Recently, a 35-year-old woman came to the department for examination and reported that she had been suffering from generalized bone pain for more than 2 years, with progressive aggravation. On the instruction of one of the directors of our hospital, blood biochemistry showed that parathyroid hormone (PTH) was significantly elevated, with high blood calcium and low blood phosphorus. Hyperparathyroidism was highly suspected. After SPECT parathyroid imaging, the culprit was found to be a parathyroid adenoma hidden in the left posterior lobe of the thyroid gland! Parathyroid adenomas are most common in women in the 20s and 50s, and their clinical manifestations include abdominal distention, muscle relaxation, joint pain, and urinary calculi. Skeletal pain is predominant and is highly likely to be misdiagnosed as arthritis. Nuclear imaging can help with qualitative diagnosis as well as positioning for surgery.