What is ICD-10 code E74.21?

E74.21 is the ICD-10-CM diagnosis code for Galactosemia. An inherited metabolic disorder where the body cannot properly process galactose, causing intellectual disability, cataracts, liver damage, and growth problems if untreated. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E74.21 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E74.21 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. E74.21 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. E74.21 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.

What is the V28 vs V24 difference for E74.21?

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. E74.21 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 should coders know when reporting E74.21?

Specify the type of galactosemia if documented (classic, variant, or transferase deficiency) Document whether newborn screening was performed and current dietary management status Because E74.21 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.

E74.21: Galactosemia — ICD-10 | Other Significant Endocrine and Metabolic Disorders

ICD-10-CM Code View

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Code lookupE74.21Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E74.21

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

Galactosemia

An inherited metabolic disorder where the body cannot properly process galactose, causing intellectual disability, cataracts, liver damage, and growth problems if untreated.

Buddy Insight

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

E74Other disorders of carbohydrate metabolism

E74.2Disorders of galactose metabolism

E74.21Galactosemia

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E74.21 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E74.21 in this effective period.

Related Child Codes

Official

E74.20Disorders of galactose metabolism, unspecified

E74.29Other disorders of galactose metabolism

Includes

Official

ICD-10-CM does not list Includes notes for E74.21 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for E74.21 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E74.21 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E74.21 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E74.21 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed diagnosis of galactosemia with specific type if known (classic, Duarte variant, galactokinase deficiency)

Enzyme assay results (GALT activity) or genetic testing confirmation

Newborn screening results showing elevated galactose or galactose-1-phosphate

Current dietary management including galactose-free diet compliance

MEAT Support

HCC Buddy guidance

Confirmed diagnosis of galactosemia with specific type if known (classic, Duarte variant, galactokinase deficiency)

Enzyme assay results (GALT activity) or genetic testing confirmation

Newborn screening results showing elevated galactose or galactose-1-phosphate

Current dietary management including galactose-free diet compliance

Audit Caution

HCC Buddy guidance

Confusing galactosemia with lactose intolerance — they are fundamentally different conditions despite both involving galactose

Using the unspecified galactose code (E74.20) when galactosemia is clearly documented

Not distinguishing classic galactosemia from Duarte galactosemia, which has a much milder clinical course

Failing to code long-term complications (speech/language disorders, premature ovarian failure) separately

Common Mistakes

HCC Buddy guidance

E74.20 — Disorders of galactose metabolism, unspecified: do not use when galactosemia has been confirmed

E74.29 — Other disorders of galactose metabolism: for galactose disorders other than classic galactosemia

E73.9 — Lactose intolerance, unspecified: completely different condition; lactose intolerance is not a galactose metabolism disorder

E16.2 — Hypoglycemia, unspecified: hypoglycemia may occur but is a symptom, not the diagnosis

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is E74.21 an HCC code?

Yes. E74.21 maps to Other Significant Endocrine and Metabolic Disorders under the V24 model but is not retained in V28.

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 E74.21 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E74.21

For E74.21to 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 E74.21 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E74.21 is the ICD-10-CM diagnosis code for galactosemia. An inherited metabolic disorder where the body cannot properly process galactose, causing intellectual disability, cataracts, liver damage, and growth problems if untreated. E74.21 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, E74.21 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.

Specify the type of galactosemia if documented (classic, variant, or transferase deficiency). Because E74.21 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 E74.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Specify the type of galactosemia if documented (classic, variant, or transferase deficiency)
•Document whether newborn screening was performed and current dietary management status

Clinical Significance

Galactosemia is a serious inherited metabolic disorder where the body cannot convert galactose to glucose due to enzyme deficiency, most commonly galactose-1-phosphate uridylyltransferase (GALT) deficiency. Without immediate galactose-free diet in neonates, it causes liver failure, sepsis, cataracts, and death. Even with treatment, patients often develop speech disorders, learning disabilities, and premature ovarian insufficiency.

Documentation Requirements

✓Confirmed diagnosis of galactosemia with specific type if known (classic, Duarte variant, galactokinase deficiency)
✓Enzyme assay results (GALT activity) or genetic testing confirmation
✓Newborn screening results showing elevated galactose or galactose-1-phosphate
✓Current dietary management including galactose-free diet compliance
✓Documentation of long-term complications: speech disorders, developmental status, ovarian function in females

Commonly Confused Codes

•E74.20: Disorders of galactose metabolism, unspecified: do not use when galactosemia has been confirmed
•E74.29: Other disorders of galactose metabolism: for galactose disorders other than classic galactosemia
•E73.9: Lactose intolerance, unspecified: completely different condition; lactose intolerance is not a galactose metabolism disorder
•E16.2: Hypoglycemia, unspecified: hypoglycemia may occur but is a symptom, not the diagnosis