Autonomic Function Testing CPT Code: 7 Essential Facts for Physicians

The autonomic function testing CPT code family — CPT 95921, 95922, 95923, and 95924 — describes the standardized, non-invasive tests physicians use to measure how well a patient’s autonomic nervous system regulates heart rate, blood pressure, and sweat response. Choosing the correct autonomic function testing CPT code depends on exactly which components you perform and document: cardiovagal (parasympathetic), vasomotor adrenergic (sympathetic), sudomotor, or a combined battery. For independent practices adding in-office autonomic and vascular screening, understanding this code family is essential for accurate billing, clean claims, and defensible documentation.

This guide breaks down all four codes, the medical-necessity rules that govern coverage, the most common coding mistakes, and how an FDA-cleared in-office system like the CMAT Advantage™ fits the workflow.

CPT® is a registered trademark of the American Medical Association. The codes and descriptors below reflect current AMA and Medicare guidance; always confirm coverage and code selection with your payer and your Medicare Administrative Contractor (MAC).

What Is the Autonomic Function Testing CPT Code Family?

The autonomic function testing CPT code set lives in the 95921–95924 range, and each code maps to a specific branch of autonomic physiology. In plain terms: 95921 measures the parasympathetic (cardiovagal) response, 95922 measures the sympathetic (vasomotor adrenergic) response, 95923 measures sudomotor (sweat) function, and 95924 covers a combined parasympathetic-plus-sympathetic battery performed in the same session. A related code, 95943, describes a simultaneous parasympathetic and sympathetic measurement based on time-frequency analysis of heart rate variability without a tilt table, but its coverage varies widely by carrier and it has been retired from several payer policies.

Because most autonomic disorders are diagnosed clinically, these tests serve a primary, adjunctive, or confirmatory role — and the right autonomic function testing CPT code is the one that reflects the tests you actually performed and documented.

What Does CPT Code 95921 Cover (Cardiovagal/Parasympathetic)?

CPT 95921 reports testing of cardiovagal innervation — parasympathetic function — and requires two or more of the following: heart rate response to deep breathing with a recorded R-R interval, the Valsalva ratio, and the 30:15 ratio. In practice, this is the heart-rate-variability side of autonomic assessment, the same physiology covered in our overview of the heart rate variability test. Documentation should capture each maneuver performed, the recorded ratios, and the interpreting provider’s findings.

If you perform only a single qualifying component, the test does not meet the descriptor for 95921, so confirm that at least two maneuvers are recorded before you assign this autonomic function testing CPT code.

What Does CPT Code 95922 Cover (Sympathetic Adrenergic)?

CPT 95922 reports vasomotor adrenergic innervation — sympathetic adrenergic function — including beat-to-beat blood pressure and R-R interval changes during the Valsalva maneuver and at least five minutes of passive tilt. Both the passive tilt and the Valsalva maneuver must be performed to report the full code. Per Medicare billing guidance, if only one of those two components is performed, append modifier 52 (reduced services) to 95922.

Because 95922 depends on continuous beat-to-beat blood pressure recording and a tilt protocol, it is typically performed in dedicated autonomic labs rather than a standard exam room.

What Does CPT Code 95923 Cover (Sudomotor)?

CPT 95923 reports sudomotor testing — the autonomic control of sweat glands — including one or more of the following: the quantitative sudomotor axon reflex test (QSART), silastic sweat imprint, the thermoregulatory sweat test, and changes in sympathetic skin potential. Sudomotor testing is one of the earliest and most sensitive indicators of small-fiber and diabetic autonomic neuropathy, which is why it pairs naturally with cardiovagal testing. We cover the clinical side in depth in our guide to understanding sudomotor testing.

As with the other codes, the medical record must specify which sudomotor method was used and the quantitative result that supports the autonomic function testing CPT code you submit.

When Do You Use CPT Code 95924 (Combined Testing)?

CPT 95924 represents combined parasympathetic and sympathetic adrenergic function testing performed together, with at least five minutes of passive tilt. Two billing rules matter here. First, report 95924 only when both the parasympathetic (cardiovagal) and vasomotor adrenergic functions are tested in the same session with the required tilt.

Second, consistent with CPT direction, do not report 95924 together with 95921 or 95922 for the same encounter — 95924 already bundles that combined work. Misapplying this rule is one of the fastest ways to trigger a denial or a post-payment audit, so the combined autonomic function testing CPT code should be reserved for the specific combined-battery scenario it describes.

Autonomic Function Testing CPT Code Comparison

How Do You Document Medical Necessity for Autonomic Function Testing?

Coverage for every autonomic function testing CPT code hinges on documented medical necessity. Medicare coverage is governed by the national framework reflected in LCD L33609 (Autonomic Function Tests) and the associated billing-and-coding articles, with commercial payers publishing parallel policies. To support a claim, the record should establish a relevant diagnosis, the clinical question the test answers, and the interpretation.

Examples of ICD-10-CM diagnoses that commonly support medical necessity include E11.43 (type 2 diabetes mellitus with diabetic autonomic neuropathy), E10.43 (type 1 diabetes with diabetic autonomic neuropathy), I95.1 (orthostatic hypotension), G90.09 (other idiopathic peripheral autonomic neuropathy), and G90.8/G90.9 (other and unspecified disorders of the autonomic nervous system). These are illustrative only — always check your MAC’s current article for the authoritative covered-diagnosis list and any frequency limitations, since many policies limit how often autonomic testing may be repeated absent a change in clinical status. Testing is also appropriate to monitor disease progression or to evaluate a patient’s response to treatment for a documented autonomic disorder.

What Are the Most Common Autonomic Function Testing CPT Code Mistakes?

• Billing 95924 with 95921 or 95922. The combined code already includes both branches; reporting them together is a classic unbundling error.
• Missing components. Reporting 95921 with only one maneuver, or 95922 without both tilt and Valsalva (and no modifier 52), fails the descriptor.
• Thin documentation. A printed device report alone is not interpretation; the record needs the ordering rationale, the components performed, and a signed provider interpretation.
• Coding to the device instead of the test. Select the autonomic function testing CPT code that matches the physiology you measured and documented — not simply the code with the highest reimbursement.
• Skipping coverage verification. Coverage, frequency, and covered diagnoses vary by MAC and commercial plan, so verify before the visit.

How Does In-Office Autonomic Testing Work for Independent Practices?

Independent primary care, cardiology, and pain-management practices increasingly perform autonomic and vascular screening in-office rather than referring out. The TM-Flow System that powers HealthWright’s CMAT Advantage is a non-invasive platform built on FDA-cleared component devices that completes a cardiovagal (heart-rate-variability) and sudomotor assessment in roughly seven to ten minutes — the physiology behind the 95921 and 95923 sides of the autonomic function testing CPT code family. It is not an EKG, an EHR, or a remote-monitoring product; it is a point-of-care diagnostic that produces a documented report your provider interprets.

When testing is performed for documented medical necessity, in-office autonomic testing adds an objective, documented diagnostic service — but, as covered in our look at how CMAT devices stack diagnostic CPT codes, coding must always follow the clinical indication, never the reverse. For the vascular side of the same workflow, see our companion guide to the ankle brachial index CPT code and our overview of autonomic nervous system testing methods.

Partner With HealthWright Technologies

HealthWright Technologies has helped independent physicians add non-invasive diagnostic testing since 2000, pairing FDA-cleared devices with training, implementation, and billing guidance. If your practice is evaluating in-office autonomic and vascular screening, our team can walk you through the workflow, documentation, and coverage questions specific to your payer mix. Learn more on our partnership page or contact us at contact@healthwrighttechnologies.com or (678) 322-7146.

HealthWright Technologies, 60 Bear Creek Marina Road, Mansfield, GA 30055.

Frequently Asked Questions: Autonomic Function Testing CPT Codes

What is the autonomic function testing CPT code range?

The core autonomic function testing CPT code range is 95921–95924: 95921 for cardiovagal (parasympathetic) testing, 95922 for vasomotor adrenergic (sympathetic) testing, 95923 for sudomotor testing, and 95924 for a combined parasympathetic-and-sympathetic battery. A related code, 95943, describes a heart-rate-variability-based combined measurement without a tilt table, but its coverage varies by payer.

Can you bill 95924 with 95921 or 95922?

No. CPT 95924 already represents combined parasympathetic and sympathetic adrenergic testing, so it should not be reported with 95921 or 95922 for the same session. Reporting them together is an unbundling error that commonly leads to denials.

When do you append modifier 52 to CPT 95922?

CPT 95922 requires both a passive tilt and the Valsalva maneuver. If only one of those two components is performed, append modifier 52 (reduced services) to 95922 so the claim accurately reflects the partial study.

Does Medicare cover autonomic function testing?

Medicare covers autonomic function testing when it is medically necessary and supported by a covered diagnosis, as described in LCD L33609 and the associated billing-and-coding articles. Coverage, frequency limits, and covered ICD-10 diagnoses vary by Medicare Administrative Contractor and by commercial payer, so verify the current policy before testing.

Which autonomic function testing CPT code applies to the CMAT Advantage?

The CMAT Advantage (TM-Flow System) performs non-invasive cardiovagal (heart-rate-variability) and sudomotor assessments, which correspond to the 95921 and 95923 sides of the autonomic function testing CPT code family. The specific code you report still depends on the exact components performed and documented for each patient, and on your payer’s coverage rules.

For more on the diagnostic and reimbursement workflow, review our financial and reimbursement considerations for the TM-Flow System, or consult the AMA CPT resource center for the official code descriptors.

Disclaimer: This article is for general informational and educational purposes only and does not constitute medical, legal, or billing advice. CPT® codes, coverage policies, and reimbursement rules change and vary by payer; verify current requirements with the American Medical Association, CMS, your Medicare Administrative Contractor, and each commercial payer before billing. Always consult a qualified healthcare professional for diagnosis, treatment, and clinical decision-making.