G45.4 ICD-10-CM Code: Transient global amnesia
HCC Buddy Code Card
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)
G45.4
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceTransient global amnesia
Transient global amnesia is a sudden, temporary loss of memory that typically lasts a few hours, during which a person cannot form new memories or recall recent events, though they remain alert and aware. The condition resolves completely on its own without any permanent brain damage.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for G45.4 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G45.4 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G45.4 in this effective period.
Excludes 1
Official- amnesia NOS (R41.3)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G45.4 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G45.4 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G45.4 in this effective period.
Buddy Documentation Tip
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 G45.4 an HCC code?
No. G45.4 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- G45.4
- Description
- Transient global amnesia
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
G45.4 is the ICD-10-CM diagnosis code for transient global amnesia. Transient global amnesia is a sudden, temporary loss of memory that typically lasts a few hours, during which a person cannot form new memories or recall recent events, though they remain alert and aware. The condition resolves completely on its own without any permanent brain damage. G45.4 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).
G45.4 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
This code is used for the acute episode of transient global amnesia; document the onset time and duration of the amnesia episode for clinical clarity.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G45.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is used for the acute episode of transient global amnesia; document the onset time and duration of the amnesia episode for clinical clarity
- •Ensure this diagnosis is not confused with other causes of amnesia (such as head injury, stroke, or dementia); transient global amnesia is specifically characterized by its temporary nature and complete resolution
Excludes 1, Do NOT code together
- amnesia NOS (R41.3)