Technetium-99m Thyroid Scintigraphy and Human Leukocyte Antigen - B35 in Sub-Acute Thyroiditis

Sub-acute thyroiditis possibly caused by a viral infection of thyroid gland is associated with a surge in thyroxine levels of the patient. Women in the younger age group are affected more than men. Markedly decreased radioactive iodine thyroid uptakes in a setting of thyrotoxicosis associated with elevated thyroxine levels and reduced thyroid stimulating hormone levels usually clinches the diagnosis. Patients mostly require symptomatic treatment with non-steroidal anti-inflammatory drugs. Sub-acute thyroiditis is a self-limiting disorder with most of the patients making a complete recovery in a span of three to six months. Being geographically and ethnically different the present studies was undertaken with an objective of understanding the clinical, laboratory and thyroid uptake profiles in patients of SAT during its natural history and also find the extent of genetic influences through its association with HLA B35.

32 patients in the age group of 20-59 years diagnosed to have sub-acute thyroiditis were studied. 18 patients out of 32 were subjected to HLA B35 testing. Other laboratory parameters that included hormonal profile and radioactive thyroid uptakes were performed.

Most of the patients were females and in their fourth decade of life. Thyroid stimulating hormone levels were decreased in 32 (100%). A majority of patients had normal anti TPO levels. All the patients had grossly decreased Tc-99m thyroid uptake levels at presentation. HLA B35 test done in 18 patients was reported positive in 10 (55.56%) patients.

The present study is unique in having used serial Tc-99m thyroid scintigraphy in patients of SAT. A positive HLA B 35 is associated in a majority of patients conferring genetic susceptibility.