Abstract
Background: Elevated thyroglobulin levels are most commonly associated with differentiated thyroid carcinoma and these levels are often used to monitor for disease recurrence. Thyroglobulin antibody levels can be elevated in both Hashimoto’s Thyroiditis and Graves’ Disease and these antibodies can interfere with thyroglobulin levels as detailed by Spencer, Wang (1). With benign thyroid nodules, there is limited research regarding thyroglobulin levels as studied in Chinnappa, et al (2).
Clinical Case: A 31-year woman presented with a palpable thyroid nodule and dysphagia. Her primary care physician ordered thyroid labs including normal TSH (1.3 mIU/L, n0.4-4 mIU/L), normal thyroid peroxidase antibody (56 units, n<250units), normal thyroglobulin antibody level (<1 IU/mL, n<1 IU/mL), and elevated thyroglobulin level (469.1 ng/mL, n2.8-40.9 ng/mL). Her thyroglobulin levels remained elevated on repeat testing (224.4 ng/mL, n2.8-40.9) one month later. In addition, her thyroglobulin lab studies were repeated with HAMA treatment and remained elevated (277.7 ng/mL, n2.8-40.9). Office ultrasound showed longest dimension of nodule to be 5 cm and patient received FNA biopsy. Biopsy results were reported as a benign nodule and it was recommended to follow-up in 12 months. Six months later the patient reported having increasing dysphagia. She underwent Barium swallow which showed no abnormalities. She had a growth increase of 35% on repeat imaging along with increasing neck pressure and discomfort and was referred to an ENT for surgery. Final pathology after left thyroid and isthmus thyroidectomy was reported as “Multinodular hyperplasia with background thyroid parenchyma histologically unremarkable. Negative for malignancy.” Thyroglobulin levels subsequently returned to within the normal range and the patient’s dysphagia resolved.
Conclusion: Thyroglobulin levels can be markedly elevated with benign thyroid nodules, which can mislead physicians and increase concern for thyroid cancer.
References: (1) Spencer, CA, Wang, CC. Thyroglobulin measurement. Techniques, clinical benefits, and pitfalls. Endocrinol Metab Clin North Am. 1995 Dec; 24(4): 841-63.
(2) Chinnappa, P, Taguba, L, Arciaga, R, Faiman, C, Siperstein, A, Mehta, AE, Reddy SK, Nasr, C, Gupta MK. Detection of thyrotropin-receptor messenger ribonucleic acid (mRNA) and thyroglobulin mRNA transcripts in peripheral blood of patients with thyroid disease: sensitive and specific markers for thyroid cancer. J Clin Endocrinol Metab. 2004 Aug;89(8):3705-9.