13C-octanoic acid breath test for gastric emptying measurement.

OBJECTIVES: The purpose of this multicentre study was to assess the accuracy and reproducibility of the 13C-octanoic acid breath test compared to scintigraphy for measurement of gastric emptying. METHODS: Sixty-nine healthy subjects (40 men, 29 women; mean age 30 years, range 21-61) were studied at least once by using the 13C-octanoic breath test. In 34 healthy subjects, gastric emptying was simultaneously measured by gastric scintigraphy, and the 13C-octanoic breath test was then repeated in 18 of these cases. Fifty-four patients (30 men, 24 women; mean age 46 years, range 13-74) with dyspeptic or reflux symptoms were studied according to the same procedure. RESULTS: The correlation between breath test and scintigraphic values was highly significant (r = 0.744, P<0.001). The concordance of results of scintigraphy and breath test (normal versus abnormal) and the reproducibility (Bland and Altman method) of the breath test were good (CVinter = 24%, CVintra = 15%). As compared to scintigraphy, breath test detected an abnormal gastric emptying with 67% sensitivity and 80% specificity (ROC analysis). CONCLUSION: These results confirm the value of breath test as an accurate measurement of gastric emptying. Its excellent reproducibility makes it a method of choice for pharmacological studies. However, at least when scintigraphy is considered the gold standard, breath test sensitivity may be insufficient for the detection of gastroparesis in an individual patient.

Highly sensitive immunoradiometric assay for serum thyroglobulin with minimal interference from autoantibodies.

Five monoclonal antibodies (MAbs) directed against antigenic domains on thyroglobulin (Tg) not recognized by most anti-Tg human autoantibodies (aAbs) have been used to develop an improved IRMA for serum Tg with a limit of detection of 0.2 micrograms/L. Samples are incubated for 3 h in tubes coated with four anti-Tg MAbs. After washing, the tubes are incubated with the tracer MAb for 20 h at room temperature. Dilution and reproducibility tests demonstrated assay reliability. Tests performed on samples with (n = 361) or without (n = 283) aAbs showed that the TG IRMA Pasteur is largely independent of the marked interference generally caused by aAbs. These results were confirmed with an extended population of 2759 samples. For a cutoff of 1 micrograms/L, sensitivity and specificity were 0.97 and 1, respectively, in a follow-up of differentiated thyroid carcinoma in patients treated by total thyroidectomy.