2027 ICD-10-CM Diagnosis Code E72.4Disorders of ornithine metabolism
ICD-10-CM Codes›E00–E89›E70-E88›E72
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
E72.4 is a billable ICD-10-CM diagnosis code for disorders of ornithine metabolism. 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 140 closely related codes. Coders also document this condition as disorder of ornithine metabolism. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified nutritional and metabolic disorders.
E72.4 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
E72.4 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 ornithine metabolism
- Hyperammonemia
- Hyperornithinemia
- Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome
- Ornithine aminotransferase deficiency
- Ornithine carbamoyltransferase deficiency
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to E72.4: its own notes plus those printed at E72, block E70-E88, and Chapter 4. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Hyperammonemia-Hyperornithinemia-Homocitrullinemia syndrome
- Ornithinemia (types I, II)
- Ornithine transcarbamylase deficiency
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- hereditary choroidal dystrophy (H31.2-)
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 E72.4, its category, or a range that includes it.
Excludes1 5
These codes carry an Excludes1 note naming E72.4: they are not reported together with it, unless the two conditions are unrelated.
- E72.2 Disorders of urea cycle metabolismdisorders of ornithine metabolism (E72.4)
- E72.20 Disorder of urea cycle metabolism, unspecifiedhyperammonemia-hyperornithinemia-homocitrullinemia syndrome E72.4
- R79 Other abnormal findings of blood chemistry
- R79.83 Abnormal findings of blood amino-acid level
- Block R80-R82 Abnormal findings on examination of urine, without diagnosis
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disorder (of) See Also: Disease;
Disturbance (s) See Also: Disease;
ornithine E72.4
ornithine E72.4
Hyperornithinemia E72.4
Syndrome See Also: Disease;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Amino Acid Metabolism Disorders
Metabolism is the process your body uses to make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Your digestive system breaks the food parts down into sugars and acids, your body's fuel. Your body can use this fuel right away, or it can store the energy in your body.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert E72.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About E72.4Overview
What is the ICD-10 code for disorders of ornithine metabolism?
The ICD-10-CM code for disorders of ornithine metabolism is E72.4 (sometimes written as E724). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is E72.4 (Other disorders of amino-acid metabolism) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report disorders of ornithine metabolism on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does E72.4 group to?
When disorders of ornithine metabolism 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 E72.4 a CC or MCC?
CMS lists E72.4 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 140 closely related codes in its exclusion list.
Can E72.4 be reported with a code from H31.2?
Not as a rule. The Excludes1 note on E72.4 lists "hereditary choroidal dystrophy (H31.2-)". 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 E72.4 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. E72.4 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).
