A Case of Pseudoelevation of Serum HCG Caused by Rheumatoid Factor

Serum human chorionic gonadotropin (HCG) is a glycoprotein hormone secreted by the trophoblast cells of the placenta. HCG levels are helpful in confirming and monitoring pregnancy, as well as in the diagnosis and monitoring of trophoblastic tumors. Therefore, the accuracy of HCG detection results is of great significance for the diagnosis and differential diagnosis of pregnancy and germ cell tumors.

We report a case of pseudo elevation of serum HCG in a patient with rheumatoid arthritis. The possibility of abnormal increase in HCG concentration caused by rheumatoid factor (RF) was evaluated using polyethylene glycol (PEG) precipitation method and different detection platforms.

Samples pretreated with polyethylene glycol and samples using another detection platform showed a significant decrease in serum HCG concentration and a negative reaction. Therefore, the patient's HCG result showed an abnormal increase, which is considered a false increase caused by RF interference.

When serum HCG levels are abnormally elevated in patients with rheumatoid arthritis but there is no evidence of pregnancy or clinical symptoms related to trophoblastic tumors, staff should consider the possibility of RF interference in HCG detection, take corresponding corrective measures, and communicate with clinical doctors in a timely manner.