Biometric Evaluation of Gastric Urease Activity in Man

Abstract

The ¹⁴C-urea breath test is claimed to be the best test for detection of Helicobacter pylori infection. We present a procedure for estimating its cutoff value on the basis of biometric evaluation only, without involving other diagnostic methods. Cumulative gastric urease activity (CA) was determined during the first 30 min after oral administration of ¹⁴C-urea (92.5 kBq) in 56 random volunteers and 49 consecutive patients with peptic ulcer disease. The distribution of CA in random volunteers was positively skewed. Logarithmic transformation yielded two separate populations, each normally distributed. Their normal probability density functions intercepted at log cutoff value. A bimodal distribution of log CA was confirmed in patients with peptic ulcer disease before and after treatment aimed at H. pylori eradication. Cutoff values were determined for both random volunteers and patients with peptic ulcer disease. By application of the present procedure for determination of cutoff value, the ¹⁴C-urea breath test distinguishes between individuals who have an increased gastric urease activity and individuals who do not, with the smallest possible arbitrariness.

Key Words:

• ¹⁴C-urea breath test
• cutoff value
• diagnostic test
• Helicobacter pylori
• peptic ulcer disease