Total β-hCG Research Articles

A-337 The Utility of Urinary Human Chorionic Gonadotropin Testing in the Emergency Department

Abstract Background Human chorionic gonadotropin (hCG) levels are measured in both urine and blood as an indication of suspected pregnancy, and assessment of progress of conception. It is also measured in the investigation of patients presenting with acute abdomen and suspected of ectopic or molar pregnancy. This study reviewed the utility of urine pregnancy test in a large university teaching hospital. Methods Results of all urinary hCG tests (using hCG Combo Pregnancy kit, MEDLINE, IL) performed as point of care in the emergency department during the year 2023 were obtained. Corresponding plasma hcG levels performed (Total β-HCG Alinity immunoassay, Abbott Diagnostics, IL) were also obtained. Analysis of hCG testing outcomes were assessed. Results A total of 2848 urinary hCG tests were performed during the study period. The majority 2113 (74.2%) of samples were negative for hCG whereas 835 samples (29.3) were positive. Among the positive hCG urine samples, 401 patients (48%) had plasma hCG requested and performed. Plasma hCG values ranged from < 2.4 (26.5) to 219,462.5 mIU/mL (median 16,872.35 mIU/mL). One plasma sample with corresponding positive urinary hCG result had plasma hCG level <2.4 mIU/mL which is below the detection limit of the assay suggesting a false positive urinary hCG result. Among the 13 patients with serial plasma hCG values, only one patient exhibited doubling (48 hours) hCG values when less than 13,000 mIU/mL. One patient had a declining serial hCG plasma values suggesting failing conception. The remaining patients with consecutive plasma hCG values cannot be assessed as either the time gap was excessive or hCG values were markedly elevated (> 30,000 mIU/mL). Conclusions Although the utility of urinary hCG testing in the emergency department appeared appropriate, unnecessary repeat analysis with appropriate plasma request represented 3.2%. An electronic test request duplicate notification may help resolve this unnecessary repeat.

B-008 An Evaluation of the Analytical Performance of the New Beckman Coulter DxC 500i Clinical Analyzer

Abstract Background The DxC 500i Clinical Analyzer* is Beckman Coulter’s latest integrated Clinical Chemistry and Immunoassay analyzer. It provides reliability, scalability, and workflow efficiency via a flexible independent maintenance mode, increased uptime, and a dynamic sample handler to optimize sample management. Standard Beckman Coulter Chemistry and Immunoassay consumables and reagents ensure network standardization and commutability. The purpose of this study was to evaluate the analytical performance of the new DxC 500i analyzer and to compare the performance against the Beckman Coulter stand-alone Clinical Chemistry and Immunoassay analyzers on the market. Methods To assess performance over a range of assay methodologies, several DxC 500i Beckman Coulter Immunoassays and Chemistry assays were evaluated. Precision was assessed using human samples following CLSI EP05-A3 guidelines. Linear range was assessed following CLSI EP06-A guidelines. Method Comparison and Bias Estimation studies compared the DxC 500i Clinical Analyzer against the Access 2 Immunoassay System, the AU480 and the DxC 700 AU Clinical Chemistry analyzers, following CLSI EP09c-ED3 guidelines. To investigate carryover potential as samples are processed across the integrated system, a carryover study was designed. This focused on evaluating potential sample-to-sample carryover caused by the AU sample probe and its effects on immunoassay samples during reflex scenarios. Results DxC 500i Chemistry results: Glucose Serum (OSR6x21) Assessments of repeatability and within laboratory precision at multiple critical analyte concentrations showed total imprecision of <3% and within-run imprecision of <3%. The Glucose serum assay demonstrated acceptable linearity throughout the 10-800 mg/dL analytical measuring range. Method comparison studies compared the DxC 500i analyzer against the AU480 and DxC 700 AU systems. A Weighted Deming regression of serum patient samples (n>100 measured across the analytical range) yielded a 0.986 slope, 0.227 mg/dL intercept, and R=0.9999 correlation coefficient against the DxC 700 AU and a 0.995 slope, 0.356 mg/dL intercept, and R=0.9999 correlation coefficient against the AU480. DxC 500i Immunoassay results: Cortisol (33600) Beckman Coutler’s Cortisol assay exhibited total imprecision of <12%CV at <5 μg/dL or <10CV% at ≥5 μg/dL for serum. The Cortisol assay demonstrated acceptable linearity throughout the 0.4-60 μg/dL analytical measuring range. A method comparison study compared the DxC 500i against the Access 2 system. A Weighted Deming regression of serum patient samples (n>100 measured across the analytical range) yielded a 0.9785 slope, 0.2764 μg/dL intercept, and R=0.9932 correlation coefficient. DxC 500i Carryover Assessment The Total βhCG (5th IS) assay was used to evaluate the potential of chemistry analyzer to immunoassay analyzer sample carryover. The study used High hCG serum samples (>1,000,000 mIU/mL) and Low hCG serum samples (4-6 mIU/mL). The DxC 500i exhibited a cumulative carryover of ≤2 parts per million (PPM) for serum. Conclusions These studies demonstrate excellent analytical performance for the new Beckman Coulter DxC 500i Clinical Analyzer* and confirm comparable performance to current Beckman Coulter standalone Clinical Chemistry and Immunoassay analyzers on the market. *Pending clearance by the United States Food and Drug Administration; not yet available for in vitro diagnostic use in the U.S. Product availability and regulatory status depends on country registration per applicable regulations.

An assessment of analytical performance using the six sigma scale in second-trimester maternal prenatal screening practices in China

ObjectivesWe aimed to evaluate the analytical performance of second-trimester maternal serum screening in China, and to compare if there are differences in sigma levels across different methods and months. MethodsA retrospective study was conducted to assess the analytical quality levels of laboratories by calculating the Sigma metrics with prenatal screening biomarkers: AFP, Total β-hCG, free β-hCG, uE3. Data from 591 laboratories were selected. Sigma metrics were computed using the formula: Sigma metrics(σ) = (%TEa - |%Bias|)/%CV. The Friedman test and Mann-Whitney test were used to compare differences across various methods and different months. The Hodges–Lehmann was used for determining 95 % confidence intervals of pseudo-medians. ResultsOnly uE3 showed significant monthly variations in sigma calculations. However, around 8 % of laboratories across all four analytes demonstrated sigma levels both above 6 and below 3 in different months. Laboratories utilizing time-resolved fluorescence methods significantly outperformed those using chemiluminescence in sigma level. For AFP, the pseudo-median difference between these methods lies within a 95 % confidence interval of (−3.22, −1.93), while for uE3, it is at (−2.30, −1.40). Notably, the median sigma levels for all analytes reached the 4-sigma threshold, with free β-hCG even attaining the 6-sigma level. ConclusionWith current standards, China's second-trimester maternal serum screening is of relatively high analytical quality, and variations in sigma levels exist across different months and methods.

The relationship between first and second trimester biochemical parameters used to screen down syndrome and intrahepatic cholestasis of pregnancy

Objective: To assess the role of first and second-trimester screening biomarkers pregnancy-associated plasma protein-A(PAPP-A), free beta-human chorionic gonadotropin(free ß-hCG), estriol, alpha-fetoprotein and total β-hCG in the early diagnosis of intrahepatic cholestasis of pregnancy (ICP). Materials and Methods: Patients with ICP admitted to Mersin University Hospital for delivery between 2015 and 2019 and had first and second-trimester aneuploidy screening tests performed in the same facility were retrospectively assessed. Randomly 60 pregnant women without comorbid conditions during the same period were included as controls. Data regarding demographic characteristics, laboratory values including free ß-hCG and PAPP-A in first-trimester screening and total ß-hCG, estriol and alpha- fetoprotein in second-trimester screening were compared. Results: There were 46 eligible patients with ICP. In first trimester screening, it was found that PAPP-A MoM was significantly lower (0.89±0.55 vs. 1.94±0.73; p=0.035) while free ß-hCG MoM was significantly higher in ICP group when compared to controls (1.84±0.59 vs. 0.99±0.47; p=0.018). In second trimester screening, no significant difference was detected in aneuploidy markers between groups. For prediction of ICP development, first trimester free β-hCG >1.44 MoM was found to have a sensitivity of 50%, a specificity of 80% and positive and negative predictive values of 33% and 88.9% respectively. Similarly first trimester PAPP-A values <1.075 MoM was found to have 80% and 75% sensitivity and specificity with positive and negative predictive values of 75% and 44% respectively. Conclusion: Low PAPP-A MoM value and elevated free ß-hCG in first trimester seem to be associated with ICP development.

The Effect of Ethynil Estradiol and Desogestrel on Proliferation and Apoptosis Hydatidiform Mole Trophoblast Cell

Background: To explore the effect of ethynil estradiol and desogestrel on proliferation and apoptosis hydatidiform mole trophoblast cell.
 Methods: From April 2008 until March 2009, we collected 15 samples of hydatidiform mole tissue. Trophoblast cells was isolated and culture at RPMI 20% FBS medium. Only 7 samples (46%) shown good growth. Cell was identified using cytology and β HCG test. Trophoblast cells good quality than devided into three groups observation. First group get ethynil estradiol 10 nmol/mL, second group get desogestrel 100 nmol/mL, Third group get DMSO 1%. Cells incubated and observe at 24, 48, 72, 96 hours. Cell cycle, apoptosis and β HCG was evaluated at each time observation. Cell cycle evaluation using BD cycle test plus DNA reagent, apoptosis evaluation using FITC-Annexin V. Analyze using FACSCalibur flowcytometer. β HCG evaluation using Abbott AxSym total β-HCG reagent pack.
 Results: The group of cell that get ethynil estradiol in concentration 10 nmol/mL had cell proliferation index, amount cells and β HCG level higher than control after 72 hours observation. The group of cell that get desogestrel in concentration 100 nmol/mL have cell proliferation index, amount cells and β HCG level lower than control after 48 hours observation. There are no differences of apoptosis between the two group and control.
 Conclusion: Ethynil estradiol will increase proliferation of hydatidiform mole trophoblast cell, while desogestrel will decrease proliferation of hydatidiform mole trophoblast cell. There are no effect of ethynil estradiol and desogestrel on apoptosis of hydatidiform mole trophoblast cell.

The Effect of Ethynil Estradiol and Desogestrel on Proliferation and Apoptosis Hydatidiform Mole Trophoblast Cell

A B S T R A C TIntroduction To explore the effect of ethynil estradiol and desogestrel onproliferation and apoptosis hydatidiform mole trophoblast cell. Methods: From April2008 until March 2009, we collected 15 samples of hydatidiform mole tissue.Trophoblast cells was isolated and culture at RPMI 20% FBS medium. Only 7samples (46%)shown good growth. Cell was identified using cytology and β HCG test.Trophoblast cells good quality than devided into three groups observation. Firstgroup get ethynil estradiol 10 nmol/mL, second group get desogestrel 100 nmol/mL,Third group get DMSO 1%. Cells incubated and observe at 24, 48, 72, 96 hours. Cellcycle, apoptosis and β HCG was evaluated at each time observation. Cell cycleevaluation using BD cycle test plus DNA reagent, apoptosis evaluation using FITC-Annexin V. Analyze using FACSCalibur flowcytometer. β HCG evaluation usingAbbott AxSym total β-HCG reagent pack. Results: The group of cell that get ethynilestradiol in concentration 10 nmol/mL had cell proliferation index, amount cells andβ HCG level higher than control after 72 hours observation. The group of cell thatget desogestrel in concentration 100 nmol/mL have cell proliferation index, amountcells and β HCG level lower than control after 48 hours observation. There are nodifferences of apoptosis between the two group and control. Conclusion: Ethynilestradiol will increase proliferation of hydatidiform mole trophoblast cell, whiledesogestrel will decrease proliferation of hydatidiform mole trophoblast cell. Thereare no effect of ethynil estradiol and desogestrel on apoptosis of hydatidiform moletrophoblast cell.

Sleep quality and obstructive sleep apnoea and triple screen test results in pregnancy

In this study, we aimed to examine the relationship between sleep quality, sleep apnoea and triple screen test results. This was an observational descriptive research study. The STOP questionnaire and the STOP-BANG questionnaire were performed to assess obstructive sleep apnoea risk and Pittsburgh Sleep Quality Index was used to evaluate sleep quality. The average Pittsburgh Sleep Quality Index score of the participants was 5.92 ± 3.26. According to the STOP test, 11.40% (87) of the pregnant women had a high risk of OSAS, and, according to the STOP-BANG test, 32 participants were under high risk of OSAS. An increased risk was detected in 1.30% of the participants in terms of Trisomy18 and in 1.60% in terms of neural tube defects. A direct and significant relationship was detected between Trisomy 21 risk and STOP-BANG score. This is the first study to show this relationship. Sufficient evidence needs to be collected on this issue. Testing in earlier weeks of pregnancy and in the conception period may allow more meaningful assessment of the relationship of OSAS with chromosomal abnormalities. IMPACT STATEMENT What is already known on this subject? There is a link between OSAS and epigenetic changes. Components of the triple screen test, levels of serum total β-hCG and unconjugated oestriol are increased in OSAS. What do the results of this study add? An increase in Trisomy 21 risk is correlated with increased OSAS risk. Alpha Fetoprotein levels were higher in the low OSAS risk group. What are the implications of these findings for clinical practice and/or further research? This is the first study to show this relationship. Sufficient evidence needs to be collected on this issue. Treatment of OSAS may be necessary during pregnancy.

How comparable are total human chorionic gonadotropin (hCGt) tumour markers assays?

Background Total human chorionic gonadotropin (hCGt) tumour marker testing is regarded as an "off label" application for most commercial methods. We compared four assays in patients with a hCGt tumour marker request. We hypothesised that regression slopes would be altered and that outliers would be more common with tumour marker than with pregnancy samples if the detection of malignancy associated hCG molecular forms differed amongst assays. Further such systematic differences would be obvious and large enough to change clinical management decisions. Results We measured hCGt in 390 samples from 137 females and 253 males with a tumour marker request and 208 pregnancy controls with the following methods: Access Total βhCG, Architect Total-βhCG, Cobas hCG + β and Immulite HCG. The between method regressions determined on tumour marker and pregnancy samples were not significantly different. The outlier rates were similar for male and female tumour marker and the pregnancy groups: 1.6% (95% confidence interval [CI] 0%-3.1%), 2.2% (95% CI 0%-4.7%) and 2.9% (95% CI 0.6%-5.2%). The outliers were randomly distributed amongst the methods and we were confident that they would not adversely influence clinical decisions. Conclusions The hCGt results were clinically equivalent with no systematic difference amongst the four assays.

Evaluation of the next generation I-STAT® point-of-care prothrombin time test (I-STAT PTPLUS) against other commercially available prothrombin time tests

The ability to perform quantitative hCG testing in whole blood at the point-of-care is desirable. The purpose of this study was to perform an analytical validation of the Abbott i-STAT Total β-hCG test.Whole blood, plasma, and serum samples were prepared by the addition of hCG and were used to evaluate precision, linearity, analytical sensitivity, accuracy, the high-dose hook effect, and dilution recovery.Imprecision was highest with whole blood (CV = 16.0% and 6.7% at 10 and 1184 IU/l, respectively) and lowest in serum (CV = 8.1% and 4.3% at 11 and 1305 IU/l, respectively). The limits-of-quantitation were 8 and < 5 IU/l for whole blood and both plasma and serum, respectively. The assay was linear between 5 and 2000 IU/l in all sample types (R2 ≥ 0.998). i-STAT results agreed most closely with the Architect Total β-hCG assay and with greater differences observed with Beckman DxI Total βhCG and Roche Cobas e601 hCG+β assays (mean differences across all sample types were 9.3% and 12.3%, respectively). A high-dose hook effect was observed at concentrations > 400,000 IU/l. Accuracy was achieved in samples diluted with serum but not saline.The i-STAT Total β-hCG test demonstrates acceptable performance for quantifying hCG in whole blood, plasma and serum.

Human chorionic gonadotropin suspected heterophile interference investigations in immunoassays: a recommended approach.

Background Heterophile antibody (HAb) interferences in immunoassays can cause falsely elevated hCG concentrations leading to incorrect diagnosis and treatments options. When results are not consistent with the clinical findings, hCG HAb interference investigation may be requested by the physician. A retrospective evaluation of the frequency of HAb interference was performed among cases of physician-requested investigations and the effectiveness of commercially available blocking reagents to detect HAb interference in two immunoassay systems was evaluated. Methods One hundred and thirteen physician requests for hCG HAb investigation from 2008 to 2017 were reviewed. The primary method used to measure hCG was the Beckman Coulter Access Total βhCG (2008-2010) and the Roche Elecsys HCG+β (2014-2017). HAb investigation included measurement by two immunoassays before and after treatment of samples with heterophile blocking reagents and serial dilution studies. Results Five cases of HAb and HAb-like interference were identified. The interference frequency was 6.7% for the Beckman assay and 2.9% for the Roche assay. The presence of HAb was detected using heterophile blocking reagents and an alternative method in three cases. The other two cases were detected due to discrepant results with an alternative method and non-linear serial dilutions (HAb-like). Conclusions HAb interference was observed in the Beckman and the Roche assays. The heterophile blocking reagents failed to detect 40% of interference cases. Blocking reagents should not solely be used for these investigations. Multiple strategies including the use of serial dilutions and using an alternative platform are critical when troubleshooting interferences in hCG immunoassays.

Analytical evaluation of the Radiometer AQT90 FLEX βhCG assay

ObjectivesMany hospitals cannot afford an hCG assay on a central lab analyzer and turn to point of care testing (POCT) solutions. The Radiometer AQT90 FLEX is a small benchtop immunoareement between the AQT90 and comparator methods for samples with hCG ssay analyzer for use in the laboratory or at the patient bedside. This study evaluated the analytical performance of the AQT90's βhCG assay. MethodsPrecision was assessed using whole blood patient samples and two levels of quality control. Linearity was assessed by dilution of a high hCG plasma sample. Carryover and hook effect were assessed using high and low hCG samples. Method comparisons were done against Abbott i-STAT Total βhCG, Beckman Coulter Total βhCG (5th IS), and Roche hCG+β. Sample concentrations ranged from<2 IU/L to 4,973 IU/L. ResultsRepeatability and within-laboratory precision passed most manufacturer's claims and allowable error criteria. Linearity was validated from<2 IU/L to 4,741 IU/L. Hook effect was not observed up to 2,446,448 IU/L. Carryover was<4.0 ppm. A linear relationship was observed with i-STAT, Beckman and Roche methods. At>20 IU/L, biases were apparent against all three comparator assays (i-STAT: +20%, Roche: +30%, Beckman: +5 to 15%). At ≤20 IU/L, the acceptability of agreement varied according to TAE specifications. Concordance between AQT90 and comparator assays using 5 IU/L as the medical decision level ranged from 69% to 81%. ConclusionsOverall, the AQT90 hCG assay performed well and would be suitable for smaller suburban or rural hospitals. Some limitations have been noted and should be kept in mind during clinical testing.

Invited Product Profile Alere RALS Connectivity for Point-of-Care Testing

Although many qualitative point-of-care tests are commercially available for detection of pregnancy including urine and serum human chorionic gonadotropin (hCG) tests, these products are often associated with higher risk of false-negative results and are not easy to use. The ADEXUSDx hCG Test uses only 1 drop (35–40 μL) of whole blood sample for the detection of hCG, making it suitable for capillary blood testing. Comparison with Access Total βhCG (5th IS) assay using 392 finger stick samples from women of child-bearing age demonstrated an overall agreement of 98.1%. Performance of the ADEXUSDx hCG Test was prospectively evaluated in 40 pregnant and 40 nonpregnant women aged 18 to 44 years. The hCG test generated 100% sensitivity and 100% specificity. Study of additional 318 nonpregnant women in various age groups demonstrated 99.7% specificity. The ADEXUSDx hCG Test is a rapid test (10 minutes) with demonstrated ease of use and clinical performance, making it a useful point-of-care test as well as over-the-counter test.

Reducing False-Positive Pregnancy Test Results in Patients With Cancer

To assess whether the use of a laboratory test specific for intact human chorionic gonadotropin (hCG) would reduce the number of false-positive pregnancy test results. From October 21, 2014, to January 20, 2015, and April 1, 2015, to June 2, 2015, all serum samples sent for pregnancy screening at a large cancer center with a value of 5 milli-international units/mL or greater total β-hCG were frozen and stored and then retested using intact hCG reagent. We compared the accuracy of total β-hCG and intact hCG results for the diagnosis of clinically confirmed pregnancy. A negative test was defined as 14 milli-international units/mL or less, our current institutional cutoff. We also assessed a cutoff of less than 5 milli-international units/mL, a historical cutoff to rule out pregnancy. We performed intact hCG testing on 64 patient samples, of which 34 had originally resulted positive when tested for total β-hCG. These included 21 cases of clinically confirmed pregnancy and 13 false-positive cases. No women were pregnant when their intact hCG concentration was 14 milli-international units/mL or less, and all pregnancies were detected at and above this concentration. Intact hCG reduced the number of false-positive pregnancy test results from 13 to 1, a 92% reduction (95% CI 64-99%), corresponding to a reduction in the false-positive rate from 38% (95% CI 22-56%) to 3% (95% CI 1-15%). The use of intact hCG reagent in patients with cancer reduces the rate of false-positive pregnancy test results without increasing the rate of false-negative test results.

Utility of βhCG monitoring in the follow-up of medical management of miscarriage.

To evaluate the percentage change in total βeta-unit human chorionic gonadotropin (βhCG) levels (%ΔβhCG) in the prediction of treatment outcomes following intravaginal misoprostol for missed miscarriage before 13weeks. A secondary analysis of a randomised controlled study of medical management of miscarriage was performed. Total βhCG levels were collected before misoprostol (baseline) and after a planned seven day interval (follow-up), when a transvaginal ultrasound (TVUS) reported a gestational sac as present or not. If no sac at TVUS, surgery was indicated on clinical criteria. %ΔβhCG ((baseline βhCG - follow-up βhCG)/baseline βhCG×100) was evaluated in the prediction of a sac at TVUS and surgery on clinical criteria. %ΔβhCG was calculated for cases with βhCG levels within twodays of misoprostol and TVUS; calculation interval determined case number. The median %ΔβhCG for 24 cases with a persistent sac (6-9day interval) was significantly lower than for 145 with no sac (58.75% (interquartile range (IQR): 37.59-76.69; maximum 86.54) vs 97.65% (IQR: 95.44-98.43); P<0.0001). The median %ΔβhCG for eight cases needing surgery on clinical criteria (5-9day interval) was significantly lower than for 140 cases with no sac not needing surgery (79.68% (IQR: 64.63-91.15; maximum 94.06) vs 97.68% (IQR: 95.61-98.50); P<0.0001). The area under the receiver-operator curve was 0.975 for prediction of a persistent sac and 0.944 for prediction of surgery on clinical criteria, respectively. %ΔβhCG>87% predicted no sac at TVUS. %ΔβhCG>94.5% predicted no surgery on clinical criteria. %ΔβhCG calculation over one week reliably predicted treatment outcomes after medical management of missed miscarriage.

Could first- and second-trimester biochemical markers for Down syndrome have a role in predicting intrahepatic cholestasis of pregnancy?

IntroductionThe aim of this study is to compare first- and second-trimester Down syndrome biochemical screening markers in intrahepatic cholestasis of pregnancy (ICP) and normal pregnancies.Material and methodsThis observational case-control study was conducted at Health Sciences University Zeynep Kamil Maternity and Children’s Health Training and Research Hospital and the Department of Obstetrics and Gynecology at Erciyes University Medical Faculty during 2016–2017. The study included 165 patients, and consisted of 62 women who had been diagnosed with ICP (the ICP-diagnosed group) and 103 healthy pregnant women (the control group). First-trimester free β-human chorionic gonadotropin (β-hCG), pregnancy-associated plasma protein-A (PAPP-A) and second-trimester total β-hCG, estriol (E3), α-fetoprotein (AFP), and inhibin A levels were compared between the two groups.ResultsThe mean patient age was 28.67 ±5.96 years, with no significant difference between the groups (p > 0.05). Average PAPP-A levels were significantly lower in the ICP-diagnosed group (p < 0.001). When the cut-off value for PAPP-A was taken as ≤ 0.93 multiple of median (MoM), the sensitivity and specificity values for ICP were 73.8% and 56.3%, respectively (95% CI, AUC ± SE: 0.663 ±0.042).ConclusionsThe decrease in PAPP-A MoM value indicates an increase in the risk of developing ICP, while changes in other markers were not sufficient to predict ICP.

Analytical performance evaluation of the i-STAT Total β-human chorionic gonadotropin immunoassay

BackgroundThe ability to perform quantitative hCG testing in whole blood at the point-of-care is desirable. The purpose of this study was to perform an analytical validation of the Abbott i-STAT Total β-hCG test. MethodsWhole blood, plasma, and serum samples were prepared by the addition of hCG and were used to evaluate precision, linearity, analytical sensitivity, accuracy, the high-dose hook effect, and dilution recovery. ResultsImprecision was highest with whole blood (CV=16.0% and 6.7% at 10 and 1184IU/l, respectively) and lowest in serum (CV=8.1% and 4.3% at 11 and 1305IU/l, respectively). The limits-of-quantitation were 8 and <5IU/l for whole blood and both plasma and serum, respectively. The assay was linear between 5 and 2000IU/l in all sample types (R2≥0.998). i-STAT results agreed most closely with the Architect Total β-hCG assay and with greater differences observed with Beckman DxI Total βhCG and Roche Cobas e601 hCG+β assays (mean differences across all sample types were 9.3% and 12.3%, respectively). A high-dose hook effect was observed at concentrations >400,000IU/l. Accuracy was achieved in samples diluted with serum but not saline. ConclusionsThe i-STAT Total β-hCG test demonstrates acceptable performance for quantifying hCG in whole blood, plasma and serum.

Performance characteristics of the Beckman Coulter total βhCG (5th IS) assay

BackgroundBeckman Coulter recently released the first commercially available hCG reagent calibrated against the 5th International Standard (IS) for hCG (total βhCG (5th IS)). We performed a comprehensive analytical validation of this reagent. MethodsPrecision experiments were completed using 3 concentrations of commercial quality control material. Linearity, sample stability, and analytical sensitivity were evaluated using pools of human serum. Reportable range was assessed by comparing manual dilutions to those performed by the instrument. Male and female reference intervals were established using residual serum specimens submitted for routine testing. Inter-lot variability of hCG assay reagent was assessed by analyzing serum specimens with detectable hCG using 2 different reagent lots. Inter-assay variability was established using 203 serum specimens analyzed for hCG on 6 different reagent platforms. ResultsInter-day precision showed a CV of <6.0% for all concentrations of QC material. LOB, LOD, and LOQ were determined to be 0.3, 0.4, and 0.6U/l, respectively. The Access (5th IS) reagent has an average positive bias of approximately 20% when compared to most platforms and the previous generation Beckman hCG assay. Results were consistent between lots. Female reference intervals varied by age: <1.0U/l (<41y), <6.0U/l (41–50y), and <8.0U/l (>50y). Male reference intervals were <2.0U/l. ConclusionsThe analytical performance of the total βhCG (5th IS) was established. Care should be taken to re-baseline patients needing serial monitoring and/or notify physicians when transitioning to the total βhCG (5th IS) reagent.

Validation of the Abbott i-STAT total β-hCG cartridge for use in rural Alberta hospitals

Validation of the Abbott i-STAT total β-hCG cartridge for use in rural Alberta hospitals

PMM.88 Screening for Down’s Syndrome in Women with Renal Disease

IntroductionIn 2001, the UK National Screening Committee advised that all pregnant mothers should be offered a screening test for Down’s syndrome (DS). This is performed at first (biomarkers and ultrasound)...

Down syndrome screening: Suitability of a WHO 5 standardized total hCG assay

ObjectiveTo determine how the adoption of the new WHO 5th International Standard (IS 07/364) will affect the suitability of total βhCG as a marker for second trimester Down syndrome screening, compared to the current WHO 3rd IS (75/537). Design and methodsAssays employing both standards were evaluated on the Beckman Coulter DxI platform. Matched βhCG results from 232 fresh second trimester maternal serum samples were compared. In addition, stored samples from 51 Down syndrome and 251 matched control sera were also tested with both assays and results converted to weight-adjusted multiples of the median (MoMs). These results were combined with maternal age and the existing alpha-fetoprotein, unconjugated estriol and inhibin-A MoM levels to compute patient-specific Down syndrome risk. ResultsCorrelation between the two sets of results on fresh samples was high (r=0.993), but showed a proportional increase of 33% (95% CI 31% to 35%) in results using the new versus old assay across the range of measurements. βhCG results in the case/control dataset were also highly correlated (0.994) and showed a similar proportional increase (34%). After computing assay-specific MoMs, the resulting ‘triple’ and ‘quadruple’ Down syndrome risks were highly correlated, and resulted in no difference in either of the two detection rates (78% and 88%, respectively) or false positive rates (6.4%, 6.8%). ConclusionsLaboratories using the DxI platform with the new total βhCG 5th IS assay will need to compute new reference (medians), but can expect no impact on the clinical validity of the associated Down syndrome screening programs.