A81.00 ICD-10-CM Code: Creutzfeldt-Jakob disease, unspecified
A81.00 maps to CMS-HCC V28 127. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Viral and prion infections of the central nervous system (A80-A89)
A81.00
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceCreutzfeldt-Jakob disease, unspecified
Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive brain disorder caused by abnormal proteins called prions that destroy brain tissue. This code is used when the specific type or variant of CJD has not been determined.
Buddy Insight
Creutzfeldt-Jakob disease is a rapidly progressive, uniformly fatal prion disease that causes devastating neurological decline within months.
CMS-HCC V28
MappedHCC 127
Coefficient HCC 127: 0.341 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
MappedHCC 52
Code-level coefficient reference
RXHCC
MappedHCC 112
Code-level coefficient reference
Code Book Path
Inclusion Terms
Official- Jakob-Creutzfeldt disease, unspecified
Excludes 2
Official- carrier or suspected carrier of infectious disease (Z22.-)Inherited from A00-B99
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)Inherited from A00-B99
- infectious and parasitic diseases specific to the perinatal period (P35-P39)Inherited from A00-B99
- influenza and other acute respiratory infections (J00-J22)Inherited from A00-B99
Related Codes
Includes
Official- diseases generally recognized as communicable or transmissibleInherited from A00-B99, A81
- diseases of the central nervous system caused by prionsInherited from A00-B99, A81
Excludes 1
Official- certain localized infections - see body system-related chaptersInherited from A00-B99, A80-A89
- postpolio syndrome (G14)Inherited from A00-B99, A80-A89
- sequelae of poliomyelitis (B91)Inherited from A00-B99, A80-A89
- sequelae of viral encephalitis (B94.1)Inherited from A00-B99, A80-A89
Code First
OfficialNo Code First sequencing instructions are included in this display for A81.00. Check the code and parent instructions in the Code Book.
Use Additional
Official- code to identify resistance to antimicrobial drugs (Z16.-)Inherited from A00-B99, A81
- code, if applicable, to identify:Inherited from A00-B99, A81
- dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)Inherited from A00-B99, A81
- dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)Inherited from A00-B99, A81
- dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)Inherited from A00-B99, A81
- dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)Inherited from A00-B99, A81
- dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)Inherited from A00-B99, A81
- mild neurocognitive disorder due to known physiological condition (F06.7-)Inherited from A00-B99, A81
Code Also
OfficialNo Code Also instructions are included in this display for A81.00. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 A81.00 an HCC code?
Yes. A81.00 (Creutzfeldt-Jakob disease, unspecified) maps to HCC 127, Dementia, Mild or Unspecified under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.341. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: A81.00 is billable and maps to V28 HCC 127, Dementia, Mild or Unspecified. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- A81.00
- Description
- Creutzfeldt-Jakob disease, unspecified
- HCC (V28)
- HCC 127 — Dementia, Mild or Unspecified
- RAF reference coefficient
- 0.341
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work A81.00 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for A81.00
For A81.00, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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What This Code Means
A81.00 is the ICD-10-CM diagnosis code for creutzfeldt-jakob disease, unspecified. Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive brain disorder caused by abnormal proteins called prions that destroy brain tissue. This code is used when the specific type or variant of CJD has not been determined. A81.00 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering viral and prion infections of the central nervous system (a80-a89).
Under the CMS-HCC V28 risk adjustment model, A81.00 maps to Dementia, Mild or Unspecified (HCC 127) with a source-labeled community, non-dual, aged reference coefficient of 0.341. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
If the type of CJD is documented (sporadic, familial, iatrogenic, or variant), use the more specific subcategories A81.01-A81.09 rather than the unspecified code A81.00. For A81.00, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for A81.00 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •If the type of CJD is documented (sporadic, familial, iatrogenic, or variant), use the more specific subcategories A81.01-A81.09 rather than the unspecified code A81.00
- •CJD is a reportable disease in most jurisdictions; verify local public health reporting requirements and ensure proper documentation of disease progression and clinical presentation
Clinical Significance
Creutzfeldt-Jakob disease is a rapidly progressive, uniformly fatal prion disease that causes devastating neurological decline within months. The unspecified code should prompt a provider query to determine the type (sporadic, familial, iatrogenic, or variant), as this affects surveillance, family counseling, and public health reporting.
Documentation Requirements
- ✓Diagnostic criteria met: rapidly progressive dementia with at least two of myoclonus, visual/cerebellar disturbances, pyramidal/extrapyramidal features, or akinetic mutism
- ✓Diagnostic testing results: brain MRI (diffusion-weighted imaging abnormalities), EEG (periodic sharp wave complexes), CSF 14-3-3 protein or RT-QuIC assay
- ✓Stage of disease documented (early cognitive, progressive, or terminal)
- ✓Type of CJD if known (sporadic, familial, iatrogenic, variant) — query if not documented
- ✓Public health reporting documentation
Commonly Confused Codes
- •A81.01 (Variant Creutzfeldt-Jakob disease): vCJD is specifically linked to bovine spongiform encephalopathy exposure; use A81.00 only when the specific type is unknown
- •A81.09 (Other Creutzfeldt-Jakob disease): For familial or iatrogenic CJD subtypes not fitting the standard or variant categories
- •G30.9 (Alzheimer disease, unspecified): Early CJD may mimic Alzheimer but progresses much faster (months vs. years); distinguish by rate of decline and diagnostic testing
- •F03.90 (Unspecified dementia without behavioral disturbance): CJD causes dementia but is a specific prion disease, not an unspecified dementia