Gestational trophoblastic disease: current management of hydatidiform moleBMJ 2008; 337 doi: https://doi.org/10.1136/bmj.a1193 (Published 15 August 2008) Cite this as: BMJ 2008;337:a1193
All rapid responses
The review on gestational trophoblastic disease states that disease
response is monitored by measurement of serum hCG (human chorionic
gonadotrophin) . However, the authors fail to discuss the analytical
problems associated with this assay. There have been numerous reports of
interference with this assay since 1984 and the most important was made by
Rotmensch and Cole in 2000 . They described 12 women who had a false
diagnosis; 11 of whom had been subjected to needless, and in some cases
quite extensive, surgery or chemotherapy. The problem has not disappeared
and we still uncover cases of assay interference in women who have serial
hCG measurements for pregnancy testing. The frequency of hCG interference
is unknown but in our study of thyroid and gonadotrophin assays, we
detected clinically relevant interference in 0.5% of all assays .
A further problem is in the variation between assays provided by
different manufacturers. Mitchell and Seckl  have clearly demonstrated
this variation and, have included examples of patient with tumours whose
hCG is detectable by some assays but is undetectable by others.
hCG assays are only approved by the regulatory authorities for
pregnancy testing and the risk to patients with trophoblastic disease or
germ cell tumours will continue until assays are formally validated for
1: Sebire NJ, Seckl MJ. Gestational trophoblastic disease: current
management of hydatidiform mole. BMJ 2008;337:453-45.
2: Rotmensch S, Cole L. False diagnosis and needless therapy of
presumed malignant disease in women with false-positive human chorionic
gonadotropin concentrations. Lancet 2000;355:712-715.
3: Ismail AA, Walker PL, Barth JH, Lewandowski KC, Jones RG, Burr WA.
Wrong biochemistry results: two case reports and observational study in
5310 patients on potentially misleading thyroid-stimulating hormone and
gonadotropin immunoassay results. Clin Chem 2002;48:2023-2029.
4: Mitchell H, Seckl MJ. Discrepancies between commercially available
immunoassays in the detection of tumour-derived hCG. Mol Cell Endocrinol
Competing interests: No competing interests