Endocrine Abstracts

Context

The effects of COVID-19 on the thyroid axis remain uncertain. Recent evidence has been conflicting, with Euthyroid-Sick-Syndrome-ESS, thyrotoxicosis or suppression of thyroid-function-tests (TFTs) reported which can lead to inadequate diagnoses and treatments.

Objective

The aim of this case report is to describe, for the first time, a possible interference of macro-TSH in a patient with SARS-CoV2 and thyroid carcinoma.

Case report

56-year-old male evaluated in the Emergency-Department for fever, fatigue and cough. Chest-X-rays: lung parenchyma with multiple bilateral ground-glass areas suggestive of viral pneumonia in the context of the COVID-19 pandemic. Positive RT-PCR nasopharyngeal swab.

Patient’s medical-history

Parathyroidectomy (hyperparathyroidism secondary to parathyroid adenoma) and total thyroidectomy (multinodular goiter). Fine Needle Aspiration (FNA) of dominant nodule in left-thyroid-lobe: negative for malignancy. Multifocal papillary microcarcinoma (right-thyroid-lobe [3.3 mm] and left-thyroid-lobe [4.0 mm]) as an incidental finding; without ablative treatment with I131. Replacement therapy: Levothyroxine 137 µg/day. During admission, TFTs were developed, and we observed that TSH levels increased compared to previous studies. The Levothyroxine was readjusted (150 µg/day). Malabsorption (parenteral nutrition) and/or incorrect dose are ruled out. TFTs can seem discordant/incongruent with the clinical picture, so we decided to develop a study of possible interference.

Conclusion and discussion

We identified a possible interference of non-functional macro-TSH complexes (mostly TSH-IgG) in the determination of thyrotropin in patients with underlying thyroid pathology and infection by SARS-CoV2 performed on immunoassay platforms. Interference-detection and mitigation methods: serial dilutions and precipitation with polyethylene-glycol-PEG (currently the most widely used technique to detect macro-TSH) vs. gel-filtration-chromatography (expensive and not available most Hospitals). Heterophilic-antibodies (HAMA) and Rheumatoid-Factor: negatives. An exceptional finding, not described to date and, on many occasions, forgotten or underestimated, since can lead to incorrect diagnoses and treatments. Thyroid function should not be assessed in seriously ill patients unless there is a thyroid dysfunction. The thyroid dysfunction caused in COVID-19 presents a dynamic evolution with a tendency towards progressive recovery. It is essential to take into account this fact that allows an adequate quality of care and patient safety in the context of COVID-19. Screening macro-TSH should be developed before hormone replacement therapy by discordant results.