ECE2008 Poster Presentations Thyroid (146 abstracts)
Interference in assay of thyroid hormones due to auto-antibodies against thyroxine and triiodothyronine: report on two patients with Hashimoto’s thyroiditis
Oscar Moreno-Pérez 1 , Joaquin Serrano 1 , Rocio Alfayate 2 , Maite López 2 , Sandra Martinez-Fuster 1 , Nieves Arias 1 , Monsrrat Mauri 2 & Antonio Miguel Picó 1
1Department of Endocrinology and Nutrition, Alicante General University Hospital, Alicante, Spain; 2Department of Hormone Laboratory, Alicante General University Hospital, Alicante, Spain.
Introduction: Characteristically the discordant thyroid function test has been attributed to TSH-producing hypophyseal adenoma, familial dysalbuminemic hyperthyroxinemia and thyroid hormone resistance syndrome. We presented 2 cases with raised peripheral thyroid hormones with detectable TSH due to the presence of auto-antibodies against the peripheral thyroid hormones (PTAAb).
| TSH (EQLA) | FT4 (EQLA) | FT4 (CMIA) | AAcT4 (%125I-T4) | FT3 (EQLA) | FT3 (CMIA) | AAcT3 (%125I-T3) | Sub-α (IRMA) | SHBG (QLA) | |
| 1 | 25 | 2.3 | 0.9 | 57.3 | 3.6 | 3.22 | 31.8 | 0.5 | 75 |
| 2 | 98.4 | 3.08 | 0.55 | 67.5 | 3.16 | 1.53 | 10.4 | 0.68 | 59 |
| nv | 0.38–4.84 μU/ml | 0.8–2 ng/dl | 0.7–1.48 ng/dl | <1.6% | 1.8–4.6 pg/ml | 1.71–3.71 pg/ml | <2% | 0–0.9 mU/ml | 11–124 nmol/l |
Subjects and methods: A 24-year-old woman (1) and a 79-year-old woman (2) with auto-immune primary hypothyroidism diagnosed 4 and 3 years ago, with symptoms and signs of clinical hypothyroidism and without levothyroxine treatment was referred to our centre after a finding of discordant thyroid function values (Table). Hormonal and radioimmunoprecipitation studies. Subunit-α was determined by IRMA (Immunotech de Beckman Coulter©), SHBG by QLA (Immulite 2000 (DPC©), TSH was determined by EQLA, following series dilution (1/2, 1/5) of the sample. Samples were sent to another laboratory for determination of TP by ‘two-step’ immunoassay (CMIA, Architect (Abbott Lab©). TPAAb was determined by incubating samples with I125-T4 and I125-T3, followed by precipitation in polyethylene–glycol. Precipitate count was obtained using a gamma-counter (Packard Cobra). Euthyroid patients with no auto-immune pathology were used as controls.
Results: The presence of PTAAb was detected in both cases (table), confirming the initial diagnosis of primary hypothyroidism.
Conclusion: The presence of PTAAb is an unusual cause of discordant thyroid function values that it must have in mind to the correct management of thyroid disease.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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