ICD-10 Spotlight: Know the codes (Code first)

January 31, 2012


There are a number of significant changes involved with the transition to ICD-10. In addition to ensuring that systems and processes are updated to be ICD-10-compliant by the mandated implementation date of October 1, 2013, providers and office staff must become familiar with the new ICD-10 codes to ensure accurate clinical documentation.

The thought of transitioning from approximately 24,000 codes to over 140,000 codes might seem daunting. To help educate providers and office staff about what to expect when coding various diagnoses with the new ICD-10 codes, beginning with this month?s edition of Partners in Health UpdateSM, we will include examples of how ICD-9 codes translate to ICD-10 codes in this new section called ?ICD-10 Spotlight: Know the codes.? We will present coding examples from different specialties and popular disease categories to demonstrate the granularity that the new ICD-10 code set will provide.


This example of coding obesity demonstrates how many of the new codes may require documentation using ICD-10 Coding Guidelines such as the "code first" guideline.

ICD-10 has a coding convention that requires the underlying or causal condition be sequenced first followed by the manifested condition, which is referred to as the "code first" guideline.

For example, if a patient is on the antidepressant drug Tryptanol (amitriptyline), and this drug is what caused the patient's weight gain, it is considered an adverse effect and is the underlying or causal condition of the patient' sobesity. Therefore, diagnosis code T43.015 (adverse effect of tricyclic antidepressants) must be coded first.

ICD-9 coding table*

ICD-10 coding table*

Clinical documentation of diagnosis: Code first

  • 278.01 Morbid obesity
  • 278.02 Overweight
  • 278.03 Obesity hypoventilation syndrome
  • E66.01 Morbid (severe) obesity due to excess calories
  • E66.09 Other obesity due to excess calories
  • E66.1 Drug-induced obesity
  • E66.2 Morbid (severe) obesity with alveolar hypoventilation
  • E66.3 Overweight
  • E66.8 Other obesity
  • E66.9 Obesity, unspecified

T43.015 Adverse affects of tricyclic antidepressants

E66.1 Drug-induced obesity

*Condensed list of codes

Go to our ICD-10 web page for additional information related to IBC's transition to ICD-10.