Persistently elevated serum concentrations of human chorionic gonadotropin (hCG)

We describe a woman with constantly elevated hCG levels in serum. Since assay interference, pregnancy or cancer did not explain the elevated levels, we measured the concentrations of hCG, its β subunit (hCGβ) and its core fragment (hCGβcf) in serum and urine using specific assays, to understand the nature of the elevated hCG levels.

We used 3 assays for total hCG (these assays also recognize hCGβ and to various degrees hCGβcf), 3 for intact hCG heterodimer, 3 for free hCGβ and one for hCGβcf.

With an hCG assay detecting total hCG the serum concentrations were in the range of 150-260 IU/L for the whole study period of almost 5 years, except for a peak of 1,200 IU/L, coinciding with a spontaneous abortion. Quantitation of different forms of hCG with specific immunoassays showed that the immunoreactivity in serum consisted of hCGβ. Urine contained hCGβ and hCGβcf.

The laboratory findings are in keeping with familial hCG syndrome. However, so far the condition remains to be determined in any family members. Elevated hCG levels without any explanation are problematic as they cause suspicion of cancer or ectopic pregnancy and may lead to harmful therapy. Specific assays, as used here, will aid in diagnosis of such cases.