Background: Accurate differentiation between Graves’ disease (GD) and destructive thyroiditis (DT) is crucial in the management of thyrotoxicosis because treatment strategies differ significantly. However, overlapping clinical and biochemical features often complicate diagnosis, particularly in mild cases and resource-limited settings. This study evaluated the diagnostic utility of technetium-99m pertechnetate (99mTc) thyroid uptake, thyrotropin receptor antibody (TRAb) testing, and color flow Doppler ultrasonography (CFD-USG) in distinguishing GD from DT and explored a practical diagnostic algorithm adaptable to different healthcare settings.

Methods: This prospective observational study included patients presenting with thyrotoxicosis. All participants underwent clinical evaluation, biochemical testing, 99mTc thyroid scintigraphy, TRAb measurement, and CFD-USG. Doppler assessment included measurement of peak systolic velocity of the inferior thyroid artery (PSV-ITA). Diagnostic performance of individual modalities and their combinations was assessed against the final clinical diagnosis using standard statistical methods.

Results: Both 99mTc uptake and TRAb demonstrated high sensitivity and specificity for diagnosing GD. Their combined use provided near-perfect diagnostic accuracy. TRAb levels >3 IU/L reliably identified GD, whereas intermediate values (1.5–3 IU/L) required further evaluation with CFD-USG. PSV-ITA exhibited high specificity but lower sensitivity, supporting its role as a useful confirmatory test. In contrast, the T3/T4 ratio showed limited diagnostic value. A tiered diagnostic approach integrating TRAb, scintigraphy, and CFD-USG according to resource availability enabled accurate and cost-effective etiological classification of thyrotoxicosis.

Conclusions: No single modality is universally definitive for differentiating GD from DT. However, a structured diagnostic pathway incorporating TRAb, 99mTc uptake, and CFD-USG significantly enhances diagnostic accuracy and clinical decision-making. This resource-adaptable approach aligns with current international recommendations and may facilitate timely, reliable etiological diagnosis across diverse clinical settings.

Anu Wilson is a Consultant Endocrinologist with extensive clinical experience in the diagnosis and management of a broad spectrum of endocrine and metabolic disorders, including diabetes mellitus, thyroid diseases, pituitary and adrenal disorders, osteoporosis, obesity, and reproductive endocrinology. My clinical practice is grounded in evidence-based medicine, with a strong emphasis on individualised patient care and multidisciplinary collaboration. She has been actively involved in both inpatient and outpatient endocrine services, managing complex and challenging cases in tertiary care settings. Alongside clinical responsibilities, I have contributed to academic medicine through teaching, training junior doctors, and participating in continuous medical education activities. Her academic interests include thyroid dysfunction, metabolic syndrome, and reproductive endocrinology, and I have engaged in research and quality improvement initiatives aimed at enhancing patient outcomes and optimising endocrine care pathways. I have also presented at national and international platforms, contributing to scientific discussion and knowledge exchange within the speciality. She is a member of the Endocrine Society and the Endocrine Society of India, reflecting my commitment to maintaining high professional standards and staying updated with advances in endocrinology.