Esophageal passage of iodine-131 capsules

The purpose of this study was to determine the orogastric transit time of standard 131I capsules and the incidence of transit delay.

We studied 58 consecutive subjects receiving outpatient diagnostic and therapeutic 131I dosages. A standard ion chamber survey meter, placed over the left upper quadrant of the abdomen, monitored orogastric transit. Each subject had ample water to subjectively swallow their capsule. Orogastric transit times, volume of water ingested, capsule size, and demographic and historical data were recorded for each subject.

Seventeen subjects (29%) had delayed transit, with an orogastric transit time > 90 sec (median 140 sec, range 100-930 sec). Forty-one subjects had normal transit (median 14 sec, range 4-51 sec). We identified delayed transit in 7 of 37 women (19%) and 10 of 21 men (48%) (p = 0.035). Age, capsule size and initial water volume ingested did not differ significantly between subject groups.

Men were more likely than women to have prolonged orogastric transit of standard 131I capsules. Other than sex, we found no identifiable clinical feature or medical history to predict delayed orogastric transit. A standard survey meter can identify adherent capsules to minimize esophageal radiation exposure.