Isotope Dilution LC-MS/MS for Thyroid Hormone Quantification
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Solution Overview
Problem
Current methods for measuring 3-iodothyronamine (T1AM) in human serum are not sensitive enough, lacking specificity and accuracy, particularly during pregnancy when maternal thyroid hormones are crucial for fetal brain development, and existing assays fail to detect T1AM at clinically relevant concentrations.
Innovation Solution
A highly sensitive and specific isotope dilution tandem mass spectrometry method for simultaneously measuring T1AM, T4, T3, and 3,3'-diiodo-L-thyronine (3,3'-T2) in human plasma or serum, allowing quantitation at concentrations below 100 pg/mL, using differentially labeled reference compounds for calibration and separation by liquid chromatography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If immunoassays are used to measure T4 and T3, then measurement can be performed, but specificity is insufficient and susceptibility to interferences occurs
Solution Approach 1:
The patent replaces immunoassay methods with mass spectrometry detection. Mass spectrometry measures the mass-to-charge ratio of ions, providing direct molecular identification based on mass rather than antibody-antigen recognition. This substitution eliminates interference from heterophile antibodies and other immunological artifacts, achieving superior specificity and reliability for thyroid hormone measurement.
Solution Approach 2:
The patent introduces isotope-labeled internal standards (isotope dilution) as intermediaries in the measurement process. These labeled standards co-elute with endogenous thyroid hormones during chromatography and are distinguished by mass spectrometry through their different mass-to-charge ratios. This intermediary approach corrects for matrix effects, ion suppression, and variability in sample preparation, significantly improving measurement reliability.
2Measurement precision
If LC-MS/MS methods are used to detect T1AM, then detection sensitivity improves, but quantification of endogenous T1AM at clinically relevant concentrations remains challenging
Solution Approach 1:
The patent employs isotope dilution by spiking samples with known amounts of isotope-labeled T1AM internal standard. This changes the concentration parameter of the analytical system, creating a calibration relationship between the ratio of labeled to unlabeled T1AM signals and the absolute concentration. This approach enables accurate quantification of endogenous T1AM at clinically relevant concentrations despite the low abundance of the analyte.
Solution Approach 2:
The patent uses isotope-labeled internal standards that co-process with endogenous T1AM throughout sample preparation and analysis. The known concentration of the internal standard provides a reference feedback signal that allows correction for variations in extraction efficiency, ionization efficiency, and instrument response, enabling accurate quantification of trace endogenous T1AM.
3Adaptability or versatility
If simultaneous measurement of multiple thyroid hormones is performed, then comprehensive assessment is achieved, but measurement complexity increases
Solution Approach 1:
The patent develops a universal LC-MS/MS method that can simultaneously measure multiple thyroid hormones (T4, T3, T2, T1AM, rT3) in a single run. The mass spectrometry detector universally detects all these hormones based on their unique mass-to-charge ratios, eliminating the need for separate assays for each hormone. This multi-functional approach comprehensively assesses thyroid status while streamlining the measurement process.
Solution Approach 2:
The patent segments the measurement of different thyroid hormones by monitoring their unique mass-to-charge ratio transitions in tandem mass spectrometry. Each hormone is identified and quantified by its specific precursor ion to product ion transition, allowing simultaneous measurement through segmented detection channels. This segmentation approach handles multiple analytes efficiently without increasing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise and accurate quantification of T1AM and other thyroid hormones at low concentrations, improving clinical assessment and treatment of various diseases, including hypertension, diabetes, and thyroid disorders, with enhanced sensitivity and specificity compared to previous assays.
Implementation Method 1
separation by liquid chromatography
Implementation Method 2
isotope dilution tandem mass spectrometry method for simultaneously measuring T1AM, T4, T3, and 3,3'-diiodo-L-thyronine (3,3'-T2)
Data Source
AI summary
The invention provides methods for simultaneously detecting or simultaneously quantifying any combination of thyroxine (T4), triiodothyronine (T3), 3,3′-diiodo-L-thyronine (3,3′-T2), 3-iodothyronamine (T1AM), and, optionally, reverse T3 (rT3) in a sample obtained from a human. The method involves a simple, sensitive, accurate, and specific isotope dilution tandem mass spectrometry method for the simultaneous quantification of any combination of T4, T3, 3,3′-T2, T1AM, and, optionally, rT3 in a sample obtained from a human, e.g., in human plasma or serum samples. This assay is far more sensitive than previously described assays for thyronamines and allows quantitation of T1AM in human plasma or serum, including from healthy controls.