Diagnosis of hydatidiform mole and persistent trophoblastic disease: diagnostic accuracy of total human chorionic gonadotropin (hCG), free hCG {alpha}- and {beta}-subunits, and their ratios.
OBJECTIVE
Human chorionic gonadotropin (hCG) is widely used in the management of hydatidiform mole and persistent trophoblastic disease (PTD). Predicting PTD after molar pregnancy might be beneficial since prophylactic chemotherapy reduces the incidence of PTD.


METHODS
A retrospective study based on blood specimens collected in the Dutch Registry for Hydatidiform Moles. A group of 165 patients with complete moles (of which 43 had PTD) and 39 patients with partial moles (of which 7 had PTD) were compared with 27 pregnant women with uneventful pregnancy.


METHODS
Serum samples from patients with hydatidiform mole with or without PTD were assayed using specific (radio) immunoassays for free alpha-subunit (hCGalpha), free beta-subunit (hCGbeta) and 'total' hCG (hCG + hCGbeta). In addition, we calculated the ratios hCGalpha/hCG + hCGbeta, hCGbeta/hCG + hCGbeta, and hCGalpha/hCGbeta. Specificity and sensitivity were calculated and paired in receiver-operating characteristic (ROC) curve analysis, resulting in areas under the curves (AUCs).


RESULTS
hCGbeta, hCGbeta/hCG + hCGbeta and hCGalpha/hCGbeta show AUCs ranging between 0.922 and 0.999 and, therefore, are excellent diagnostic tests to distinguish complete and partial moles from normal pregnancy. To distinguish partial from complete moles the analytes hCGbeta, hCG + hCGbeta and the ratio hCGalpha/hCGbeta have AUCs between 0.7 and 0.8. Although hCGalpha, hCGbeta and hCG + hCGbeta concentrations are significantly elevated in patients who will develop PTD compared with patients with spontaneous regression after evacuation of their moles, in predicting PTD, these analytes and parameters have AUCs <0.7.


CONCLUSIONS
Distinction between hydatidiform mole and normal pregnancy is best shown by a single blood specimen with hCGbeta, but hCGbeta/hCG + hCGbeta and hCGalpha/hCGbeta are also excellent diagnostic parameters. To predict PTD, hCGalpha, hCGbeta, hCG + hCGbeta and hCGalpha/hCGbeta are moderately accurate tests, although they are not accurate enough to justify prophylactic chemotherapy treatment for prevention of PTD.
van Trommel
Nienke E
NE
Department of Chemical Endocrinology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
Sweep
Fred C G J
FC
Schijf
Charles P T
CP
Massuger
Leon F A G
LF
Thomas
Chris M G
CM
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D006063:Chorionic Gonadotropin / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D005260:Female; D031901:Gestational Trophoblastic Disease / Q000097:blood / Q000175:diagnosis*; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood; D006801:Humans; D006828:Hydatidiform Mole / Q000097:blood / Q000175:diagnosis*; D008875:Middle Aged; D011247:Pregnancy; D011863:Radioimmunoassay; D012680:Sensitivity and Specificity
D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D015292:Glycoprotein Hormones, alpha Subunit