I10ICD-10-CM

Essential (primary) hypertension

Billable at three charactersMalignant hypertension is classified hereDisplaced when heart or kidney disease is present

How the code is built

Chapter

Diseases of the circulatory system

What ICD-10 code I10 means

I10 is the ICD-10-CM code for essential (primary) hypertension. It applies when a provider documents hypertension with no identified secondary cause and no documented heart or kidney involvement.

It is complete at three characters. That makes it one of a small number of codes in ICD-10-CM that need nothing further, and it is why claims carrying I10 never trip a specificity edit for length. The absence of further characters is doing something, though. It means the code says nothing about severity, control, or stage.

Code

I10

Descriptor

Essential (primary) hypertension

Chapter

Diseases of the circulatory system

Block

Hypertensive diseases

Billable

Yes, at three characters

Inclusion terms

None listed at the code line

Excludes1

Hypertensive disease complicating pregnancy, childbirth and the puerperium

Excludes2

Hypertension involving vessels of brain, hypertension involving vessels of eye

Attribute	Detail
Code	I10
Descriptor	Essential (primary) hypertension
Chapter	Diseases of the circulatory system
Block	Hypertensive diseases
Billable	Yes, at three characters
Inclusion terms	None listed at the code line
Excludes1	Hypertensive disease complicating pregnancy, childbirth and the puerperium
Excludes2	Hypertension involving vessels of brain, hypertension involving vessels of eye

The single most useful fact about this code is in the Alphabetic Index. The entry reads hypertension, hypertensive, followed by accelerated, benign, essential, idiopathic, malignant and systemic in parentheses. Those are non-essential modifiers, which means every one of them classifies to I10.

So malignant hypertension is I10. So are accelerated hypertension, benign hypertension, and labile hypertension. ICD-9-CM distinguished malignant from benign with separate codes, and ICD-10-CM collapsed both into this one. The general equivalence mappings confirm it: both legacy codes point here.

That matters because malignant hypertension reads as an emergency, and coders reach for a crisis code when they see it. The word changes nothing.

2Code structure

What displaces I10, and what sits beside it

I10 has no subdivisions. What determines whether it is the right code is entirely about what else the record documents.

The presumed causal relationships, which displace I10 automatically

Nothing else

I10

Heart disease

I11.-, hypertensive heart disease

Chronic kidney disease

I12.-, hypertensive chronic kidney disease

Both heart and kidney disease

I13.-

A secondary cause

I15.-, with the underlying condition coded also

Also documented	Code
Nothing else	I10
Heart disease	I11.-, hypertensive heart disease
Chronic kidney disease	I12.-, hypertensive chronic kidney disease
Both heart and kidney disease	I13.-
A secondary cause	I15.-, with the underlying condition coded also

The classification presumes the relationship between hypertension and heart disease, and between hypertension and chronic kidney disease, without requiring the provider to state a link. So a patient with hypertension and stage 3 chronic kidney disease does not get I10 and a kidney code. They get a combination code from I12, and the kidney stage is reported alongside it. I10 is correct only when neither of those conditions is present.

The rest of the block, which coexists with a hypertension code

Hypertensive urgency

I16.0

Hypertensive emergency

I16.1

Hypertensive crisis, type not stated

I16.9

Resistant hypertension

I1A.0

Documented state	Code
Hypertensive urgency	I16.0
Hypertensive emergency	I16.1
Hypertensive crisis, type not stated	I16.9
Resistant hypertension	I1A.0

The crisis codes and the resistant hypertension code are not alternatives to I10. Each requires the underlying hypertensive disease to be reported as well, so a hypertensive emergency in a patient with essential hypertension produces two codes. For resistant hypertension, the published advice is more specific still: the type of hypertension is sequenced first, and the resistant hypertension code follows.

Resistant hypertension is a recent addition. The I1A category was created in the FY 2024 code set, which is recent enough that older superbills and EHR pick lists do not contain it.

What the code does not record

Blood pressure values

None

Stage or grade

None

Controlled or uncontrolled

None

Number of medications

None, unless the provider documents resistant hypertension

Documented detail	Effect on the code
Blood pressure values	None
Stage or grade	None
Controlled or uncontrolled	None
Number of medications	None, unless the provider documents resistant hypertension

3Clinical picture

Clinical findings documented under I10

Hypertension is established by measurement and is usually asymptomatic, which shapes what a supporting record contains.

Measurements

Office readings across visits, home or ambulatory readings where obtained

Symptoms

Typically absent, and often documented as such

Target organ assessment

Renal function, urinalysis for protein, electrocardiogram, echocardiography where obtained

Comorbidity

Chronic kidney disease, heart failure, coronary disease, diabetes, obesity

Secondary cause screening

Renal artery disease, endocrine causes, medication contributors

Management

Antihypertensive regimen, adherence, response, lifestyle measures

The target organ row is what most often changes the code. A documented reduced ejection fraction or a documented chronic kidney disease stage moves the encounter out of I10 and into a combination code.

4Documentation

What the chart must show

A provider-stated diagnosis of hypertension
Whether it is essential or secondary, and the secondary cause if identified
Whether heart disease is present, since that changes the code family
Whether chronic kidney disease is present, and at what stage
Whether the encounter involves a crisis, urgency, or emergency
Whether the hypertension is documented as resistant, if that code is intended
Pregnancy status, since hypertensive disease in pregnancy classifies elsewhere entirely
An assessment and plan showing the condition was addressed at this encounter

The element most often missed is the link the coder does not need. Because the classification presumes the relationship with heart and kidney disease, the provider does not have to state a causal connection, and the coder has to notice the comorbidity even when the note treats it as a separate problem.

5Decision guide

When to assign I10, and when not to

Hypertension, or high blood pressure, nothing else documented

I10

Malignant, accelerated, benign, or labile hypertension

I10, since those are non-essential modifiers

Uncontrolled hypertension

I10, since control is not a code axis

Hypertension with heart failure

The applicable I11 code, plus the heart failure type code

Hypertension with chronic kidney disease

The applicable I12 code, plus the CKD stage code

Hypertension with both heart and kidney disease

The applicable I13 code

Secondary hypertension

The applicable I15 code, with the cause coded also

Hypertensive urgency or emergency

The I16 code, plus the hypertensive disease code

Resistant hypertension

The type of hypertension first, then I1A.0

Hypertensive disease in pregnancy or the puerperium

The obstetric chapter code, never I10

Hypertensive retinopathy

The H35.0 code and I10 together, since each points at the other

Hypertensive encephalopathy or cerebrovascular involvement

The applicable code from I60 to I69, reportable alongside

An elevated reading with no established diagnosis of hypertension

R03.0

Postprocedural hypertension

I97.3

The record says	Assign
Hypertension, or high blood pressure, nothing else documented	I10
Malignant, accelerated, benign, or labile hypertension	I10, since those are non-essential modifiers
Uncontrolled hypertension	I10, since control is not a code axis
Hypertension with heart failure	The applicable I11 code, plus the heart failure type code
Hypertension with chronic kidney disease	The applicable I12 code, plus the CKD stage code
Hypertension with both heart and kidney disease	The applicable I13 code
Secondary hypertension	The applicable I15 code, with the cause coded also
Hypertensive urgency or emergency	The I16 code, plus the hypertensive disease code
Resistant hypertension	The type of hypertension first, then I1A.0
Hypertensive disease in pregnancy or the puerperium	The obstetric chapter code, never I10
Hypertensive retinopathy	The H35.0 code and I10 together, since each points at the other
Hypertensive encephalopathy or cerebrovascular involvement	The applicable code from I60 to I69, reportable alongside
An elevated reading with no established diagnosis of hypertension	R03.0
Postprocedural hypertension	I97.3

Query rather than default when the problem list carries chronic kidney disease or heart failure but the claim carries only I10, and when the note describes a hypertensive crisis without saying urgency or emergency.

6Tabular list

Instructional notes at I10 and above

Excludes1 at I10

Hypertensive disease complicating pregnancy, childbirth and the puerperium (O10 to O11, O13 to O16)

Excludes2 at I10

Essential (primary) hypertension involving vessels of brain (I60 to I69)

Excludes2 at I10

Essential (primary) hypertension involving vessels of eye (H35.0-)

Code also at H35.0-

Any associated hypertension (I10), pointing back at this code

Code also at I15

The underlying condition for secondary hypertension

Excludes1 at I15

Postprocedural hypertension (I97.3)

Note	Content
Excludes1 at I10	Hypertensive disease complicating pregnancy, childbirth and the puerperium (O10 to O11, O13 to O16)
Excludes2 at I10	Essential (primary) hypertension involving vessels of brain (I60 to I69)
Excludes2 at I10	Essential (primary) hypertension involving vessels of eye (H35.0-)
Code also at H35.0-	Any associated hypertension (I10), pointing back at this code
Code also at I15	The underlying condition for secondary hypertension
Excludes1 at I15	Postprocedural hypertension (I97.3)

The code line is unusually clean: one prohibition and two permissions. That is fewer notes than almost any high-volume code in this glossary, and it is part of why I10 gets over-applied. Very little in the tabular list constrains it. What constrains it is the presumed causal relationship convention, which lives in the guidelines rather than in a note.

The pregnancy exclusion is absolute. Hypertensive disease in pregnancy, childbirth, or the puerperium is classified in the obstetric chapter, and I10 cannot appear alongside those codes.

The brain and eye notes are Excludes2, so both are permissions. Cerebrovascular disease may be reported alongside I10, and coders drop it on an assumed conflict.

The eye relationship goes further than a permission, and this is the part most easily missed. The guidelines direct that the background retinopathy and retinal vascular changes subcategory be used *with* a code from the hypertensive disease range to capture the systemic hypertension, with sequencing based on the reason for the encounter. The tabular list reinforces it from the other side: the retinopathy subcategory carries a code also with an instruction naming I10 directly. So hypertensive retinopathy is not merely allowed alongside I10. The classification asks for both.

7Comparison

Codes frequently confused with I10

I11.-

Descriptor

Hypertensive heart disease, with or without heart failure

Use instead when

Heart disease is documented, since the relationship is presumed

I12.-

Descriptor

Hypertensive chronic kidney disease, by CKD stage

Use instead when

Chronic kidney disease is documented, since the relationship is presumed

I13.-

Descriptor

Hypertensive heart and chronic kidney disease

Use instead when

Both are documented

I15.0, I15.1, I15.2, I15.8, I15.9

Descriptor

Renovascular hypertension, hypertension secondary to other renal disorders, to endocrine disorders, other secondary, and secondary unspecified

Use instead when

A secondary cause is documented, with that cause coded also

I16.0

Descriptor

Hypertensive urgency

Use instead when

Urgency is documented, reported with the hypertension code

I16.1

Descriptor

Hypertensive emergency

Use instead when

Emergency is documented, reported with the hypertension code

I16.9

Descriptor

Hypertensive crisis, unspecified

Use instead when

A crisis is documented without a stated type

I1A.0

Descriptor

Resistant hypertension

Use instead when

The hypertension is documented as resistant

I97.3

Descriptor

Postprocedural hypertension

Use instead when

Hypertension follows a procedure, which the I15 Excludes1 blocks

H35.0-

Descriptor

Background retinopathy and retinal vascular changes

Use instead when

Hypertensive retinopathy is documented, reported together with I10 per the code also note

I60 to I69

Descriptor

Cerebrovascular diseases

Use instead when

Cerebrovascular involvement is documented, reportable alongside

O10 to O16

Descriptor

Hypertensive disorders in pregnancy, childbirth and the puerperium

Use instead when

The patient is pregnant or postpartum, which the Excludes1 blocks

R03.0

Descriptor

Elevated blood-pressure reading, without diagnosis of hypertension

Use instead when

A reading is elevated, and no diagnosis of hypertension is established

I27.0, I27.2-

Descriptor

Primary pulmonary hypertension, other secondary pulmonary hypertension

Use instead when

The hypertension is pulmonary rather than systemic

N18.-

Descriptor

Chronic kidney disease, by stage

Use instead when

Reported alongside the I12 or I13 combination code

I50.-

Descriptor

Heart failure, by type and acuity

Use instead when

Reported alongside the I11.0 or I13 combination code

Code	Descriptor	Use instead when
I11.-	Hypertensive heart disease, with or without heart failure	Heart disease is documented, since the relationship is presumed
I12.-	Hypertensive chronic kidney disease, by CKD stage	Chronic kidney disease is documented, since the relationship is presumed
I13.-	Hypertensive heart and chronic kidney disease	Both are documented
I15.0, I15.1, I15.2, I15.8, I15.9	Renovascular hypertension, hypertension secondary to other renal disorders, to endocrine disorders, other secondary, and secondary unspecified	A secondary cause is documented, with that cause coded also
I16.0	Hypertensive urgency	Urgency is documented, reported with the hypertension code
I16.1	Hypertensive emergency	Emergency is documented, reported with the hypertension code
I16.9	Hypertensive crisis, unspecified	A crisis is documented without a stated type
I1A.0	Resistant hypertension	The hypertension is documented as resistant
I97.3	Postprocedural hypertension	Hypertension follows a procedure, which the I15 Excludes1 blocks
H35.0-	Background retinopathy and retinal vascular changes	Hypertensive retinopathy is documented, reported together with I10 per the code also note
I60 to I69	Cerebrovascular diseases	Cerebrovascular involvement is documented, reportable alongside
O10 to O16	Hypertensive disorders in pregnancy, childbirth and the puerperium	The patient is pregnant or postpartum, which the Excludes1 blocks
R03.0	Elevated blood-pressure reading, without diagnosis of hypertension	A reading is elevated, and no diagnosis of hypertension is established
I27.0, I27.2-	Primary pulmonary hypertension, other secondary pulmonary hypertension	The hypertension is pulmonary rather than systemic
N18.-	Chronic kidney disease, by stage	Reported alongside the I12 or I13 combination code
I50.-	Heart failure, by type and acuity	Reported alongside the I11.0 or I13 combination code

Two rows deserve emphasis. The pulmonary hypertension codes are a different condition entirely and sit in the pulmonary circulation block, not here. And R03.0 is the code for a high reading without a diagnosis, which is the correct answer when a screening blood pressure is elevated, and the provider has not yet diagnosed hypertension.

8Claim context

Services commonly reported with I10

I10 is among the highest-volume diagnoses in outpatient medicine. It supports office evaluation and management, the laboratory and imaging that assess target organ status, chronic care management, and blood pressure monitoring services including self-measured monitoring and ambulatory monitoring.

Ambulatory blood pressure monitoring is governed by a national determination, and the covered indications are narrower than practices expect. Coverage is for the diagnosis of hypertension in two specific situations: suspected white coat hypertension and suspected masked hypertension. Each is defined by specific average office readings across at least two separate visits with at least two measurements at each visit, paired with out-of-office readings that meet stated thresholds. The determination also requires the study to run for at least 24 hours, requires physician interpretation, and sets device standards.

The practical consequence is that the record has to establish the suspected pattern with the readings the policy names. A patient carrying an established hypertension diagnosis is not the population the covered indications describe, so an ambulatory monitoring claim built on I10 alone does not demonstrate the criteria.

Self-measured blood pressure monitoring services have their own documentation and time requirements and are governed by contractor policy. Confirm the national determination for ambulatory monitoring and the contractor's policy for self-measured monitoring before submission.

9Denials

Coding errors that cause denials

Reporting I10 when heart disease is documented

Assign the applicable I11 code, since the relationship is presumed

Reporting I10 when chronic kidney disease is documented

Assign the applicable I12 code, plus the CKD stage

Reporting I10 and a separate heart or kidney code instead of the combination code

Use the combination code

Reaching for a crisis code because the note says malignant hypertension

Assign I10, since malignant is a non-essential modifier

Reporting a crisis code alone

Add the hypertensive disease code, per the instruction at I16

Reporting I10 for a pregnant or postpartum patient

Assign the obstetric chapter code

Dropping the cerebrovascular code on an assumed conflict

Report both, since that note is an Excludes2

Reporting hypertensive retinopathy without the hypertension code

Report both, since the guidelines and the code also note at H35.0- require it

Sequencing I1A.0 ahead of the type of hypertension

Sequence the type first

Assigning I10 from a single elevated reading with no diagnosis

Assign R03.0

Using I10 for pulmonary hypertension

Assign the pulmonary circulation code

Building an ambulatory monitoring claim on I10 alone

Document the suspected white coat or masked pattern with the readings the policy requires

Working from a pick list that predates the resistant hypertension code

Update the encounter form

Error	Correction
Reporting I10 when heart disease is documented	Assign the applicable I11 code, since the relationship is presumed
Reporting I10 when chronic kidney disease is documented	Assign the applicable I12 code, plus the CKD stage
Reporting I10 and a separate heart or kidney code instead of the combination code	Use the combination code
Reaching for a crisis code because the note says malignant hypertension	Assign I10, since malignant is a non-essential modifier
Reporting a crisis code alone	Add the hypertensive disease code, per the instruction at I16
Reporting I10 for a pregnant or postpartum patient	Assign the obstetric chapter code
Dropping the cerebrovascular code on an assumed conflict	Report both, since that note is an Excludes2
Reporting hypertensive retinopathy without the hypertension code	Report both, since the guidelines and the code also note at H35.0- require it
Sequencing I1A.0 ahead of the type of hypertension	Sequence the type first
Assigning I10 from a single elevated reading with no diagnosis	Assign R03.0
Using I10 for pulmonary hypertension	Assign the pulmonary circulation code
Building an ambulatory monitoring claim on I10 alone	Document the suspected white coat or masked pattern with the readings the policy requires
Working from a pick list that predates the resistant hypertension code	Update the encounter form

10Sources

Where to verify I10

ICD-10-CM Official Guidelines for Coding and Reporting, Chapter 9 section

The presumed causal relationships with heart and kidney disease, the requirement to pair hypertensive retinopathy with a hypertensive disease code, the two-code rule for secondary hypertension, and the rule limiting R03.0 to patients with no established diagnosis

ICD-10-CM Tabular List at I10 and across the I10 to I1A block

The single Excludes1, the two Excludes2 notes, and the combination code structure at I11 through I13

CMS ICD-10 code page and the FY 2026 files

Current code files, the annual addenda, and the resistant hypertension category added in FY 2024

NCD 20.19, Ambulatory Blood Pressure Monitoring

The covered indications for suspected white coat and masked hypertension, the measurement thresholds, and the device and interpretation requirements

Medicare Coverage Database

Search your contractor's determinations for self-measured blood pressure monitoring and target organ testing.

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Last reviewed August 2026

This page is a free reference for billing and coding teams and is not coding, legal, or clinical advice. Code selection depends on the documentation in the record and on the policy of the payer being billed. Verify every code, instructional note, and sequencing rule against the current ICD-10-CM files and the Official Guidelines for Coding and Reporting for the applicable date of service. ICD-10-CM is maintained by the CDC's National Center for Health Statistics and published by CMS. CPT is a registered trademark of the American Medical Association. TruCare is not affiliated with CMS, NCHS, the AHA, or the AMA.

Essential (primary) hypertension

What ICD-10 code I10 means

What displaces I10, and what sits beside it

The presumed causal relationships, which displace I10 automatically

The rest of the block, which coexists with a hypertension code

What the code does not record

Clinical findings documented under I10

What the chart must show

When to assign I10, and when not to

Instructional notes at I10 and above

Codes frequently confused with I10

Services commonly reported with I10

Coding errors that cause denials

Where to verify I10

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