The 75-g glucose tolerance test in pregnancy: a reference range determined on a low-risk population and related to selected pregnancy outcomes.

OBJECTIVE: To determine a reference range for the 75-g glucose tolerance test (GTT) in pregnancy using a group of women at low risk for gestational diabetes mellitus (GDM) and to determine the validity of this reference range by examining selected pregnancy outcomes for glucose-tolerant women with a 2-h result on the GTT up to 1.0 mmol/l below the diagnostic level for GDM compared with treated women with GDM. RESEARCH DESIGN AND METHODS: The reference range for the GTT was determined in 573 Caucasian women with an age <25 years and a BMI of <25 kg/m2. Selected pregnancy outcomes were compared between 272 treated women with GDM (diagnosed on the basis of a 2-h glucose level > or =8.0 mmol/l) and 308 women with a 2-h glucose level of 7.0-7.9 mmol/l. RESULTS: There was 95% confidence that at least 95% of all the fasting glucose levels are < or =5.1 mmol/l(92 mg/dl) and 95% confidence that at least 95% of all the 2-h glucose levels were < or =7.8 mmol/l (140 mg/dl). Treated women with GDM had a significantly reduced rate of large-for-gestational-age infants compared with glucose-tolerant women, without any increase in the rate of small-for-gestational-age infants or obstetric interventions. CONCLUSIONS: The reference range for the GTT in pregnancy should be determined on a low-risk population rather than on a total population. Consideration should be given to lowering the fasting glucose level to 5.0 mmol/l (90 mg/dl) and the 2-h level to 7.8 mmol/ (140 mg/dl). Glucose-tolerant women below this relatively low reference range have an increased rate of large-for-gestational-age infants and may benefit from treatment.

Comparison of Chemcard cholesterol test and laboratory cholesterol measurements.

BACKGROUND: The Chemcard cholesterol test has been designed to estimate cholesterol levels in patients in General Practitioners' surgeries. The patients displaying elevated cholesterol levels may then be referred for a more accurate test at a recognised laboratory. AIMS: To compare the accuracy of the Chemcard cholesterol procedure with a standardised laboratory procedure for estimating cholesterol levels. METHODS: The Chemcard cholesterol procedure was applied to 200 subjects from the community, who were enrolled in a cardiovascular risk assessment programme. RESULTS: The correlation coefficient between the paired measurements was 0.83. The Chemcard cholesterol procedure gave slightly higher results than did the laboratory procedure as shown by the mean (+/-standard deviation) difference between the two methods of 0.16 +/- 0.58 mmol/L. CONCLUSIONS: The poor agreement between the two methods and the potential misclassification by Chemcard suggests that the Chemcard is not a reliable test system. The high level of risk group misclassification found in this study refutes the manufacturer's claims and does not eliminate the need for formal laboratory cholesterol measurement.

Separation of tryptophan metabolites by reversed-phase high-performance liquid chromatography with amperometric and fluorescence detection.

An isocratic method for the separation of most of the tryptophan metabolites in the oxidative degradation pathway is described. The chromatographic analysis utilizes the combined selectivity and sensitivity of amperometric and fluorimetric detection. The effect of pH, ionic strength and operating potential on retention times and detector responses are evaluated. The use of dual electrochemical cells at two operating potentials together with a programmable fluorescence detector allows for improved selectivity for the detection of metabolites. The sensitivity achieved with this method allows for the detection of the metabolites in biological fluids at the picomole level. The method has been used to monitor serum samples obtained during a tryptophan load test.

An evaluation and comparison of Reflolux II and Glucometer II, two new portable reflectance meters for capillary blood glucose determination.

The Reflolux II and the Glucometer II, two new battery-operated portable reflectance meters (PRMs) for blood glucose measurement have been evaluated for accuracy, precision and ease of operation. Both PRMs are pocket-size and simple to use. The calibration of the two instruments is fundamentally different, but in both cases the calibration data are provided with the reagent test strips and require minimal operator participation. The analysis time is 50 s for the Glucometer II and 120 s for the Reflolux II. The Reflolux II has a measuring range of 0.5-27.7 mmol/l, which is superior to the 2-22 mmol/l range of Glucometer II. Both PRMs had excellent correlation (r greater than 0.97) and minimal bias when compared by regression analysis to a laboratory method on capillary and whole blood samples. The precision of the Reflolux II was marginally better than the Glucometer II with coefficients of variation less than 6.57% for the Glucometer II and less than 5.21% for the Reflolux II. Neither the Reflolux II nor the Glucometer II offer significant advantages one over the other, both are adequate for their designed use, and both are distinct improvements over their predecessors.

Quality control of portable reflectance meter capillary blood glucose results by measurement of glucose on filter paper.

The capillary blood glucose (CBG) estimated by some of the most frequent users of portable reflectance meters (PRMs) were assessed using blood applied to Whatman 31 ET filter paper at the time of the performance of the CBG. The performance of nursing staff on hospital wards, community groups screened for diabetes and patients exercising self monitoring of blood glucose (SMBG) at home were evaluated. The glucose was extracted from the filter paper with 5% trichloroacetic acid (TCA) and analyzed within 5 days of collection on a Technicon RA-1000 analyzer using Merck glucose dehydrogenase reagents. Of the 1255 samples collected, 385 were rejected due to inadequate sample collection, and a further 196 were rejected as they were received more than 5 days after collection, the time interval allowed for glucose stability on the filter paper. The CBGs obtained by the nursing staff were 2.2 - 17.1 mmol/l with a mean of 7.6 mmol/l; the community screened subjects CBGs were 1.5 -22.4 mmol/l with a mean of 5.2 mmol/l; and the SMBG users at home obtained CBGs of 1.0 - 15.1 mmol/l with a mean of 5.07 mmol/l. Of the 674 samples analyzed only 36.6% were within 10% of the laboratory blotting paper glucose (BPG) result. An alarming 35.8% exceeded 20% and 10.2% exceeded 50% of the BPG result. The correlation of all 3 groups with the BPG obtained by the laboratory were similar (correlation coefficient = 0.86, 0.85, 0.87 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Improved estimation of fructosamine, as a measure of glycated serum protein, with the Technicon RA-1000 analyzer.

We present an improved fructosamine assay for use with the Technicon RA-1000 analyzer. Features of this assay include: specimen throughput of 100 per hour, within-batch CV of 1.5%, between-batch CV of 2.4%, standard curve linear up to 24.9 mmol of fructosamine per liter, and good correlation (r = 0.82) with hemoglobin A1.

Measurement of sodium valproate in serum by direct-insertion chemical-ionization/mass spectrometry.

To quantitatively determine sodium valproate, we use a stable isotope-labeled internal standard and chemical-ionization/mass spectrometry, without prior chromatographic separation. The technique is rapid, simple, sensitive, and provides for the routine analysis of 100 microL of serum with good within-day and day-to-day precision. The technique also allows for the simultaneous determination of phenobarbital, mephobarbital, carbamazepine, primidone, and phenytoin.

Iminopeptiduria, skin ulcerations, and edema in a boy with prolidase deficiency.

A 12-year-old boy with recurrent skin ulceration, chronic generalized lymphedema, and mild mental retardation was found to excrete massive amounts of dipeptides, most (but not all) of which had proline or hydroxyproline as the carboxyl terminal residue. Glycylproline predominated. Prolidase deficiency was demonstrated in red blood cells and in fibroblastic cells. Prolidase activity was present in continuous lymphoid cell cultures at the same low level observed in control cells.

The mass spectrometric identification of dipeptides in the urine of a patient suffering from chronic skin ulceration and oedema.

The identification of a complex ninhydrin positive mixture present in the urine of a child suffering from chronic skin ulceration and oedema by direct chemical ionisation mass spectrometric analysis is described. The compounds were shown to be dipeptides, of which glycylproline was the major constituent. At least 15 dipeptides were identified in the urine, most of which contained proline or hydroxyproline in the carboxy terminal position. The results suggested that the patient suffered from a defect in collagen metabolism. This hypothesis was subsequently confirmed by a grossly diminished level of prolidase in cultured fibroblasts and erythrocytes.

The mass spectrometric identification of dipeptide mixtures obtained from dipeptidylaminopeptidase. I--Hydrolysates.

The amino acid sequence of a polypeptide can be deduced by an identification of all the dipeptides obtained from a Dipeptidylaminopeptidase I hydrolysate of the original polypeptide and its des N-terminal amino acid derivative. The components of such dipeptide mixtures can be readily identified from the chemical ionization (helium) mass spectra of their N-ethoxycarbonylpropenyl methyl ester derivatives without prior separation. The pyrolytic conversion of N-protected peptide dimethyltrideuteromethyl anilinium salts to their methyl esters in the direct insertion probe of a mass spectrometer was found to be most suitable for the derivatization of such dipeptide mixtures.