The stability of blood samples for the measurement of the free β subunit of chorionic gonadotrophin

Stone, S; Henley, R

doi:10.1002/pd.1970150123

Cited by 11 publications

(10 citation statements)

References 3 publications

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“…Stability was an issue during the introduction of serum free -subunit as a screening test for Down syndrome (Knight and Cole, 1991;Spencer et al, 1993;Stone and Henley, 1995). The results presented here indicate that urine free -subunit has significantly greater stability problems.…”

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confidence: 56%

Stability of hCG free β-subunit and β-core fragment in urine

Cole

1997

Prenat. Diagn.

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confidence: 56%

Stability of hCG free β-subunit and β-core fragment in urine

Cole

1997

Prenat. Diagn.

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“…23 40-44 Others have identified problems of monoclonal antibody specificity measuring diVerent variants (nicked and nonnicked) of free -HCG, 45 and have queried the validity of free -HCG results because of sample instability. [46][47][48][49][50][51] In common with the diVerence between a double and a triple test, all studies demonstrating the benefit of free -HCG have been small. Therefore, there is once again no evidence that free -HCG is significantly superior to total HCG.…”

Section: Software and Population Parametersmentioning

confidence: 99%

Down's syndrome screening: a controversial test, with more controversy to come!

Reynolds

2000

J Clin Pathol

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By 1998, most health authorities oVered antenatal screening for Down's syndrome, usually by biochemical methods. To date, the development of this form of screening has not been coordinated by a national body and, consequently, there are wide variations in practice between localities. Fortunately, many of these variations have not led to any noticeable inequality of health provision, but the wide variation in risk cut oVs used by diVerent centres does. Other variations merely lead to potentially unnecessary expenditure; whereas it is believed that adding extra tests to the screening procedure is beneficial (such as double test to triple test), statistical evaluation of the confidence intervals for the detection rates quoted indicates that there is no evidence that the extra test provides an increase in detection. The cervical screening programme has progressively improved, partly through the auspices of a national framework. A similar national approach would benefit Down's screening and is only now being considered: the national screening committee (NSC) is currently drafting recommendations. To ensure optimum screening performance, the NSC should specify the risk thresholds applied, the screening protocols to be used-that is, an opt-in programme with a minimum (possibly even a maximum) of two biochemical analytes or a nuchal fold evaluation-and perhaps should even recommend national population parameters to be used for risk calculation. It might even be advisable for statistical work to be carried out to determine whether local derivation of medians is truly necessary. Furthermore, defined options for older women could be specified-for example, should all older patients have the option to proceed directly to amniocentesis if they wish or should National Health Service amniocentesis only be available for those with a "high risk" screening result. The diYculties that will face the NSC in deciding which screening policy to adopt are also considered; specifically, the lack of evidence to suggest that triple testing is superior to double testing, and the lack of evidence to prove the superiority of one analyte over another. This inadequacy of evidence is not from want of trying, but is caused by the problems of collecting enough data to provide statistical significance. Finally, there is one important difference between cervical and Down's syndrome screening that has a major impact on the advice given by any "expert"; namely, patents. Many aspects of Down's screening are subject to patents and, therefore, there is more potential for apparently uncontroversial decisions to rebound with future retrospective patent infringement claims. Thus, it would be sensible to insist that any member of a national body deciding upon Down's screening policy must fully disclose all potential conflicts of interest, both personal and family, before they are allowed to sit on the committee. Furthermore, if a national policy is decided upon, worldwide patent searches should be carried out to determine whether there are any possibl...

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“…Several authors have described the stability of free -subunit measurements in whole blood and in serum, with and without antimicrobials (Knight and Cole, 1991;Wald et al, 1993;Zimmermann et al, 1994;Spencer et al, 1993;Stevenson et al, 1993;Stone and Henley, 1995;Beaman et al, 1996;Kardana and Cole, 1997). However, Spencer et al (1993), and Cuckle and Jones (1994; found that the effect of hCG dissociation on the risk assessment of a whole screened population is not as important as the experimental findings suggest.…”

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confidence: 99%

“…Pregnancy serum free -subunit concentration is normally less than 1/100 of the hCG mass (Cole et al, 1993;Stone and Henley, 1995). Variable proportions of the hCG and the free -subunit molecules in the circulation are nicked.…”

mentioning

confidence: 99%