Reproducibility of technetium-99m mercaptoacetyltriglycine clearance in patients with impaired renal function.

BACKGROUND: The aim of this study was to determine the reproducibility of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) clearance in patients with a 99mTc-MAG3 clearance below 100 ml/min/1.73 m2. METHODS: Two separate multi-sample clearance studies were performed in 16 patients at a 1 week interval. The clearances were calculated according to the open two-compartment model of Sapirstein et al., accepting the 90, 120 and 180 min samples as the last points of the biexponential curve. The clearance measurements were also performed according to the single-sample methods of Russell et al. and Bubeck using the fitted value at 44 min. RESULTS: There was no significant difference between the two clearance measurements for all five samples (P>0.05). There was a systematic increase in clearance measurements of 8.0+/-2.7% from the 180 to 120 min samples and 4.8+/-2.0% from the 120 to 90 min samples. Both single-sample methods (Bubeck and Russell et al.) gave more divergent results than multi-sample methods. The mean and standard deviation (%) of the normalized differences between two successive tests were -3.9+/-12.6, -2.4+/-13.1, -1.9+/-14.9, -4.1+/-53.5 and -13+/-82.1 for 90, 120 and 180 min samples and the Russell et al. and Bubeck methods, respectively. CONCLUSION: Single-sample methods give very poor reproducibility and accuracy and should not be used in patients with poor renal function. The reproducibility of 99mTc-MAG3 clearance using the multi-sample method (90 min) in patients with impaired renal function is 12.6%, which is similar to that in patients with good renal function and that obtained with other tubular agents. Whether this level of reproducibility is satisfactory for documenting serial changes in an individual patient with a 99mTc-MAG3 clearance below 100 ml/min/1.73 m2 depends on the expectation of the clinician.

Analysis of the PAX8 gene in congenital hypothyroidism caused by different forms of thyroid dysgenesis in a father and daughter.

Thyroid dysgenesis occurs sporadically with only rare familial presentation. We report a father and daughter with congenital hypothyroidism caused by different forms of thyroid dysgenesis. The father had a severely hypoplastic thyroid gland in a normal location, whereas the daughter had an ectopic thyroid gland in a sublingual position. Her brother had a hypoplastic thyroid but was euthyroid. The involvement of the candidate gene, PAX8, as the cause of thyroid dysgenesis in this family was partially excluded by linkage analysis, and the possibility of a de novo mutation excluded by sequencing.

Reflux of nasopharyngeal content into middle ear through the eustachian tube.

Whether nasopharyngeal content passes into the middle ear in patients without any head and neck pathology during the recovery phase of anesthesia is shown with an objective and prospective method. Thirty-eight patients, 21 female and 17 male, aged between 17 and 76, were included in the study. During the recovery phase of general anesthesia, 10 ml of 5 mCi Tc-99m-MAA was administered intranasally to the patients with a 10-F catheter. A manometer-adapted cuffed intubation tube was placed in the nasal passage so that the cuff was located at the choana. The pressure changes reflecting to the nasopharynx were recorded. The patients were extubated 10 min after the radionuclide was applied. The scintigraphic evaluation was done at the end of the 1st hour of the application of radionuclide. Transmission and emission views were taken with a gamma camera. Passage of nasopharyngeal content into the middle ear via the eustachian tube was not a statistically significant observation. The mean value of maximum pressure reflecting from the nasopharynx did not differ significantly between patients. Our study does not support the hypothesis that nasopharyngeal content passes directly through the eustachian tube into the middle ear and causes deleterious effects.