Elevated HCG outside of pregnancy--diagnostic considerations and laboratory evaluation.

UNLABELLED: Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by trophoblastic tissues, and its identification is frequently relied upon to establish the diagnosis of pregnancy. Entities other than pregnancy, such as false-positive hCG results, pituitary hCG, exogenous hCG, and both trophoblastic and nontrophoblastic neoplasias, can also cause laboratory assays for hCG to show positive results. Because of their rarity, these conditions are not commonly recognized, and the steps to differentiate between them are not widely known. Discriminating between the causes of elevated hCG in nonpregnant patients can be confusing. An understanding of the differential diagnosis and awareness of available diagnostic modalities are essential for accurate diagnosis and avoidance of potentially harmful treatments.

TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES: After completion of this article, the reader should be able to state the importance of types of human chorionic gonadotropin (hCG), recall their presence in both trophoblastic and nontrophoblastic neoplasias, and explain how important it is to distinguish between the various causes of an elevated serum hCG to avoid harmful treatments.