Detection of 3-iodothyronamine in human patients: A preliminary study

Abstract

Context and Objective: The primary purpose of this study was to detect and quantify 3-iodothyronamine (T 1AM), an endogenous biogenic amine related to thyroid hormone, in human blood. Design: T 1AM, total T 3, and total T 4 were assayed in serum by a novel HPLC tandem mass spectrometry assay, which has already been validated in animal investigations, and the results were related to standard clinical and laboratory variables. Setting and Patients: The series included one healthy volunteer, 24 patients admitted to a cardiological ward, and 17 ambulatory patients suspected of thyroid disease, who underwent blood sampling at admission for routine diagnostic purposes. Seven patients were affected by type 2 diabetes, and six patients showed echocardiographic evidence of impaired left ventricular function. Interventions: No intervention or any patient selection was performed. Main Outcome Measures: serum T 1AM, total and free T 3 and T 4, routine chemistry, routine hematology, and echocardiographic parameters were measured. Results: T 1AM was detected in all samples, and its concentration averaged 0.219 ± 0.012 pmol/ml. The T 1AM concentration was significantly correlated to total T 4 (r = 0.654, P < 0.001), total T 3 (r = 0.705, P < 0.001), glycated hemoglobin (r = 0.508, P = 0.013), brain natriuretic peptide (r = 0.543, P = 0.016), and γ-glutamyl transpeptidase (r = 0.675, P < 0.001). In diabetic vs. nondiabetic patients T 1AM concentration was significantly increased (0.232 ± 0.014 vs. 0.203 ± 0.006 pmol/ml, P = 0.044), whereas no significant difference was observed in patients with cardiac dysfunction. Conclusions: T 1AM is an endogenous messenger that can be assayed in human blood. Our results are consistent with the hypothesis that circulating T 1AM is produced from thyroid hormones and encourage further investigations on the potential role of T 1AM in insulin resistance and heart failure. Copyright © 2012 by The Endocrine Society.