Measurement of Human Chorionic Gonadotrophin in Women with Gestational Trophoblastic Disease

OBJECTIVES

The objective of this study was to collect information on human chorionic gonadotrophin (hCG) laboratory testing and reporting in women with gestational trophoblastic disease (GTD), to assess the associated challenges, and to offer perspectives on hCG testing harmonisation.

DESIGN

Information was collected from laboratories by electronic survey (SurveyMonkey) using a questionnaire designed by members of the European Organisation for the Treatment of Trophoblastic Disease (EOTTD) hCG working party.

PARTICIPANTS

The questionnaire was distributed by the EOTTD board to member laboratories and their associated scientists who work within the GTD field.

SETTING

The questionnaire was distributed and accessed via an online platform.

METHODS

The questionnaire consisted of 5 main sections. These included methods used for hCG testing, quality procedures, reporting of results, laboratory operational aspects, and non-GTD testing capability. In addition to reporting these survey results, examples of case scenarios which illustrate the difficulties faced by laboratories providing hCG measurement for GTD patient management were described. The benefits and challenges of using centralised versus non-centralised hCG testing were discussed alongside the utilisation of regression curves for management of GTD patients.

RESULTS

Information from the survey was collated and presented for each section and showed huge variability in responses across laboratories even for those using the same hCG testing platforms. An educational example was presented, highlighting the consequence of using inappropriate hCG assays on clinical patient management (Educational Example A), along with an example of biotin interference (Educational Example B) and an example of high-dose hook effect (Educational Example C), demonstrating the importance of knowing the limitations of hCG tests. The merits of centralised versus non-centralised hCG testing and use of hCG regression curves to aid patient management were discussed.

LIMITATIONS

To ensure the survey was completed by laboratories providing hCG testing for GTD management, the questionnaire was distributed by the EOTTD board. It was assumed the EOTTD board held the correct laboratory contact, and that the questionnaire was completed by a scientist with in-depth knowledge of laboratory procedures.

CONCLUSIONS

The hCG survey highlighted a lack of harmonisation of hCG testing across laboratories. Healthcare professionals involved in the management of women with GTD should be aware of this limitation. Further work is needed to ensure an appropriate, quality-assured laboratory service is available for hCG monitoring in women with GTD.

Biochemical Screening for Fetal Trisomy 21: Pathophysiology of Maternal Serum Markers and Involvement of the Placenta

It is now well established that maternal serum markers are often abnormal in fetal trisomy 21. Their determination is recommended for prenatal screening and pregnancy follow-up. However, mechanisms leading to abnormal maternal serum levels of such markers are still debated. Our objective was to help clinicians and scientists unravel the pathophysiology of these markers via a review of the main studies published in this field, both in vivo and in vitro, focusing on the six most widely used markers (hCG, its free subunit hCGβ, PAPP-A, AFP, uE3, and inhibin A) as well as cell-free feto-placental DNA. Analysis of the literature shows that mechanisms underlying each marker's regulation are multiple and not necessarily directly linked with the supernumerary chromosome 21. The crucial involvement of the placenta is also highlighted, which could be defective in one or several of its functions (turnover and apoptosis, endocrine production, and feto-maternal exchanges and transfer). These defects were neither constant nor specific for trisomy 21, and might be more or less pronounced, reflecting a high variability in placental immaturity and alteration. This explains why maternal serum markers can lack both specificity and sensitivity, and are thus restricted to screening.

Clinical Application for Screening Down's Syndrome by Using Carboxylated Graphene Oxide-Based Surface Plasmon Resonance Aptasensors

BACKGROUND

Advanced medical detection technology requires high sensitivity and accuracy to increase the disease detection rate. We showed that carboxyl-functionalized graphene oxide (carboxyl-GO) biosensing materials are capable of accurate detection.

METHODS

We developed a carboxylated GO-based surface plasmon resonance (SPR) aptasensor suitable for screening Down's syndrome in clinical serum. This biosensing material could rapidly and accurately detect hCG protein with a low concentration to identify fetal Down's syndrome. The developed carboxyl-GO-based SPR aptasensor showed excellent sensitivity and limit of detection without the use of antibodies and without any specific preference.

RESULTS

hCG protein detection limits of 1 pM in buffer samples and 1.9 pM in clinical serum samples were achieved. The results showed that the carboxyl-GO-based chip could detect hCG well below the normal physiological level of serum protein (5.0 mIU/mL). High affinity, sensitivity, and better detection limit were obtained in the range of 1.9 pM to 135 pM. The results showed a 5k-fold dilution factor, and that an SPR angle shift of more than 20 millidegrees (mo) was associated with a significant risk of fetal Down's syndrome compared to normal pregnant women. The results clearly showed that the detection of hCG protein in serum samples from pregnant women at 12-19 weeks could be used to screen Down's syndrome with high selectivity and sensitivity.

CONCLUSION

Our findings suggest the potential application of carboxyl-GO film in proof-of-concept studies for serum assays as a new type of SPR material. In addition, peptide and carboxyl-GO films may be conducive to the development of future point of care testing and rapid diagnostic devices for other diseases such as cancer.

Insights into the hyperglycosylation of human chorionic gonadotropin revealed by glycomics analysis

Human chorionic gonadotropin (hCG) is a glycoprotein hormone that is essential for the maintenance of pregnancy. Glycosylation of hCG is known to be essential for its biological activity. "Hyperglycosylated" variants secreted during early pregnancy have been proposed to be involved in initial implantation of the embryo and as a potential diagnostic marker for gestational diseases. However, what constitutes "hyperglycosylation" is not yet fully understood. In this study, we perform comparative N-glycomic analysis of hCG expressed in the same individuals during early and late pregnancy to help provide new insights into hCG function, reveal new targets for diagnostics and clarify the identity of hyperglycosylated hCG. hCG was isolated in urine collected from women at 7 weeks and 20 weeks' gestation. hCG was also isolated in urine from women diagnosed with gestational trophoblastic disease (GTD). We used glycomics methodologies including matrix assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry (MS) and MS/MS methods to characterise the N-glycans associated with hCG purified from the individual samples. The structures identified on the early pregnancy (EP-hCG) and late pregnancy (LP-hCG) samples corresponded to mono-, bi-, tri-, and tetra-antennary N-glycans. A novel finding was the presence of substantial amounts of bisected type N-glycans in pregnancy hCG samples, which were present at much lower levels in GTD samples. A second novel observation was the presence of abundant LewisX antigens on the bisected N-glycans. GTD-hCG had fewer glycoforms which constituted a subset of those found in normal pregnancy. When compared to EP-hCG, GTD-hCG samples had decreased signals for tri- and tetra-antennary N-glycans. In terms of terminal epitopes, GTD-hCG had increased signals for sialylated structures, while LewisX antigens were of very minor abundance. hCG carries the same N-glycans throughout pregnancy but in different proportions. The N-glycan repertoire is more diverse than previously reported. Bisected and LewisX structures are potential targets for diagnostics. hCG isolated from pregnancy urine inhibits NK cell cytotoxicity in vitro at nanomolar levels and bisected type glycans have previously been implicated in the suppression of NK cell cytotoxicity, suggesting that hCG-related bisected type N-glycans may directly suppress NK cell cytotoxicity.

Reversion of gold nanoparticle aggregates for the detection of Cu2+ and its application in immunoassays

A high concentration of copper is a hazardous element to organisms and human health. Although various strategies have been reported for the sensitive detection of copper, a facile and rapid detection of aqueous copper has seldom been addressed to date. Here, we present an easy and accessible colorimetric method to detect Cu²⁺ using the redispersion of cysteamine-modified gold nanoparticles (CA-AuNPs). Initially, CA caused the aggregation of AuNPs due to the electrostatic interaction and aggregated AuNPs can be regenerated in basic medium. The subsequent addition of Cu²⁺ to the CA-AuNP dispersion could effectively trigger the aggregation of CA-AuNPs, resulting from the coordination reactivity between the deprotonated CA and Cu²⁺. This strategy resulted in a detection limit (LOD) of 1.52 μM in drinking water, which is below the U.S. Environmental Protection Agency permissible limit (20 μM). To demonstrate the broad application of CA-AuNPs, we further applied this method to plasmonic immunoassays based on the competitive interaction of Cu²⁺ between CA-AuNPs and enzymes. The LOD of the Down syndrome biomarker hyperglycosylated human chorionic gonadotropin (H-hCG) was 0.125 mIU mL^-1, which is better than that of commercial immunoassays. Importantly, the determination of H-hCG in serum indicates its applicability for the measurement of real samples. Our assay agrees well with the current immunoassay systems and thus it can easily be expanded to a more common sensing platform for different types of biotargets by changing the corresponding antibodies.

Human Chorionic Gonadotropin Assays for Testicular Tumors: Closing the Gap between Clinical and Laboratory Practice

BACKGROUND

Clinical practice guidelines recommend the measurement of human chorionic gonadotropin (hCG) and/or hCGβ in serum for management of testicular germ cell tumors (GCTs). These guidelines, however, disregard relevant biochemical information on hCG variants to be detected for oncological application. We set out to provide a critical review of the clinical evidence together with a characterization of the selectivity of currently marketed hCG immunoassays, identifying assays suitable for management of GCTs.

CONTENT

Evidence sources in the available literature were critically appraised. Most instances of misdiagnosis and mismanagement of testicular GCTs have been associated with hCG results. According to the clinical evidence, 36% of patients with seminoma show an exclusive hCGβ increase, and 71% of patients with nonseminomatous GCTs (NSGCTs) show an increase of intact hCG and/or hCG + hCGβ, whereas the hCGβ increase in NSGCTs is variable according to the tumor stage and histology.

SUMMARY

hCG + hCGβ assays that display an equimolar recognition of hCG and hCGβ, or at least do not overtly underestimate hCGβ, may be employed for management of testicular GCTs. Assays that underestimate hCGβ are not recommended for oncological application. In addition to the hCG + hCGβ assay in service, an additional assay with broader selectivity for other hCG variants should be considered when false-negative or false-positive results are suspected on the basis of clinical data.

Clinical Utility of Hyperglycosylated hCG in Serum Taken before Hydatidiform Mole Evacuation to Predict Persistent Trophoblastic Disease

Objective

Human chorionic gonadotropin (hCG) is widely used in the management of hydatidiform mole and persistent trophoblastic disease (PTD). Studies on hyperglycosylated human chorionic gonadotropin (invasive trophoblast antigen, ITA) in PTD are limited. In serum samples taken before evacuation of molar pregnancies we measured the concentrations of free hCG β-subunit (free hCGβ), “total” hCG (hCG+hCGβ) and ITA, and determined whether ITA, the two other hCG analytes, or the calculated ratios of hCGβ/hCG+hCGβ, hCGβ/ITA and hCG+hCGβ/ITA could predict the later development of PTD.

Design

A retrospective study based on blood specimens collected in the Dutch Central Registry for Hydatidiform Moles. The study group comprised 97 patients with hydatidiform moles who did not develop PTD after mole evacuation and 33 patients who did develop PTD.

Methods

Serum samples from 130 patients with hydatidiform mole with or without PTD were assayed using specific (radio)immunoassays for free hCGβ, total hCG, and ITA. From these analytes we also calculated the ratios hCGβ/hCG+hCGβ, hCGβ/ITA, and hCG+hCGβ/ITA. To predict the development of PTD from these analytes and parameters we performed receiver-operating characteristic (ROC) curve analysis, resulting in areas under the curve (AUCs) that represented the diagnostic accuracy which was rated in a range from excellent (AUC >0.9 or <0.1) to poor (AUC 0.4–0.6).

Results

The diagnostic accuracy of ITA was moderate (0.618) and not different from that of free hCGβ (0.610) and hCG+hCGβ (0.622).

Conclusions

ITA as well as the other analytes and parameters in serum taken prior to evacuation from patients with molar pregnancies cannot be used to predict the subsequent development of persistent trophoblastic disease.

Urine tests for Down's syndrome screening

BACKGROUND

Down's syndrome occurs when a person has three copies of chromosome 21, or the specific area of chromosome 21 implicated in causing Down's syndrome, rather than two. It is the commonest congenital cause of mental disability and also leads to numerous metabolic and structural problems. It can be life-threatening, or lead to considerable ill health, although some individuals have only mild problems and can lead relatively normal lives. Having a baby with Down's syndrome is likely to have a significant impact on family life. The risk of a Down's syndrome affected pregnancy increases with advancing maternal age.Noninvasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing. Before agreeing to screening tests, parents need to be fully informed about the risks, benefits and possible consequences of such a test. This includes subsequent choices for further tests they may face, and the implications of both false positive and false negative screening tests (i.e. invasive diagnostic testing, and the possibility that a miscarried fetus may be chromosomally normal). The decisions that may be faced by expectant parents inevitably engender a high level of anxiety at all stages of the screening process, and the outcomes of screening can be associated with considerable physical and psychological morbidity. No screening test can predict the severity of problems a person with Down's syndrome will have.

OBJECTIVES

To estimate and compare the accuracy of first and second trimester urine markers for the detection of Down's syndrome.

SEARCH METHODS

We carried out a sensitive and comprehensive literature search of MEDLINE (1980 to 25 August 2011), EMBASE (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), The Database of Abstracts of Reviews of Effectiveness (The Cochrane Library 2011, Issue 7), MEDION (25 August 2011), The Database of Systematic Reviews and Meta-Analyses in Laboratory Medicine (25 August 2011), The National Research Register (archived 2007), Health Services Research Projects in Progress database (25 August 2011). We studied reference lists and published review articles.

SELECTION CRITERIA

Studies evaluating tests of maternal urine in women up to 24 weeks of gestation for Down's syndrome, compared with a reference standard, either chromosomal verification or macroscopic postnatal inspection.

DATA COLLECTION AND ANALYSIS

We extracted data as test positive or test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria. We used hierarchical summary ROC (receiver operating characteristic) meta-analytical methods to analyse test performance and compare test accuracy. We performed analysis of studies allowing direct comparison between tests. We investigated the impact of maternal age on test performance in subgroup analyses.

MAIN RESULTS

We included 19 studies involving 18,013 pregnancies (including 527 with Down's syndrome). Studies were generally of high quality, although differential verification was common with invasive testing of only high-risk pregnancies. Twenty-four test combinations were evaluated formed from combinations of the following seven different markers with and without maternal age: AFP (alpha-fetoprotein), ITA (invasive trophoblast antigen), ß-core fragment, free ßhCG (beta human chorionic gonadotrophin), total hCG, oestriol, gonadotropin peptide and various marker ratios. The strategies evaluated included three double tests and seven single tests in combination with maternal age, and one triple test, two double tests and 11 single tests without maternal age. Twelve of the 19 studies only evaluated the performance of a single test strategy while the remaining seven evaluated at least two test strategies. Two marker combinations were evaluated in more than four studies; second trimester ß-core fragment (six studies), and second trimester ß-core fragment with maternal age (five studies).In direct test comparisons, for a 5% false positive rate (FPR), the diagnostic accuracy of the double marker second trimester ß-core fragment and oestriol with maternal age test combination was significantly better (ratio of diagnostic odds ratio (RDOR): 2.2 (95% confidence interval (CI) 1.1 to 4.5), P = 0.02) (summary sensitivity of 73% (CI 57 to 85) at a cut-point of 5% FPR) than that of the single marker test strategy of second trimester ß-core fragment and maternal age (summary sensitivity of 56% (CI 45 to 66) at a cut-point of 5% FPR), but was not significantly better (RDOR: 1.5 (0.8 to 2.8), P = 0.21) than that of the second trimester ß-core fragment to oestriol ratio and maternal age test strategy (summary sensitivity of 71% (CI 51 to 86) at a cut-point of 5% FPR).

AUTHORS' CONCLUSIONS

Tests involving second trimester ß-core fragment and oestriol with maternal age are significantly more sensitive than the single marker second trimester ß-core fragment and maternal age, however, there were few studies. There is a paucity of evidence available to support the use of urine testing for Down's syndrome screening in clinical practice where alternatives are available.

Luteinizing hormone and human chorionic gonadotropin: origins of difference

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are widely recognized for their roles in ovulation and the support of early pregnancy. Aside from the timing of expression, however, the differences between LH and hCG have largely been overlooked in the clinical realm because of their similar molecular structures and shared receptor. With technologic advancements, including the development of highly purified and recombinant gonadotropins, researchers now appreciate that these hormones are not as interchangeable as once believed. Although they bind to a common receptor, emerging evidence suggests that LH and hCG have disparate effects on downstream signaling cascades. Increased understanding of the inherent differences between LH and hCG will foster more effective diagnostic and prognostic assays for use in a variety of clinical contexts and support the individualization of treatment strategies for conditions such as infertility.

First-trimester hyperglycosylated human chorionic gonadotropin and development of hypertension

OBJECTIVE

This study aimed to determine whether urine levels of hyperglycosylated human chorionic gonadotropin (HhCG) in the first trimester are predictive of subsequent development of hypertension during pregnancy

METHOD

This prospective cohort study consisted of women seeking care before 12 weeks gestation. A clean catch urine was obtained at the first prenatal visit and tested for HhCG and creatinine levels. The median HhCG levels and multiples of the median (MoM) by gestational age were compared between the groups that either developed hypertension or did not.

RESULTS

Urine HhCG were determined for 204 women between 4 weeks 4 days to 11 weeks 6 days. The median HhCG of those who developed gestational hypertension (n = 7) or preeclampsia (n = 15) did not differ from the group that did not (median: 284 ng/mg creatinine vs 365 ng/mg; p = 0.55). If the MoM of HhCG for the no hypertension group was 1.00, the MoM of HhCG for the hypertension group was 0.93 (p = 0.93). A possible association was observed after 10 weeks between low HhCG levels and the development of late-onset hypertension (≥34 weeks).

CONCLUSIONS

Prenatal screening for subsequent hypertension is unreliable with a single measurement of maternal urine HhCG at 10 weeks or less.

Human chorionic gonadotropin (hCG) in the secretome of cultured embryos: hyperglycosylated hCG and hCG-free beta subunit are potential markers for infertility management and treatment

Human chorionic gonadotropin (hCG) is produced by trophoblast cells throughout pregnancy, and gene expression studies have indicated that hCG-beta subunit (hCGβ) expression is active at the 2 blastomere stage. Here, we investigated the qualitative hCG output of developing embryos in culture and hCG isoforms expressed in the secretome as a novel sensitive method for detecting hCG. Culture media was collected from the culture plates of 118 embryos in culture (including controls and embryos at different stages of culture) from 16 patients undergoing routine fertility treatment. The hCGβ was detectable in media from 2 pronuclear (2PN) stage embryos through to the blastocyst stage. The hCGβ was absent in 1PN and arrested embryos as well as all media controls. Prior to hatching, hyperglycosylated hCG (hCGh) was observed selectively in 3PN embryos, but after hatching, along with hCG, became the dominant hCG molecule observed. We have reported at the 2PN stage the earliest evidence of hCGβ expression in embryos. There is a suggestion this may be indicative of quality in early embryos, and hCGh seen at the pronuclear stage may suggest triploid abnormality. The dominance of hCG, and hCGh expression, seen after blastocyst hatching may be indicative of potential implantation success. Thus, hCG isoforms have potential roles as biomarkers of embryo viability for embryo/blastocyst transfer.

The hCG assay or pregnancy test

This review examines human chorionic gonadotropin (hCG) or pregnancy tests from multiple perspectives. It first investigates the molecule hCG and shows that the term represents five independent molecules differing in carbohydrate and meric structure that share a common amino acid sequence. The review goes on to show that multiple degradation produces also the need to be tested for an hCG or pregnancy test to be optimally efficient. The review then carefully examines the literature showing the sensitivity and specificity of automated laboratory tests. Point-of-care pregnancy tests are then investigated along with over-the-counter pregnancy tests. Appropriate detection of hyperglycosylated hCG, nicked hCG, nicked hCG missing the β-subunit C-terminal peptide and nicked hyperglycosylated hCG is a limitation on all pregnancy tests. In the opinion of the author, just one automated laboratory test, the Siemen’s Immulite, one point-of-care test, the Beckman-Coulter Icon 25, and one brand of over-the-counter device, First Response, are suitable for early pregnancy detection and possibly other applications.

Extragonadal actions of chorionic gonadotropin

The primary embryonic signal in primates is chorionic gonadotropin (CG, designated hCG in humans), that is classically associated with corpus luteum rescue and progesterone production. However, research over the past decade has revealed the presence of the hCG receptor in a variety of extragonadal tissues. Additionally, discoveries of the multiple variants of hCG, namely, native hCG, hyperglycosylated hCG (hyp-hCG) and the β- subunit of the hyperglycosylated hCG (hCG-free β) has established a role for extragonadal actions of hCG. For the initiation and maintenance of pregnancy, hCG mediates multiple placental, uterine and fetal functions. Some of these include development of syncytiotrophoblast cells, mitotic growth and differentiation of the endometrium, localized suppression of the maternal immune system, modulation of uterine morphology and gene expression and coordination of intricate signal transduction between the endometrium. Recurrent pregnancy loss, pre-eclampsia and endometriosis are associated with altered responses of hCG, all of which have a detrimental effect on pregnancy. A role for hyp-hCG in mediating the development of both trophoblastic and non-trophoblastic tumors has also been suggested. Other significant non-gonadal applications of hCG include predicting preeclampsia, determining the risk of Down's syndrome and gestational trophoblastic disease, along with relaxing myometrial contractility and preventing recurrent miscarriages. Presence of hCG free-β in serum of cancer patients enables its usage as a diagnostic tumor marker. Thus, the extragonadal functions of hCG encompasses a wide spectrum of applications and is an open area for continued investigation.

hCG, five independent molecules

INTRODUCTION

The hCG amino acid sequence supports 5 glycoproteins. All are called hCG forms. This review examines all 5 molecules, the hormone as produced by the placental syncytiotrophoblast cells, the sulfated hormone produced by the pituitary gonadotrope cells, the hyperglycosylated hCG autocrine made by placental cytotrophoblast cells, and the autocrine cancer promoters hyperglycosylated hCG, hCGß and hyperglycosylated hCGß as made by all malignancies. This review examines all the molecules and multiple proven functions, ranging from evolution to cancer promotion to hormone action.

RESULTS AND DISCUSSION

hCG forms are critical super-growth factors in humans, with an exceptional wide range of functions.

Human chorionic gonadotropin and associated molecules

When considering human chorionic gonadotropin (hCG) and hCG tests, it is important to realize that it is not a single biological molecule. The regular form of hCG produced by differentiated syncytotrophoblast cells (regular hCG) is a hormone made with the primary function of maintaining the myometrial and decidual spiral arteries and the vascular supply of the placenta during the full course of pregnancy. Hyperglycosylated hCG (hCG with double-size O-linked oligosaccharides) is made by undifferentiated cytotrophoblast cells. This is an autocrine hormone with separate functions, it maintains invasion as in implantation of pregnancy and malignancy in gestational trophoblastic diseases. A hyperglycosylated free beta-subunit is produced by a high proportion of all malignancies. This functions as an autocrine hormone to promote the growth and invasion of the malignancy. It is important to realize when ordering an hCG test what you are measuring and whether the test ordered will detect appropriately these three variant of hCG as well as their degradation products. Most automated commercial laboratory tests, point-of-care test and over-the-counter tests are limited in what is detected, focusing only on regular hCG. This is in part due to the US FDA, who only consider hCG as a pregnancy test, and to whom only detection of regular hCG is critical. This may be a cause of test errors since primarily hyperglycosylated hCG is produced in early pregnancy, choriocarcinoma and germ cell testicular malignancies, and only free beta-subunit may be produced in other germ cell malignancies (all applications for hCG test). The exceptions are the older style hCGbeta radioimmunoassay and the Siemen's Immulite platform hCG test which detect all variant and their degradation product appropriately. Regardless of test specificity limitations, assays for hCG variants are widely used clinically in pregnancy detection, early pregnancy detection, prediction of spontaneously aborting and ectopic pregnancies and prediction of trisomy pregnancies. hCG tests are essential in managing gestational trophoblastic diseases, whether hydatidiform mole, invasive mole or choriocarcinoma, and are very useful in management of testicular malignancies and other germ cell malignancies.

New discoveries on the biology and detection of human chorionic gonadotropin

Human chorionic gonadotropin (hCG) is a glycoprotein hormone comprising 2 subunits, alpha and beta joined non covalently. While similar in structure to luteinizing hormone (LH), hCG exists in multiple hormonal and non-endocrine agents, rather than as a single molecule like LH and the other glycoprotein hormones. These are regular hCG, hyperglycosylated hCG and the free beta-subunit of hyperglycosylated hCG. For 88 years regular hCG has been known as a promoter of corpus luteal progesterone production, even though this function only explains 3 weeks of a full gestations production of regular hCG. Research in recent years has explained the full gestational production by demonstration of critical functions in trophoblast differentiation and in fetal nutrition through myometrial spiral artery angiogenesis. While regular hCG is made by fused villous syncytiotrophoblast cells, extravillous invasive cytotrophoblast cells make the variant hyperglycosylated hCG. This variant is an autocrine factor, acting on extravillous invasive cytotrophoblast cells to initiate and control invasion as occurs at implantation of pregnancy and the establishment of hemochorial placentation, and malignancy as occurs in invasive hydatidiform mole and choriocarcinoma. Hyperglycosylated hCG inhibits apoptosis in extravillous invasive cytotrophoblast cells promoting cell invasion, growth and malignancy. Other non-trophoblastic malignancies retro-differentiate and produce a hyperglycosylated free beta-subunit of hCG (hCG free beta). This has been shown to be an autocrine factor antagonizing apoptosis furthering cancer cell growth and malignancy. New applications have been demonstrated for total hCG measurements and detection of the 3 hCG variants in pregnancy detection, monitoring pregnancy outcome, determining risk for Down syndrome fetus, predicting preeclampsia, detecting pituitary hCG, detecting and managing gestational trophoblastic diseases, diagnosing quiescent gestational trophoblastic disease, diagnosing placental site trophoblastic tumor, managing testicular germ cell malignancies, and monitoring other human malignancies. There are very few molecules with such wide and varying functions as regular hCG and its variants, and very few tests with such a wide spectrum of clinical applications as total hCG.

Tumor Markers In Biological Fluids Associated With Pregnancy

Proteins that are expressed by both malignant and healthy fetal tissues are recognized as oncofetal. These antigens are associated with cell proliferation and differentiation and are produced in high concentrations in pregnancy and malignancy. Their biological role in malignancy is the suppression of the host's immune system, while in pregnancy they affect the maternal immune response, generating maternal tolerance toward the embryo. This review describes the levels of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), carcinoembryonic antigen (CEA), cancer antigen 125 (CA 125), squamous cell carcinoma antigen (SCC), cancer antigen 15-3 (CA 15-3), mucin-like carcinoma-associated antigen (MCA), tissue polypeptide-specific antigen (TPS), carbohydrate antigen 19-9 (CA 19-9), and prostate-specific antigen (PSA) in maternal serum (MS), umbilical cord serum (UC), and amniotic fluid (AF) and outlines their roles in the assessment of pregnancy and malignancy. All antigens studied, except CA 15-3, are oncofetal. The presence of considerable concentrations of AFP, hCG, CEA, CA125, SCC, MCA, TPS, CA 19-9, and PSA in AF during pregnancy may be attributed to their involvement in biological functions associated with fetal development, differentiation, and maturation. MS CEA, CA 15-3, and CA 19-9, in contrast to all the others, are not influenced significantly by pregnancy and thus remain reliable tumor markers in monitoring malignancy in pregnant patients.

The normal variabilities of the menstrual cycle

OBJECTIVE

To address conflicts in the normal variabilities of the menstrual cycle using the newest generation test methods and to establish normal ranges for use in clinical practice.

DESIGN

Daily urine samples were collected from 167 women eager to achieve pregnancy. Samples were tested prospectively for LH and total hCG. A total of 458 nongestational and 111 gestational menstrual cycles were evaluated.

SETTING

Division of Women's Health Research, University of New Mexico.

PATIENT(S)

One hundred sixty-seven women desiring pregnancy.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Levels of hCG and LH.

RESULT(S)

Menstrual cycles were 27.7 +/- 2.4 days in length. The LH peak indicated the onset of the presumed ovulatory window, which occurs at 14.7 +/- 2.4 days. Implantation (first day of sensitive detection of hCG) occurred in gestational menstrual cycles at 24.6 +/- 3.1 days, or 4.3 +/- 2.2 days before missing the expected onset of menses.

CONCLUSION(S)

Our data confirm epidemiological studies on menstrual cycle length and variability and hormonal studies on timing of the ovulatory window and its variability. They dispute, however, the published data on the timing and variance of implantation. As shown, implantation is limited to a 10-day interval culminating in the day of the expected onset of menses. Reference range data provide guidelines for differentiating normal and problem menstrual cycles.

Gonadotropins in doping: pharmacological basis and detection of illicit use

Parenteral administration of human chorionic gonadotropin (hCG) or luteinizing hormone (LH) stimulates the production of testosterone in males and these gonadotropins can therefore be used by athletes to enhance muscle strength. However, they are more expensive and less efficient than testosterone and anabolic steroids. Therefore their main use is probably to stimulate gonadal testosterone production during and after self-administration of testosterone or anabolic steroids. A positive effect of hCG on muscle strength has not been demonstrated in women and elevated concentrations of hCG in females are often caused by pregnancy. The use of gonadotropins is therefore prohibited only in males but not in females. HCG occurs at low but measurable concentrations in plasma and urine of healthy males and can be measured by sensitive methods. However, the characteristics of the method to be used for doping control have not been defined. Virtually all commercially available hCG assays have been designed for determination of hCG in serum rather than urine, which is used for doping control. Methods based on mass spectrometric detection of fragments derived from hCG extracted from urine by immunoadsorption have been developed but their suitability for doping control remains to be determined. The concentrations of LH in serum and urine are variable and more then 10-fold higher than those hCG. It is therefore difficult to detect illicit use of LH. The characteristics and reference values for hCG and LH assays used in doping control and the cutoff values need to be defined.

Hyperglycosylated human chorionic gonadotropin and the source of pregnancy failures

OBJECTIVE

To investigate the proportion of hyperglycosylated human chorionic gonadotropin (hCG-H) produced at the time of implantation as a predictor of pregnancy success.

DESIGN

Measuring daily urine hCG and hCG-H on the day of implantation. The time of implantation was assumed to be the first day of hCG detection (total hCG >1 mIU/mL).

SETTING

Urine samples were collected at volunteers' homes throughout city of Albuquerque.

PATIENT(S)

110 women attempting to conceive spontaneously; 62 achieved pregnancies (42 to term and 20 failed).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Measurements of the total hCG and hCG-H, and calculations of the proportion of hCG-H.

RESULT(S)

In all 42 term pregnancies, the proportion of hCG-H on the day of implantation was >50%. This was also true for 7 of the 20 failures. Statistically significant lower proportions of hCG-H (<50%) were observed in 13 of 20 pregnancies that eventually failed. The predictive values of proportion of hCG-H, concentration of hCG-H, total hCG, and regular hCG alone for detecting failures were 100%, 59%, 41%, and 21%, respectively.

CONCLUSION(S)

Hyperglycosylated is produced by cytotrophoblast cells in early pregnancy at the time of implantation. Effective proportions of hCG-H (>50%) are required for successful growth and invasion by cytotrophoblasts at the time of implantation. Low proportions of hCG-H at implantation predict failure and are likely to be the root of many pregnancy failures. The 7 of 20 failures with normal proportions of hCG-H were likely due to genetic, immune, or maternal causes. Measurement of a proportion of hCG-H <50% on the day of implantation absolutely indicates a failing pregnancy.

Hyperglycosylated hCG

Hyperglycosylated hCG (hCG-H) is a glycosylation variant of the hormone hCG. Here we review all that is known about this independently functioning molecule. As discussed, it is a very different molecule to the hormone hCG. First, hCG-H is produced by cytotrophoblast cells while regular hCG is made in syncytiotrophoblast cell. Second, it is an autocrine acting directly on the cells which produce it, while regular hCG is an endocrine acting on maternal corpus luteal cells. Third, hCG-H has minimal biological activity in promoting progesterone production compared to regular hCG. Fourth, hCG-H functions unlike regular hCG as an invasion promoter, whether invasion as in choriocarcinoma and testicular germ cell malignancies, or as in implantation of pregnancy. These functions seemingly occur through action on cytotrophoblast cell TGFbeta receptors. Fifth, hCG-H is an essential component for successful human implantation to prevent early pregnancy loss and spontaneous abortion. Sixth, hCG-H is critical for promoting the midtrimester hemochorial implantation, and for preventing preeclampsia. Seventh, measurements of hCG-H have advantages over measurements of regular hCG or total hCG, in detecting pregnancy, pregnancy outcome (failing or term pregnancy), predicting preeclampsia in pregnancy, or as a tumor marker for gestational trophoblastic diseases.

Standardization of FSH, LH and hCG--current position and future prospects

Gonadotropin measurements contribute significantly to patient management in both endocrinology and oncology. Differences in calibration, antibody specificities and assay design mean that gonadotropin results obtained in different methods are still not comparable. Comparing patient results obtained in different methods therefore remains problematic, whether for individual patient care, when assessing the results of multicentre clinical trials, or when formulating national and international guidelines and recommendations. Achieving improved comparability of results for these important analytes will require clear descriptive nomenclature, accurate calibration with highly purified standards, careful characterization of what gonadotropin isoforms methods are measuring, broad recommendations about the most clinically appropriate antibody combinations, and increased awareness of clinically relevant interferences and the action required to minimise their effect. Encouraging manufacturers to standardize and carefully describe the evaluation methods they use, such that data from different manufacturers can readily be compared, is also a pre-requisite for future progress.

Hyperglycosylated HCG expression in pregnancy: cellular origin and clinical applications

Employing a monoclonal antibody (B152) specific for a carbohydrate epitope found on a choriocarcinoma derived hCG, it was discovered that a similar hCG isoform is expressed during early pregnancy. This form differs from later pregnancy hCG in carbohydrate moieties. Profiling of these two hCG isoforms throughout pregnancy utilized two IRMA's: B152-B207 ("hyperglycosylated hCG"-specific assay) and B109-B108 (an IRMA for standard intact hCG isoforms in the WHO hCG reference preparation). The WHO hCG standard was used in both assays. Values were presented as a ratio of hCG isoform concentrations (B152/B109 ratio). In early pregnancy urine concentrations of B152 hCG were significantly higher in normal pregnancy (NP) compared to early pregnancy loss (EPL). Matched serum-urine samples from the first and third trimesters revealed that the B152 hCG form is predominant in both serum and urine in the first trimester compared with the third trimester. The proportion of the B152 hCG (HhCG) form is higher in urine than in matched serum. There was a significant difference in the B152/B109 ratio between days 5 and 20 from time of embryo transfer in normally developing pregnancy versus EPL in the urine of IVF patients. In spontaneous abortion (SA) the level of B109 hCG remained higher in NP compared with SA. However, the B152/B109 ratio declined with gestational age faster in SA than in NP suggesting perhaps a different loss mechanism in SA versus EPL. The cellular origin of the different hCG glycoforms was identified by assay of cell media from cytotrophoblasts (CTBs) and syncytiotrophoblasts (STBs). Isolated CTBs expressed predominantly HhCG. The level of expression was the highest in the first trimester. STBs were the source of the less glycosylated B109 hCG isoform. Analysis of hCG glycoforms during early pregnancy can distinguish pregnancies that will fail from those that will proceed normally. Since the B152 assay does not effectively discriminate between intact HhCG and free beta HhCG (HhCGbeta), a new HhCGbeta assay was developed. This assay recognizes the HhCGbeta which is produced by CTBs. We hypothesize that the measurement of HhCGbeta may have a potential use in screening for Down syndrome and perhaps other pregnancy disorders and certain types of cancer.

Hyperglycosylated hCG: a variant with separate biological functions to regular hCG

Hyperglycosylated hCG (hCG-H) is an over-glycosylated variant of hCG. While regular hCG is produced by differentiated syncytotrophoblast cells, hCG-H is independently secreted by stem cytotrophoblast cells. hCG-H has an independent function to regular hCG. It is the direct promoter of trophoblast invasion and malignancy. Invasion as in implantation of pregnancy and malignancy as in choriocarcinoma. Neither will occur in the absence of hCG-H. hCG-H measurements have multiple functions. Primarily or exclusively hCG-H is produced at the time of implantation of pregnancy and in the 2 weeks that follows. As such, a good pregnancy test should measure regular hCG and hCG-H equally. This is not commonly the case. Most tests poorly detect hCG-H. New pregnancy tests are needed, including those that measure only hCG-H. Considering that hCG-H is critical for implantation, hCG-H is also invaluable for determining pregnancy outcome and detecting failures. It makes a considerable more accurate test for detecting pregnancy failures and ectopic pregnancies than regular hCG. Down syndrome pregnancies are marked by poor trophoblast differentiation. As such, they are very well marked by using a combination of hCG-H measurements and other screening tests. hCG-H is also an absolute tumor marker for malignant or invasive gestational trophoblastic disease, it can discriminate active and inactive (quiescent) disease, and the need for chemotherapy.

Determination of hyperglycosylated human chorionic gonadotropin produced by malignant gestational trophoblastic neoplasias and male germ cell tumors using a lectin-based immunoassay and surface plasmon resonance

The ability to reliably detect aberrant glycosylation of human chorionic gonadotropin (hCG) may have profound implications for the diagnosis and monitoring of malignant gestational trophoblastic neoplasia, germ cell tumors, other malignancies, and pregnancy complications. To become a clinically useful assay, however, this discrimination of glycoforms should be possible on minimally treated biological specimens. Towards this end, we have developed a lectin-based sandwich-type immunoassay to compare the glycosylation patterns of hCG among urine specimens from patients presenting with a normal pregnancy, invasive mole, choriocarcinoma, and male germ cell tumors using carbohydrate-free antibody fragments as capture reagents and a panel of eight lectins, five recognizing neutral sugars and three recognizing sialic acid. There was no significant difference in the binding of any of the lectins to hCG in the urine of women over the gestational range of 6-38 weeks. Three lectins, however, exhibited differential binding to urinary hCG derived from these normal pregnant controls and that from patients with malignant forms of gestational trophoblastic disease and male germ cell tumors. Galanthus nivalis agglutinin and Maackia amurensis lectin, which bind terminal mannose and alpha(2-3)sialic acid, respectively, preferentially bound pregnancy-derived hCG, whereas the lectin, wheat germ agglutinin, which binds sialic acid and beta(1-4)N-acetylglucosamine, exhibited decreased binding to pregnancy-derived hCG compared to that from patients with male germ cell tumors and malignant gestational trophoblastic neoplasia. The differential binding observed with these three promising lectins is most encouraging and warrants further examination. The experimental paradigm also holds promise for the development of comparable assays for other glycosylated tumor markers.

Hyperglycosylated-hCG (h-hCG) and Down syndrome screening in the first and second trimesters of pregnancy

OBJECTIVE

To validate Down syndrome screening protocols that include hyperglycosylated-hCG (h-hCG) measurements.

METHODS

Measuring h-hCG in 21 641 fresh first- and second-trimester maternal serum samples, but not for clinical interpretation. Nuchal translucency (NT) and pregnancy associated plasma protein-A (PAPP-A) measurements were available in the first trimester; alpha-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG) measurements in the second trimester.

RESULTS

Of the 23 first- and 26 second-trimester Down syndrome pregnancies identified, 52 and 65% of h-hCG measurements were above the 95th centile, respectively. At a 3% false positive rate, maternal age, NT, PAPP-A and h-hCG detected 78% of cases (95% CI, 56-93%). Other combinations were consistent with previous modeling utilizing stored samples. A literature summary indicates h-hCG is as strong a marker as free-beta between 10 and 13 weeks' gestation.

CONCLUSIONS

Down syndrome screening performance of h-hCG using fresh samples meets published expectations based on stored samples. h-hCG could replace free beta measurements, at gestational ages as early as 10 weeks.

Gestational trophoblastic diseases: 2. Hyperglycosylated hCG as a reliable marker of active neoplasia

OBJECTIVES

To determine whether circulating hyperglycosylated human chorionic gonadotropin (hCG-H), a promoter of choriocarcinoma growth and tumorigenesis, is a reliable marker of active gestational trophoblastic neoplasia (GTN) or choriocarcinoma, and whether hCG-H can consistently discriminate quiescent gestational trophoblastic disease (GTD) from neoplasia.

METHODS

Patients were those referred to the USA hCG Reference Service for consultation. These included a total of 82 women with GTN, including 30 with histologic choriocarcinoma. They were compared with 26 patients with resolving hydatidiform mole and 69 with quiescent GTD (persistent positive low value of real hCG but no clinical evidence of disease). All were tested for total hCG and hCG-H. hCG-H was calculated as the percentage of total hCG (hCG-H(%)).

RESULTS

We compared the utility of total hCG and hCG-H(%) in detecting active GTN and quiescent GTD. There was no significant difference when measuring total hCG (includes regular and hyperglycosylated hCG), between women with quiescent GTD and self-resolving hydatidiform mole compared to choriocarcinoma/GTN cases (P > 0.05 and P > 0.05). In contrast, hCG-H(%) was significantly higher in choriocarcinoma/GTN cases (P < 0.000001, and P < 0.000001). The usefulness of hCG and hCG-H(%) testing was assessed for discriminating between the 69 quiescent GTD cases, which required no therapy, and choriocarcinoma/GTN which need treatment. While hCG would detect 62% and 24% of malignancies at a 5% false positive rate, hCG-H(%) would detect 100% and 84% of malignancies at this same false positive rate. Follow-up data were received and repeat consultations were performed in 23 cases in which active disease was subsequently demonstrated. In 12 of 23 cases, hCG-H(%) results were able to first identify active disease 0.5 to 11 months prior to rapidly rising hCG or detection of clinically active neoplasia. In the remaining 11 cases, hCG-H(%) active disease appeared at the same time as rising hCG or demonstrable clinical tumor.

DISCUSSION AND CONCLUSION

hCG-H(%) appears to reliably identify active trophoblastic malignancy. It is a 100% sensitive marker for discriminating quiescent GTD from active GTN/choriocarcinoma. It is also a marker for the early detection of new or recurrent GTN/choriocarcinoma. The data presented appear sufficient to encourage the adoption of hCG-H as a tumor marker in trophoblastic disease. Further studies are now urgently required to confirm and extend our findings.

Gestational trophoblastic diseases: 3. Human chorionic gonadotropin-free β-subunit, a reliable marker of placental site trophoblastic tumors

OBJECTIVES

Placental site trophoblastic tumor (PSTT) commonly presents with low and variable concentration of hCG immunoreactivity in serum which can be difficult to differentiate from early stage choriocarcinoma/gestational trophoblastic neoplasm (GTN) or quiescent gestational trophoblastic disease (quiescent GTD). Nontrophoblastic malignancies such as germ cell tumors or other tumors secreting low hCG must also be considered in the differential diagnosis. Because treatments for these conditions are different, a means of differentiating PSTT from other diagnoses is important. We investigate the usefulness of hCG-free beta-subunit to make this discrimination.

METHODS

Data collected on cases referred to the USA hCG Reference Service for consultation served as a basis for this retrospective analysis. There were 13 cases with histology proven PSTT and 12 with nontrophoblastic malignancy. hCG-free beta-subunit was measured by immunoassay and reported as a proportion of total hCG (hCG-free beta-subunit(%)). hCG-free beta-subunit(%) results were determined for all histologically proven cases of PSTT and for the nontrophoblastic malignancies. Comparisons of hCG-free beta-subunit(%) were made and compared with those of the 82 choriocarcinoma/GTN cases and 69 quiescent GTD cases. The accuracy of hCG-free beta-subunit(%) to discriminate these malignancies was analyzed by investigating the areas under receiver-operating characteristics curve +/- standard error.

RESULTS

hCG-free beta-subunit(%) was the predominant hCG form in cases of PSTT (mean +/- standard deviation, 60 +/- 19%) and nontrophoblastic malignancies (91 +/- 11%), thus discriminating these diagnoses from choriocarcinoma/GTN (9.3 +/- 9.2%) and from quiescent GTD (5.4 +/- 7.8%). The cutoff of >35% free beta-subunit is proposed. At this cutoff, 100% detection at 0% false-positive is achieved. The accuracy of hCG-free beta-subunit(%) for this discrimination is 100 +/- 0%. At a proposed cutoff of >80%, the free beta-subunit test will also distinguish PSTT from nontrophoblastic malignancy, with 77% detection at 23% false-positive or an accuracy of 92 +/- 3.2%.

CONCLUSION

Measurement of the proportion hCG-free beta-subunit(%) was found to be useful in the diagnosis of PSTT using proposed cutoff values of >35% and >80%. While this finding needs to be confirmed by larger studies, it would be reasonable to measure hCG-free beta-subunit(%) whenever the diagnosis of PSTT is considered.

The classification, functions and clinical use of different isoforms of HCG

HCG is composed of two subunits, HCGalpha and HCGbeta. During early pregnancy, HCG stimulates progesterone production in the corpus luteum, and injection of HCG is widely used to induce ovulation in assisted reproduction treatment (ART). Under experimental conditions, the free subunits have been shown to exert functions other than those of HCG, but the relevance of these remains to be determined. Intact HCG, free subunits and degraded forms of these occur in biological fluids, and determinations of these are important for diagnosis and monitoring of pregnancy, pregnancy-related disorders and several types of cancer. Development of optimal methods for the various forms has been hampered by lack of appropriate standards and expression of the concentrations of the various forms in units that are not comparable. Furthermore, the nomenclature for HCG assays is confusing and in some cases misleading. These problems can now be solved; a uniform nomenclature has been established, and new standards are available for HCG, its subunits HCGalpha and HCGbeta, the partially degraded or nicked forms of HCG and HCGbeta, and the beta-core fragment. This review describes the biochemical and biological background for the clinical use of determinations of various forms of HCG. The clinical use of HCG and studies on HCG vaccines are briefly reviewed.

A single serum test for measuring early pregnancy outcome with high predictive value

OBJECTIVES

Current testing to determine a failing pregnancy requires two separate clinic visits to measure the hCG doubling rate. Diagnosing a failing pregnancy is often done in emergency departments where simplified and accelerated testing methods are needed. Here, we investigated hyperglycosylated hCG (hCG-H) for predicting pregnancy failure.

DESIGN AND METHODS

We studied two independent sets of patient samples collected in the early weeks of gestation. One set was urine samples, and the other was serum samples. In all cases, hCG and hCG-H were measured using automated chemiluminescence immunoassays. Concentrations of hCG and hCG-H were plotted on a scattergram, and levels in failing pregnancies were compared to those in continuing pregnancies.

RESULTS

Data indicated that a threshold level of hCG-H (13 microg/L) in both serum and urine samples defined the concentration below where pregnancies were likely to fail. This cut-off corresponded to 73% detection of failures at a 2.9% false positive rate using serum and 75% detection at a 15% false positive rate using urine. Using an hCG cut-off that corresponded to the same false positive rates, hCG detected only 42% of failures using serum and 43% of failures using urine.

CONCLUSIONS

Our data indicate that hCG-H provides a much more accurate single test than hCG for assessing pregnancy outcome. Compatible with the use of serum or urine samples, a single hCG-H test might provide simpler, faster, and more accurate results for predicting the progress of a pregnancy than standard hCG testing.

Gestational trophoblastic diseases: 1. Pathophysiology of hyperglycosylated hCG

OBJECTIVE

Hyperglycosylated hCG (hCG-H) is a glycosylation variant of hCG produced by cytotrophoblast cells at implantation of pregnancy and in choriocarcinoma. We investigated the biological function of hCG-H in invasion in vitro and in vivo and the use of hCG-H antibodies in blocking tumorigenesis and cancer growth in vivo.

METHODS AND RESULTS

hCG-H accounts for 43% to 100% of total hCG immunoreactivity in the culture fluid of choriocarcinoma cell lines and 100% in primary cultures of pregnancy cytotrophoblast cells. We investigated the action of hCG and hCG-H on isolated cytotrophoblast cell primary cultures and on 3 different lines of choriocarcinoma cells cultured on Matrigel basement membrane inserts (culture models for assessing tumor invasion). The addition of hCG-H to medium significantly promoted invasion of membranes with both pregnancy and cancer cell line sources, while regular hCG had no significant effect. JEG-3 human choriocarcinoma cells were transplanted subcutaneously into athymic nude mice. Tumors rapidly formed. B152, mouse monoclonal antibody against hCG-H, and non-specific mouse IgG (control) were administered twice weekly once tumors were clearly visible. While a correlation between time and growth was observed with the control group (r(2)=0.97), no correlation was observed with the B152-treated mice (r(2)=0.15). B152 blocked tumor growth (t test, IgG vs. B152, P=0.003). In a second experiment, antibody B152 or IgG was administered to mice at the time of choriocarcinoma transplantation. B152 significantly inhibited tumorigenesis (t test P=0.0071).

CONCLUSIONS

hCG-H is a critical promoter in human cytotrophoblast and human choriocarcinoma cell invasion in vivo and in vitro, promoting tumor growth and invasion through an autocrine mechanism. hCG-H is a signal for choriocarcinoma cell invasion, making it a biological tumor marker. Antibodies against hCG-H block tumor formation and growth. Human or humanized antibodies against hCG-H may be useful in treating and managing choriocarcinoma and other gestational trophoblastic malignancies.

Gestation trophoblastic diseases: management of cases with persistent low human chorionic gonadotropin results

The finding of persistent low levels of human chorionic gonadotropin (hCG) raises concern, regardless of the antecedent history, and often provokes the evaluating physician to embark on further work-up. The USA hCG Reference Service was started in 1998 to aid physicians with these persistent low hCG cases. This article reviews the observations of the USA hCG Reference Service for 134 cases with persistent low hCG results. Examination of these cases provides clear insight for the appropriate management of those presenting with persistent low levels of hCG. Three distinct sources are discussed for persistent low hCG results: quiescence gestational trophoblastic disease, false-positive hCG results, and pituitary hCG.

Sensitivity of Over-the-Counter Pregnancy Tests: Comparison of Utility and Marketing Messages

OBJECTIVE

To determine the sensitivity of seven over-the-counter pregnancy tests (OTC-PTs) using urine containing a mixture of human chorionic gonadotropin (hCG)-related molecules as found on the first day of missed menstrual period.

DESIGN

Blinded in vitro sensitivity analysis.

SETTING

Medical school laboratory.

PARTICIPANTS

None.

INTERVENTIONS

Urine was tested with OTC-PT devices at titers of 100, 50, 25, 12.5, 6.3, and 0 mIU/mL hCG immunoreactivity, and laboratory workers rated their confidence in the test result based on whether the test result was a clear, sharp, and unquestionable band in the test window.

MAIN OUTCOME MEASURES

Analytical sensitivity, defined as the urine concentration at which all OTC-PTs tested gave a positive result regardless of operator confidence score; clinical sensitivity of OTC-PTs, defined as the proportion of pregnancies likely to be detected on the first day of a missed period and calculated from the analytical sensitivity and a recently published regression curve for total urine hCG immunoreactivity in 25 urine samples from this period of gestation; percentage of tested devices showing a band in the test window at a specific hCG concentration measured devices positive; percentage faulty devices, defined as the proportion of tested devices failing to yield a band in the control window; and confidence score, determined from operator ratings for each device at each concentration of hCG.

RESULTS

First Response Early Result had an analytical sensitivity of 6.3 mIU/mL, which was estimated to detect greater than 95% of pregnancies on the day of missed period. The sensitivity of Clearblue Easy Earliest Results was 25 mIU/mL, which indicated detection of 80% of pregnancies. The sensitivity of the five other products was 100 mIU/mL or greater, indicating detection of 16% or less of pregnancies. Three of these last products included faulty devices.

CONCLUSION

Universal claims for OTC-PTs of more than 99% laboratory accuracy and use as early as the first day of missed period, while cleared for use by the U.S. Food and Drug Administration, are ambiguous and inappropriate for many products, according to these data. The majority of products tested were found to detect only a small percentage of pregnancies on the first day of a missed menstrual period. Until more data become available on the actual clinical sensitivity of these products, pharmacists should advise consumers to be cautious in interpreting test results.

Maternal Serum Invasive Trophoblast Antigen and First-Trimester Down Syndrome Screening

Background: In the United States, Down syndrome screening is still performed mainly in the second trimester, using 3 or 4 markers. Moving screening into the first trimester has the advantage of earlier diagnosis. Currently, first-trimester screening typically includes maternal serum pregnancy-associated plasma protein-A (PAPP-A), the free β-subunit of human chorionic gonadotropin (free β), and ultrasound measurement of nuchal translucency thickness (NT). The current report describes a case–control study of serum invasive trophoblast antigen (ITA) and its possible inclusion in first-trimester screening for Down syndrome.

Methods: As part of an earlier observational study, serum samples from 54 Down syndrome and 276 matched unaffected pregnancies were collected between 9 and 15 weeks of gestation. Samples had been aliquoted and stored at −20 °C for 8 years. ITA was measured and converted to weight-adjusted multiples of the median (MoM). The distributions of other first-trimester markers are from a single published study.

Results: Median ITA MoM in Down syndrome pregnancies increase as gestational age increases (2.02 MoM at 11 and 2.44 MoM at 13 completed weeks). At 75% detection, maternal age in combination with ITA and PAPP-A measurements have an 8.0% false-positive rate, slightly lower than the 8.8% found for the free β and PAPP-A combination; adding NT measurements reduces false positives for the 2 combinations to 2.0% and 1.8%, respectively.

Conclusion: Serum ITA appears to be a useful first-trimester Down syndrome marker that could replace free β measurements while maintaining performance.

Second trimester serum markers

Prenatal screening for Down syndrome in the early second trimester with multiple maternal serum markers has been available for more than 15 years. The multiple marker combination with the highest screening performance currently available is alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and inhibin A, together with maternal age (so-called quad marker test). With this combination, a detection rate of 80% at a 5% false positive rate is achieved. Inhibin A, the newest addition to second trimester serum screening, is an alpha-beta subunit hormone of placental origin, and is measured using a monoclonal two-site ELISA validated for use in prenatal screening. Quality control parameters for inhibin A measurement are acceptable and are monitored through the proficiency testing program administered by the College of American Pathologists. Research into other possible second trimester screening markers has included studies on the maternal urine and serum levels of an hCG variant, hyperglosylated hCG (h-hCG; invasive trophoblast antigen). Recent data indicate that h-hCG is similar to hCG itself, although its measurement in maternal urine may improve the performance of the established serum marker combinations. With the introduction of first trimester screening markers and their use in an integrated first and second trimester marker approach to screening, and with the fact that many women do not seek prenatal care until the early second trimester, prenatal screening for Down syndrome using second trimester serum markers remains a major resource in obstetrical care.

Specific Measurement of O-Linked Core 2 Sugar-Containing Isoforms of Hyperglycosylated Human Chorionic Gonadotropin by Antibody B152

There have been a significant number of reports on the clinical utility of measurement of 'hyperglycosylated' isoforms of the pregnancy hormone, human chorionic gonadotropin (hCG). Although there are a variety of hCG isoforms which can be termed 'hyperglycosylated', the measurements were all made using a unique antibody designated B152. This antibody was raised using a choriocarcinoma-derived form of hCG, which was hyperglycosylated with N- and O-glycans and was also 100% 'nicked' hCG. Antibody B152 was recently mapped to a linear epitope around a single O-glycan on the beta-subunit of hCG at residue number 132. Thus, the antibody can only measure isoforms of hCG that possess a core 2 type of branched O-glycan on this portion of the hCG beta-subunit. Isoforms that are hyperglycosylated in the hCG alpha-subunit or only on the N-glycans of hCGbeta will not be recognized by antibody B152. Apparently, measurements of these core 2 hCG isoforms have important clinical application in early pregnancy during which they are the predominant isoform of hCG until the 6th week of gestation. The secretory pattern of these isoforms can be used to predict the health status of the pregnancy in fertility clinics. Moreover, the measurements of these core 2 hCG isoforms are more useful than standard hCG for the prediction of Down syndrome pregnancies. The core 2 isoforms are also of important use in cancer diagnosis and monitoring since their concentration appears to correlate with malignancy.

First- and midtrimester Down syndrome screening and detection

Overall, Down syndrome detection capabilities have improved remarkably over the last 2 decades. Widely practiced first-trimester screening and less extensively elevated midtrimester urine screening promise even greater accuracy than was available a decade ago. Recently, the combination of first- and second-trimester screening has been reported to enhance discrimination of the Down syndrome fetus from normal cases. Although the advances are welcome, they present the significant prospect of multiple competitive algorithms with the risk of confusing patients, practitioners, and health care planners. The need for reasonable consensus has never been more pressing.

Biochemical screening for congenital defects

This article discusses biochemical screening for congenital defects. Biochemical screening remains the standard for estimating the risk of aneuploidy in pregnancy. The combination of first and second trimester markers promises to further improve diagnostic accuracy for anomaly detection.

Advances in the clinical laboratory detection of gestational trophoblastic disease

BACKGROUND

Gestational trophoblastic disease (GTD) consists of a spectrum of disorders that are characterized by an abnormal proliferation of trophoblastic tissue. Gestational trophoblastic neoplasia (GTN) refers to a subset of GTD with a persistently elevated serum hCG in the absence of a normal pregnancy and with a history of normal or abnormal pregnancy. Although previously a lethal disease, GTN is considered today the most curable gynecologic cancer. However, a delay in the diagnosis may increase the patient's risk of developing malignant GTN, and therefore the prompt identification of GTN is important.

SERUM MARKERS

hCG test is essential for detection of GTN. It has emerged that there are problems with hCG tests. In addition to regular hCG, at least five major variants of hCG are present in serum samples. False-positive hCG (phantom hCG) can occur in the absence of GTN. Low-level real hCG may occasionally persist in the absence of clinical evidence of pregnancy or GTD. Alternatively, low-level real hCG may be due to pituitary hCG. Other placental hormones, human placental lactogen (hPL), inhibin and activin, and progesterone have also been evaluated as tumor markers for GTD.

CONCLUSION

hCG has high diagnostic sensitivity, approaching 100% sensitivity, for managing the treatment of GTN and for detecting recurrences of disease. It is recommended to use hCG test that recognizes all forms of the hCG molecule. In cases where low-level hCG persists, it must be differentiated whether it is real or false. Real-hCG may be due to quiescent gestational trophoblastic disease or pituitary hCG. It has not yet been established whether measurement of markers other than hCG (hPL, inhibin, activin, and progesterone) is useful in the detection and follow-up of GTD.

Maternal Serum Invasive Trophoblast Antigen (Hyperglycosylated hCG) as a Screening Marker for Down Syndrome during the Second Trimester

Background: Approximately two million pregnancies in the United States are screened for Down syndrome annually by use of second-trimester maternal serum markers. At present, a combination of four markers can identify 75% of affected pregnancies when 5% of screened women are classified as candidates for amniocentesis. Although not currently included in screening panels, invasive trophoblast antigen (ITA) is a promising screening marker in serum or urine in both the second and first trimesters. This study aims at better defining the screening performance of serum ITA in the second trimester.

Methods: In an earlier study, serum samples from an unbiased sampling of 45 Down syndrome (cases) and 238 unaffected (control) pregnancies between 14 and 20 weeks of gestation were collected from various centers in the United States. Samples were aliquoted and stored at −20 °C for 8 years. We measured ITA in these samples and determined the screening performance both univariately and in combination with other screening markers.

Results: The median ITA in Down syndrome pregnancies was &gt;3.00 multiples of the median, higher than that found for human chorionic gonadotropin (hCG) or free β-hCG. At a 5% false-positive rate, ITA univariately detected 38% and 40% of Down syndrome pregnancies, respectively, when assigned by date of last menstrual period or ultrasound date. Modeling yielded rates of 45% and 48%. ITA correlated strongly with hCG and free β-hCG. When substituted for either of these in a multiple marker panel, ITA performed comparably.

Conclusions: This study indicates that serum ITA is an effective marker for Down syndrome. It is highly correlated with both hCG and free β-hCG and could replace either of them in a multiple marker panel.

Hyperglycosylated hCG (invasive trophoblast antigen, ITA) a key antigen for early pregnancy detection

OBJECTIVES

Hyperglycosylated human chorionic gonadotrophin (hCG) is an hCG variant with extra-large O-linked oligosaccharides, produced by phenotypically invasive cytotrophoblast cells in choriocarcinoma and pregnancy. It is the principal form of hCG produced in the first weeks of gestation. We investigated the importance of hyperglycosylated hCG in pregnancy testing and its detection by current hCG tests.

DESIGN AND METHODS

We measured the concentration of hyperglycosylated hCG and total hCG in 512 pregnancies throughout gestation. We assessed and compared the abilities of 14 commonly used commercial laboratory hCG tests and 18 home pregnancy tests to detect regular and hyperglycosylated hCG.

RESULTS

Hyperglycosylated hCG is the principal source of hCG-related immunoreactivity in early pregnancy. In the week following missing menses, hyperglycosylated hCG measurements may be more sensitive than regular hCG measurements in detecting pregnancy. Of 14 commercial laboratory hCG tests, 3 appropriately detected hyperglycosylated hCG standard. Of 18 different home pregnancy products 11 poorly or very poorly detected this key antigen.

CONCLUSIONS

Hyperglycosylated hCG may be the key molecule in the detection of early pregnancy. However, the majority of tests poorly detected or failed to detect this key antigen. New pregnancy tests are needed that either solely detect hyperglycosylated hCG or equally detect regular hCG and hyperglycosylated hCG.

Invasive Trophoblast Antigen (Hyperglycosylated Human Chorionic Gonadotropin) in Second-Trimester Maternal Urine as a Marker for Down Syndrome: Preliminary Results of an Observational Study on Fresh Samples

Background: Down syndrome screening is commonly performed in the US using maternal age and three or four second-trimester maternal serum markers that can identify up to 75% of affected pregnancies by offering diagnostic studies to 5% of women. Invasive trophoblast antigen [ITA; hyperglycosylated human chorionic gonadotropin (hCG)] is a promising marker that can be measured in urine or serum in the first or second trimester. We report preliminary results for urinary ITA in an ongoing observational study.

Methods: Women undergoing second-trimester amniocentesis for reasons not associated with biochemical testing provided consent and a urine (and possibly serum) sample that was tested within a few days. Demographic and pregnancy-related information was collected, along with karyotype. Screening performance was modeled for ITA alone and in combination with serum markers

Results: Twelve recruitment centers collected urine from 2055 women with singleton pregnancies between 15 and 20 weeks of gestation (2023 unaffected, 28 Down syndrome, and 4 pregnancies with other chromosome abnormalities). After correction for gestational age, urine concentration, and maternal race and weight, the ITA measurements were higher in women with a Down syndrome pregnancy (median ITA, 4.33 multiples of the median). At a 75% detection rate, the false-positive rate could be reduced by substituting ITA for hCG measurements (from 5.6% to 2.6% for the triple test) or by adding ITA measurements to existing combinations (from 3.3% to 2.0% for the quadruple test).

Conclusions: Our data provide preliminary confirmation of the potential usefulness of urinary ITA measurements in detecting Down syndrome in a setting that simulates routine usage.