E66.01: Morbid (severe) obesity due to excess calories
Billable ICD-10-CM code, FY2027
What ICD-10-CM says
Excludes1 (never coded with E66.01)
- morbid (severe) obesity with alveolar hypoventilation (E66.2)
What E66.01 covers
E66.01 is for morbid or severe obesity caused by taking in more calories than the body uses. It is used in primary care, bariatric surgery and endocrinology.
Its sibling E66.09 covers other obesity due to excess calories. Morbid obesity with alveolar hypoventilation is E66.2, and obesity with no detail is E66.9. Obesity documented by class has its own codes in E66.81-.
Billing and coding notes
E66.01 has an excludes1 for morbid obesity with alveolar hypoventilation (E66.2). If the provider documents hypoventilation with the obesity, E66.2 replaces E66.01.
The E66 category asks for a Z68 code for the BMI when known. The BMI on its own does not establish morbid obesity; the provider has to document the diagnosis. In pregnancy, O99.21- is coded first.
Related codes under E66.0
Questions about E66.01
Can E66.01 be coded without a BMI code?
Yes, when the BMI is not documented. When it is known, the E66 category says to add the matching Z68 code.
What is the difference between E66.01 and E66.2?
Both are morbid obesity. E66.2 is morbid obesity with alveolar hypoventilation, and it is an excludes1 at E66.01, so only one is reported.
ICD-10-CM in CloudMedico
In CloudMedico, a visit's diagnoses come from the current ICD-10-CM list. For US practices, the visit flags a code that isn't billable on its date, and a superbill made from an invoice carries the visit's diagnoses.
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