Cardiology Coding Alert

Question: Does ICD-9 distinguish controlled and uncontrolled hypertension (HTN)?

Missouri Subscriber

Answer: No. Section I.C.7.a of the ICD-9 official guidelines indicates that you should assign a code from 401.x-405.x (Hypertensive disease) for both controlled and uncontrolled hypertension (guidelines available at www.cdc.gov/nchs/data/icd9/icdguide09.pdf).

Controlled hypertension "usually refers to an existing state of hypertension under control by therapy," the guidelines state. "Uncontrolled hypertension may refer to untreated hypertension or hypertension not responding to current therapeutic regimen."

Caution: Don't confuse "uncontrolled" with "malignant" hypertension, which refers to severely elevated blood pressure. To use a malignant hypertension diagnosis code, such as 401.0 (Essential hypertension; malignant), your cardiologist's documentation must specifically support your choice of a "malignant" code.