Introduction: Fulvestrant, a selective estrogen receptor degrader widely used in hormone receptor-positive breast cancer, can cause significant analytical interference with estradiol immunoassays due to structural similarity with 17β-estradiol. This interference may result in falsely elevated estradiol measurements, potentially leading to diagnostic confusion and inappropriate clinical interventions. We report a case demonstrating this clinically significant analytical interference and emphasize the importance of liquid chromatography-tandem mass spectrometry (LC-MS/MS) in hormone monitoring for patients receiving fulvestrant therapy. Case: A 31-year-old female with metastatic hormone receptorpositive breast cancer receiving combination therapy (fulvestrant, letrozole, ribociclib, and goserelin) presented with inappropriately elevated serum estradiol levels of 566 pmol/L (early follicular phase 200–500 pmol/L), measured by chemiluminescence immunoassay. Despite effective gonadotrophin suppression evidenced by low luteinizing hormone (0.2 IU /L) and follicle-stimulating hormone (4.1 IU/L) levels and clinical amenorrhea, the discordant estradiol elevation raised suspicion of assay interference. Confirmatory testing with LC-MS/MS revealed an estradiol concentration of <36 pmol/L, consistent with expected hormonal suppression and confirming immunoassay cross-reactivity with fulvestrant. The case demonstrates significant fulvestrant interference with estradiol immunoassays, resulting in a greater than 15- fold overestimation compared to LC-MS/MS measurement. The clinical presentation was consistent with effective endocrine therapy, supported by suppressed gonadotropin levels, clinical amenorrhea, and stable disease on imaging. LC-MS/MS provided accurate estradiol measurement, avoiding potential diagnostic confusion and unnecessary clinical interventions. Conclusion Clinicians should be aware of potential fulvestrant interference with estradiol immunoassays when interpreting hormone levels in breast cancer patients. Discordant laboratory findings, particularly elevated estradiol despite clinical evidence of effective hormonal suppression, should prompt consideration of LC-MS/MS confirmation. This case underscores the clinical importance of analytical method selection in hormone monitoring and highlights the need for improved laboratory-clinical communication to optimize patient care in oncology practice.
Fulvestrant ; Immunoassay

This study was to develop a new method for detecting circulating tumor cells (CTCs) with high sensitivity and specificity, therefore to detect the colorectal cancer as early as possible for improving the detection rate of the disease. To this end, we prepared some micro-column structure microchips modified with graphite oxide-streptavidin (GO-SA) on the surface of microchips, further coupled with a broad-spectrum primary antibody (antibody1, Ab₁), anti-epithelial cell adhesion molecule (anti-EpCAM) monoclonal antibody to capture CTCs. Besides, carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) were coupled with colorectal cancer related antibody as specific antibody 2 (Ab₂) to prepare complex. The sandwich structure consisting of Ab₁-CTCs-Ab₂ was constructed by the microchip for capturing CTCs. And the electrochemical workstation was used to detect and verify its high sensitivity and specificity. Results showed that the combination of immunosensor and micro-nano technology has greatly improved the detection sensitivity and specificity of the immunosensor. And we also verified the feasibility of the immunosensor for clinical blood sample detection, and successfully recognitized detection and quantization of CTCs in peripheral blood of colorectal cancer patients by this immunosensor. In conclusion, the super sandwich immunosensor based on micro-nano technology provides a new way for the detection of CTCs, which has potential application value in clinical diagnosis and real-time monitoring of disease.
Humans ; Nanotubes, Carbon/chemistry* ; Neoplastic Cells, Circulating/pathology* ; Biosensing Techniques ; Immunoassay/methods* ; Antibodies ; Colorectal Neoplasms/diagnosis* ; Electrochemical Techniques/methods* ; Gold/chemistry*

Objective To investigate the fluorescence resonance energy transfer (FRET) effect between dylight (DL) and AuNP (AuNP), and to construct a new fluorescence immunoassay for insulin in combination with the immunocompetition method. Methods Insulin antigen (Ag) and insulin antibody (Ab) were conjugated with DL and AuNP respectively to form DL-Ag conjugate and AUNp-AB conjugate. A novel fluorescence immunoassay for insulin was developed on the basis of FRET effect and the immune competition response between them. Then the performance of the method was evaluated and its application in actual samples was explored. Results The fluorescence immunoassay showed high sensitivity (0.015 ng/mL), short measurement time (4 min) and good specificity. It was successfully used in the measurement of serum insulin, and the recovery was between 96.9% and 121.1%. Conclusion FRET effect between AuNP and DL can be applied to develop a fluorescence immunoassay for the measurement of serum insulin.
Fluorescence Resonance Energy Transfer ; Insulin ; Immunoassay

Objective To compare the sensitivity and accuracy of amplified luminescent proximity homogeneous assay linked immunosorbent assay (AlphaLISA) and magnetic particles-based chemiluminescence immunoassay (MP-CLIA) for detection of staphylococcal enterotoxin C (SEC) in the simulated milk samples. Methods The AlphaLISA was constructed using goat anti-SEC polyclonal antibody-coupled receptor microspheres, biotin-labeled SEC monoclonal antibody and streptavidin-coupled donor microspheres. The MP-CLIA was constructed using goat anti-SEC polyclonal antibody conjugated alkaline phosphatase, biotin-labeled anti-SEC monoclonal antibody and streptavidin conjugated magnetic beads. Results The sensitivity of AlphaLISA to detect SEC content in simulated milk samples was 4.04 ng/L, and the coefficient of variation (CV) was 1.98%~9.82%. The sensitivity of MP-CLIA was 108.19 ng/L and CV was 4.63%~20.40%. Conclusion Compared with MP-CLIA, AlphaLISA is more sensitive and accurate to detecting SEC.
Animals ; Streptavidin ; Biotin ; Luminescence ; Milk ; Antibodies, Monoclonal ; Goats ; Immunoassay/methods*

To develop a magnetic nanoparticle chemiluminescence immunoassay (CLIA) for the determination of type Ⅰ procollagen N-terminal peptide (PINP) in human serum, we expressed a recombinant PINP-α1 protein in Corynebacterium glutamicum and used it as an immunogen to immunize BALB/c mice. We obtained three hybridoma cell lines that stably secret antibody against PINP-α1 protein. After further pairing and screening, we chose a monoclonal antibody 8C12 coupled with biotin as the capture antibody, and a monoclonal antibody 1F11 labeled horseradish peroxidase as the detection antibody. The antibodies combined with the serum samples, forming a sandwich complex which was used to detect the concentration of PINP in serum. After optimizing the conditions, we determined that the best working concentration of the capture antibody and the detection antibody were 3 μg/mL, and the incubation time was 30 minutes. The quantitative assay had a detection range of 5-1 100 ng/mL, with recovery rates between 93%-107% and the minimum detection limit of 1.22 ng/mL achieved. The intra-and inter-assay precisions were lower than 10%. The correlation coefficient of PINP results between this CLIA method and the Roche electrochemiluminescence immunoassay system was 0.906 2. Therefore, this CLIA method is specific and can be used to quantitatively detect the content of PINP in serum, which has the potential to become an auxiliary approach for bone disease examination.
Animals ; Humans ; Immunoassay ; Luminescence ; Mice ; Mice, Inbred BALB C ; Peptide Fragments/isolation & purification* ; Procollagen/isolation & purification*

PURPOSE: Various immune cells, including eosinophils and neutrophils, are known to contribute to the development of chronic rhinosinusitis with nasal polyps (CRSwNP). However, the current understanding of the role of neutrophils in the development of CRSwNP still remains unclear. Therefore, we investigated risk factors for refractoriness of CRSwNP in an Asian population. METHODS: Protein levels of 17 neutrophil-related mediators in nasal polyps (NPs) were determined by multiplex immunoassay, and exploratory factor analysis using principal component analysis was performed. Immunofluorescence analysis was conducted to detect human neutrophil elastase (HNE) or myeloperoxidase (MPO)-positive cells. Tissue eosinophilic nasal polyp (ENP) and tissue neutrophilia (Neu(high)) were defined as greater than 70 eosinophils and 20 HNE-positive cells, otherwise was classified into non-eosinophilic nasal polyp (NENP) and absence of tissue neutrophilia (Neu(low)). RESULTS: In terms of disease control status, NENP-Neu(low) patients showed the higher rate of disease control than NENP-Neu(high) and ENP-Neu(high) patients. Linear by linear association demonstrated the trend in refractoriness from NENP-Neu(low) to NENP-Neu(high) or ENP-Neu(low) to ENP-Neu(high). When multiple logistic regression was performed, tissue neutrophilia (hazard ratio, 4.38; 95% confidence interval, 1.76-10.85) was found as the strongest risk factor for CRSwNP refractoriness. Additionally, exploratory factor analysis revealed that interleukin (IL)-18, interferon-γ, IL-1Ra, tumor necrosis factor-α, oncostatin M, and MPO were associated with good disease control status, whereas IL-36α and IL-1α were associated with refractory disease control status. In subgroup analysis, HNE-positive cells and IL-36α were significantly upregulated in the refractory group (P = 0.0132 and P = 0.0395, respectively), whereas MPO and IL-18 showed higher expression in the controlled group (P = 0.0002 and P = 0.0009, respectively). Moreover, immunofluorescence analysis revealed that IL-36R⁺HNE⁺-double positive cells were significantly increased in the refractory group compared to the control group. We also found that the ratio of HNE-positive cells to α1 anti-trypsin was increased in the refractory group. CONCLUSIONS: Tissue neutrophilia had an influence on treatment outcomes in the Asian CRSwNP patients. HNE-positive cells and IL-36α may be biomarkers for predicting refractoriness in Asians with CRSwNP. Additionally, imbalances in HNE and α1 anti-trypsin may be associated with pathophysiology of neutrophilic chronic rhinosinusitis.
Asian Continental Ancestry Group ; Biomarkers ; Eosinophils ; Fluorescent Antibody Technique ; Humans ; Immunoassay ; Interleukin 1 Receptor Antagonist Protein ; Interleukin-18 ; Interleukins ; Leukocyte Elastase ; Logistic Models ; Nasal Polyps ; Necrosis ; Neutrophils ; Oncostatin M ; Peroxidase ; Principal Component Analysis ; Rhinitis ; Risk Factors ; Sinusitis

Antibodies, Viral ; blood ; Betacoronavirus ; immunology ; Coronavirus Infections ; diagnosis ; Gold Colloid ; chemistry ; Humans ; Immunoassay ; methods ; Immunoglobulin G ; blood ; Immunoglobulin M ; blood ; Pandemics ; Pneumonia, Viral ; diagnosis ; Reagent Kits, Diagnostic

Humans ; Immunoassay ; Indicators and Reagents ; Mass Spectrometry ; Methods ; Pathology, Molecular ; Spectrum Analysis

Plasma homocysteine level and megaloblastic anemia status are two factors that can affect the quality of life of patients with multiple sclerosis (MS). We conducted this study to determine the effect of vitamin B12 and folic acid supplementation on serum homocysteine, megaloblastic anemia status and quality of life of patients with MS. A total of 50 patients with relapsing remitting multiple sclerosis (RRMS) included in this study which divided into 2 groups. The vitamin group received 5 mg folic acid tablet daily and 3 doses of vitamin B12 (1,000 mcg) injection and the other group received placebo and normal saline injection (same doses). The quality of life was measured by using Multiple Sclerosis Quality of Life-54 questionnaire (MSQOL-54). Fully automated fluorescence polarization immunoassay was used to measure serum homocysteine, vitamin B12 and folate. Complete blood count blood test was conducted to determine the anemia status. The mean homocysteine level reduced by 2.49 ± 0.39 µmol/L (p = 0.001), hemoglobin increased from 11.24 ± 1.54 to 13.12 ± 1.05 g/dL (p = 0.001), and mean corpuscular volume decreased from 95.50 ± 6.65 to 89.64 ± 4.24 in the vitamin group (p = 0.001). There was a significant improvement in the mental field of life quality in the placebo group (37.46 ± 19.01 to 50.98 ± 21.64; p = 0.001), whereas both physical and mental fields of quality of life were improved significantly in the vitamin group (40.38 ± 15.07 to 59.21 ± 12.32 and 29.58 ± 15.99 to 51.68 ± 18.22, respectively; p = 0.001). Serum homocysteine level decrease and anemia status improvement with vitamin B12 and folic acid supplementation reveal the potential role of these two vitamins in improving the life quality of MS patients. TRIAL REGISTRATION: Iranian Registry of Clinical Trials Identifier: IRCT2015100313678N7
Anemia* ; Anemia, Megaloblastic ; Blood Cell Count ; Erythrocyte Indices ; Fluorescence Polarization Immunoassay ; Folic Acid* ; Hematologic Tests ; Homocysteine* ; Humans ; Multiple Sclerosis* ; Multiple Sclerosis, Relapsing-Remitting ; Plasma ; Quality of Life* ; Vitamin B 12* ; Vitamins*

Hb mutations can alter the structure, behavior, stability, or quantity of the globin chain produced. Some Hb variants shorten the erythrocyte life span, resulting in physiologically lower hemoglobin A1c (HbA1c) levels. The hemoglobin E (HbE) phenotype involves a single-nucleotide polymorphism that reduces β-globin chain synthesis. We compared the HbA1c levels of subjects with normal Hb (HbAA; N=131) and HbE (N=148) phenotypes, examining potential hematological and biochemical factors contributing to differences in HbA1c levels. All had normal fasting plasma glucose ( < 5.6 mmol/L), AST, ALT, and creatinine levels. Mean±SD HbA1c levels differed between HbAA and HbE subjects: 5.5±0.3% and 5.3±0.3% (P < 0.001) according to an immunoassay, and 5.5±0.3% and 5.3±0.3% (P < 0.001) according to cation-exchange HPLC, respectively. In multiple logistic regression, only mean corpuscular volume (P < 0.001) contributed to the difference in HbA1c levels between groups. Although a 0.2% difference in HbA1c is relatively small and unlikely to alter clinical decisions, epidemiologically, this can lead to misclassification of a significant proportion of the population, especially since the threshold of non-diabetes HbA1c (≤5.6%) falls very close to the HbA1c median of the general population.
Accidental Falls ; Blood Glucose ; Chromatography, High Pressure Liquid ; Creatinine ; Erythrocyte Indices ; Erythrocytes ; Fasting ; Globins ; Hemoglobin E ; Hemoglobins ; Immunoassay ; Logistic Models ; Phenotype