2027 ICD-10-CM Diagnosis Code I15.9Secondary hypertension, unspecified

ICD-10-CM Codes›I00–I99›I10-I1A›I15

ICD-10-CM I15.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I15.9 is a billable ICD-10-CM diagnosis code for secondary hypertension, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 304 through 305. Coders also document this condition as diastolic hypertension. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hypertension with complications and secondary hypertension.

I15.9 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 187 for payment year 2027.

Code Identity

ICD-10-CM Code
I15.9
Billable Status
Yes — Valid for Submission
Code Describes
Secondary hypertension, unspecified
Short Description
Secondary hypertension, unspecified
Same as the full description in the CMS dataset.
Parent Code
I15
Secondary hypertension

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI10-I1AHypertensive diseases
CategoryI15Secondary hypertension
This CodeI15.9Secondary hypertension, unspecified

Medicare Risk Adjustment (HCC)Billing

I15.9 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Part D (RxHCC)
RxHCC 187 — Hypertension
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Diastolic hypertension
  • Hypertensive crisis
  • Hypertensive emergency
  • Malignant hypertension
  • Malignant secondary hypertension
  • Paroxysmal hypertension
  • Perioperative hypertension
  • Pre-existing secondary hypertension complicating pregnancy, childbirth and puerperium
  • Secondary diastolic hypertension
  • Secondary hypertension

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I15.9: its own notes plus those printed at I15, block I10-I1A, and Chapter 9. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From I15 Secondary hypertension applies to 5 codes
  • postprocedural hypertension (I97.3)
From Block I10-I1A Hypertensive diseases applies to 18 codes
  • neonatal hypertension (P29.2)
  • primary pulmonary hypertension (I27.0)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From I15 Secondary hypertension applies to 5 codes
  • secondary hypertension involving vessels of brain (I60-I69)
  • secondary hypertension involving vessels of eye (H35.0-)
From Block I10-I1A Hypertensive diseases applies to 18 codes
  • hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16)
From Chapter 9 (I00-I99) Diseases of the circulatory system applies to 1,433 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • transient cerebral ischemic attacks and related syndromes (G45.-)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Block I10-I1A Hypertensive diseases applies to 18 codes
  • code to identify:
  • exposure to environmental tobacco smoke (Z77.22)
  • history of tobacco dependence (Z87.891)
  • occupational exposure to environmental tobacco smoke (Z57.31)
  • tobacco dependence (F17.-)
  • tobacco use (Z72.0)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From I15 Secondary hypertension applies to 5 codes
  • underlying condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name I15.9, its category, or a range that includes it.

Applicable To 1

These notes mention I15.9.

  • O10.4 Pre-existing secondary hypertension complicating pregnancy, childbirth and the puerperium
    Any condition in I15 specified as a reason for obstetric care during pregnancy, childbirth or the puerperium names I15, which includes this code

Excludes1 1

These codes carry an Excludes1 note naming I15.9: they are not reported together with it, unless the two conditions are unrelated.

  • I12 Hypertensive chronic kidney disease
    secondary hypertension (I15.-) names I15.-, which includes this code

Code First 1

These codes say to code first a condition named in the note, and I15.9 is one of the conditions named.

  • I1A.0 Resistant hypertension
    secondary hypertension (I15.-) names I15.-, which includes this code

Use Additional Code 3

These codes say to use an additional code from the note, and I15.9 is one of the codes named.

  • O10.4 Pre-existing secondary hypertension complicating pregnancy, childbirth and the puerperium
    code from I15 to identify the type of secondary hypertension names I15, which includes this code
  • G31.84 Mild cognitive impairment of uncertain or unknown etiology
    hypertension (I10-I1A) names I10-I1A, which includes this code
  • Block I60-I69 Cerebrovascular diseases
    hypertension (I10-I1A) names I10-I1A, which includes this code

Code Also 3

These codes say I15.9 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • I16 Hypertensive crisis
    any identified hypertensive disease (I10-I15, I1A) names I10-I15, which includes this code
  • Block I20-I25 Ischemic heart diseases
    the presence of hypertension (I10-I1A) names I10-I1A, which includes this code
  • Z15.3 Genetic susceptibility to kidney disease
    if applicable, hypertension (I10-I1A) names I10-I1A, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR008
Hypertension with complications and secondary hypertension
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Secondary Hypertension

    high blood pressure caused by an underlying medical condition.

Patient EducationClinical

High Blood Pressure

Blood pressure is the force of your blood pushing against the walls of your arteries. Each time your heart beats, it pumps blood into the arteries. Your blood pressure is highest when your heart beats, pumping the blood. This is called systolic pressure. When your heart is at rest, between beats, your blood pressure falls.

The full article covers:

  • What is blood pressure?
  • How is high blood pressure diagnosed?
  • What are the different types of high blood pressure?
  • Why do I need to worry about high blood pressure?
  • What are the treatments for high blood pressure?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I15.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
405.99 Second hypertension NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I15.9Overview

What is the ICD-10 code for secondary hypertension, unspecified?

The ICD-10-CM code for secondary hypertension, unspecified is I15.9 (sometimes written as I159). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I15.9 (Secondary hypertension) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report secondary hypertension, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does I15.9 group to?

When secondary hypertension, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 305, 304, with relative weights from 0.7579 to 1.2010 depending on complications. Higher weights mean higher Medicare reimbursement.

Can I15.9 be reported with I97.3?

Not as a rule. The Excludes1 note at I15, which applies to I15.9, lists "postprocedural hypertension (I97.3)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of I15.9?

Under the General Equivalence Mappings, secondary hypertension, unspecified converts to ICD-9-CM 405.99 (second hypertension NEC). The mapping is approximate, so confirm the match fits the documentation.

Does I15.9 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: I15.9 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 187 (Hypertension).