Persistent low hCG
The management of women with elevated but low levels of hCG is a difficult area particularly when the radiology fails to show any significant abnormalities. In these patients it is important to both investigate fully and avoid starting unnecessary and unproductive treatments. It may be appropriate to seek a specialist opinion in these cases from CXH or other national/regional Trophoblast units in other countries.
A few of the causes of elevated hCG levels that should be considered listed below;
False positive hCG
This is due to an antibody or other molecule that cross reacts with the assay (and potentially other serological tests for other tumour markers) As antibodies do not pass into the urine they do not give positive results there. However hCG levels below ~100IU/L are often below the renal threshold for many patients so a negative urine assay is not necessary confirmation that the serum level is due to a false positive. However if the serum and urine are both positive for hCG it is likely to be a real result.
This is a newly postulated condition and one we are yet to confirm at CXH despite caring for over 3000 patients treated with chemotherapy for GTD and registering over 30,000 MPs. Any issues to do with a diagnosis of ‘quiescent hCG’ from other centres should be treated with extreme caution and the patient reviewed by the clinical team at CXH.
Rarely there can production of measurable low levels (2-11mU/L) of hCG from the gonadotrope cells in the pituitary gland. This is more likely to be a problem in postmenopausal women and can be suppressed by HRT.