Gestational diabetes mellitus prevalence: Effect of the laboratory analytical variation.

AIMS: To highlight the effect of laboratory analytic variation, assessed by glucose (a) total analytic laboratory error (TAEL) present in one index laboratory and (b) total recommended allowable error (TAEa) universally applicable to all laboratories, on the prevalence of gestational diabetes mellitus (GDM). METHODS: 2337 pregnant women underwent a 75-g oral glucose tolerance test (OGTT) for universal GDM screening. Since the true value of every laboratory result fluctuates within a range, the glucose TAEL and TAEa were used to define a lower and an upper diagnostic threshold (95% confidence interval, CI) for the three glucose OGTT cut-offs of the criteria of the American Diabetes Association, ADA (2003); the Canadian Diabetes Association, CDA (2013) and the International Association of Diabetes and Pregnancy Study Groups, IADPSG (2010). RESULTS: For the ADA, CDA and IADPSG criteria, respectively, the GDM prevalence [95% CI, (glucose TAEL) (glucose TAEa)] was 13.3% [(8.0-21.8) (6.3-25.9)], 30% [(17.3-53.1) (14.3-61.3)] and 45.3% [(27.0-71.0) (22.3-79.2)]. Using the lower and higher assigned OGTT glucose thresholds for TAEL, respectively, among the different criteria, either 200 (8.6%)-601 (25.7%) additional or 122 (5.2%)-426 (18.3%) fewer women would be identified with GDM (p<0.0001). CONCLUSIONS: Independent of the diagnostic criteria, any reported GDM prevalence can potentially vary between one half to two times even for laboratories meeting recommended quality specifications. To avoid misclassifying women with GDM substantially, individual laboratories can significantly reduce this disparity by improving analytic performance. All physicians must ensure that their laboratory meets acceptable quality standards for optimal patient care.

Gestational diabetes: differences between the current international diagnostic criteria and implications of switching to IADPSG.

AIMS: To highlight the differences between eight international expert panel diagnostic criteria (either current or outdated but in use) for the diagnosis of gestational diabetes mellitus (GDM) and implications of switching to the International Association of Diabetes in Pregnancy Study Groups (IADPSG) criterion. METHODS: 2337 pregnant women underwent a 75-g oral glucose tolerance test as part of a universal screening protocol. The GDM prevalence and number of women classified differently were compared between the criteria of the American Diabetes Association (2003); Australasian Diabetes in Pregnancy Society (1998); the Canadian Diabetes Association, CDA (2003 & 2013); the European Association for the Study of Diabetes (1996); IADPSG (2010); the New Zealand Society for the Study of Diabetes (2004) and the World Health Organization (1999). RESULTS: The prevalence varied from 9.2% to 45.3% with the different criteria. The IADPSG compared a) best with CDA 2013 [356(15.2%) women classified differently, (kappa, k=68.3%)] and b) worst with CDA 2003 [843 (36.1%) women classified differently, (k=21.8%)]; p<0.001.Switching to IADPSG from the original criteria would increase the prevalence 1.5-4.9 times. CONCLUSIONS: In 2015, the various international guidelines for GDM continue to show major discrepancies in the prevalence and the women classified dissimilarly. A consensus on a single global guideline would be a giant leap forward.

Gestational diabetes: fasting capillary glucose as a screening test in a multi-ethnic, high-risk population.

AIMS: In populations at high risk of gestational diabetes mellitus (GDM), screening every pregnant woman by an oral glucose tolerance test (OGTT) is very demanding. The aim of this study was to determine the value of the fasting capillary glucose (FCG) as a screening test for GDM. METHODS: FCG was measured by a plasma-correlated glucometer in 1465 pregnant women who underwent a one-step diagnostic 75-g OGTT for universal screening of GDM. RESULTS: One hundred and ninety-six (13.4%) women had GDM as defined by the criteria of the American Diabetes Association. The area under the receiver operating characteristic curve (AUC) of the FCG was 0.83 (95% confidence interval 0.80-0.86). A FCG threshold of 4.7 mmol/l (at an acceptable sensitivity of 86.0%) independently could rule-out GDM in 731 (49.9%) women, while the FCG could rule-in GDM (100% specificity) in 16 (1.1%) additional women; therefore, approximately half of the women would not need to continue with the cumbersome OGTT. CONCLUSIONS: Screening using a FCG significantly reduces the number of OGTTs needed for the diagnosis of GDM. Wider assessment, particularly in low-risk populations, would confirm the potential value of the FCG as a screening test for GDM.

Cord blood thyroxine and thyroid stimulating hormone screening for congenital hypothyroidism: how useful are they?

AIM: To determine and compare the usefulness of cord blood screening for free thyroxine (FT4) and thyroid stimulating hormone (TSH). BACKGROUND: There is a vast amount of literature on capillary heel prick screening tests, but relatively little on cord blood testing particularly FT4. For a decade all infants born at Tawam Hospital had cord blood FT4 and at Oasis Hospital cord TSH measured through the hospital-based screening programme. On January 1st 1998, the national screening programme (NSP) for congenital hypothyroidism (CH) in the United Arab Emirates (UAE) started using capillary TSH measurement (Delfia method). Since then newborns in both hospitals have been screened both ways, i.e. cord blood and capillary blood screening. METHODS: We reviewed retrospectively all infants born from January 1998 until the end of June 2004 with CH who had double screening: cord FT4 or TSH and 4th-5th day TSH screening. RESULTS: Thirteen infants (one in 1,778) had CH in Tawam Hospital. In six of these the cord blood FT4 was low (<9.1 pm/l) (0.73 ng/dl) and in seven the cord blood FT4 was normal, i.e., over half were missed. Eight infants (one in 1,198) had CH in the Oasis Hospital. Cord blood TSH was high in six of them (>13 IU/l) and two were normal. Cord FT4 detected the most severe cases, but missed most others. Cord TSH detected six out of eight cases, but there was a recall rate of one in 23. CONCLUSIONS AND RECOMMENDATIONS: Cord FT4 identifies only infants with severe CH. Cord TSH is more sensitive than cord FT4 screening. Capillary TSH dried blood spot testing on the 3rd-5th day is the most sensitive method.

Gestational diabetes: utility of fasting plasma glucose as a screening test depends on the diagnostic criteria.

AIMS: To demonstrate the effect of diagnostic criteria, as defined by four international expert panels, on the usefulness of fasting plasma glucose (FPG) as a screening test for gestational diabetes mellitus (GDM). METHODS: We tested 4602 pregnant women using a 75-g oral glucose tolerance test (OGTT) for universal GDM screening. The area under the receiver operating characteristic curve (AUC) was used to determine the FPG performance to detect GDM by the criteria of the American Diabetes Association (ADA), the Australasian Diabetes in Pregnancy Society, the European Association for the Study of Diabetes, and the World Health Organization (WHO). RESULTS: By applying ADA, Australasian, European and WHO criteria, respectively, the FPG: (i) AUC (95% CI) was 0.882 (0.866-0.897), 0.830 (0.809-0.852), 0.808 (0.791-0.825) and 0.690 (0.670-0.710); (ii) independently could 'rule-in' GDM (with 100% specificity) in 74 (10.9%), 620 (53.5%), 252 (45.3%) and 74 (7.6%) women; (iii) independently could 'rule-out' GDM in an additional 2864 (62.2%), 928 (20.2%), 1510 (32.8%) and 1171 (25.4%) women, at FPG thresholds (with 85% sensitivity); (iv) false-positive rate (FPR) was 29.4, 75.5, 63.8 and 71.2%, at these thresholds. CONCLUSIONS: The value of the FPG as a screening test for GDM is highly dependent on the diagnostic criteria. The performance is excellent with the ADA criteria. With the other criteria, the high FPR (poor specificity) would limit its utility as a screening test. Regardless of the criteria used, initial testing by FPG can significantly decrease the number of cumbersome OGTTs needed for the diagnosis of GDM.

Gestational diabetes: an alternative, patient-friendly approach for using the diagnostic 100-g OGTT in high-risk populations.

OBJECTIVE: To simplify the 100-g oral glucose tolerance test (OGTT) for making a diagnosis of gestational diabetes mellitus (GDM). METHODS: During a 6-year period, 6,801 pregnant women underwent the 3-h, 100-g OGTT in a high-risk, multiethnic population. All these women had either a positive glucose challenge test/clinical history or were part of a universal screening protocol. The area (AUC) under the receiver-operating characteristic curve was used to compare the performance of the fasting plasma glucose (FPG), 1-h, 2-h and 3-h glucose values for GDM diagnosis. Ideal cut-offs of the best performing glucose value alone and in combination were used to find the best predictor for GDM with minimal loss of sensitivity and specificity. RESULTS: Using the American Diabetes Association criteria, 2,127 (31.3%) women were classified as having GDM. The 2-h value was the best performing (AUC 0.933) glucose value; at an optimal cut-off of >or=8.6 mmol/l, the sensitivity was 83.6% with a specificity of 92.8%. It did not achieve sufficient collective specificity and sensitivity at various thresholds to be useful. However, in combination with FPG (either FPG >or=5.3 mmol/l or 2-h >or=8.6 mmol/l) or (either FPG >or=5.6 mmol/l or 2-h >or=8.6 mmol/l), the sensitivity/specificity were 98.5%/84.7% and 92.5%/89.3%, respectively. CONCLUSION: An abbreviated 100-g OGTT, using only the FPG and 2-h glucose value, may be a useful alternative in high-risk populations to make a diagnosis of GDM by being cost-effective and patient-friendly.

Gestational diabetes: dilemma caused by multiple international diagnostic criteria.

AIMS: To highlight the variation in the diagnosis of gestational diabetes (GDM) as defined by six well-accepted international expert panels. METHODS: Two thousand, five hundred and fifty-four pregnant women underwent a 75-g oral glucose tolerance test for routine, antenatal GDM screening. They were classified using the criteria of the American Diabetes Association, Australasian Diabetes in Pregnancy Society, the Canadian Diabetes Association, the European Association for the Study of Diabetes, the New Zealand Society for the study of Diabetes and the World Health Organization (WHO). RESULTS: Between any two criteria, both the GDM prevalence (range; 7.9-24.9%) and the women classified differently [range; 70 (2.7%)-454 (17.8%) women], was significant (P<0.001). The most inclusive criteria, i.e. Australasian, despite generating the highest prevalence of GDM, did not pick up all the women identified by the most restrictive criteria, i.e. Canadian. The Australasian and the WHO criteria were associated with an increase in the number of Caesarean sections [odds ratio (OR); 1.64, 1.45, respectively] while the American, Canadian and New Zealand criteria identified an increase in macrosomia (birthweight>or=4000 g) incidence (OR; 2.09, 2.01, 1.92, respectively). CONCLUSIONS: The guidelines of the various professional committees, being based on consensus and expert opinion, show major discrepancies in their ability to identify women with GDM and their capacity to predict adverse pregnancy outcome. Only evidence-based criteria derived from reliable and consistent scientific data will eliminate the confusion caused in clinical practice.

Novel test and its automation for the determination of erythrocyte acetylcholinesterase and its application to organophosphate exposure.

BACKGROUND: Because of the lack of a problem-free, reliable method for determination of erythrocyte acetylcholinesterase (AChE), we developed a simple kinetic method, which we found to be both reliable and suitable for automation in the routine clinical laboratory. METHODS: Acetylthiocholine, used as substrate, is hydrolysed by acetylcholinesterase to yield acetate and thiocholine. Thiocholine reacts with dichlorophenolindophenol, a blue coloured compound, which is reduced to a colourless product, producing a linear decrease in absorption at 606 nm. If required, this assay can also be run at 600 nm with equally acceptable results. RESULTS: The method was automated on the Synchron LX20 multianalyser (Beckman Instruments) and blood samples of 80 patients with clinically symptomatic organophosphate poisoning and 153 normal controls were evaluated. Acetylcholinesterase values were in the range of 0-14 UgHb(-1) in cases of organophosphate poisoning, in contrast with normal controls, who had AChE values of 24.4--37.9 UgHb(-1). No overlap was found between AChE values of controls and poisoned cases. Intra- and inter-assay coefficients of variation were 1.68 and 3.71%, respectively. CONCLUSION: The method we propose for measurement of AChE was found to be simple, reliable and easily automatable in the routine clinical laboratory.