Internal Medicine Coding Alert

Question: My internist often writes "hypertension" as a diagnosis. It is important for him also to include primary or secondary?

Alabama Subscriber

Answer: Yes, knowing whether the patient has primary or secondary hypertension often determines your coding choices. If a patient has primary hypertension, which means another cause hasn't caused hypertension, then you should assign the hypertension ICD-9 as the primary diagnosis.

For example, the internist diagnoses a patient with benign hypertensive heart disease with heart failure. You should report 402.11 (Hypertensive heart disease; benign; with heart failure), because the code indicates the patient's complete hypertensive status. And, you should list 428.0 (Congestive heart failure, unspecified) to specify the type of heart failure.

Note: If the physician documents that the patient has heart disease due to hypertension, he should also indicate whether the disease is with or without heart failure. And if the patient does have heart failure, remember to assign a separate code to indicate the type of heart failure.

A patient has secondary hypertension if another condition has caused the disease. ICD-9-CM defines secondary hypertension as "high arterial blood pressure due to or with a variety of primary diseases, such as renal disorders, CNS disorders, endocrine and vascular diseases."

For secondary hypertension, you should report the causal condition as the primary diagnosis and the hypertension as secondary. For example, if a patient has primary aldosteronism that is causing benign hypertension, you might report 255.10 (Primary aldosteronism) as the primary diagnosis and 405.19 (Secondary hypertension; benign; other) as the secondary.