What is ICD-10 code E70.21?

E70.21 is the ICD-10-CM diagnosis code for Tyrosinemia. A rare inherited metabolic disorder where the body cannot properly break down the amino acid tyrosine, leading to toxic buildup in the liver, kidneys, and other organs. E70.21 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E70.21 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. E70.21 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. E70.21 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 E70.21 map to under V28?

E70.21 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 E70.21 pay in RAF?

E70.21 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 E70.21?

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. E70.21 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 E70.21?

Tyrosinemia has multiple types (I, II, III); review documentation to determine if a more specific code applies This code may require additional codes for complications such as liver disease or kidney dysfunction Because E70.21 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 E70.21: Tyrosinemia

E70.21 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · free HCC coding tools

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupE70.21Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E70.21

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

Tyrosinemia

A rare inherited metabolic disorder where the body cannot properly break down the amino acid tyrosine, leading to toxic buildup in the liver, kidneys, and other organs.

Buddy Insight

Tyrosinemia is a group of rare inherited metabolic disorders caused by enzyme deficiencies in the tyrosine degradation pathway, leading to toxic accumulation of tyrosine and its metabolites.

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 28

HHS-HCC 28

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

E70Disorders of aromatic amino-acid metabolism

E70.2Disorders of tyrosine metabolism

E70.21Tyrosinemia

Inclusion Terms

Official

Hypertyrosinemia

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E70.21 in this effective period.

Related Child Codes

Official

E70.20Disorder of tyrosine metabolism, unspecified

E70.29Other disorders of tyrosine metabolism

Includes

Official

ICD-10-CM does not list Includes notes for E70.21 in this effective period.

Excludes 1

Official

transitory tyrosinemia of newborn (P74.5)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E70.21 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E70.21 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E70.21 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation should specify the type of tyrosinemia (I, II, or III) when known, confirmed through enzyme activity testing or genetic analysis.

Include plasma tyrosine levels, succinylacetone levels (elevated in Type I), liver and renal function tests, and ophthalmologic examination results.

Current treatment with nitisinone (for Type I) and phenylalanine/tyrosine-restricted diet should be documented along with monitoring parameters.

MEAT Support

HCC Buddy guidance

Documentation should specify the type of tyrosinemia (I, II, or III) when known, confirmed through enzyme activity testing or genetic analysis.

Include plasma tyrosine levels, succinylacetone levels (elevated in Type I), liver and renal function tests, and ophthalmologic examination results.

Current treatment with nitisinone (for Type I) and phenylalanine/tyrosine-restricted diet should be documented along with monitoring parameters.

Audit Caution

HCC Buddy guidance

Do not confuse the three types of tyrosinemia, as they have vastly different clinical presentations and prognoses.

Type I is the most severe and requires immediate treatment.

Transient neonatal tyrosinemia is common and self-resolving, and should not be coded as tyrosinemia.

Code all organ-specific complications (liver disease, renal dysfunction, corneal pathology) separately.

Common Mistakes

HCC Buddy guidance

E70.20 (Disorder of tyrosine metabolism, unspecified) is less specific and should not be used when tyrosinemia is diagnosed.

E70.29 (Other disorders of tyrosine metabolism) covers non-tyrosinemia disorders.

K74.x (Hepatic fibrosis and cirrhosis) may be needed as an additional code for liver complications.

N25.x (Disorders resulting from impaired renal tubular function) may code the renal manifestations.

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 E70.21 an HCC code?

Yes. E70.21 maps to Other Significant Endocrine and Metabolic Disorders under the V24 model but is not retained in V28.

Code: E70.21
Description: Tyrosinemia
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 E70.21 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E70.21

For E70.21 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 E70.21 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

Get the V28 RAF + MEAT cheat sheet

One printable page: confirm a code's V28 HCC status, its RAF weight, and the MEAT your note needs to make it stick. Free, no card.

Free PDF. No card. Unsubscribe anytime.

What This Code Means

E70.21 is the ICD-10-CM diagnosis code for tyrosinemia. A rare inherited metabolic disorder where the body cannot properly break down the amino acid tyrosine, leading to toxic buildup in the liver, kidneys, and other organs. E70.21 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, E70.21 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.

Tyrosinemia has multiple types (I, II, III); review documentation to determine if a more specific code applies. Because E70.21 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 E70.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Tyrosinemia has multiple types (I, II, III); review documentation to determine if a more specific code applies
•This code may require additional codes for complications such as liver disease or kidney dysfunction

Clinical Significance

Tyrosinemia is a group of rare inherited metabolic disorders caused by enzyme deficiencies in the tyrosine degradation pathway, leading to toxic accumulation of tyrosine and its metabolites. Type I (hepatorenal) is the most severe, causing progressive liver disease and renal tubular dysfunction. Type II causes corneal crystals and palmar keratosis, while Type III primarily affects the nervous system. Early treatment with nitisinone and dietary restriction can prevent organ damage.

Documentation Requirements

✓Documentation should specify the type of tyrosinemia (I, II, or III) when known, confirmed through enzyme activity testing or genetic analysis.
✓Include plasma tyrosine levels, succinylacetone levels (elevated in Type I), liver and renal function tests, and ophthalmologic examination results.
✓Current treatment with nitisinone (for Type I) and phenylalanine/tyrosine-restricted diet should be documented along with monitoring parameters.

Commonly Confused Codes

•E70.20 (Disorder of tyrosine metabolism, unspecified) is less specific and should not be used when tyrosinemia is diagnosed.
•E70.29 (Other disorders of tyrosine metabolism) covers non-tyrosinemia disorders.
•K74.x (Hepatic fibrosis and cirrhosis) may be needed as an additional code for liver complications.
•N25.x (Disorders resulting from impaired renal tubular function) may code the renal manifestations.