Almost 120 million adults in the US (48.1%) have hypertension, and of those, 92.9 million (77.4%) have uncontrolled hypertension, according to a JAMA study published in September 2024. Proper ICD-10 coding of hypertension can help demonstrate the severity of the patient’s illness, which can impact payment under value-based payment models. As documentation and coding for hypertension can be confusing, many providers rely on medical billing and coding services to ensure accurate reporting of patient conditions.
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Diagnosing Hypertension
Accurate coding relies on precise and thorough diagnoses. Proper documentation of the type, severity, and any associated conditions is essential to assign the correct ICD-10 codes. This not only ensures compliance with coding guidelines but also supports effective treatment planning, appropriate reimbursement, and accurate risk adjustment scoring.
According to the guidelines issued by the American College of Cardiology (ACC) and the American Heart Association (AHA), a blood pressure reading between 120 and 129 mm Hg for the top (systolic) number and more than 80 mm Hg for the bottom (diastolic) number is considered elevated. Additionally, any blood pressure reading above 130/80 mm Hg classifies as hypertension.
- Normal: Systolic pressure is below 120 mm Hg and diastolic is below 80 mm Hg.
- Elevated: Systolic pressure is between 120 and 129 mm Hg and diastolic pressure is below 80 mm Hg.
- Stage 1: Systolic pressure is between 130 and 139 mm Hg or diastolic pressure is between 80 and 89 mm Hg.
- Stage 2: Systolic pressure is a minimum of 140 mm Hg or diastolic pressure is a minimum 90 mm Hg.
There are two main types of hypertension: primary and secondary.
Primary (essential) hypertension: Above-normal blood pressure is typically anything over 120/80 mmHg and indicates primary (essential) hypertension.
Secondary hypertension: Secondary hypertension refers to a diagnosis of high blood pressure (hypertension) classified as stage 2, where the elevated blood pressure is caused by an underlying medical condition, like kidney disease, rather than a primary factor; meaning the high blood pressure is a secondary symptom of another issue.
Documentation and Coding
An article from the American Academy of Family Physicians (AAFP) recommends that when a patient presents with elevated blood pressure, the documentation and coding should accurately reflect the severity of their condition. The AAFP notes that documentation and coding should depend on the following:
- Is hypertension the diagnosis, or is elevated blood pressure the appropriate diagnosis?
- If hypertension is the diagnosis, is it primary or secondary?
- Is there hypertensive urgency or emergency?
- Does the patient also have heart or kidney disease?
The ICD-10 codes for hypertensive diseases include:
- I10: Essential (primary) hypertension
- I11: Hypertensive heart disease
- I12: Hypertensive chronic kidney disease
- I13: Hypertensive heart and chronic kidney disease
- I15: Secondary hypertension
- I16: Hypertensive crisis
- I1A: Other hypertension
- I1A.0: Resistant hypertension
- I16.1: Hypertensive emergency
Physicians need to provide a clear clinical picture of the patient’s condition for accurate coding. The AAFP article recommends asking four questions to ensure correct code assignment:
- “Is hypertension the diagnosis, or is elevated blood pressure the appropriate diagnosis?”
If a patient has elevated blood pressure without a diagnosis of hypertension, assign ICD-10 code R03.0, which indicates to borderline, transient, or white-coat hypertension.
R03.0 Elevated blood-pressure reading, without diagnosis of hypertension
- “If hypertension is the diagnosis, is it primary or secondary?”
If the diagnosis is primary hypertension, report:
ICD-10 code I10 Essential (primary) hypertension
For secondary hypertension, use secondary hypertension ICD-10 codes from category “I15” with the specific underlying cause:
I15.0 – Renovascular hypertension
I15.1 – Hypertension secondary to other renal disorders
I15.2 – Hypertension secondary to endocrine disorders
I15.8 – Other secondary hypertension
I15.9 – Secondary hypertension, unspecified
- “Is there hypertensive urgency or emergency?”
When a patient presents with hypertensive crisis or urgency, use codes from the “I16” category alongside the appropriate code for the underlying hypertension type.
I16 Hypertensive crisis
I16.0 Hypertensive urgency
I16.1 Hypertensive emergency
I16.9 Hypertensive crisis, unspecified
- “Does the patient also have heart or kidney disease?”
If a patient with hypertension is confirmed to have co-morbid heart and/or kidney disease, it should be reported using for following ICD-10 codes:
Hypertension and Heart Disease
I11.0 Hypertensive heart disease with heart failure
I11.9 Hypertensive heart disease without heart failure
Report I11.0 for a diagnosis of hypertension and heart failure with an additional code from I50.- code range to identify the type of heart failure
Hypertension and Chronic Kidney Disease
If the patient has hypertension and then develops chronic kidney disease, that condition is regarded as hypertensive chronic kidney disease in ICD-10.
I12 – Hypertensive chronic kidney disease
I12.0 – Hypertensive chronic kidney disease with stage 5 chronic kidney disease or end stage renal disease
I12.9 – Hypertensive chronic kidney disease with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease
Both these codes require an additional N18 code to specify the stage of kidney disease.
N18.1 – Chronic kidney disease, stage 1
N18.2 – Chronic kidney disease, stage 2 (mild)
N18.3 – Chronic kidney disease, stage 3 (moderate)
N18.4 – Chronic kidney disease, stage 4 (severe)
N18.5 – Chronic kidney disease, stage 5
N18.6 – End-stage renal disease
N18.9 – Chronic kidney disease, unspecified
However, if a patient develops chronic kidney disease before experiencing hypertension, the hypertension is considered a result of the pre-existing kidney condition. In this case, report a code from the “secondary hypertension” category (typically I15 in ICD-10) alongside the code for the chronic kidney disease itself.
Hypertension, Heart Disease and Chronic Kidney Disease
The ICD-10 codes for the three-disease combination (if the patient has all the three conditions, hypertension, heart disease and chronic kidney disease) are classified according to the degree of chronic kidney disease rather than the presence or absence of heart failure.
I13 – Hypertensive heart and chronic kidney disease
I13.0 – Hypertensive heart and chronic kidney disease with heart failure and stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease
I13.1 – Hypertensive heart and chronic kidney disease without heart failure
I13.10 – Hypertensive heart and chronic kidney disease without heart failure, with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease
I13.11 – Hypertensive heart and chronic kidney disease without heart failure, with stage 5 chronic kidney disease, or end stage renal disease
I13.2 – Hypertensive heart and chronic kidney disease with heart failure and with stage 5 chronic kidney disease, or end stage renal disease
Just as the two-disease combination codes, the above codes also require additional codes from the N18 series to specify the stage of kidney disease.
Hypertension and Risk Adjustment
Hypertensive heart or kidney disease impacts a patient’s risk-adjustment score if the proper hierarchical condition category (HCC) codes are assigned. Accurate documentation and coding of risk-adjusted conditions can potentially increase reimbursement as well. Here’s an example:
I11.0 Hypertensive heart disease with heart failure
HCC85 Congestive heart failure
Coding for Tobacco Use or Exposure
An additional ICD-10 code is required for all hypertension codes if the patient uses tobacco currently or had used it earlier. The codes for tobacco use are:
- F17: Nicotine dependence
- F17.20: Unspecified
- F17.21: Cigarettes
- F17.22:Chewing tobacco
- F17.29:Other tobacco product
Each of these four categories requires a sixth character:
- 0 – uncomplicated
- 1 – in remission
- 3 – with withdrawal
- 8 – with other specified nicotine-induced disorder
- 9 – with unspecified nicotine-induced disorder
If you find that occupational and environmental exposure to tobacco is influencing the health status of your patient, report that using the following ICD-10 codes:
- Z57.31:Occupational exposure to environmental tobacco smoke
- Z72.0: Problems related to lifestyle, tobacco use
- Z77.22:Exposure to environmental tobacco smoke (includes second-hand smoke exposure and passive smoking)
- Z87.891:Personal history of nicotine dependence
Other Hypertension Codes
- I27.0: Other primary pulmonary hypertension (Primary hypertension NOS)
- I27.2: Other secondary pulmonary hypertension (Code also associated underlying condition)
- I27.89: Other specified pulmonary heart diseases
- R03.0: Elevated blood-pressure reading, without diagnosis of hypertension
The code R03.0 should be used to indicate an episode of elevated blood pressure in a patient when no formal diagnosis of hypertension has been made, or as an incidental finding.
Stay Up-to-Date
The key points to note when coding hypertension are:
- Primary code for hypertension: “I10” (Essential (primary) hypertension)
- Secondary hypertension codes: Use codes from category “I15” with the specific underlying cause
- Resistant hypertension code: “I1A.0”
- Coding “Code first” rule: When coding resistant hypertension, always first code the specific type of existing hypertension (e.g., I10)
- Hypertensive crisis/urgency codes: Use codes from category “I16” along with the appropriate hypertension type code
With the growing focus on population health management and the need for accurate documentation to ensure proper HCC coding for risk adjustment scoring, it is more crucial than ever for physicians to stay informed about current codes and guidelines. Partnering with a specialized medical billing and coding company can be a game changer. Experienced coders collaborate closely with clinicians to capture the complete clinical picture of hypertension, ensuring precise ICD-10 code assignment and prompt claim submission.
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