ICD10 Guideline for coding altered mental status

This page contains an ICD10 Coding Guideline for ICD10 collection. See ICD10 coding guidelines for similar pages.

• This Guideline addresses the large and confusing topic of ACUTE alterations in cognition
• It is confusing for 3 main reasons:
  • (1) There is a large range of mental changes, from mild confusion all the way up to coma. In hospital, this range prominently includes delirium, which is defined as an acute confusional state that tends to wax and wane relatively rapidly (over hours or even shorter), and may be accompanied by agitation or psychomotor depression.
  • (2) Such alterations in cognition have MANY different causes
  • (3) The clinical terminology is variable, confusing, and often nonspecific
    • For example, the terms "altered mental status", "encephalopathy" and "delirium" are often used loosely and interchangeably.
• As usual in ICD10, you should use the most specific code available, and use "waste basket/NOS codes" only when a more specific code is not available.
• And also, as usual, if you do know the cause, you can combine the code for the cause with the code identifying the nature of the brain problem
• If what you've got is actual coma (a statue of unarousable unresponsiveness where the person looks asleep, with eyes closed, no voluntary movements, and unable to be awoken), then use one of the coma codes, not delirium or encephalopathy
• If it's not coma, or Persistent vegetative state, then use the most specific code available:
  • If the cause is a substance, toxin or drug, use Encephalopathy, toxic
  • If the cause is sepsis, use Encephalopathy, septic or metabolic
  • If the cause is "metabolic" (except for hepatic encephalopathy), use Encephalopathy, septic or metabolic -- this includes electrolyte disturbances (e.g.hypernatremia, hyponatremia, hypercalcemia), uremic encephalopathy, hypoglycemic or hyperglycemia encephalopathy (to be distinguished from Diabetic coma, which is an actual coma
  • If the cause is hepatic encephalopathy, use one of these:
    • Liver failure w/wo hepatic encephalopathy, acute or subacute NOS
    • Liver failure w/wo hepatic encephalopathy, alcoholic
    • Liver failure w/wo hepatic encephalopathy, chronic NOS
    • Liver failure due to toxin/drug NOS, w/wo hepatic encephalopathy
    • Liver failure w/wo hepatic encephalopathy, not specified as acute or chronic
    • Note that if you do code one of these liver failure codes in a person with hepatic encephalopathy, there is no need to also code one of the "free-standing" encephalopathy codes.
  • If the cause of the encephalopathy/altered mental status is not one of those, then the choices are:
    • Delirium, not due to drugs or alcohol -- use this if the person is CAM-positive (CAM is a tool used to detect delirium) of if the patient otherwise fits the clinical definition of delirium as an acute confusional state that tends to wax and wane relatively rapidly (over hours or even shorter), and may be accompanied by agitation or psychomotor depression.
    • Encephalopathy, NOS -- if the person doesn't meet the delirium definition, then you probably should use this code
    • Somnolence, stupor or obtundation -- this is one of the "signs & symptoms" codes and as usual should only be used when an actual diagnosis is not known. Thus, although you could use this code for "Altered mental status", one of the above is preferable, if applicable.

Codes to Consider

• Coma codes:
  • Myxedema with coma
  • Diabetic coma
  • Coma NOS
• Encephalopathy-related codes
  • Delirium, not due to drugs or alcohol
  • Encephalopathy, toxic
  • Encephalopathy, septic or metabolic
  • Encephalopathy, NOS -- {sc:toxic/drug-induced, metabolic, septic, hypertensive}
  • Encephalopathy, hypertensive
  • Liver failure w/wo hepatic encephalopathy, acute or subacute NOS
  • Liver failure w/wo hepatic encephalopathy, alcoholic
  • Liver failure w/wo hepatic encephalopathy, chronic NOS
  • Liver failure due to toxin/drug NOS, w/wo hepatic encephalopathy
  • Liver failure w/wo hepatic encephalopathy, not specified as acute or chronic
  • Wernicke's encephalopathy (Wernicke-Korsakoff syndrome)
• Overlapping symptom codes
  • Somnolence, stupor or obtundation
  • Disorientation
  • Amnesia
  • Dizziness
  • Hallucinations
  • Agitation, restlessness
  • Violent behavior
  • Symptom or sign involving emotional state, NOS
• Other/misc related codes
  • Anoxic brain injury, NOS
  • Organic brain disorder, NOS
  • Persistent vegetative state