Evaluation of 14C-urinary excretion and its comparison with 14CO2 in breath after 14C-urea administration in Helicobacter pylori infection

Abstract

Objectives: 1) to estimate levels of 14C-urinary excretion in Helicobacter pylori-infected and noninfected patients after 14C-urea ingestion, 2) to compare 14C-urinary excretion and 14CO2 breath results with biopsy findings, and 3) to find out correlation between 14C-urinary excretion with 14CO2 breath results, if any.

Methods: Twenty-four-hour 14C-urinary excretion was measured in 26 patients of non-ulcer dyspepsia after oral administration of 5 microCi 14C-urea to each patient. One-mmol CO2 breath samples at baseline, 2, 5, 15, and 45 min were collected and 14C content measured. Four gastric biopsies were obtained endoscopically from each patient for histology, culture, Gram staining, and rapid urease test.

Results: 14C-urinary excretion in H. pylori-positive patients was 27.38 +/- 13.35% (mean +/- SD) as compared to 67.05 +/- 14.19% in H. pylori-negative patients. Five-, 15-, and 45-min 14CO2 breath values in H. pylori-positive cases were 0.07 +/- 0.041%, 0.063 +/- 0.041%, and 0.028 +/- 0.017% of administered 14C-urea/mmol CO2 exhaled, respectively, which were significantly higher (p < 0.001) from their corresponding values in negative cases. The 14C-urinary excretion data, when compared with biopsies results, discriminated well in 17 of the 18 H. pylori-positive cases, resulting in sensitivity of 94.4%, specificity 100%, and diagnostic accuracy 96.1%, whereas 15 min 14CO2 breath results were 100% accurate. Strong negative correlation between 14C-urinary excretions and 15 min 14CO2 breath was obtained (r = -0.717, p < 0.001).

Conclusions: Measurement of 14C in 24-h urine and in 15-min breath sample may be employed as a cross confirmatory reliable technique for the detection of viable H. pylori colonization.