M31.1 – Thrombotic microangiopathy

ICD-10-CM 2027 diagnosis code · Systemic connective tissue disorders

Non-billable header

ICD-10-CM code M31.1

Code: M31.1 (claims format: M311)
Description: Thrombotic microangiopathy
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 13. Diseases of the musculoskeletal system and connective tissue (M00-M99)
Block: M30-M36 Systemic connective tissue disorders
Parent codes: M31

Billable codes under M31.1

M31.1 is a header code and cannot be used on claims. Choose the most specific code:

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Block M30-M36

Includes:

autoimmune disease NOS
collagen (vascular) disease NOS
systemic autoimmune disease
systemic collagen (vascular) disease

Excludes1 (not coded here):

autoimmune disease, single organ or single cell-type -code to relevant condition category

Related codes in M31

M31.0 – Hypersensitivity angiitisBillable
M31.2 – Lethal midline granulomaBillable
M31.3 – Wegener's granulomatosisHeader
M31.4 – Aortic arch syndrome [Takayasu]Billable
M31.5 – Giant cell arteritis with polymyalgia rheumaticaBillable
M31.6 – Other giant cell arteritisBillable
M31.7 – Microscopic polyangiitisBillable
M31.8 – Other specified necrotizing vasculopathiesBillable
M31.9 – Necrotizing vasculopathy, unspecifiedBillable

Frequently asked questions

What is ICD-10 code M31.1?

M31.1 is the ICD-10-CM code for thrombotic microangiopathy, in the block M30-M36 (Systemic connective tissue disorders).

Is M31.1 a billable code?

No. M31.1 is a header code with more specific child codes; report one of the billable codes listed above.

What category does M31.1 belong to?

It belongs to category M31 – Other necrotizing vasculopathies.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.