I10
I10 — Essential (primary) hypertension
Chapter 9: Diseases of the Circulatory System (I00-I99)
I10-I16 — Hypertensive diseases
Clinical Definition
Essential (primary) hypertension is a chronic medical condition characterized by persistently elevated systemic arterial blood pressure that has no identifiable secondary cause. According to current ACC/AHA guidelines, hypertension is defined as a systolic blood pressure of 130 mmHg or higher, or a diastolic blood pressure of 80 mmHg or higher, confirmed on two or more separate clinical encounters. Essential hypertension accounts for approximately 90-95% of all hypertension cases and is a major modifiable risk factor for cardiovascular disease, stroke, chronic kidney disease, and heart failure.
ICD-10-CM code I10 is assigned when the provider documents essential hypertension, primary hypertension, arterial hypertension, systemic hypertension, or simply "hypertension" without further qualification indicating a secondary cause, hypertensive crisis, or target organ involvement such as hypertensive heart disease or hypertensive chronic kidney disease. The code includes high blood pressure that is documented as benign, malignant, or unspecified as to benign or malignant status, as the ICD-10-CM classification no longer distinguishes between these historical subtypes. I10 should not be used when the hypertension is documented as secondary to an identifiable underlying condition (use I15.x instead) or when there is documented hypertensive involvement of the heart (I11.x), kidneys (I12.x), or both (I13.x).
Management of essential hypertension typically involves lifestyle modifications including dietary sodium restriction, the DASH diet, regular aerobic exercise, weight management, and moderation of alcohol intake, combined with pharmacologic therapy when indicated. First-line antihypertensive agents include thiazide diuretics, ACE inhibitors, angiotensin receptor blockers (ARBs), and calcium channel blockers. Blood pressure targets and treatment intensity are individualized based on the patient's cardiovascular risk profile, age, comorbidities, and evidence of target organ damage.
When to Use I10
- ✓The provider documents essential hypertension, primary hypertension, or simply 'hypertension' without specifying a secondary cause or target organ involvement.
- ✓The patient has a confirmed diagnosis of high blood pressure on two or more office visits, and the medical record does not indicate an identifiable underlying etiology such as renal artery stenosis, pheochromocytoma, or Cushing syndrome.
- ✓The encounter involves ongoing management of previously diagnosed essential hypertension, including medication adjustments, blood pressure monitoring, or lifestyle counseling.
- ✓Elevated blood pressure is documented as a chronic condition on the patient's active problem list and is being treated with antihypertensive therapy.
- ✓The patient presents with hypertension in the setting of a routine health examination or chronic disease management visit, and no hypertensive heart disease, hypertensive CKD, or hypertensive crisis is documented.
- ✓Coding from an operative or procedural note where the anesthesia team documents 'hypertension' as a comorbid condition contributing to surgical risk.
Common Coding Mistakes
- ⚠Using I10 when the documentation states 'hypertensive heart disease' — use I11.0 (with heart failure) or I11.9 (without heart failure) instead, as ICD-10-CM guidelines require linking hypertension with heart disease when both are documented.
- ⚠Using I10 when the patient has both hypertension and chronic kidney disease — per ICD-10-CM Official Guidelines Section I.C.9.a.2, a causal relationship is assumed; use I12.0 or I12.9 for hypertensive CKD, with an additional code from N18.x for the CKD stage.
- ⚠Assigning I10 for secondary hypertension caused by an identifiable condition such as renal artery stenosis, primary aldosteronism, or pheochromocytoma — use I15.0, I15.1, I15.2, I15.8, or I15.9 as appropriate, and code the underlying cause.
- ⚠Using I10 for hypertensive urgency or emergency — use I16.0 (hypertensive urgency) or I16.1 (hypertensive emergency) when the provider documents these acute presentations with severely elevated blood pressure.
- ⚠Assigning I10 for elevated blood pressure reading without a confirmed diagnosis of hypertension — use R03.0 (elevated blood pressure reading without diagnosis of hypertension) when the provider has not established a diagnosis.
- ⚠Using I10 alongside I11.9 or I12.9 for the same patient — the combination codes (I11.x, I12.x, I13.x) already include the hypertension, so I10 should not be reported separately when a more specific hypertensive disease code applies.
Related & Differential Codes
| Code | Description | Relationship |
|---|---|---|
| I11.0 | Hypertensive heart disease with heart failure | Related |
| I11.9 | Hypertensive heart disease without heart failure | Related |
| I12.0 | Hypertensive chronic kidney disease with stage 5 CKD or ESRD | Related |
| I12.9 | Hypertensive chronic kidney disease with stage 1 through stage 4, or unspecified CKD | Related |
| I13.0 | Hypertensive heart and chronic kidney disease with heart failure and stage 1-4 or unspecified CKD | Related |
| I13.10 | Hypertensive heart and chronic kidney disease without heart failure, with stage 1-4 or unspecified CKD | Related |
| I15.0 | Renovascular hypertension | Excludes |
| I15.9 | Secondary hypertension, unspecified | Excludes |
| I16.0 | Hypertensive urgency | Related |
| I16.1 | Hypertensive emergency | Related |
| R03.0 | Elevated blood pressure reading, without diagnosis of hypertension | Excludes |
| E11.9 | Type 2 diabetes mellitus without complications | Related |
| R07.9 | Chest pain, unspecified | Related |
Documentation Requirements
- 1Type of hypertension: clearly document whether the hypertension is essential (primary) or secondary to an identifiable cause, as this determines whether I10 or I15.x is assigned.
- 2Blood pressure readings: record the systolic and diastolic values obtained at the encounter, including the method of measurement (office, ambulatory, home monitoring).
- 3Target organ involvement: explicitly state whether hypertensive heart disease (I11.x), hypertensive chronic kidney disease (I12.x), or both (I13.x) are present, as ICD-10-CM combination codes must be used when applicable.
- 4Current antihypertensive medications: list all blood pressure medications with dosages, and document any changes made during the encounter including rationale for adjustments.
- 5Blood pressure control status: document whether the hypertension is controlled or uncontrolled on the current regimen, as this impacts care management coding and quality measure reporting.
- 6Comorbid conditions: document associated conditions such as diabetes mellitus, hyperlipidemia, obesity, chronic kidney disease, and coronary artery disease to support medical necessity and risk adjustment.
- 7Lifestyle modification counseling: record any discussion of dietary changes, exercise, weight loss, sodium restriction, smoking cessation, or alcohol reduction.
- 8Follow-up plan: document the interval for the next blood pressure check, any laboratory tests ordered (renal function, electrolytes, lipids), and referrals if applicable.
Reimbursement & Billing Notes
ICD-10-CM code I10 is a valid, billable code accepted by Medicare, Medicaid, and all commercial payers for services related to essential hypertension. It is one of the most commonly reported diagnosis codes across all clinical settings. I10 can be used as a primary or secondary diagnosis depending on the reason for the encounter. Chronic care management (CCM) services, remote patient monitoring (RPM) for blood pressure, and annual wellness visits frequently include I10 as a qualifying condition. Payers generally do not require additional specificity beyond I10 for essential hypertension, as it is already a complete, terminal code with no further subcategories.
For Medicare Advantage and other risk-adjusted payment models, I10 maps to HCC 22 (in CMS-HCC V28 model) which does not carry a risk adjustment factor — essential hypertension alone is not an HCC condition that increases the RAF score. However, when hypertension is associated with target organ damage (hypertensive heart disease I11.x, hypertensive CKD I12.x), those combination codes do map to higher-value HCCs and significantly impact risk adjustment. This creates a documentation improvement opportunity: ensuring that providers document the causal relationship between hypertension and heart disease or CKD results in more accurate coding and appropriate risk adjustment. Auditors frequently review claims with I10 to verify that combination codes (I11.x, I12.x, I13.x) were not overlooked when clinical evidence of target organ involvement exists.
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Try Free — No Credit Card RequiredFrequently Asked Questions
What is the ICD-10 code for hypertension?
The ICD-10-CM code for essential (primary) hypertension is I10. This code is used when a provider documents hypertension, high blood pressure, essential hypertension, or primary hypertension without specifying a secondary cause or target organ involvement such as hypertensive heart disease or hypertensive kidney disease. I10 is a complete, billable code and is one of the most frequently reported diagnosis codes in outpatient and inpatient settings.
What is the difference between I10 and I15?
I10 is used for essential (primary) hypertension, which means the high blood pressure has no identifiable underlying cause. I15.x codes are used for secondary hypertension, where the elevated blood pressure is caused by a known condition such as renovascular disease (I15.0), endocrine disorders like pheochromocytoma or primary aldosteronism (I15.1, I15.2), or other specified secondary causes (I15.8). When coding secondary hypertension, both the I15.x code and the code for the underlying condition should be reported.
Can I10 be used with chronic kidney disease codes?
No. Per ICD-10-CM Official Guidelines Section I.C.9.a.2, when a patient has both hypertension and chronic kidney disease, a causal relationship is assumed unless the provider explicitly documents that the conditions are unrelated. The correct coding is I12.0 or I12.9 (hypertensive chronic kidney disease) with an additional code from N18.1-N18.9 to identify the CKD stage. I10 should not be reported separately alongside hypertensive CKD combination codes.
Is I10 a billable ICD-10 code?
Yes, I10 is a valid, billable ICD-10-CM code that is accepted by Medicare, Medicaid, and commercial payers. It is a three-character code with no further subcategories, meaning it is already at the highest level of specificity available for essential hypertension. It can be used as either a primary or secondary diagnosis depending on the purpose of the encounter.
When should I use R03.0 instead of I10?
Use R03.0 (elevated blood pressure reading, without diagnosis of hypertension) when a patient has a high blood pressure reading at an encounter but the provider has not established or confirmed a diagnosis of hypertension. This commonly occurs during screening visits, preoperative evaluations, or initial elevated readings that require confirmation on subsequent visits. Once the provider formally diagnoses hypertension based on repeated elevated readings or clinical assessment, I10 should be assigned instead of R03.0.
Should I use I10 when the patient has hypertension and heart failure?
No. Per ICD-10-CM Official Guidelines Section I.C.9.a.1, when hypertension and heart disease are both documented, a causal relationship is assumed unless the provider explicitly states the heart disease is not due to hypertension. The correct code is I11.0 (hypertensive heart disease with heart failure) along with an additional code from I50.x to specify the type of heart failure. I10 should not be reported separately when a hypertensive heart disease combination code applies.