2026 ICD-10-CM Diagnosis Code I27.21Secondary pulmonary arterial hypertension
ICD-10-CM Codes›I00–I99›I26-I28›I27
- Billable — Valid for Submission
- Chronic Condition
I27.21 is a billable ICD-10-CM diagnosis code for secondary pulmonary arterial hypertension. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pulmonary heart disease.
This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such hypertension.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Associated pulmonary arterial hypertension
- Pulmonary arterial hypertension associated with chronic hemolytic anemia
- Pulmonary arterial hypertension associated with congenital heart disease
- Pulmonary arterial hypertension associated with congenital systemic-to-pulmonary shunt
- Pulmonary arterial hypertension associated with connective tissue disease
- Pulmonary arterial hypertension associated with HIV infection
- Pulmonary arterial hypertension associated with schistosomiasis
- Pulmonary arterial hypertension induced by drug
- Pulmonary arterial hypertension induced by toxin
- Pulmonary hypertension due to familial pulmonary capillary hemangiomatosis
- Pulmonary hypertension due to pulmonary capillary hemangiomatosis
- Pulmonary hypertension due to pulmonary veno-occlusive disease
- Secondary pulmonary hypertension
- Small vessel pulmonary hypertension
- Solitary pulmonary hypertension
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- (Associated) (drug-induced) (toxin-induced) pulmonary arterial hypertension NOS
- (Associated) (drug-induced) (toxin-induced) (secondary) group 1 pulmonary hypertension
Code Also
- associated conditions if applicable, or adverse effects of drugs or toxins, such as:
- adverse effect of appetite depressants T50.5X5
- congenital heart disease Q20 Q28
- human immunodeficiency virus HIV disease B20
- polymyositis M33.2
- portal hypertension K76.6
- rheumatoid arthritis M05
- schistosomiasis B65
- Sjögren syndrome M35.0
- systemic sclerosis M34
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
A "code also" note instructs that two codes may be required to fully describe a condition, but this note does not provide sequencing direction.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Hypertension, hypertensive(accelerated) (benign) (essential) (idiopathic) (malignant) (systemic)
- pulmonary
- arterial (associated) (drug-induced) (toxin-induced)
- Hypertension, hypertensive(accelerated) (benign) (essential) (idiopathic) (malignant) (systemic)
- pulmonary
- group 1 (associated) (drug-induced) (toxin-induced)
- Hypertension, hypertensive(accelerated) (benign) (essential) (idiopathic) (malignant) (systemic)
- pulmonary
- secondary
- arterial
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Pulmonary Hypertension
Pulmonary hypertension, sometimes called PH, is a serious condition that affects the blood vessels in the lungs. It develops when the blood pressure in your lungs is higher than normal.
The full article covers:
- What is pulmonary hypertension?
- What causes pulmonary hypertension?
- Who is more likely to develop pulmonary hypertension?
- What are the symptoms of pulmonary hypertension?
- What other problems can pulmonary hypertension cause?
- How is pulmonary hypertension diagnosed?
- What are the treatments for pulmonary hypertension?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I27.21 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code History & ChangesHistory
Replacement I27.21 replaces the following previously assigned code(s):
- I27.2 - Other secondary pulmonary hypertension
Questions About I27.21Overview
Is I27.21 (Other secondary pulmonary hypertension) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report secondary pulmonary arterial hypertension on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does I27.21 group to?
When secondary pulmonary arterial hypertension is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of I27.21?
Under the General Equivalence Mappings, secondary pulmonary arterial hypertension converts to ICD-9-CM 416.8 (chr pulmon heart dis NEC). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:
- The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
- The condition places limitations on self-care, independent living, and social interactions.
