Rokuro Ito

Correlation between Serum Levels of 3,3ʹ,5ʹ-Triiodothyronine and Thyroid Hormones Measured by Liquid Chromatography-Tandem Mass Spectrometry and Immunoassay

Objective For measuring serum 3,3′,5′-triiodothyronine (rT3) levels, radioimmunoassay (RIA) has traditionally been used owing to the lack of other reliable methods; however, it has recently become difficult to perform. Meanwhile, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has recently been attracting attention as a novel alternative method in clinical chemistry. To the best of our knowledge, there are no studies to date comparing results of the quantification of human serum rT3 between LC-MS/MS and RIA. We therefore examined the feasibility of LC-MS/MS as a novel alternative method for measuring serum rT3, thyroxine (T4), and 3,5,3′-triiodothyronine (T3) levels. Methods Assay validation was performed by LC-MS/MS using quality control samples of rT3, T4, and T3 at 4 various concentrations which were prepared from reference compounds. Serum samples of 50 outpatients in our department were quantified both by LC-MS/MS and conventional immunoassay for rT3, T4, and T3. Correlation coefficients between the 2 measurement methods were statistically analyzed respectively. Results Matrix effects were not observed with our method. Intra-day and inter-day precisions were less than 10.8% and 9.6% for each analyte at each quality control level, respectively. Intra-day and inter-day accuracies were between 96.2% and 110%, and between 98.3% and 108.6%, respectively. The lower limit of quantification was 0.05 ng/mL. Strong correlations were observed between the 2 measurement methods (correlation coefficient, T4: 0.976, p < 0.001; T3: 0.912, p < 0.001; rT3: 0.928, p < 0.001). Conclusions Our LC-MS/MS system requires no manual cleanup operation, and the process after application of a sample is fully automated; furthermore, it was found to be highly sensitive, and superior in both precision and accuracy. The correlation between the 2 methods over a wide range of concentrations was strong. LC-MS/MS is therefore expected to become a useful tool for clinical diagnosis and research.

Serum chemokine (C-X-C motif ) ligand 10 levels are elevated in patients with Graves' disease in long-term remission.

Chemokine (C-X-C motif ) ligand 10 (CXCL10) is one of the CXC chemokines and is associated with T-helper 1-mediated immune responses (1). Recently, many studies have reported increased serum CXCL10 levels in the initial phase of Graves’ disease (GD) (2). In addition, it has been reported that the increased serum CXCL10 levels are decreased by methimazole (MMI) treatment in some studies (3–5). On the other hand, there are only a few investigations that have reported on serum CXCL10 levels in remission or relapse of GD after termination of antithyroid drug (ATD) treatment (3). This investigation (3), however, included insufficiently treated patients. If serum CXCL10 values in remission are lower than those at onset, they could be useful for distinguishing between complete and incomplete remission of GD when followingup the patients with a history of thyrotoxicosis due to GD. Therefore, we performed a study of serum CXCL10 levels in patients with GD who were in apparent long-term remission. Patients with clinical evidence of destructive thyroiditis were not included. The study was approved by the ethics committee of our hospital. We enrolled patients who had been treated with MMI for at least 2 years before they met our criteria for discontinuing MMI. Our criteria required those patients taking less than 5 mg of MMI daily, whose test for serum antithyrotropin receptor antibody (TRAb) is negative, and who are euthyroid with a serum thyrotropin of >0.5 mIU=mL. We divided these patients into two groups. The remission group consisted of euthyroid patients who were not taking ATDs and had been euthyroid for at least 2 years while not on ATDs. The relapse group consisted of patients who developed thyrotoxicosis after MMI had been discontinued. We also studied a third group that consisted of thyrotoxic patients with GD who were in the early onset stage of their disease before ATD treatment had been started as this is a group in which elevated serum CXCL10 levels have been noted in many studies. We measured CXCL10 and other laboratory data at the same time (Table 1). We excluded pregnant patients, those taking corticosteroid therapy, or those with autoimmune diseases. Serum CXCL10 levels were determined by quantitative sandwich immunoassay using a commercially available kit (R&D System, Minneapolis, MN). Values are presented as means standard deviation for normally distributed variables. Mean group values were compared by the Kruskal– Wallis test. Proportions were compared by the w test. The mean values of CXCL10 were 146 100 pg=mL in the remission group, 101 70 pg=mL in the relapse group, and 133 55 pg=mL in the early onset thyrotoxic group. There were no significant differences in serum CXCL10 levels among the three groups. To minimize a possible influence of age, we eliminated patients younger than 30 years or older than 60 years. Serum CXCL10 levels were similar in the three groups: 116 80 pg=mL in the remission group (n1⁄4 12), 128 62 pg=mL in the relapse group (n1⁄4 8), and 143 55 pg=mL in the early onset thyrotoxic group (n1⁄4 13). The mean age of each group was 46 8, 46 12, and 42 10 years. In the remission group, there was no significant difference in serum CXCL10 levels between patients who had positive TRAb (n1⁄4 4) and negative TRAb (n1⁄4 27) (data not shown). The mean serum CXCL10 value in healthy volunteers (n1⁄4 14) was 62.5 13.5 pg=mL. This is in agreement with previous reports and is significantly less than the remission group with GD. Therefore, our data did not support the hypothesis that serum CXCL10 levels would not be elevated in patients with a history of GD who were in apparent remission. Domberg et al. also reported that there was no difference in serum CXCL10 levels between 25 patients with GD who were thought to be in remission and 25 patients who had a relapse of thyrotoxicosis after ATD treatment was stopped (6). However, this report was not clear both about the treatment duration and the definition of apparent remission. This might not have required consideration of serum TRAb value. Their high relapse rate of 50% among all patients suggests that the duration or some aspect of ATD treatment was less efficacious than for the patients in our remission group. Further, the study of Domberg et al. (6) cannot be compared with our (present) study because in their study the serum CXCL10 analysis was done during ATD treatment. Moreover, though 38 of 50 cases were euthyroid when studied, 12 were hyper-

Changes in overactive bladder symptoms after sodium glucose cotransporter‐2 inhibitor administration to patients with type 2 diabetes

The aim of this study was to investigate the changes in overactive bladder symptoms after selective sodium glucose cotransporter‐2 (SGLT2) inhibitor administration to patients with type 2 diabetes.