M10.09

Idiopathic gout affecting multiple joints simultaneously, where no identifiable secondary cause (such as medication, renal disease, or lead exposure) underlies the hyperuricemia and crystal deposition.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 8
Region: Multi-region

Drawn from CDCCMSIcdcodesSpryptPrecisionhub

Documentation tips

What should appear in the chart to support M10.09.

Source · Editorial brief grounded in 6 cited references ↓

List every affected joint by name and side — e.g., 'right first MTP and left ankle' — so multiple-site coding is defensible on audit.
Document that gout is idiopathic (primary); explicitly note absence of a secondary cause such as diuretic use, CKD, or lead toxicity to justify M10.0x over M10.1–M10.4.
Record serum uric acid level and, when available, synovial fluid analysis confirming monosodium urate crystals, to establish medical necessity for the gout diagnosis.
Distinguish acute flare from chronic gout in the assessment — presence of tophi or radiographic joint erosions points to M1A.09, not M10.09.
Document pain severity, functional limitations, and any prior treatment (colchicine, NSAIDs, allopurinol) to support E/M level and medical necessity for any injections billed.

Related CPT procedures

Procedure codes commonly billed with M10.09. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

20610 $68.81

Aspiration and/or injection of a major joint or bursa (shoulder, hip, knee, or subacromial bursa) performed without ultrasound guidance.

20611 $104.21

Aspiration or injection of a major joint or bursa performed under real-time ultrasound guidance, with permanent image documentation.

99213 $95.19

Established patient office or outpatient visit requiring 20–29 minutes of total time or low-complexity medical decision-making.

99214 $135.61

Office visit for an established patient requiring moderate-complexity medical decision making (MDM), or 30–39 minutes of total provider time on the date of service.

99215 $192.39

Highest-level office or outpatient E/M visit for an established patient, qualifying via high-complexity medical decision making or 40–54 minutes of total provider time on the date of service.

83550 View procedure details

86200 View procedure details

J3301 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M10.09 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Defaulting to M10.9 (unspecified gout, unspecified site) when the note clearly names multiple joints — M10.09 is always more specific and preferred.
Using M10.09 when a secondary cause is documented: diuretic-induced gout codes to M10.2x, CKD-related gout to M10.3x — always check the etiology.
Applying M10.09 to a patient with tophi or chronic joint damage; those cases belong under M1A.09 (chronic idiopathic gout, multiple sites).
Coding M10.09 for separate single-joint encounters billed on different dates — the multi-site code is appropriate only when the provider documents simultaneous polyarticular involvement within a single encounter.
Failing to query the provider when documentation says 'gout flare, bilateral feet' without confirming whether this is an acute idiopathic episode or a chronic condition — the distinction drives M10 vs. M1A.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

M10.09 is the correct code when a provider documents an acute idiopathic gout flare involving more than one joint and no underlying etiology is identified. 'Idiopathic' means primary gout — hyperuricemia without a documented drug, metabolic, or toxic cause. If a secondary cause exists (e.g., diuretic use, chronic kidney disease, lead exposure), move to the appropriate M10.1–M10.4 subcategory instead.

The '09' suffix signals polyarticular involvement across the M10.0x family: M10.00 is unspecified site, M10.01–M10.07 cover individual named joints with laterality, and M10.09 captures the multi-site presentation. Use M10.09 only when the encounter note documents involvement of two or more distinct joints in the same episode — not when a patient has a history of gout at different joints across separate encounters.

Distinguish M10.09 (acute idiopathic gout, multiple sites) from M1A.09 (chronic idiopathic gout, multiple sites). If tophi are present or the provider documents chronic gouty arthropathy, the correct parent category is M1A, not M10. Acute flares superimposed on chronic disease should be clarified by the provider; code what is documented.

Sibling codes

Other billable codes under M10.0 (laterality / anatomic variants).

M10.08

Idiopathic gout, vertebrae

M10.00

Idiopathic gout, unspecified site

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When does polyarticular gout qualify for M10.09 vs. individual per-joint codes?

Use M10.09 when the provider documents multiple joints involved in a single acute gout episode. If the note addresses one specific joint at a time — even across multiple visits — assign the single-site code for each joint instead.

02What separates M10.09 (idiopathic gout) from M10.19, M10.29, etc.?

The second digit identifies etiology: M10.0x = idiopathic/primary, M10.1x = lead-induced, M10.2x = drug-induced, M10.3x = due to renal impairment, M10.4x = other secondary gout. Always confirm etiology in the provider note before selecting M10.09.

03Can M10.09 and M1A.09 be coded together?

Generally no — they represent distinct disease states (acute vs. chronic). If an acute flare occurs in a patient with documented chronic gout, query the provider to clarify the primary diagnosis for the encounter. Code what is explicitly documented.

04Does M10.09 require a 7th character?

No. Chapter 13 M-codes do not use 7th-character encounter extensions (A/D/S). Those extensions apply to fracture and injury codes in Chapters 19–20.

05Is a synovial fluid crystal analysis required to use M10.09?

Not strictly — the provider's clinical diagnosis governs code assignment. However, documenting synovial fluid analysis showing monosodium urate crystals or a DECT confirming urate deposition significantly strengthens medical necessity and audit defense, particularly when multiple joints are involved.

06What CPT codes commonly pair with M10.09?

Joint aspiration or injection (20610/20611) for large joints, office E/M codes (99213–99215), serum uric acid lab (83550), and triamcinolone injection (J3301) are the most frequent pairings in an orthopedic or rheumatology setting.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures joint names, laterality, and acuity language (e.g., 'acute flare,' 'polyarticular,' 'bilateral') from the encounter note, along with serum uric acid results and any documented secondary causes of hyperuricemia. That data locks in M10.09 over the unspecified fallback M10.9 and prevents a downstream audit flag for missing site specificity or miscategorization as chronic gout.

See how Mira captures M10.09 documentation