Falsely elevated thyroid hormone levels caused by anti-ruthenium interference in the Elecsys assay resembling the syndrome of inappropriate secretion of thyrotropin.

The syndrome of inappropriate secretion of thyrotropin (SITSH) is defined as the inappropriate non-suppression of serum TSH in the presence of elevated free thyroid hormone; TSH-secreting pituitary adenomas and the syndrome of resistance to thyroid hormone are the main etiologies of SITSH. In addition, erroneous thyroid function testing may result in the diagnosis of this syndrome. A 63-year-old woman was referred because of suspected SITSH. Laboratory tests showed a normal TSH (0.52 µIU/L; normal range: 0.5-5.0) measured by sandwich Elecsys, and elevated FT4 (3.8 ng/dL; normal range: 0.9-1.6) and FT3 (7.6 pg/mL; normal range: 2.3-4.0), determined by competitive Elecsys. To exclude possible assay interference, aliquots of the original samples were retested using a different method (ADVIA Centaur), which showed normal FT4 and FT3 levels. Eight hormone levels, other than thyroid function tests measured by competitive or sandwich Elecsys, were higher or lower than levels determined by an alternative analysis. Subsequent examinations, including gel filtration chromatography, suggested interference by substances against ruthenium, which reduced the excitation of ruthenium, and resulted in erroneous results. The frequency of similar cases, where the FT4 was higher than 3.2 ng/dL, in spite of a non-suppressed TSH, was examined; none of 10 such subjects appeared to have method-specific interference. Here, a patient with anti-ruthenium interference, whose initial thyroid function tests were consistent with SITSH, is presented. This type of interference should be considered when thyroid function is measured using the Elecsys technique, although the frequency of such findings is likely very low.

Analysis of vasovagal syncope in the blood collection room in patients undergoing phlebotomy.

Vasovagal syncope (VVS) is well-known to occur in patients undergoing phlebotomy, however, there have been no large-scale studies of the incidence of VVS in the blood collection room. The aim of our present retrospective study was to investigate the conditions of phlebotomy and determine the incidence/factors predisposing to the development of VVS. We investigated 677,956 phlebotomies performed in outpatients in the blood collection room, to explore factors predisposing to the development of VVS. Our analysis revealed an overall incidence of VVS of 0.004% and suggested that use of more than 5 blood collection tubes and a waiting time of more than 15 min were associated with a higher risk of VVS. The odds ratios of these factors were 8.10 (95% CI 3.76-17.50) and 3.69 (95% CI 0.87-15.60), respectively. This is the large-scale study to analyze factors of the development of VVS in the blood collection room, and according to our results, use of a large number of blood collection tubes and a prolonged waiting time for phlebotomy may be risk factors for the development of VVS.

[Antimicrobial susceptibility and beta-lactamase producibility of bacteria clinically isolated during the period from December 1999 to February 2000].

Antimicrobial susceptibility and beta-lactamase producibility were tested in 848 clinical strains collected at 8 hospitals in Kanagawa prefecture during the period from December 1999 to February 2000. Positive rates of beta-lactamase used the nitrocefin method (Cefinase) were 21.9% of Staphylococcus aureus, 10.0% of Haemophilus influenzae, and 99.0% of Moraxella catarrhalis. Furthermore, on the acidometric method (P/Case test) penicillinase (PCase), cephalosporinase (CEPase), and both of PCase and CEPase were found to be positive in 19.0%, 16.0%, and 16.0% for Escherichia coli, 6.2/0/3.1% for Klebsiella pneumoniae, 0/66.3/26.5% for Enterobacter cloacae, 2.8/57.7/15.5% for Serratia marcescens, and 4.0/15.0/22.0% for Pseudomonas aeruginosa, respectively. Based on the assessment of minimal inhibitory concentrations (MICs) of antibacterial agents among beta-lactamase producing strains, there were 5 strains (4 strains of K. pneumoniae and 1 strain of E. coli) that may be ESBLs producing bacteria out of a total of 466 strains of Enterobacteriaceae and P. aeruginosa. During this process, 1 strain of class-B beta-lactamase-producing E. cloacae was isolated. MRSA were found in 79.2% of S. aureus, and BLNAR were found in 8.9% of H. influenzae.

Albumin concentration determined by the modified bromocresol purple method is superior to that by the bromocresol green method for assessing nutritional status in malnourished patients with inflammation.

BACKGROUND: The controlling nutritional status (CONUT) score (CS), a simple score for assessing nutritional status, is calculated using laboratory data, including serum albumin concentration. Although dye-binding assays such as the bromocresol green (BCG) and modified bromocresol purple (mBCP) methods are widely used for albumin measurement, acute-phase proteins interfere with the BCG method. OBJECTIVE: We aimed to determine whether the choice of albumin assay affects assessment of nutritional status using CONUT scores (CSs). DESIGN: We measured serum albumin concentrations by the BCG (ALBBCG) and mBCP (ALBmBCP) methods in 44 malnourished inpatients, 27 of whom underwent nutritional intervention, and compared them to 30 age-matched healthy volunteers. In treated patients, CSs were calculated by ALBBCG (CS-BCG) and ALBmBCP (CS-mBCP). RESULTS: C-reactive protein (CRP) concentrations were positively correlated with the difference between ALBBCG and ALBmBCP in malnourished inpatients (r = 0.59, p < 0.001). CS-BCG was always lower than CS-mBCP (lower CS indicates superior nutritional status) in treated patients with persistently high CRP levels. However, in patients whose CRP decreased gradually, this difference diminished over the clinical course. CS-BCG and CS-mBCP were similar throughout their courses in patients with normal CRP concentrations. Adding haptoglobin to the human albumin solutions increased ALBBCG in a dose-dependent manner. CONCLUSIONS: The choice of albumin assay affected the assessment of nutritional status using CSs in patients with inflammation. We recommend that the modified BCP assay be used to assess nutritional status, particularly in patients with inflammation.

Evaluation of a new rapid and fully automated electrochemiluminescence immunoassay for thyrotropin receptor autoantibodies.

BACKGROUND: Hyperthyroidism in Graves' disease is caused by autoantibodies to the TSH receptor (TSHR), and measurement of the TSHR autoantibody (TRAb) yields important information to diagnose and decide on the course of treatment of Graves' disease. We evaluated basic and clinical performance of a new, rapid, and fully automated electrochemiluminescence immunoassay Elecsys Anti-TSHR (Elecsys TRAb) for measuring serum TRAb. METHODS: For evaluation of basic performance of the assay, we carried out intra- and interassay precision studies using five serum pools and three serum pools, respectively, and the assay was compared with four commercial TRAb assays. Clinical performance of the assay was evaluated with sera from 298 patients with untreated Graves' disease, 220 patients with destructive (painless and subacute) thyroiditis, and 332 healthy volunteers. The optimal cutoff point, which was calculated by receiver operating characteristic (ROC) analysis with the above subjects, was then used to classify an independent sample set of 80 patients with untreated Graves' disease, and 152 patients with destructive thyroiditis. RESULTS: Intraassay coefficient of variation (CV) was 4.24% at 1.85 IU/L and interassay CV was 10.1% at 1.46 IU/L. All the correlation coefficient values calculated against four commercial assays were larger than 0.85. ROC analysis resulted in a specificity of 99.1% with a sensitivity of 97.0% at a decision limit of 1.86 IU/L from comparison with untreated Graves' disease and destructive thyroiditis. The cutoff point yielded a sensitivity of 87.5% and specificity of 96.7% with the independent sample set. CONCLUSION: In spite of the short measuring time of only 27 minutes, the assay showed the same or better results with the existing commercial products. The short measuring time would contribute to speedy, preconsultation diagnosis of thyroid disease, especially of Graves' disease.

Electrorheological Response and Structure Growth of Colloidal Silica Suspensions.

The electrorheological response and structure growth of colloidal silica suspension was studied with in situ measurements of the shear stress, electric conductivity, and dielectric permittivity of the suspension. The measurements were carried out under steady and sweep shears after the application of an electric field of alternative current (100 Hz) using silica particles with a diameter of 630 nm and a water content of 4.5 wt%. The measurements of the conductivity enabled the detection of structure growth formed by particle aggregation and clarified that the development of the particle aggregation enlarged the dielectric permittivity and the shear stress. Hysteretic behavior observed in the electrorheological response was explained by considering structure growth of the particle aggregation. The correlation equation for the shear stress and the dielectric permittivity obtained in our previous work (1) was found to be applicable to the present results. Copyright 2001 Academic Press.