Validation of a stable isotope gastric emptying test for normal, accelerated or delayed gastric emptying

To validate a 13 C‐Spirulina platensis breath test for measurement of accelerated or delayed gastric emptying, we measured gastric emptying of egg containing 13 C‐S. platensis and 99m Tc‐sulphur colloid by breath 13 CO 2 every 15 min over 3 h and scintigraphy every 15–30 min over 5 h in 57 healthy volunteers. Thirty‐three received no treatment, 10 received erythromycin, and 14 atropine. A generalized linear regression model predicted half‐emptying time by scintigraphy (t 1/2S ) from breath 13 CO 2 (t 1/2B ) data. Accuracy was assessed by standard deviation (SD) of differences between t 1/2S and t 1/2B and by receiver operating characteristic (ROC) curves. Regression models using breath samples at baseline, and 45, 90, 105 and 120 min, predicted t 1/2B (mean ± SD) at 118 ± 59 min, similar to t 1/2S (118 ± 67 min). Correlation between t 1/2B and t 1/2S was significant (r=0.88; P < 0.0001). Differences between t 1/2S and t 1/2B were: 18–19.2 min for t 1/2  < 70–150 min, and 68.3 min for t 1/2  > l50 min. Breath test detected abnormal emptying with a sensitivity of 86% and specificity of 80%. Thus, the 13 C‐S. platensis test measures gastric emptying t 1/2 for solids, which is accelerated or delayed to mimic a range of conditions from dumping syndrome to severe gastroparesis, with high sensitivity and specificity. Additional breath samples are needed to increase sensitivity in detecting accelerated gastric emptying.