Elevate Your Knowledge of Hypertension Coding
The guidelines lower your risk for inaccurate diagnosis reporting of heart disease.
When ICD-10-CM was on the horizon for the United States, the first ICD-10-CM code most medical coders learned was the one for hypertension. It was easy to remember. What most coders forgot about was all the other hypertension codes that exist under I10 Essential (primary) hypertension. Quality reporting requires us to dig deeper.
In this article, we will focus on the first three topics under Section I.C.9.a in the 2022 Official Guidelines for Coding and Reporting because this is where most hypertension coding errors are identified.
Back to the Basics
In coding, we must always go back to the basics. ICD-10-CM coding guideline I.C.9.a Hypertension states:
The classification presumes a causal relationship between hypertension and heart involvement and between hypertension and kidney involvement, as the two conditions are linked by the term “with” in the Alphabetic Index. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated.
For hypertension and conditions not specifically linked by relational terms such as “with,” “associated with” or “due to” in the classification, provider documentation must link the conditions in order to code them as related.
If you open to your ICD-10-CM code book and look up hypertension in the Alphabetic Index (page 211 in AAPC’s 2022 ICD-10-CM Expert code book), you will notice there are a lot more codes than just I10. The above guideline tells us that any indention under “with” has a causal relationship. A causal relationship means relating to or acting as a cause. Notice under the indention of “with” heart failure, heart involvement (conditions in I50. or I51.4-I51.7, I51.89, I51.9) and kidney involvement are listed.
Always check the category heading for additional instructional notes in the Tabular List. Category I10-I16 has an instructional note to use an additional code to identify tobacco exposure.
Hypertension With Heart Disease
ICD-10-CM guideline I.C.9.a.1 states:
Hypertension with heart conditions classified to I50.- or I51.4-I51.7, I51.89, I51.9, are assigned to a code from category I11, Hypertensive heart disease. Use additional code(s) from category I50, Heart failure, to identify the type(s) of heart failure in those patients with heart failure.
The same heart conditions (I50.-, I51.4-I51.7, I51.89, I51.9) with hypertension are coded separately if the provider has documented they are unrelated to the hypertension. Sequence according to the circumstances of the admission/encounter.
TIP: It’s important to code from the guidelines, Alphabetic Index, and Tabular List of your code book. Never simply look up a code in the Alphabetic Index and call it a day. Watch a tutorial for tips on navigating the ICD-10-CM code book in the electronic version of this magazine (member login required).
Notice this guideline tells you to code from category I11 and to a use an additional code when the physician’s documentation confirms that the patient has heart failure. If you turn to the Tabular List in your ICD-10-CM code book (page 668 in AAPC’s 2022 ICD-10-CM Expert code book) you will see a similar instructional note under I11.0 Hypertensive heart disease with heart failure that states “Use additional code to identify type of heart failure (I50.-).”
Now turn to I50 Heart failure in your code book (page 678 in AAPC’s ICD-10-CM Expert code book). Notice the instructional note here states code first heart failure due to hypertension … followed by a list of codes and descriptions.
In other words, you should code the hypertension (I11.-) and then the heart failure (I50.-). Make sure you are coding heart failure to the highest level of specificity documented. But don’t forget the guideline states “sequence according to the circumstances of the admission/encounter.”
Hypertensive Chronic Kidney Disease
ICD-10-CM guideline I.C.9.a.2 states:
Assign codes from category I12, Hypertensive chronic kidney disease, when both hypertension and a condition classifiable to category N18, Chronic kidney disease (CKD), are present. CKD should not be coded as hypertensive if the provider indicates the CKD is not related to the hypertension.
The appropriate code from category N18 should be used as a secondary code with a code from category I12 to identify the stage of chronic kidney disease.
See Section I.C.14. Chronic kidney disease.
If a patient has hypertensive chronic kidney disease and acute renal failure, the acute renal failure should also be coded. Sequence according to the circumstances of the admission/encounter.
This guideline also has a “use additional code” instructional note. Now turn to N18 Chronic kidney disease (CKD) in the Tabular List (page 886 in AAPC’s ICD-10-CM Expert code book). In red, you will see the “code first any associated” note … with a list of diagnoses, including I12-. There is also a “use additional code” note to identify kidney transplant status, if applicable. And if you scroll down a little farther to N18.6 End stage renal disease, you will notice a “use additional code” instructional note to identify dialysis status.
A commonly missed instructional note under N18.5 Chronic kidney disease, stage 5 states that this code excludes “chronic kidney disease, stage 5 requiring chronic dialysis (N18.6).” A patient with chronic kidney disease (CKD) stage 5 who requires chronic dialysis is coded to N18.6 End stage renal disease. Just like hypertension with heart disease, if you look back at the guideline, it says to “sequence according to the circumstances of the admission/encounter.”
Hypertensive Heart and Chronic Kidney Disease
ICD-10-CM guideline I.C.9.3 states:
Assign codes from combination category I13, Hypertensive heart and chronic kidney disease, when there is hypertension with both heart and kidney involvement. If heart failure is present, assign an additional code from category I50 to identify the type of heart failure.
The appropriate code from category N18, Chronic kidney disease, should be used as a secondary code with a code from category I13 to identify the stage of chronic kidney disease.
See Section I.C.14. Chronic kidney disease.
The codes in category I13, Hypertensive heart and chronic kidney disease, are combination codes that include hypertension, heart disease and chronic kidney disease. The Includes note at I13 specifies that the conditions included at I11 and I12 are included together in I13. If a patient has hypertension, heart disease and chronic kidney disease, then a code from I13 should be used, not individual codes for hypertension, heart disease and chronic kidney disease, or codes from I11 or I12.
For patients with both acute renal failure and chronic kidney disease, the acute renal failure should also be coded. Sequence according to the circumstances of the admission/encounter.
As you probably already guessed, you should use an additional code for heart failure (when applicable) and CKD when coding I13.-. If you follow the same steps taken for the last two sections, you will find similar instructional notes for I13 in the Tabular List (page 668 in AAPC’s 2022 ICD-10-CM Expert code book) and instruction to “sequence according to the circumstances of the admission/encounter” in the guidelines.
Hypertensive Cerebrovascular Disease
ICD-10-CM guideline I.C.9.4 states, “For hypertensive cerebrovascular disease, first assign the appropriate code from categories I60-I69, followed by the appropriate hypertension code.”
Notice there is not a specific combination code for hypertensive cerebrovascular disease. You are instructed to code for both the cerebrovascular disease and hypertension based on the documentation. Section I60-I69 in the Tabular List has a “use additional code” note to identify tobacco exposure, if applicable.
ICD-10-CM guideline I.C.9.5 states, “Subcategory H35.0, Background retinopathy and retinal vascular changes, should be used with a code from category I10-I15, Hypertensive disease to include the systemic hypertension. The sequencing is based on the reason for the encounter.”
An instructional note in the Tabular List for H35.0- states to “code also any associated hypertension (I10).”
ICD-10-CM guideline I.C.9.6 states, “Secondary hypertension is due to an underlying condition. Two codes are required: one to identify the underlying etiology and one from category I15 to identify the hypertension. Sequencing of codes is determined by the reason for admission/encounter.”
An instructional note in the Tabular List for I15.- states to “code also the underlying condition.”
ICD-10-CM guideline I.C.9.7 states, “Assign code R03.0, Elevated blood pressure reading without diagnosis of hypertension, unless patient has an established diagnosis of hypertension. Assign code O13.-, Gestational [pregnancy-induced] hypertension without significant proteinuria, or O14.-, Pre-eclampsia, for transient hypertension of pregnancy.”
This guideline brings us to another important topic for hypertension: As coders, we cannot look at a blood pressure reading and determine whether the patent is hypertensive and code hypertension, nor can we code elevated blood pressure as hypertension if a diagnosis of hypertension does not exist in the patient’s medical record. There is an ICD-10-CM code for a patient with elevated blood pressure reading without the diagnosis of hypertension. As coders, only code for hypertension when the provider documents “hypertension.”
ICD-10-CM guideline I.C.9.8 states, “This diagnostic statement usually refers to an existing state of hypertension under control by therapy. Assign the appropriate code from categories I10-I15, Hypertensive diseases.”
ICD-10-CM guideline I.C.9.9 states, “Uncontrolled hypertension may refer to untreated hypertension or hypertension not responding to current therapeutic regimen. In either case, assign the appropriate code from categories I10- I15, Hypertensive diseases.”
ICD-10-CM guideline I.C.9.10 states, “Assign a code from category I16, Hypertensive crisis, for documented hypertensive urgency, hypertensive emergency or unspecified hypertensive crisis. Code also any identified hypertensive disease (I10-I15). The sequencing is based on the reason for the encounter.”
ICD-10-CM guideline I.C.9.11 states, “Pulmonary hypertension is classified to category I27, Other pulmonary heart diseases. For secondary pulmonary hypertension (I27.1, I27.2-), code also any associated conditions or adverse effects of drugs or toxins. The sequencing is based on the reason for the encounter, except for adverse effects of drugs (See Section I.C.19.e.).”
Example: A patient presents to the cardiologist for hypertension and chronic diastolic heart failure. The patient has a social history of former smoker who quit one year ago after 30 years of smoking cigarettes. The provider has documentation to support both diagnoses were addressed at the encounter.
I11.0 Hypertensive heart disease with heart failure
I50.32 Chronic diastolic (congestive) heart failure
Z87.891 Personal history of nicotine dependence
TIP: If your provider does not document diastolic or systolic heart failure, but indicates HFrEF, which stands for heart failure reduced ejection fraction, or HFpEF, which stands for heart failure preserved ejection fraction, there is a Coding Clinic that instructs us to code HFrEF as systolic and HFpEF as diastolic. You will also notice in the Tabular List that these two terms/abbreviations are listed as inclusion terms.
Hone Your Craft
It’s important as a coder to read the diagnosis coding guidelines at least once a year (more often if you’re new to the profession). The more you read the guidelines, the more familiar with them you will become. This will help you when taking a certification exam, when coding, and when educating providers. Open communication with your provider(s) is important. Providers did not go to school for coding and do not know all the coding guidelines. If you have a healthcare provider who treats patients with hypertension, it’s important for you to educate the provider on the details needed for accurate coding to the highest level of specificity known. Educating the provider supports the importance of your role as a certified coder.
2022 Official Guidelines for Coding and Reporting, April 1, 2022, release: