Most hormone levels are measured using immunoassays that utilize animal-based reagent antibodies to identify the analytes of interest. With advances in immunoassay technology, modern instruments are required to minimize potential interference and ensure accuracy. Exaggerated analytical errors are currently uncommon. Herein, we report a 61-yearold woman with an elevated thyroid-stimulating hormone level (> 100 uIU/mL) in her health checkup report. Unexpectedly, other hormones were also high, including prolactin, luteinizing hormone, follicle-stimulating hormone and estradiol. Considerably different results were obtained in alternative analysis platforms. Further investigation revealed that the patient had a high level of rheumatoid factor. Patient sample was pretreated with heterophilic blocking tube, the rheumatoid factor level was significantly reduced, and hormone levels were close to normal on the original analytical platform. We believe the false high results of multiple hormones caused by rheumatoid factor-related interference.