Citations

AbstractIntroductionParathyroid scintigraphy (PS) may be used to localize hyperactive parathyroid glands preoperatively. Performance of PS in the setting of secondary and tertiary hyperparathyroidism (HPT) is not well quantified. The performance of PS in secondary/tertiary HPT versus primary HPT may reflect physiologic as well as radiopharmaceutical kinetic differences between multigland hyperplasia versus adenoma. The aim of this study was to review the performance of PS in secondary/tertiary HPT with a comparison to that for primary HPT. Moreover, we evaluated (1) the sensitivity of PS in detecting enlarged glands, and (2) PS detectability as a function of gland weight.MethodsWe performed a retrospective review of the Mayo Clinic database from 2000 to 2004. We identified 40 patients with secondary or tertiary HPT as well as a matched control group of 40 patients with primary HPT who had had preoperative PS and underwent parathyroid surgery.ResultsParathyroid scintigraphy correctly localized all enlarged glands in 88% of patients in the primary HPT group. PS correctly identified both the number and locations of all hyperplastic glands in only 28% of the secondary/tertiary HPT patients. PS failed to identify one enlarged gland in 23% of the patients and two or more enlarged glands in 40% of the patients. PS correctly detects the largest gland in 88% of the patients with secondary and tertiary HPT. The mean gland weight detectable by PS was 612 ± 120 mg for primary HPT. In secondary/tertiary HPT, glands detected by PS had a mean weight of 950 ± 109 mg, whereas the mean weight was 276 ± 34 mg for undetected glands (P < 0.002).ConclusionsParathyroid scintigraphy is a sensitive study for localizing parathyroid glands preoperatively in primary HPT patients. Its sensitivity is low in secondary and tertiary HPT patients. Thus PS has limited value as a preoperative localization study in secondary/tertiary HPT patients.

Abstract Background: Immunoassay-based screening for amphetamines has a variable positive predictive value (PPV) for detecting amphetamine abuse. The lack of immunoassay specificity necessitates confirmatory testing by gas chromatography–mass spectrometry (GC/MS), but the technical complexity and expense of GC/MS limit its availability. Physicians may make decisions regarding patient disposition based on unverified results. In this study we assessed the utility of using dose–response properties to distinguish urine samples containing amphetamines from samples containing cross-immunoreactive species. Methods: Urine was supplemented with known concentrations of amphetamine, methamphetamine, methylenedioxymethamphetamine (MDMA), or pseudoephedrine. Using a series of dilutions, we determined the maximum change in rate over the fractional change in concentration for each compound in the Emit® II amphetamine/methamphetamine immunoassay. Patient urine samples that screened positive for amphetamines were diluted 1:1, 1:10, and 1:20, and maximum slope estimates within the dynamic assay range were determined. An optimal slope cutoff that differentiated samples containing (meth)amphetamine from those containing cross-reacting species was determined by ROC analysis. Results: The slope of the dose response was largest for amphetamine and methamphetamine, followed by MDMA and pseudoephedrine. The optimum slope cutoff for identifying patient specimens containing (meth)amphetamine was 320 (sensitivity, 96%; specificity, 90%; PPV, 92%). High concentrations of less reactive compounds may mask low concentrations of amphetamines. Conclusions: Use of the slope of the dose–response relationship in patient urine specimens can enhance the PPV of presumptive positive immunoassay results but does not exclude the presence of low amphetamine concentrations in samples containing high concentrations of cross-reactive species.

Purpose Serum B-lymphocyte stimulator (BLyS) levels have been found to be elevated in a number of immune disease models. Therefore, we sought to establish whether BLyS levels were elevated in patients with B-cell lymphoproliferative disorders and to determine whether elevated BLyS levels correlated with clinical characteristics of the disease. Patients and Methods Specimens were collected from the peripheral blood of individuals diagnosed with B-cell chronic lymphocytic leukemia (B-CLL; n = 70) or from age- and sex-matched patients seen at the same institution (n = 41). Serum BLyS levels were determined by enzyme-linked immunosorbent assay, and sequencing of the BLyS promoter was performed by conventional methods and confirmed by restriction fragment length polymorphism analysis. Results We found that elevated BLyS levels were more common in patients with familial B-CLL than individuals with sporadic B-CLL or normal controls. Because of this association, we sequenced the BLyS promoter in patients with B-CLL and normal controls and identified a polymorphic site, −871 C/T. We found that the wild-type sequence was significantly underrepresented in patients with familial B-CLL (4%) compared with patients with sporadic B-CLL (30%; P = .01) or controls (24%; P = .04). Furthermore, using a luciferase reporter under control of the BLyS promoter containing either a C or a T at position −871, we found that the reporter construct containing a T at −871 had a 2.6-fold increase in activity (P = .004). Conclusion Our data suggest serum BLyS levels are elevated in patients with familial B-CLL and that elevated BLyS levels correlate with the presence of a T at −871 in the BLyS promoter.