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Tokumaru M, Ohba K, Kashiwabara Y, Takase H, Hayashi C, Iwaki T, Suzuki Y, Matsushita A, Sasaki S, Suda T, Maekawa M. Falsely elevated thyroid hormone levels associated with fibrin interference in patients receiving oral anticoagulant therapy. Ann Clin Biochem 2023:45632231159280. [PMID: 36750429 DOI: 10.1177/00045632231159280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
OBJECTIVE Unique clinical courses were observed in two asymptomatic patients receiving warfarin who referred to our hospital because of suspected central hyperthyroidism. We eventually diagnosed these patients with falsely elevated thyroid hormone levels caused by macroscopically invisible fibrin. Although false results caused by fibrin interference in vitro have been identified in various immunoassays, especially in blood samples from patients receiving anticoagulant therapy, no studies on thyroid function testing have been reported. The experience in evaluating these cases prompted us to investigate the independent influence of oral anticoagulants via putative fibrin interference on thyroid function testing. METHODS We retrospectively reviewed known contributing factors that affect thyroid function testing including age, gender, medication history, body mass index, estimated glomerular filtration rate, smoking status, alcohol consumption, and the seasons of hospital visits from participants who presented the Department of Health Checkup between April 2010 and December 2020. RESULTS A propensity-matched analysis revealed that the median serum free thyroxine levels under oral anticoagulant were significantly higher (17.9 pmol/L, n = 60) than those without anticoagulants (16.0 pmol/L, n = 60; p < 0.001). It was noted that this difference was the largest among contributing factors we analyzed. No significant differences were noted in serum thyroid-stimulating hormone levels. CONCLUSIONS We report two patients receiving warfarin with falsely elevated thyroid hormone levels caused by fibrin interference resembling central hyperthyroidism for the first time. Our retrospective study suggests that the medication status of oral anticoagulants should be considered when evaluating thyroid function tests.
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Affiliation(s)
- Mitsuaki Tokumaru
- Division of Endocrinology, Department of Internal Medicine, Seirei Hamamatsu General Hospital, Hamamatsu, Japan.,Second Division, Department of Internal Medicine, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Kenji Ohba
- Second Division, Department of Internal Medicine, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan.,Department of Internal Medicine, Enshu Hospital, Hamamatsu, Japan.,Medical Education Center, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yumiko Kashiwabara
- Division of Endocrinology, Department of Internal Medicine, Seirei Hamamatsu General Hospital, Hamamatsu, Japan
| | - Hiroyuki Takase
- Department of Internal Medicine, Enshu Hospital, Hamamatsu, Japan
| | - Chiga Hayashi
- Division of Endocrinology, Department of Internal Medicine, Seirei Hamamatsu General Hospital, Hamamatsu, Japan
| | - Takayuki Iwaki
- Department of Pharmacology, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yasuhide Suzuki
- Department of Laboratory Medicine, Enshu Hospital, Hamamatsu, Japan
| | - Akio Matsushita
- Second Division, Department of Internal Medicine, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Shigekazu Sasaki
- Second Division, Department of Internal Medicine, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Takafumi Suda
- Second Division, Department of Internal Medicine, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masato Maekawa
- Department of Laboratory Medicine, 12793Hamamatsu University School of Medicine, Hamamatsu, Japan
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Paisdzior S, Schuelke M, Krude H. What is the Role of Thyroid Hormone Receptor Alpha 2 (TRα2) in Human Physiology? Exp Clin Endocrinol Diabetes 2022; 130:296-302. [PMID: 35255520 DOI: 10.1055/a-1716-7980] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Thyroid hormone receptors are nuclear receptors that function as transcription factors and are regulated by thyroid hormones. To date, a number of variants and isoforms are known. This review focuses on the thyroid hormone receptor α (TRα), in particular TRα2, an isoform that arises from alternative splicing of the THRA mRNA transcript. Unlike the TRα1 isoform, which can bind T3, the TRα2 isoform lacks a ligand-binding domain but still binds to DNA thereby antagonizing the transcriptional activity of TRα1. Although a regulatory role has been proposed, the physiological function of this TRα2 antagonism is still unclear due to limited in vitro and mouse model data. Recently, the first patients with resistance to thyroid hormone due to mutations in THRA, the TRα encoding gene, affecting the antagonistic function of TRα2 were described, suggesting a significant role of this particular isoform in human physiology.
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Affiliation(s)
- Sarah Paisdzior
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Markus Schuelke
- NeuroCure Cluster of Excellence; Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.,Department of Neuropediatrics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
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