syndromes (Q79.6-)
Notes
General instructions on how these codes are used.
- All neoplasms, whether functionally active or not, are classified in Chapter 2. Appropriate codes in this chapter (i.e. E05.8, E07.0, E16-E31, E34.-) may be used as additional codes to indicate either functional activity by neoplasms and ectopic endocrine tissue or hyperfunction and hypofunction of endocrine glands associated with neoplasms and other conditions classified elsewhere.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name E79.9, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming E79.9: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 1
These codes carry an Excludes2 note naming E79.9: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disorder (of) See Also: Disease;
purine E79.9
pyrimidine E79.9
purine metabolism E79.9
pyrimidine metabolism E79.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Metabolic Disorders
Metabolism is the process your body uses to get or make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive system break the food parts down into sugars and acids, your body's fuel.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert E79.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About E79.9Overview
What is the ICD-10 code for disorder of purine and pyrimidine metabolism, unspecified?
The ICD-10-CM code for disorder of purine and pyrimidine metabolism, unspecified is E79.9 (sometimes written as E799). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is E79.9 (Disorders of purine and pyrimidine metabolism) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report disorder of purine and pyrimidine metabolism, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does E79.9 group to?
When disorder of purine and pyrimidine metabolism, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 642 (inborn and Other Disorders of Metabolism), which carries a relative weight of 1.3226. Higher weights mean higher Medicare reimbursement.
Is E79.9 a CC or MCC?
CMS lists E79.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 35 closely related codes in its exclusion list.
Can E79.9 be reported with Q87.19?
Not as a rule. The Excludes1 note at E79, which applies to E79.9, lists "Ataxia-telangiectasia (Q87.19)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
Does E79.9 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. E79.9 mapped to HCC 23 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 23 (Other Significant Endocrine and Metabolic Disorders), ESRD (V21) category 23 (Other Significant Endocrine and Metabolic Disorders), ESRD (V24) category 23 (Other Significant Endocrine and Metabolic Disorders), and RxHCC Part D (V08) category 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders).
