AMS ICD-10 Code R41.82: Altered Mental Status Coding

The ICD-10-CM code for altered mental status (AMS) is R41.82, Altered mental status, unspecified, a billable symptom code valid in the FY 2027 code set. It also covers a change in mental status not otherwise specified. Because it’s a symptom code, R41.82 belongs on the claim only until the provider identifies a cause. This page covers when to use it, when to drop it, the codes that commonly replace it, and how to keep AMS claims from stalling.

When to Use the AMS ICD-10 Code

Use R41.82 when the provider documents an altered or changed mental status and no underlying diagnosis has been established. That’s common in emergency visits, early inpatient days and outpatient visits where the workup is still underway.

The tabular list sends you elsewhere in three situations. A drowsy, stuporous or comatose patient has an altered level of consciousness, coded from R40.-. Confusion or delirium without a stated cause is R41.0. And an altered mental status due to a known condition is coded to that condition instead of R41.82. AMS sits among the frequent symptom codes in our list of top ICD-10 codes every biller should know.

When R41.82 Comes Off the Claim

Under Section I.B.4 and I.B.5 of the ICD-10-CM Official Guidelines for Coding and Reporting FY 2027, symptom codes are acceptable when no definitive diagnosis has been established, and signs and symptoms that are routinely part of a confirmed diagnosis aren’t coded separately. Once the provider ties the mental status change to a cause, code the cause.

In short: R41.82 while the cause is unknown, the confirmed condition once it’s documented, a specific brain diagnosis if the provider names one, and setting-specific rules if the cause stays uncertain.

If the diagnosis is still uncertain at the end of the encounter, the setting matters. In the inpatient setting, a condition documented as probable or suspected at discharge is coded as if it exists (Section II.H). In outpatient settings, you don’t code uncertain diagnoses; you code the symptoms, such as R41.82 (Section IV.H).

Codes That Commonly Replace R41.82

Two corrections to older references: ICD-10-CM has no F05.0 or F05.1. Delirium due to a known condition is the single billable code F05. And hepatic encephalopathy now has its own code, K76.82, so K72.90 or G93.40 shouldn’t be used to describe it.

AMS With UTI, Sepsis or Dehydration

When the provider documents that a urinary tract infection caused the confusion, code the UTI (N39.0, plus the organism if known) and leave R41.82 off, because the tabular note says AMS due to a known condition is coded to that condition. If the provider instead diagnoses metabolic encephalopathy due to the infection, report G93.41 with the infection code.

With sepsis, follow the sepsis sequencing rules in Section I.C.1.d and add G93.41 when septic encephalopathy is documented. For dehydration (E86.0) or hyponatremia (E87.1) explained as the cause, code the condition; the mental status change goes in the note, not on the claim.

Sample Coding Scenario

Sample (fictional data). An 82-year-old patient comes to the emergency department with new confusion. The ED note documents altered mental status, workup pending, and the patient is admitted. On day two, the hospitalist documents acute metabolic encephalopathy due to E. coli urinary tract infection.

ED claim: R41.82, since the cause wasn’t known at that visit. Inpatient claim: G93.41, N39.0 and B96.20, sequenced according to the circumstances of admission, with no R41.82. Change the codes to match your own patient’s documentation.

Common Mistakes With AMS Coding

Symptom codes that linger after a diagnosis is known weaken the medical necessity picture on the claim, a pattern our guide to how accurate coding reduces claim denials explains. For behavior-focused presentations without a mental status change, see our bizarre behavior ICD-10 coding guide.

Frequently Asked Questions

What is the ICD-10 code for AMS?

AMS, or altered mental status, is coded R41.82, Altered mental status, unspecified. It’s billable and valid in the FY 2027 code set, and it also covers a change in mental status not otherwise specified. Use it only while no underlying cause has been documented; once the provider confirms a cause, code that condition instead.

What is the difference between R41.82 and R41.0?

R41.82 describes an altered mental status without further detail. R41.0, Disorientation, unspecified, covers confusion and delirium when no cause is stated. If the provider writes “delirium” without a cause, R41.0 is the better match. If delirium is due to a known condition, the code becomes F05, with that condition coded first.

Is there a CPT code for AMS?

No. AMS is a diagnosis, so it’s reported with an ICD-10-CM code. The services performed during the workup, such as an evaluation and management visit, a head CT (70450 without contrast) or an EEG, have their own CPT codes, and R41.82 can support them while the cause is unknown.

Should I code R41.82 with metabolic encephalopathy?

Usually not. When the provider documents metabolic encephalopathy, G93.41 explains the mental status change, so the symptom code isn’t added. Code the underlying cause too, such as an infection or electrolyte disorder. Query the provider if the record shows confusion and abnormal labs but never names a diagnosis.

Getting AMS ICD-10 Coding Right

The AMS ICD-10 code R41.82 works best as a temporary diagnosis that the record eventually replaces. When documentation names the cause, the claim should too. If your team needs help with symptom-to-diagnosis coding or provider queries, EzMedPro offers coding support through our medical billing and coding services.

Sources: CMS ICD-10-CM FY 2027 code set; ICD-10-CM Official Guidelines for Coding and Reporting FY 2027. CPT is a registered trademark of the American Medical Association. This page explains coding and billing only and is not medical advice.