Hyperthyroidism: An underappreciated cause of diffuse bone disease

A 37-year-old man and a 40-year-old woman were referred for evaluation of skeletal complaints. Tc-99m MDP bone scans were obtained. Tc-99m MDP bone scanning of the man revealed a metabolic super-scan pattern. Tc-99m MDP images of the woman mimicked autoimmune arthritis. A thyroid workup was performed at a substantial interval after bone scanning. Thyroid laboratory indices in both patients suggested Graves' Disease. I-123 scanning revealed diffuse increased uptake in both patients, confirming the diagnosis of Graves' Disease. Successful treatment was eventually achieved with I-131. We conclude that nuclear medicine physicians should be aware that hyperthyroidism may present either as a pattern of metabolic superscan or may resemble an autoimmune arthritic process; in other words, it should be understood that insofar as bone imaging, Graves' Disease is the 'Great Imitator.' Similarly, referring clinicians need to be aware of these relationships, and appropriately screen patients with skeletal complaints. This is especially important in an era when generalists and ancillary medical personnel are involved in the screening of patients with complex and misleading disease processes.