What is the ICD-10 code for an older adult patient with memory issues, potentially due to dementia or Alzheimer's disease, being referred to a neurologist?

ICD-10 Coding for Neurologist Referral Due to Memory Issues

For an older adult with memory issues being referred to a neurology specialist, use ICD-10 code R41.81 (Age-related cognitive decline) if the patient has subjective memory complaints without objective impairment, or G31.84 (Mild cognitive impairment, so stated) if there is documented objective cognitive impairment on testing but preserved functional independence. 1

Primary Coding Options Based on Clinical Presentation

For Subjective Memory Complaints Without Objective Impairment

• R41.81 (Age-related cognitive decline) is appropriate when the patient or informant reports memory concerns but cognitive testing remains within normal limits 1
• This code captures the clinical concern that warrants specialist evaluation without prematurely diagnosing a neurocognitive disorder 2

For Documented Mild Cognitive Impairment

• G31.84 (Mild cognitive impairment, so stated) should be used when:
  • Objective evidence of impairment exists on formal or bedside cognitive testing 2
  • The patient maintains independence in functional abilities 2
  • The patient does not meet criteria for dementia 2
• This code requires documentation of objective cognitive testing showing impairment in one or more cognitive domains 1

For Memory Impairment Not Otherwise Specified

• R41.3 (Other amnesia) can be used for memory-specific complaints when the etiology is unclear 3
• R41.89 (Other symptoms and signs involving cognitive functions and awareness) serves as a broader code for cognitive symptoms requiring further evaluation 3

Important Coding Considerations

Documentation Requirements

• The referral should include results of cognitive screening using validated instruments such as the Montreal Cognitive Assessment (MoCA), Mini-Cog, or AD8 informant questionnaire 1
• Document whether memory is the primary impaired domain or if other cognitive domains (executive function, language, visuospatial abilities) are affected 1
• Include collateral informant history, as patients often cannot reliably report their own cognitive errors due to diminished insight 4

When to Consider Alternative Codes

• F03.90 (Unspecified dementia without behavioral disturbance) should only be used if the patient already meets full criteria for dementia with impairment in multiple cognitive domains interfering with instrumental activities of daily living 2, 5
• G30.9 (Alzheimer's disease, unspecified) requires clinical diagnosis of probable Alzheimer's disease with insidious onset and progressive cognitive decline 2
• Do not use dementia codes prematurely before specialist evaluation confirms the diagnosis 3

Critical Pitfalls to Avoid

Common Coding Errors

• Never attribute cognitive complaints to "normal aging" (senility, code R54) without objective assessment, as this dismisses potentially treatable conditions 4
• Avoid using F06.8 (Other specified mental disorders due to known physiological condition) without identifying the specific underlying cause 3
• Do not code based solely on patient self-report without corroborating informant history or objective testing 4

Conditions That Must Be Excluded First

Before finalizing cognitive impairment codes, ensure documentation excludes:

• Delirium from acute medical conditions, infections, or medications 6
• Acute cerebrovascular events (stroke involving strategic areas like thalamus or hippocampus) 6
• Metabolic disorders including hypoglycemia, hyponatremia, or thyroid dysfunction 6
• Medication effects, particularly anticholinergics, benzodiazepines, or opioids 6
• Structural lesions such as subdural hematoma or brain tumor 6

Specialist Referral Indications

When Neurologist Evaluation Is Essential

Referral to a neurologist or dementia subspecialist is strongly indicated for patients presenting with: 2

• Atypical cognitive abnormalities including aphasia, apraxia, or agnosia 2
• Young-onset presentations (age <65 years), where non-memory presentations occur in approximately one-third of cases 7
• Rapid progression of symptoms developing over weeks to months 2, 6
• Accompanying neuropsychiatric symptoms such as visual hallucinations, personality changes, or psychosis 2
• Sensorimotor dysfunction including movement disorders, gait abnormalities, or cortical visual problems 2

Documentation to Support Referral

The referral should specify:

• Results of mandatory laboratory testing (CBC, comprehensive metabolic panel, TSH, vitamin B12, HbA1c) 1
• Brain MRI findings or indication that neuroimaging is needed to exclude structural lesions and assess atrophy patterns 2, 1
• Cognitive screening scores demonstrating objective impairment 1
• Informant-reported functional changes in daily activities 2

Additional Coding for Comorbid Conditions

When memory issues coexist with other conditions, use additional codes to capture:

• Z86.73 (Personal history of transient ischemic attack and cerebral infarction without residual deficits) for vascular risk factors 6
• F32.x or F33.x (Depressive disorder codes) when late-onset depression accompanies cognitive symptoms 2
• G47.33 (Obstructive sleep apnea) if untreated sleep disorder contributes to cognitive impairment 1

The key principle is to code what is documented and known at the time of referral, avoiding premature diagnostic labels while capturing the clinical concern that necessitates specialist evaluation. 3