Usage Information
Citation Information: J Clin Invest. 2005;115(9):2524-2533. https://doi.org/10.1172/JCI25083.
Abstract
The relative roles of the types 1 and 2 iodothyronine deiodinases (D1 and D2) in extrathyroidal 3,5,3′-triiodothyronine (T3) production in humans are unknown. We calculated the rate of thyroxine (T4) to T3 conversion by intact cells transiently expressing D1 or D2 at low (2 pM), normal (20 pM), and high (200 pM) free T4 concentrations. Deiodinase activities were then assayed in cell sonicates. The ratio of T3 production in cell sonicates (catalytic efficiency) was multiplied by the tissue activities reported in human liver (D1) and skeletal muscle (D2). From these calculations, we predict that in euthyroid humans, D2-generated T3 is 29 nmol/d, while that of D1-generated T3 is 15 nmol/d, from these major deiodinase-expressing tissues. The total estimated extrathyroidal T3 production, 44 nmol/d, is in close agreement with the 40 nmol T3/d based on previous kinetic studies. D2-generated T3 production accounts for approximately 71% of the peripheral T3 production in hypothyroidism, but D1 for approximately 67% in thyrotoxic patients. We also show that the intracellular D2-generated T3 has a greater effect on T3-dependent gene transcription than that from D1, which indicates that generation of nuclear T3 is an intrinsic property of the D2 protein. We suggest that impairment of D2-generated T3 is the major cause of the reduced T3 production in the euthyroid sick syndrome.
Authors
Ana Luiza Maia, Brian W. Kim, Stephen A. Huang, John W. Harney, P. Reed Larsen
Usage data is cumulative from April 2024 through April 2025.
| Usage | JCI | PMC |
|---|---|---|
| Text version | 756 | 137 |
| 72 | 65 | |
| Figure | 327 | 30 |
| Table | 39 | 0 |
| Citation downloads | 64 | 0 |
| Totals | 1,258 | 232 |
| Total Views | 1,490 | |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)