Pattern of C-peptide response to oral glucose tolerance test: Interest and cut-off values.

OBJECTIVE: The oral glucose tolerance test (OGTT) classifies subjects as normal, glucose intolerant or diabetic depending on glycemia at 120 min (T120) post-test. Five insulin profiles associated with different incidences of diabetes over 10 years' follow-up were previously described following OGTT. However, insulin measurement is sensitive to hemolysis, and can be replaced by C-peptide assay on hemolyzed samples. However, little is known about patterns of C-peptide response to OGTT. DESIGN AND METHODS: In total, 128 patients were included, to establish preliminary baseline C-peptide values and to evaluate C-peptide response to OGTT in comparison to insulin response, using the Liaison XL immunoanalyzer. RESULTS: Hundred patients had a normal glycemic response, 19 were classified as glucose intolerant and 9 as diabetic. In normal subjects, median C-peptide values (nmol/L, with 5-95 percentiles) were 0.53 (0.23-1.37) at baseline, peaking at 2.36 (0.94-1.83) at T60, and decreasing to 2.09 (1.13-4.36) at T120. The C-peptide response pattern was similar but flatter than the insulin pattern because of different catabolism pathways. Nevertheless, C-peptide and insulin response profiles were discordant in only 9.4% of cases. Profile 3 (C-peptide peaking at T60) was the most prevalent in normal patients whereas profile 4 (peak at 120 min and lower level at T30 than at T60) was the most prevalent in glucose intolerant and diabetic patients. CONCLUSIONS: In OGTT, C-peptide could replace insulin determination on hemolyzed blood samples to predict the risk of type 2 diabetes.

Serum 1,25(OH)2 Vitamin D and 25(OH) Vitamin D Ratio for the Diagnosis of Sarcoidosis-Related Uveitis.

Purpose: The diagnostic workup of uveitis is challenging, with 30 to 50% of cases remaining of undetermined etiology despite multiple investigations. Sarcoid granuloma-related increase of 1,25(OH)2D levels could be helpful for the diagnosis of ocular sarcoidosis.Methods: Monocentric retrospective cohort study of patients for whom serum 25(OH)D and 1,25(OH)2D levels were measured during the etiologic workup of unexplained uveitis in a tertiary referral center. The diagnoses of uveitis' underlying diseases were established according to international diagnostic criteria.Results: Fifty-nine patients were included. The diagnosis of defined, presumed or probable sarcoidosis was made in 37% of patients while 41% of cases remained of undetermined origin. The median serum levels of 25(OH)D in patients with ocular sarcoidosis and in those with uveitis due to another cause were 34.50 [21.2-40.8] and 43.20 [32.2-58.3] nmol/L (P=0.02), respectively. In the same subgroups of patients, the median serum levels of 1,25(OH)2D were 132.4 [107.4-163.9] and 108.0 [84.30-130.5] pmol/l (P=0.02), and the median 1,25(OH)2D/25(OH)D ratio was 4.17 [3.11-5.09] and 2.56 [1.54-3.37] (P=0.0007) respectively. A 1,25(OH)2D/25(OH)D ratio >3.5 was associated with the diagnosis of sarcoidosis with a 68 % sensitivity and a 78% specificity and, in univariate analysis, was associated with an abnormal chest CT-scan (OR=5.7, P=0.003), granulomas on bronchial biopsy (OR=14.7, P=0.007) and bronchoalveolar lavage fluid lymphocytosis (OR=12.4, P=0.0006).Conclusion: The measurement of serum 25(OH)D and 1,25(OH)2D levels is a useful tool in the etiological workup of patients with unexplained uveitis, since a high 1,25(OH)2D/25(OH)D ratio is suggestive of ocular sarcoidosis.

[Premature rupture of the membranes: analytical evaluation of diagnostic tests]. / Rupture prématurée des membranes : étude comparative des performances analytiques des tests de diagnostic biologique.

Premature rupture of the membranes (PROM) is a frequent event affecting 3% of pregnancies. PROM causes 30% of premature deliveries and 20% of perinatal mortality. The diagnosis relies mainly on the clinical visualization of the amniotic fluid flow in the vagina. If not, clinicians can use bedside tests detecting either the change of the vaginal pH or the presence of amniotic components mainly IGFBP-1 or AFP in the vaginal fluid. We aimed to study the technical and analytical characteristics of 5 immunochromatographic tests (easyProm®, ActimProm®, Toda Amniodiag 5 strip®, Amnioquick® Duo, Amnisure®) that mainly detect IGFBP-1 in order to compare our results with the data from the manufacturer. We evaluated the pre-analytical phase (sampling, sample stability and elution) and the analytical phase (limit of detection, reading time and interferences related to a physiological contamination). Compliance with the pre-analytical step is crucial because the absorption and the elution of the samples in the buffer vary with the swab. Once eluted, the sample is stable. The recommended reading times are adequate but must not be exceeded, otherwise the result can be falsely positive. The detection limits announced appear to be to optimistic. The presence of maternal blood but not maternal urine can perturb the results.