BACKGROUND: The purpose of this study is to compare validity of 5 diagnostic tests of helicobacter pylori with each other: stool antigen test, urea breath test (UBT), rapid urease test (RUT), serology and histology.METHODS: A total of 94 patients who had indication of endoscopy entered the study. All of the 5 tests were performed for each patient. When the results of at least 2 tests were positive (except serology), Helicobacter pylori infection was considered to be positive. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and area under receiver operating characteristic (ROC) curve of these 5 tests were determined.RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and area under ROC curve of these 5 tests are as below, respectively. Histology: 89%, 78%, 93%, 91%, 85% and 0.881, RUT: 93%, 75%, 95%, 94%, 86% and 0.831, serology: 50%, 54%, 46%, 61%, 52% and 0.563, stool antigen test: 96%, 83%, 98%, 96%, 91% and 0.897, UBT: 89%, 73%, 92%, 90%, 82% and 0.892.CONCLUSIONS: Stool antigen test is the most accurate test for Helicobacter pylori diagnosis before eradication of these bacteria.

Background: Although the activity of the cytosolic hepatic enzyme phenylalanine hydroxylase is impaired in phenylketonuria (PKU), the microsomal function, necessary for the metabolism of xenobiotics, has never been assessed. The aim of the study was to assess the microsomal liver function in PKU patients by 13C-methacetin breath test (13C-MBT), which measures cytochrome P450 activity. Methods: Twenty patients with classical PKU, aged 15-34 years, were enrolled in the study. The control group comprised of 20 healthy subjects matched for age and sex. The 13C-MBT was performed in every subject at rest after an overnight fast. Results: The values of cumulative percentage dose recovery at 120 minutes of the test (CPDR median < interquartile range >) were significantly lower in the PKU group than in the control group (25. 1 < 21. 8-28. 83 > vs 32. 8 < 27. 4-34. 1 >; P = 0. 0067). The lower values of the maximum momentary 13C recovery (Dmax) were observed in the PKU group than in the control group (26. 6 < 22. 4-28. 7 > vs. 32. 1 < 27. 18-34. 08 >; P = 0. 0227). The values of time to reach Dmax (Tmax) did not differ (20 < 17-20 > vs. 20 < 20-20 >; P = 0. 8410). The values of CPDR, Dmax and Tmax were not different between the group with abnormal (> 10 mg/dL) and normal (< 10 mg/dL) Phe level (P = 0. 2799; 0. 7959; 0. 4812, respectively). Conclusions: The present study demonstrates that the cytochrome P450 activity in PKU patients may be reduced. However, further research is required, particularly in regards to the effect that patient diet compliance has on the microsomal liver function.

The carbon -14 urea breath test (UBT)is a non-invasive and simple method for the diagnosis of Helicobacter pylori infection. Attempts have been made to use lower doses of 14C-urea in the UBT in order to reduce the radiation risk of the test. The aim of this study was to assess the accuracy of a microdose (1 µCi [37 KBq]) 14C-UBT in Iranian population for validation of its diagnostic accuracy against gold standard methods. Eighty and two patients were subjected to upper gastrointestinal endoscopy as well as 14C-UBT in one week. Rapid urease test and histological examinations were used as gold standard. Breath samples were collected 10, 20 and 30 minute after ingestion of 1 µCi of 14C- urea solution and their activities were measured using a scintillation counter and expressed as counts per minute (cpm) and disintegration per minute (dpm). Good agreement was observed between the 14C-UBT and gold standard for samples which were collected 20 minutes after 14C-urea administration. The 14CUBT showed 100% sensitivity, 95% specificity, 95.45% positive predictive value, 100% negative predictive value and 97.50% accuracy. The results of this study showed good concordance between the 14C-UBT and invasive methods.