Coding Symptoms Inherent in a Disease

In the first quarter of 2010, the following question was submitted to Coding Clinic:

What is the correct code assignment for a diagnosis of “compensated respiratory acidosis” in a patient with chronic obstructive pulmonary disease (COPD)?

Coding Clinic advised that only one code should be assigned--496 for the COPD.  This answer illustrates a coding principle that sometimes is problematic--symptoms of a disease are not coded when they are inherent to the disease.  Often, physicians will list these symptoms or signs when they are causing a specific problem for the patient.  For example, tremor is a hallmark of Parkinson's disease, and a physician may note that the tremor exists, is increasing or is decreasing.  Coders may be tempted to code the tremor because the physician has evaluated it--but it's a part of the disease. In that case, only the Parkinson's disease should be coded.

Sometimes, it's not so clear that a problem is a usual part of the disease.  For example, in the second quarter of 2010, a patient presented with gross hematuria due to a prostate malignancy.  While the prostate malignancy caused the hematuria, it isn't a usual part of the disease, and the questioner was instructed to code the hematuria, and the prostate cancer as a secondary diagnosis. In that case, the hematuria was a complication, and complications are coded separately.

When in doubt, coders should query the physician as to whether a listed symptom or sign is a usual part of the disease process, or a complication.  This affords coders a great opportunity to work collaboratively with the physician--it allows the coder the opportunity to both gain information from the physician, and provide the physician with information regarding coding rules.