Health Information Management

Documentation and coding for toxic metabolic encephalopathy

HIM-HIPAA Insider, March 10, 2009

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Q: I need further clarification regarding documentation of toxic metabolic encephalopathy. I have two separate cases in which a physician documents acute mental status change secondary to infectious process. In each case, the patient’s metabolic panels don’t look too bad; however, one of the patients is septic. The physician says that sepsis often denotes encephalopathy, so documenting it separately is "unbundling." However, I disagree and think that this demonstrates severity. What is the correct logic to use in each of these cases? 

A: Based on the information you’ve provided, code 349.82 (toxic metabolic encephalopathy) seems to be more specific; however, it also requires an E code to identify the toxic substance that caused this condition.

From the details you’ve provided, code 348.31 (septic encephalopathy) more accurately describes the patient who has sepsis. Otherwise, the documentation "acute mental status change secondary to infectious process" is lacking in specificity and very well may negatively affect reimbursement.

Tell the physician that "unbundling" is a term referring to procedural—not diagnostic—coding. The term never refers to documentation. Remind the physician that he or she must document all of the details involved in his or her medical decision-making process that relate to the confirmed diagnosis. This will permit you to identify the important terms necessary for accurate coding.

Note that there is a difference between metabolic encephalopathy and toxic metabolic encephalopathy. The difference is the cause of the condition. Toxic metabolic encephalopathy is specifically caused by a toxic substance, which is why it requires an additional E code. The actual definition of toxic encephalopathy is "brain tissue degeneration due to toxic substance." Report code 349.82 (toxic metabolic encephalopathy) for this diagnosis.

Septic encephalopathy is the same as metabolic encephalopathy (i.e., it is listed as an additional diagnostic statement included with code 348.31). ICD-9-CM specifically excludes toxic metabolic encephalopathy from code 348.31 and instead references code 349.82.

Editor’s note: Shelley C. Safian, MAOM/HSM, CCS-P, CPC-H, CHA, of Safian Communications Services in Orlando, FL, answered this question. She is a senior assistant professor teaching medical billing and insurance coding at Herzing College Online in Milwaukee, WI. You can reach her at This Q&A originally appeared on

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