2026 ICD-10-CM Diagnosis Code E70.5Disorders of tryptophan metabolism

ICD-10-CM Codes›E00–E89›E70-E88›E70

ICD-10-CM E70.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

E70.5 is a billable ICD-10-CM diagnosis code for disorders of tryptophan metabolism. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified nutritional and metabolic disorders.

Code Identity

ICD-10-CM Code
E70.5
Billable Status
Yes — Valid for Submission
Code Describes
Disorders of tryptophan metabolism
Short Description
Disorders of tryptophan metabolism
Same as the full description in the CMS dataset.
Parent Code
E70
Disorders of aromatic amino-acid metabolism

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE70-E88Metabolic disorders
CategoryE70Disorders of aromatic amino-acid metabolism
This CodeE70.5Disorders of tryptophan metabolism

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Deficiency of acetylserotonin methyltransferase
  • Deficiency of kynurenine 3-monooxygenase
  • Deficiency of kynurenine-oxoglutarate aminotransferase
  • Deficiency of tryptophan 2,3-dioxygenase
  • Deficiency of tryptophan 5-monooxygenase
  • Deficiency of tryptophan-tRNA ligase
  • Disorder of tryptophan metabolism
  • Familial hypertryptophanemia
  • Hooft's syndrome
  • Indicanuria
  • Kynureninase deficiency
  • Tryptophanemia
  • Tryptophanuria
  • Tryptophanuria with dwarfism

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disorder(of)
      • metabolism NOS
        • amino-acid
          • aromatic
            • tryptophan
    • Disorder(of)
      • tryptophan metabolism
    • Disturbance(s)
      • metabolism
        • tryptophan

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR END016
Other specified and unspecified nutritional and metabolic disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

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 E70.5 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
270.2 Arom amin-acid metab NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About E70.5Overview

Is E70.5 (Disorders of aromatic amino-acid metabolism) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report disorders of tryptophan metabolism on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of E70.5?

Under the General Equivalence Mappings, disorders of tryptophan metabolism converts to ICD-9-CM 270.2 (arom amin-acid metab NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.