Description
Gastric emptying occurs when normal gastrointestinal motor function moves food and liquids from the stomach to the small intestine. Gastroparesis is a syndrome of delayed gastric emptying. The gastric emptying breath test (GEBT) assesses gastrointestinal motor function.

Regulatory Status
Food and Drug Administration (FDA)
This section should include the following wording “Many labs have developed specific tests that they must validate and perform in house. These laboratory-developed tests (LDTs) are regulated by the Centers for Medicare and Medicaid (CMS) as high-complexity tests under the Clinical Laboratory Improvement Amendments of 1988 (CLIA ’88). LDTs are not approved or cleared by the U. S. Food and Drug Administration; however, FDA clearance or approval is not currently required for clinical use.”

Policy
Application of coverage criteria is dependent upon an individual’s benefit coverage at the time of the request.

1. For individuals with suspected gastroparesis (see Note 1), an initial 13C-Spirulina Gastric Emptying Breath Test (GEBT) is considered MEDICALLY NECESSARY.
2. For individuals with the onset of a new symptomatic episode (see Note 1), repeat testing with the 13C-Spirulina GEBT is considered MEDICALLY NECESSARY.
3. For individuals with gastroparesis, the 13C-Spirulina GEBT is considered NOT MEDICALLY NECESSARY.

NOTES:

Note 1: Individuals with suspected gastroparesis meet all of the following:

• Are symptomatic for gastroparesis:^1,2
  • Bloating
  • Chronic nausea
  • Early satiety
  • Postprandial fullness
  • Upper abdominal discomfort
  • Vomiting
• Have no evidence of obstruction
• Have no alternative etiology

Table of Terminology

Rationale
The GEBT is an example of a noninvasive functional test that has been developed to replace invasive testing alternatives to assess the function of the gastrointestinal system, specifically gastric emptying.

Gastric emptying occurs when normal gastrointestinal motor function moves food and liquids from the stomach to the small intestine. Gastroparesis is a syndrome of delayed gastric emptying. The symptoms of gastroparesis include nausea, vomiting, early satiety, abdominal pain, and bloating. Traditionally, gastric emptying has been diagnosed by gastric emptying scintigraphy (GES), a nuclear medicine test that images radiotracers as they move through the stomach.³ GES can be expensive, exposes patients to radiation, and requires specialized nuclear medical centers. The 13C-Spirulina GEBT is a more accessible alternative that does not require specialized equipment or training. The GEBT has been validated against 4-hour GES and determined to be a “safe, standardized, non-radioactive and FDA-approved alternative to nuclear medicine-based gastric emptying evaluations conducted in a nuclear medicine center.”⁴

Proprietary Testing
The Cairn Diagnostics 13C-Spirulina GEBT is a non-invasive, FDA-approved diagnostic test used as a substitute for GES to measure gastric emptying of solids and aid in the diagnosis of gastroparesis. The test utilizes a stable isotope (13C) incorporated into a standardized test meal, with serial breath samples analyzed via isotope ratio mass spectrometry. The test includes pre-meal baseline breath samples, meal ingestion, and serial breath collections over 4 hours. Results are reported as time-specific excretion rates (kPCD), derived gastric emptying parameters, including time to peak excretion (Tmax) and half-emptying time, and a graphical interpretation. The test is indicated for patients with symptoms suggestive of gastroparesis.⁴

Clinical Utility and Validity
Bharucha, et al. (2013) conducted a prospective comparative study to evaluate the performance and reproducibility of the 13C-Spirulina GEBT relative to GES in both healthy individuals and patients with suspected gastric motility disorders. The study included 39 control participants and 15 participants with dyspepsia. Participants underwent simultaneous testing with GEBT and scintigraphy using a standardized solid meal, with a subset undergoing repeat testing to assess intraindividual variability. The study demonstrated strong concordance between the two modalities, with correlation coefficients ranging from approximately 0.80 to 0.90 across gastric emptying parameters, including early emptying rates and half-emptying time. Additionally, the study found that day-to-day variability in gastric emptying measurements was comparable between GEBT and scintigraphy, supporting the reproducibility of the breath test. The authors also confirmed that a simplified 6-sample breath collection protocol maintained diagnostic accuracy, supporting feasibility in clinical practice. These findings support the clinical validity and reliability of GEBT as a non-invasive alternative to scintigraphy for measuring gastric emptying, although the study was limited by moderate sample size and did not evaluate downstream clinical outcomes.⁵

Varma, et al. (2025) conducted a prospective, comparative study to evaluate the diagnostic performance and reproducibility of the 13C-Spirulina GEBT relative to GES in a cohort of 28 patients with diabetes mellitus. Participants underwent simultaneous dual testing with both GEBT and scintigraphy using a standardized solid test meal, with repeat assessments performed one week apart to evaluate intraindividual variability. The study demonstrated strong concordance between GEBT-derived and scintigraphic gastric emptying parameters, including half-emptying time, supporting the physiologic validity of the breath test. “The intraindividual reproducibility was 34% (scintigraphy) and 15% (GEBT).” The authors concluded that “among patients with poorly controlled diabetes, the 13C-spirulina GEBT can accurately and precisely assess GE and effectively distinguish between normal, delayed, and accelerated GE.”⁶

Karrento, et al. (2026) conducted a multicenter comparative study to establish normative values for the 13C-Spirulina GEBT in a pediatric population and to evaluate its ability to distinguish between healthy children and those with gastroparesis-like symptoms. The study enrolled 301 children between the ages of seven and 18 years, with 216 healthy controls completing the standardized 4-hour breath test protocol, and results were compared to a cohort of symptomatic children. The study assessed multiple gastric emptying parameters, including time to peak excretion (Tmax), half-emptying time, peak 13CO₂ excretion (kPCD), and area under the curve. “An algorithm incorporating key variables demonstrated 80.8% sensitivity for diagnosis of gastroparesis.” Findings demonstrated significant differences in gastric emptying between healthy and symptomatic populations, with healthy subjects exhibiting shorter Tmax and half-emptying time, consistent with more rapid gastric emptying.⁷

American Gastroenterological Association (AGA)
The AGA describes gastroparesis as “a disorder of gastric motility defined by a measurable delay in gastric emptying associated with a constellation of upper gastrointestinal (GI) symptoms in the absence of mechanical obstruction.” They note that variations in diagnostic testing strategies can make diagnosis and effective treatment challenging. They also note that despite diagnostic challenges, “symptoms suggestive of gastroparesis are highly prevalent, and patients with gastroparesis incur significant direct and indirect health care costs, as well as a reduction in quality of life.”¹

The AGA recommends four-hour gastric emptying studies compared to two-hour (or shorter) gastric emptying studies to evaluate delayed gastric emptying in individuals with suspected gastroparesis. “The 4-hour threshold applies to both scintigraphy and breath test gastric emptying studies.”¹ These tests are recommended for individuals with suspected gastroparesis, which they define as individuals with chronic nausea, vomiting, early satiety, and/or postprandial fullness with no evidence of obstruction on upper endoscopy and no alternative etiology.

American College of Gastroenterology (ACG)
The ACG states that gastroparesis is “a motility disorder characterized by symptoms and objective documentation of delayed gastric emptying (GE) of solid food without mechanical obstruction, which should be excluded by imaging studies such as upper gastrointestinal (GI) endoscopy or radiology (1,2). The chronic symptoms experienced by patients with GP may be associated with acute exacerbation of symptoms after oral intake of food; the symptoms include postprandial fullness, nausea, vomiting, and upper abdominal pain” and in their testing algorithm, include bloating as an additional symptom. The ACG guideline explicitly recognizes ¹³C-spirulina breath testing as a validated and clinically appropriate diagnostic method, stating “Stable isotope (¹³C-spirulina) breath test is a reliable test for the evaluation of gastroparesis in patients with upper GI [gastrointestinal] symptoms” as a “conditional recommendation, low quality of evidence.” The guidelines also note that “This test is also approved for use in children.”²

The ACG considers “Scintigraphic gastric emptying assessment is the standard test for the evaluation of gastroparesis in patients with upper GI symptoms” and suggests tests lasting at least 3 hours. The ACG does note: “The stable isotope GE breath test using 13-carbon spirulina has been validated in simultaneous measurements performed with the gold standard scintigraphy.”²

Society of Nuclear Medicine (SNM)
The SNM published a guideline focused on assisting nuclear medicine practitioners in recommending, performing, interpreting, and reporting results of gastric-emptying and motility studies in adults. In it, they note that a “repeat of the gastric-emptying study after a change in symptoms or therapy may be helpful for monitoring changes in motility.”⁸

United European Gastroenterology (UEG) and European Society for Neurogastroenterology and Motility (ESNM)
The UEG and ESNM consensus on gastroparesis recognize GEBT as an “FDA-approved method for the evaluation of GE,” stating “previous studies have shown high correlation (0.73–0.95) between scintigraphy and breath test GE times.” The guideline recommendations state both “breath test assessment is a valid test for diagnosing gastroparesis” and “gastric emptying can reliably be assessed by scintigraphy or breath test.”⁹

References

1. American Gastroenterological Association. Clinical guidance on the management of gastroparesis. Updated September 19, 2025. https://gastro.org/clinical-guidance/clinical-guidance-on-the-management-of-gastroparesis/
2. Camilleri M, Kuo B, Nguyen L, et al. ACG Clinical Guideline: Gastroparesis. Am J Gastroenterol. Aug 1 2022;117(8):1197-1220. doi:10.14309/ajg.0000000000001874
3. Camilleri M. Gastroparesis: Etiology, clinical manifestations, and diagnosis. Updated August 28, 2026. https://www.uptodate.com/contents/gastroparesis-etiology-clinical-manifestations-and-diagnosis 4. A New Approach to Diagnosing Gastroparesis. 2026. https://www.cairndiagnostics.com/
4. Bharucha AE, Camilleri M, Veil E, Burton D, Zinsmeister AR. Comprehensive assessment of gastric emptying with a stable isotope breath test. Neurogastroenterol Motil. Jan 2013;25(1):e60-9. doi:10.1111/nmo.12054
5. Varma R, Williams CE, McClain ES, Bailey KR, Ordog T, Bharucha AE. Utility of a (13)C-Spirulina Stable Isotope Gastric Emptying Breath Test in Diabetes Mellitus. Neurogastroenterol Motil. May 2025;37(5):e15008. doi:10.1111/nmo.15008
6. Karrento K, Chumpitazi BP, Zhang L, Simpson P, Shulman RJ. 13 C-Spirulina Gastric Emptying Breath Test Normative Values in Healthy Children: A Multicenter Study With Comparison to Symptomatic Children. Am J Gastroenterol. Feb 1 2026;121(2):491-500. doi:10.14309/ajg.0000000000003545
7. Donohoe KJ, Maurer AH, Ziessman HA, et al. Procedure guideline for adult solid-meal gastric-emptying study 3.0. J Nucl Med Technol. Sep 2009;37(3):196-200. doi:10.2967/jnmt.109.067843
8. Schol J, Wauters L, Dickman R, et al. United European Gastroenterology (UEG) and European Society for Neurogastroenterology and Motility (ESNM) consensus on gastroparesis. United European Gastroenterology Journal. 2021;9(3):287-306. doi:10.1002/ueg2.12060

Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each Policy. They may not be all-inclusive.

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies and accredited national guidelines.

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