Clinical and laboratory issues associated with persistent low-level elevations of hCG in a female of childbearing age.

Persistent low-level elevations of serum concentrations of hCG in a non-pregnant female of childbearing age were investigated by a number of laboratory techniques including heterophile blocking reagents, polyethylene glycol precipitation, serial dilutions and hCG measurements on several different instrument/reagent systems. The results of these studies indicated that this patient had immunoreactive hCG in her serum that was not the intact hCG molecule but primarily the free β-hCG subunit. Differential diagnoses are discussed along with recommendation for continued surveillance of serum hCG concentrations.