D89.44 ICD-10-CM Code: Hereditary alpha tryptasemia

Code

D89.44

Description

Hereditary alpha tryptasemia

HCC (V28)

No CMS-HCC V28 mapping

RAF reference coefficient

—

Billable

Yes

Payment year

2026

HCC Category Mapping

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work D89.44 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for D89.44

What This Code Means

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for D89.44 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

• •Requires documentation of elevated baseline tryptase levels and family history
• •This is a genetic predisposition code; document any associated mast cell activation symptoms

Clinical Significance

Hereditary alpha tryptasemia is a genetic condition caused by increased copy number of the TPSAB1 gene encoding alpha-tryptase, resulting in elevated baseline serum tryptase levels. It affects approximately 5-6% of the general population and can present with mast cell activation-like symptoms including flushing, gastrointestinal dysmotility, connective tissue laxity, and dysautonomia. While often asymptomatic, symptomatic individuals may experience significant morbidity.

Documentation Requirements

• ✓Documentation should include genetic testing confirming increased TPSAB1 gene copy number, baseline elevated serum tryptase levels, and associated clinical symptoms.
• ✓Family history of elevated tryptase or similar symptoms supports the diagnosis.
• ✓The provider should document whether the patient is symptomatic or the finding is incidental, and note any treatment with anti-mediator therapy.

Commonly Confused Codes

• •D47.02 (Systemic mastocytosis) also causes elevated tryptase but is a neoplastic process with bone marrow involvement.
• •D89.41 (Monoclonal mast cell activation syndrome) requires clonal markers on mast cells rather than germline tryptase gene amplification.
• •D89.42 (Idiopathic mast cell activation syndrome) should be reconsidered if the patient has confirmed hereditary alpha tryptasemia as the underlying cause of their symptoms.

Child Codes