Calculated globulin (CG) as a screening test for antibody deficiency

Calculated globulin (total protein - albumin) is usually tested as part of a liver function test profile in both primary and secondary care and determines the serum globulin concentration, of which immunoglobulins are a major component. The main use hitherto of calculated globulin is to detect paraproteins when the level is high. This study investigated the potential to use low levels of calculated globulin to detect antibody deficiency. Serum samples with calculated globulin cut-off < 18 g/l based on results of a pilot study were collected from nine hospitals in Wales over a 12-month period. Anonymized request information was obtained and the samples tested for immunoglobulin levels, serum electrophoresis and, if appropriate, immunofixation. A method comparison for albumin measurement using bromocresol green and bromocresol purple was undertaken. Eighty-nine per cent (737 of 826) samples had an immunoglobulin (Ig)G level of < 6 g/l using the bromocresol green methodology with a cut-off of < 18 g/l, and 56% (459) had an IgG of < 4 g/l. Patients with both secondary and primary antibody deficiency were discovered and serum electrophoresis and immunofixation showed that 1·2% (10) had previously undetected small paraproteins associated with immune-paresis. Using bromocresol purple, 74% of samples had an IgG of < 6 g/l using a cut-off of < 23 g/l. Screening using calculated globulin with defined cut-off values detects both primary and secondary antibody deficiency and new paraproteins associated with immune-paresis. It is cheap, widely available and under-utilized. Antibody-deficient patients have been discovered using information from calculated globulin values, shortening diagnostic delay and time to treatment with immunoglobulin replacement therapy.

Immediate hypersensitivity to chlorhexidine is increasingly recognised in the United Kingdom

BACKGROUND

Chlorhexidine is widely used as an antiseptic agent. It is a potentially allergenic substance that can cause severe hypersensitivity reactions.

OBJECTIVE

We describe six patients who had anaphylactic reactions attributed to chlorhexidine during surgery. These patients were exposed to chlorhexidine in gels, swabs and catheters.

MATERIALS AND METHODS

Six patients from three UK centres with clinical history suggestive of anaphylaxis during surgery are reported. Detailed history, review of case notes, determination of chlorhexidine specific IgE, mast cell tryptase and skin tests were performed.

RESULTS

On detailed assessment five of six patients demonstrated a previous history of reactions on re-exposure to chlorhexidine. All six patients had elevated specific IgE to chlorhexidine. Skin prick test with chlorhexidine was performed in four of the six patients and was found to be positive.

CONCLUSION

Immediate hypersensitivity to chlorhexidine appears to be common but underreported in the UK. We recommend that centres investigating patients with reactions during anaesthesia and surgery should routinely include testing for chlorhexidine allergy.

South Asians are Under-Represented in a Clinic Treating Atrial Fibrillation in a Multicultural City in the UK

The Leeds rapid access atrial fibrillation (AF) clinic was set up to streamline and standardise management of patients with newly diagnosed AF. Anecdotal evidence suggests that there is under-representation of south Asians in these clinics.All patient attendances between June 2007 and June 2011 were documented and combined with ethnicity data from patient administration records. Local population demographics for 2009 were obtained from the office of national statistics. This was used to estimate the expected prevalence of AF across the different ethnic groups in Leeds taking age into account. One thousand two hundred and ten patients were referred. The study sample included 992 patients, and the number of south Asians attending was 88% less than expected (Chi squared analysis; p<0.0001). These results suggest that there is an under-representation of south Asians in a large centre that serves a cosmopolitan population. Potential reasons for this discrepancy including barriers to accessing treatment for this population or a lower prevalence of AF in south Asians due to an as yet unidentified genetic factor.

Do ribosomopathies explain some cases of common variable immunodeficiency?

The considerable clinical heterogeneity of patients with common variable immunodeficiency disorders (CVID) shares some similarity with bone-marrow failure disorders such as Diamond-Blackfan anaemia (DBA) and Shwachman-Diamond syndrome (SDS), now recognized as defects in ribosome biogenesis or ribosomopathies. The recognition of a patient with DBA who subsequently developed CVID lends support to our previous finding of a heterozygous mutation in the SBDS gene of SBDS in another CVID patient, suggesting that ribosome biogenesis defects are responsible for a subset of CVID. Genetic defects in the ribosomal translational machinery responsible for various bone marrow failure syndromes are recognized readily when they manifest in children, but diagnosing these in adults presenting with complex phenotypes and hypogammaglobulinaemia can be a challenge. In this perspective paper, we discuss our clinical experience in CVID patients with ribosomopathies, and review the immunological abnormalities in other conditions associated with ribosomal dysfunction. With genetic testing available for various bone marrow failure syndromes, our hypothesis that ribosomal abnormalities may be present in patients with CVID could be proved in future studies by testing for mutations in specific ribosomal genes. New knowledge might then be translated into novel therapeutic strategies for patients in this group of immunodeficiency disorders.

A randomised controlled trial of placental cord drainage to reduce feto-maternal transfusion

OBJECTIVES

To determine whether placental drainage via the umbilical cord prior to placental delivery reduces the size of feto-maternal transfusion and thus the chance of rhesus isoimmunisation in rhesus negative women.

STUDY DESIGN

A randomised controlled trial conducted in a tertiary hospital setting in the UK compared 18 rhesus negative women who had placental drainage (10 caesarean section and 8 vaginal deliveries) with 18 rhesus negative women where the cord remained clamped until placental delivery (8 caesarean section and 10 vaginal deliveries). Maternal venous blood samples were taken before delivery and at a mean of 142 min after delivery of the placenta, and analysed using flow cytometry to calculate the size of the feto-maternal transfusion. The statistical analysis was performed using SPSS Version 13 statistical software. The main outcome measure was the quantification of the volume of fetal cells in the maternal circulation before and after delivery.

RESULTS

In the 72 specimens taken, 40 demonstrated measurable amounts of fetal cells in the maternal circulation. In the 18 women who had placental drainage, the mean (SD) size of the feto-maternal transfusion was 0.50 ml (0.79) before and 0.39 ml (0.58) after delivery. In the 18 women who had a clamped cord, the mean (SD) feto-maternal transfusion was 0.46 ml (0.84) before and 0.78 ml (1.1) after delivery. There was no significant difference between the net feto-maternal transfusions in the two groups (Mann-Whitney U 122.5, p 0.19).

CONCLUSION

Placental drainage does not reduce the amount of feto-maternal transfusion and this method of placental delivery is not recommended to reduce feto-maternal transfusion.

The influence of maternal opiate use in pregnancy on second trimester biochemical markers for Down syndrome

OBJECTIVE

The object of this study is to examine the influence of maternal opiate use on the levels of second trimester biochemical markers for Down syndrome. Maternal opiate use is known to be associated with problems of placental origin and it is possible that the secretion of alpha-feto protein (AFP), free-beta human chorionic gonadotrophin (HCG) and unconjugated oestriol (UE) differs from that of a normal population.

METHOD

Seventy nine women who used opiates in pregnancy were compared to a control group of seventy nine women who did not use opiates and their adjusted marker levels analysed.

RESULTS

The adjusted median MoM in the opiate and control groups respectively were: AFP (1.00 vs 0.94), HCG (0.95 vs 1.04) and UE (0.96 vs 1.02), with no significant difference between these groups.

CONCLUSION

This study suggests that the current practice of calculating the risk of Down syndrome from second trimester biochemistry in women using opiate can be performed using data derived from a normal population.

Limited value of testing for intrinsic factor antibodies with negative gastric parietal cell antibodies in pernicious anaemia

BACKGROUND

The appropriate testing strategy for diagnosing pernicious anaemia using gastric parietal cell (GPC) and/or intrinsic factor antibodies (IFA) is controversial. Intrinsic factor antibodies are found in only about 70% of cases. Indirect immunofluorescence screening for gastric parietal cell antibodies is more sensitive, labour intensive, and less specific.

METHODS

The frequency of antibody positivity (IFA and/or GPC) was retrospectively examined in patients tested for both autoantibodies over a three-year period. It was investigated whether B12 levels were related to antibody status. These findings were validated in a prospective study of IFA in 91 GPC negative patients with low B12 levels.

RESULTS

Of 847 samples identified in the retrospective study, 4 (0.47%) were positive for only intrinsic factor antibodies, 731 (86.3%) positive for GPC alone, and 112 (13.2%) for both. Student t test on log-transformed data showed B12 levels had no bearing on autoantibody status. 91 consecutive patients with low B12 levels were tested for both autoantibodies; all were negative for gastric parietal cell antibodies. Only one sample was positive for intrinsic factor antibody using the porcine intrinsic factor assay, but was negative by a human recombinant intrinsic factor-based ELISA.

CONCLUSIONS

This study provides evidence that testing for gastric parietal cell antibodies is an appropriate screening test for pernicious anaemia, with intrinsic factor antibodies reserved for confirmatory testing or in patients with other autoantibodies that mask the GPC pattern; B12 levels are not related to autoantibody status.

Uptake of invasive testing following a positive triple test for Down's syndrome. Are midwives different counsellors compared with obstetricians?

A review of the uptake rate of diagnostic tests following a positive triple test was undertaken in the two maternity units of the Hull and East Yorkshire NHS Trust. In one unit, midwives were actively involved in counselling and in the other, counselling was performed by Consultant obstetricians. During the study period, there were 721 (7.1% positive rate) positive triple tests. Of these, 212 (29.4%) and 509 (70.6%) were counselled by midwives and Consultant obstetricians, respectively. There was no significant difference in uptake of amniocenteses or chorionic villous sampling with respect to the counsellor with an uptake of 60.4% in the midwife counselled group compared with 67.6% in the Consultant counselled group (p = NS). We believe the determinants of the uptake rate of a diagnostic test are patient centred if adequate counselling is provided. Midwives will continue to play a role in counselling and should be encouraged to do so to reduce the burden on obstetricians.

The clinical significance of antinucleolar antibodies

BACKGROUND

The importance of antinucleolar antibodies seen by indirect immunofluorescence on HEp-2 cells, although associated with systemic sclerosis (SSc), in unselected patients is unknown.

AIMS

To determine the true clinical significance of antinucleolar antibodies in an unselected patient population.

METHODS

Antinucleolar antibody (ANoA) positive samples were identified in the immunology laboratory during routine autoimmune screening tests; case notes were reviewed using a standard proforma.

RESULTS

104 patients with ANoA were identified and ANoA+ samples were subclassified into homogeneous, clumpy and speckled antinucleolar types. SSc was evident in only two (1.8%) patients. Other connective tissue diseases were identified in 33 patients (32%); 22 patients (21%) had evidence of various malignancies. Both disordered liver function and anaemia were seen in 22 patients and were the commonest laboratory abnormalities.

CONCLUSIONS

Neither the presence nor subtype of ANoA is specific for systemic sclerosis. Laboratory comments appended to results should reflect this fact.

Maternal serum screening for Down syndrome: are women’s perceptions changing?

OBJECTIVES

To document trends in serum screening for Down's syndrome.

BACKGROUND

Trends in the uptake of serum screening for Down syndrome have not been documented in a UK population.

DESIGN

A retrospective review of the rate of uptake in a unit that has offered serum screening for Down syndrome to all pregnant women.

SETTING

A large north of England hospital that has offered universal Down syndrome screening using the 'triple test' since 1992.

PATIENTS

A total of 47,998 women who booked for antenatal care.

MAIN OUTCOME MEASURES

Uptake of serum screening for Down syndrome.

METHODS

The results of the screening programme were contemporaneously recorded on a computer database, and the study team accessed the data.

RESULTS

There was a significant reduction in the uptake of serum screening for Down syndrome from a maximum of 82.6% in 1993 to 41.4% in 2005. There was a significant but small trend upwards in the age of women accepting screening and also a significant trend in the increase in the screen-positive rates.

CONCLUSIONS

The reduction in uptake of Down syndrome screening over the past 13 years must be taken into account when planning a screening programme. Other units should be encouraged to review their rate of uptake to determine if our data are representative of a wider trend.

Orlistat is as beneficial as metformin in the treatment of polycystic ovarian syndrome

The objective of this study was to evaluate and compare the effect of treatment with orlistat vs. metformin on the hormonal and biochemical features of patients with polycystic ovarian syndrome (PCOS). Twenty-one Caucasian women with PCOS [mean (+/-SEM) age 27 +/- 0.9 yr and body mass index 36.7 +/- 3.3 kg/m(2)] participated in this prospective, randomized, open-labeled study. All subjects had an 8-wk run-in period of dietary modification and then randomized to receive either metformin (500 mg three times daily) or orlistat (120 mg three times daily) for 3 months. Weight, blood pressure, and fasting blood samples were taken at screening, randomization, and on completion. Insulin resistance (IR) was calculated using the homeostasis model of assessment (HOMA)-IR method [HOMA-IR = (insulin x glucose)/22.5]. The results are expressed as mean +/- SEM. When compared with baseline, treatment with both orlistat [93.5 +/- 11.5 ng/dl (3.24 +/- 0.4 nmol/liter) vs. 114.5 +/- 11.5 ng/dl (3.97 +/- 0.4 nmol/liter), P = 0.039] and metformin [97.2 +/- 11.5 ng/dl (3.37 +/- 0.4 nmol/liter) vs. 120.0 +/- 8.7 ng/dl (4.16 +/- 0.3 nmol/liter), P = 0.048] produced a significant reduction in total testosterone. Treatment with orlistat produced a 4.69% reduction in weight (99.0 +/- 6.0 vs. 94.6 +/- 6.1 kg, P = 0.002), and this reduction was more significant than the reduction produced by metformin (4.69 vs. 1.02%, P = 0.006). There was no significant reduction seen after either treatment group for fasting insulin, HOMA-IR, SHBG, or any of the lipid parameters studied. In this study, orlistat produced a significant reduction in weight and total testosterone. The reduction in total testosterone was similar to that seen after treatment with metformin. Therefore, orlistat may prove to be a useful adjunct in the treatment of PCOS.

The biological variation of insulin resistance in polycystic ovarian syndrome

Increased insulin resistance (IR) is a cardinal feature of overweight patients with polycystic ovarian syndrome (PCOS). However, there are no data on the variability of IR for subjects with PCOS. The biological variation of IR (homeostasis model assessment model) was assessed by measuring IR at 4-d intervals on 10 consecutive occasions in 12 overweight PCOS patients (median age, 28 yr; range, 18-31 yr) and 11 weight-matched control women having regular menses and without PCOS (median age, 30 yr; range, 19-33 yr). The distribution of IR was log Gaussian in PCOS and Gaussian distribution in the control group. The IR in PCOS subjects was significantly greater than in the controls [mean (range), 5.85 U (1-42.1) vs. 1.67 U (0.48-3.49); P = 0.001]. After accounting for analytical variation, the mean intraindividual variance was also substantially greater in PCOS patients than in controls (mean, 1.19 vs. 0.23). As a consequence, at any level of IR, a subsequent sample must rise by more than 322% or fall by more than 31% to be considered significantly different from the first. IR, measured using the homeostasis model assessment model, is significantly greater and more variable for overweight patients with PCOS. Therefore, this inherent variability needs to be accounted for in studies of IR in PCOS.

Use of computer terminals on wards to access emergency test results: a retrospective audit

OBJECTIVE

To assess delay in clinicians obtaining emergency biochemistry test results when the telephoning of results by laboratory staff is supplanted by installation of computer ward terminals.

DESIGN

Retrospective observational study.

SETTING

Accident and emergency department and acute medical admissions ward of a teaching hospital.

SAMPLE

3228 emergency requests for biochemistry tests sent from the accident and emergency department and 1836 from the medical admissions ward during August 1999 to January 2000 when there was no recorded telephone contact for results.

MAIN OUTCOME MEASURES

Proportion of emergency biochemistry results accessed via a ward terminal within 1 or 3 hours of becoming available and the proportion never seen by this means.

RESULTS

The results from 1443/3228 (45%) of urgent requests from accident and emergency and 529/1836 (29%) from the admissions ward were never accessed via the ward terminal. Results from 794/3228 (25%) of accident and emergency requests and 413/1836 (22%) of admissions ward requests were seen within 1 hour of becoming available while a further 491/3228 (15%) and 341/1836 (19%) respectively were accessed between 1 and 3 hours. In up to 43/1443 (3%) of the accident and emergency test results that were never looked at the findings might have led to an immediate change in patient management.

CONCLUSIONS

When used as the sole substitute for telephoning results, the provision of terminal access to laboratory results on wards can hinder rather than promote the communication of emergency blood results to healthcare staff.

Biochemical screening for Down syndrome: patients' perception of risk

OBJECTIVES

To determine the utility of the triple test in routine clinical practice and in addition to the document, the acceptability of a cut-off of 1:250 for invasive testing.

DESIGN

Retrospective analysis of data from screening and invasive testing for Down syndrome over a 5-year period in Hull Maternity Hospital. Computer-based records were accessed and individual data drawn from case notes were analyzed.

RESULTS

14827 (78%) of all patients opted for the triple test. A positive result (1:250 or greater) was found in 586 (4%). Fifteen percent of this group refused further testing with amniocentesis. 0.08% requested amniocentesis despite a negative triple test result. Of the screened pregnancies the triple test and selective invasive testing identified nine out of 15 (60%) of Down syndrome cases.

CONCLUSION

Sixty percent of Down syndrome pregnancies were identified with a 4% invasive testing rate. Fifteen percent of women who had a positive test did not agree with the cut-off of 1:250 and therefore declined invasive testing. Invasive procedure complication rates do not equate with patients' perception of Down syndrome.

Combining inhibin A with existing second-trimester markers in maternal serum screening for Down's syndrome

To assess the value of inhibin A as an additional second-trimester maternal serum marker of Down's syndrome we studied 56 affected and 280 unaffected pregnancies matched for gestational age. The median level in the cases was 1.62 multiples of the gestation-specific median (MOM) in the controls, with 95 per cent confidence limits of 1.34-1.96. The distribution of inhibin levels in affected and unaffected pregnancies was approximately log Gaussian, with means about 1 standard deviation apart. This degree of separation was similar to that for human chorionic gonadotropin (hCG), free beta-hCG, and unconjugated oestriol (uE3), but about double that of alpha-fetoprotein (AFP) measured in the same samples. Inhibin was largely uncorrelated with AFP and uE3, whereas the log correlation coefficient with hCG was 0.29 (P = 0.19) for Down's syndrome and 0.41 (P < 0.0001) for unaffected pregnancies; with free beta-hCG, it was 0.18 (P = 0.38) and 0.38 (P < 0.0001), respectively. On the basis of these results and other published studies, we estimate that measuring inhibin A in addition to AFP and hCG or free beta-hCG (with or without uE3) will increase the detection rate for a fixed 5 per cent false-positive rate by about 7 per cent.

Nomograms to help inform women considering Down's syndrome screening

OBJECTIVE

To derive graphical information for use in counselling women considering whether or not to have maternal serum screening for Down's syndrome.

DESIGN

Statistical modelling of the frequency distribution of estimated Down's syndrome risk for four marker combinations.

RESULTS

Nomograms are provided showing for each maternal age: (a) the detection and false-positive rates, and (b) the proportion of pregnancies with different estimated risks.

CONCLUSION

When screening is offered, clinicians need to have information readily available on test accuracy and the likely result, which is specific to the individual.

Taking account of vaginal bleeding in screening for Down's syndrome

OBJECTIVE

To derive a method for revising the risk of Down's syndrome in maternal serum marker screening when there is vaginal bleeding. The effect on screening performance of routinely allowing for the presence or absence of bleeding in all women is also assessed.

DESIGN

Overview of published studies on the rate of reported vaginal bleeding in pregnancies with Down's syndrome, on the rate according to maternal age and on the association of bleeding with alpha-fetoprotein (AFP) level. The publications are supplemented with data on unconjugated oestriol (uE3), human chorionic gonadotrophin (hCG) and AFP levels in a consecutive series of screened women.

SETTING

Routine Down's syndrome screening tests carried out on women having antenatal care at the St James's University Hospital, Leeds.

SUBJECTS

Eight hundred and nine screened women.

RESULTS

In five studies the rate of vaginal bleeding in Down's syndrome pregnancies was 1.7 times that in unaffected pregnancies on average. In three studies, the vaginal bleeding rate increased proportionally by 2.2% on average for each year of maternal age. Three studies and our own data were consistent with a 10% increase in the mean AFP level associated with vaginal bleeding, but it did not appear to materially alter uE3 and hCG levels or the standard deviations and correlation coefficients for any of the three analytes. An individual woman's risk was calculated by multiplying her age-specific odds of Down's syndrome by two likelihood ratios, one relating to the vaginal bleeding itself and one from the marker levels. Routine allowance for the presence or absence of vaginal bleeding was estimated to increase the detection rate by less than 1%.

CONCLUSION

Our method is of clinical value in revising the risk when there is concern that vaginal bleeding might be responsible for a negative maternal serum Down's syndrome screening result. A policy of routinely incorporating information on vaginal bleeding in risk estimation for all women would have too small an effect on overall screening performance to recommend it.

Maternal serum inhibin levels in second-trimester Down's syndrome pregnancies

Maternal serum inhibin levels were measured in 19 second-trimester pregnancies affected by fetal Down's syndrome and 95 unaffected control pregnancies matched for gestational age. A statistically significant elevation was found in the affected pregnancies compared with the controls (Wilcoxon rank sum test: one-tail P = 0.02). The median level in the cases was 1.3 times that in the controls, with 95 per cent confidence limits of 0.9-1.9. Although the inhibin levels were unrelated to those of alpha-fetoprotein and unconjugated oestriol in the same samples, there was a statistically significant correlation with human chorionic gonadotropin. This together with the relatively small elevation in cases suggests that inhibin would be of limited value in maternal screening for Down's syndrome.

Clinical experience with the triple test for Down's syndrome screening

The introduction of maternal serological screening for chromosome disorders in pregnancy in women aged over 30 years at the estimated date of delivery was monitored in two hospitals. The test used involved measurement of three substances in maternal serum combined with maternal age (the triple test). This is the first report of such screening applied to an unselected antenatal clinic population. Test uptake was high but there was no overall increase in amniocentesis numbers because the increase in younger mothers was compensated for by a decrease in older women who previously, without serological testing, might have gone directly to amniocentesis. It is anticipated that widespread introduction of such testing will lead to improved detection of Down's syndrome as predicted from retrospective studies.