Is I27.21 a billable ICD-10-CM code?

Yes. I27.21 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does I27.21 sit in the tabular list?

Diseases of the circulatory system (I00-I99), in the block Pulmonary heart disease and diseases of pulmonary circulation (I26-I28).

What cannot be coded together with I27.21?

I27.21 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above I27.21 (I27.2) and apply to it just the same.

I27.21

I27.21 — Secondary pulmonary arterial hypertension

Billable / specific codeICD-10-CM

I27.21 is a billable, specific ICD-10-CM code for secondary pulmonary arterial hypertension. It is valid for submission on a claim.

Code also

Both codes may be needed to describe the encounter fully. Sequencing depends on the reason for the visit.

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.-)

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

(Associated) (drug-induced) (toxin-induced) pulmonary arterial hypertension NOS
(Associated) (drug-induced) (toxin-induced) (secondary) group 1 pulmonary hypertension

Excludes1 inherited from the categories above I27.21

These are not written on I27.21, but they bind it: a note on a category applies to every code beneath it. Billing I27.21 with anything listed here is a denial.

Written on I27.2 — Other secondary pulmonary hypertension

Eisenmenger's syndrome (I27.83)

Other codes that can never be billed with I27.21

These codes carry an Excludes1 note pointing at I27.21. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading I27.21 alone.

I27.0Primary pulmonary hypertension

Risk adjustment

I27.21 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

HCC 226 Heart Failure, Except End Stage and Acute0.360 RAF

Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.

Medicare coverage

I27.21 is named in 36 Medicare coverage policies — 36 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A52466Nebulizers - Policy Article
A52466Nebulizers - Policy Article
A52466Nebulizers - Policy Article
A52466Nebulizers - Policy Article

How I27.21 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to I27.21.

Hypertension, hypertensive›pulmonary›arterial(associated) (drug-induced) (toxin-induced)
Hypertension, hypertensive›pulmonary›group 1(associated) (drug-induced) (toxin-induced)
Hypertension, hypertensive›pulmonary›secondary›arterial

Code history

I27.21 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Related codes at this level

Codes that share I27.2. If I27.21 is not quite right, the correct code is usually one of these.

Questions about I27.21

Is I27.21 a billable ICD-10-CM code?: Yes. I27.21 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does I27.21 sit in the tabular list?: Diseases of the circulatory system (I00-I99), in the block Pulmonary heart disease and diseases of pulmonary circulation (I26-I28).
What cannot be coded together with I27.21?: I27.21 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above I27.21 (I27.2) and apply to it just the same.