Interference against a newly labeled substance with ruthenium sulfonate complexes showing discrepant thyroid function test results.

We report here two patients exhibiting a combination of falsely elevated serum levels of free thyroxine (FT4), free triiodothyronine (FT3), and thyrotropin receptor antibodies (TRAb), measured using Elecsys assay kits (Roche Diagnostics GmbH). The first patient was a 74-year-old man misdiagnosed with Graves' disease and treated with methimazole. The second patient was a 48-year-old woman whose serum FT4 and FT3 concentrations were found to be high during a blood test. These patients denied taking biotin or any other supplements. Further detailed examination, including a heterophilic blocking tube test, revealed the presence of serum antibodies. The abnormal reactions were observed only using the improved assay kits using ruthenium (Ru) sulfonate instead of Ru as a chemiluminescent agent. Therefore, serum antibodies to the Ru sulfonate complex caused the pseudo-high levels of FT4, FT3, and TRAb. To our knowledge, this is the first report showing that antibodies to the Ru sulfonate complex in the electrochemiluminescence immunoassay can cause falsely elevated levels of the combination, leading to discrepant thyroid function test results. We emphasize that in cases of abnormal test results, alternative assay methods should be considered for further examination; unusual test results should not be impulsively interpreted, even when using revised assay kits.

Association of urinary free cortisol with bone formation in patients with mild autonomous cortisol secretion.

CONTEXT: Mild autonomous cortisol secretion (ACS) is associated with an increased risk of vertebral fractures (VFx). However, the influence of this condition on bone turnover or its association with mild ACS is still controversial. OBJECTIVE: This study aimed to evaluate the impact of mild ACS on bone quality among patients living with the disease. DESIGN AND SETTING: A retrospective study was conducted using data from 55 mild ACS and 12 nonfunctioning adrenal tumour (NFT) patients who visited Chiba University Hospital, Japan, from 2006 to 2018. PATIENTS AND MAIN OUTCOME MEASURES: We analysed clinical features and bone-related factors, including bone mineral density (BMD) and VFx, performed blood tests to assess bone metabolism markers in patients with mild ACS and NFT, and assessed the associations between bone-related markers and endocrinological parameters in patients with mild ACS. RESULTS: No significant differences between mild ACS and NFT patients were observed with respect to the presence or absence of VFx and BMD. Urinary free cortisol (UFC) was higher in mild ACS patients with VFx than those without (p = .037). The T-score and young adult mean (YAM) of the BMD of the femoral neck in mild ACS patients with a body mass index <25 were positively correlated with dehydroepiandrosterone sulphate levels (ρ: 0.42, p = .017; ρ: 0.40, p = .024, respectively). Pearson's correlation analysis showed that bone-specific alkaline phosphatase was negatively correlated with UFC in the patients with mild ACS (ρ: -0.37, p = .026). CONCLUSIONS: These results suggest that urinary free cortisol may be useful for predicting bone formation in mild ACS patients.

Steroid metabolites for diagnosing and predicting clinicopathological features in cortisol-producing adrenocortical carcinoma.

BACKGROUND: Approximately 60% of adrenocortical carcinomas (ACC) are functional, and Cushing's syndrome is the most frequent diagnosis that has been revealed to have a particularly poor prognosis. Since 30% of ACC present steroid hormone-producing disorganization, measurement of steroid metabolites in suspected ACC is recommended. Previous reports demonstrated that steroid hormone precursors or their urine metabolites, which can be assessed using liquid chromatography tandem mass spectrometry (LC-MS/MS) or gas chromatography mass spectrometry (GC-MS) respectively, are useful for distinguishing ACC from cortisol-producing adenomas (CPA); however, despite high precision, LC-MS/MS and GC-MS require a highly trained team, are expensive and have limited capacity. METHODS: Here, we examined 12 serum steroid metabolites using an immunoassay, which is a more rapid and less costly method than LC-MS/MS, in cortisol-producing ACC and CPA. Further, the correlation of each steroid metabolite to the classification stage and pathological status in ACC was analyzed. RESULTS: Reflecting disorganized steroidogenesis, the immunoassay revealed that all basal levels of steroid precursors were significantly increased in cortisol-producing ACC compared to CPA; in particular, 17-hydroxypregnenolone (glucocorticoid and androgen precursor) and 11-deoxycorticosterone (mineralocorticoid precursor) showed a large area under the ROC curve with high sensitivity and specificity when setting the cut-off at 1.78 ng/ml and 0.4 mg/ml, respectively. Additionally, a combination of androstenedione and DHEAS also showed high specificity with high accuracy. In cortisol-producing ACC, 11-deoxycortisol (glucocorticoid precursor) showed significant positive correlations with predictive prognostic factors used in ENSAT classification, while testosterone showed significant positive correlations to the Ki67-index in both men and women. CONCLUSION: Less expensive and more widely available RIA and ECLIA may also biochemically distinguish ACC from CPA and may predict the clinicopathological features of ACC.