What is responsible for subacute thyroiditis? Virus or immune system: A case report

Dilek Geneș; Zafer Pekkolay; Mehmet Güven; Mehmet Şimșek; Hüsna Saraçoğlu; Tuzcu Alpaslan Kemal

doi:10.1530/endoabs.70.EP507

Background: Subacute thyroiditis (SAT) is a transient thyrotoxic state characterized by suppressed TSH and low uptake of iodine 123 on thyroid scanning. SAT is a self limiting, possibly viral and inflammatory thyroid disorder that is usually associated with thyroid pain and systemic symptoms. Many factors can cause SAT. Infections are considered the most common cause. Vaccines can also lead to SAT.

Case report: A 46-year-old male with a history of type 1 diabetes mellitus admitted to the hospital with fatigue, weight loss, myalgia and mild anterior neck pain. In November 2019, about four weeks before admission to our hospital, the patient received the seasonal influenza vaccine [VaxigripTetra- Quadrivalent influenza vaccine; batch number T3J232V, Sanofi Pasteur, Val de Reuil, France, containing the following strains: A/Brisbane/02/2018 (H1N1) pdm09; A/Kansas/14/2017 (H3N2); B/Colorado/06/2017; and B/Phuket/3073/2013], and at the time of vaccination, there was no prior history of thyroid disease or symptoms to suggest a recent viral infection. However, one week following the vaccination, the patient developed fever, sore throat, fatigue, myalgia and muscle weakness. He received antibiotherapy for two weeks. The patient had no symptoms or physical examination findings of upper respiratory system infection, and he had no obvious fever at the time of admission to the hospital. His heart rate was 112/min and regular. He had tenderness in both thyroid lobes. His laboratory tests showed a white blood cell (WBC) count of 9.12/µl (normal, 4.6–10.2), His kidney and liver functions were normal. Tests for thyroid autoimmune antibodies (thyroperoxidase and thyroglobulin) were negative. Ultrasonographic imaging and thyroid scintigraphy confirmed diagnosis of SAT. The table presents the time-varying laboratory parameters at admission and after steroid treatment (Table 1). The patient was started on 32 mg/day oral methylprednisolone treatment. His symptoms improved with treatment. With the two-month treatment period, the steroid dose was gradually reduced and discontinued. The patient asymptomatic in the third month of follow-up.

**Table 1** Laboratory parameters following influenza vaccine.
	4. week	7. week	9. week	15.week	Referance range
TSH	0.01	4.15	10.08	5.82	0.5–5.5–mIU/l
FT4	2.17	0.78	1.09	1.22	0.89–1.76–ng/ml
FT3	4.81	1.94	2.67	3.25	2.3–4.2–pmol/l
ESR	21	9	5	3	0–15–mm/h
CRP	<0.34	0.02	<0.34	<0.34	0–0.5–mg/dl
TSH; thyroid-stimulating hormone, FT4; free thyroxine, FT3; free triiodothyronine, ESR; erythrocyte sedimentation rate, CRP; C reactive protein

Conclusion: SAT should be suspected if influenza-like symptoms and pain in the thyroid region develop after influenza vaccination.

Endocrine Abstracts

EP507