Is D89.43 a billable ICD-10-CM code?

Yes. D89.43 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does D89.43 sit in the tabular list?

Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89), in the block Certain disorders involving the immune mechanism (D80-D89).

What cannot be coded together with D89.43?

D89.43 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 D89.43 (D89.4, D89) and apply to it just the same.

D89.43

D89.43 — Secondary mast cell activation

Billable / specific codeICD-10-CM

D89.43 is a billable, specific ICD-10-CM code for secondary mast cell activation. 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.

underlying etiology, if known

Inclusion terms

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

Secondary mast cell activation syndrome

Excludes1 inherited from the categories above D89.43

These are not written on D89.43, but they bind it: a note on a category applies to every code beneath it. Billing D89.43 with anything listed here is a denial.

Written on D89.4 — Mast cell activation syndrome and related disorders

aggressive systemic mastocytosis (C96.21)
congenital cutaneous mastocytosis (Q82.2)
(non-congenital) cutaneous mastocytosis (D47.01)
(indolent) systemic mastocytosis (D47.02)
malignant mast cell neoplasm (C96.2-)
malignant mastocytoma (C96.29)
mast cell leukemia (C94.3-)
mast cell sarcoma (C96.22)
mastocytoma NOS (D47.09)
other mast cell neoplasms of uncertain behavior (D47.09)
systemic mastocytosis associated with a clonal hematologic non-mast cell lineage disease (SM-AHNMD) (D47.02)

Written on D89 — Other disorders involving the immune mechanism, not elsewhere classified

hyperglobulinemia NOS (R77.1)
monoclonal gammopathy (of undetermined significance) (D47.2)

Excludes2 inherited from the categories above D89.43

Also inherited, and the opposite of Excludes1: these conditions are not part of D89.43, but a patient can have both, so you may code both.

Written on D89 — Other disorders involving the immune mechanism, not elsewhere classified

transplant failure and rejection (T86.-)

Risk adjustment

D89.43 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

D89.43 is named in 15 Medicare coverage policies — 15 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A56638Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs)
A56642Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs)
A57689Billing and Coding: Lab: Flow Cytometry
A58575Billing and Coding: Respiratory Pathogen Panel Testing

How D89.43 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 D89.43.

Activation›mast cell›secondary

Code history

D89.43 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 D89.4. If D89.43 is not quite right, the correct code is usually one of these.

Questions about D89.43

Is D89.43 a billable ICD-10-CM code?: Yes. D89.43 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does D89.43 sit in the tabular list?: Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89), in the block Certain disorders involving the immune mechanism (D80-D89).
What cannot be coded together with D89.43?: D89.43 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 D89.43 (D89.4, D89) and apply to it just the same.