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Summary.  Objectives and patients: We compared the template bleeding time (BT) and closure time (CT) in the PFA‐100® as screening tests in 148 consecutive patients with unequivocal mucocutaneous bleeding and positive family history. Exclusion criteria: drug intake, concomitant diseases including minor infections, low platelet count, diseases of secondary hemostasis.Results: Type 1 von Willebrand disease (VWD‐1) was diagnosed in 26 patients, primary platelet secretion defect (PSD) in 33, VWD‐1 + PSD in nine, whereas 80 patients did not comply with the criteria for known hemostatic disorders (UD, unknown diagnosis). BT and CT were prolonged in 35.8% and 29.7% of all the patients, respectively (P = 0.23). Sensitivity increased to 48% if an abnormality of BT and/or CT was considered. Same comparisons for BT and CT in each diagnostic category were, respectively: 42 vs. 61.5% in VWD‐1 (P = 0.18), 42 vs. 24% in platelet secretion defects (P = 0.11), 67 vs. 89% in VWD‐1 + PSD (P = 0.50), and 27.5 vs. 15% in UD (P = 0.06). Conclusion: Both tests were relatively insensitive and not significantly different in detecting incoming patients with mucocutaneous hemorrhages. In patients with VWD‐1, the PFA‐100® performed slightly better, whereas the opposite occurred in those patients with platelet secretion defects. In the UD group, both tests lost sensitivity, but the BT detected 1.8 times more patients than the PFA‐100®. Given the large proportion of undiagnosed bleeders and the overall low sensitivity of these tests, clinical decisions still rely on the medical history and etiological diagnosis of the bleeding disorder.

Summary Light transmission platelet aggregation (PA), adapted to measure platelet secretion (PS), is the reference test for diagnosing platelet functional disorders (PFD). Problems with these assays include lack of standardisation, unknown reproducibility and lack of universally accepted diagnostic criteria. We addressed these issues in patients with inherited mucocutaneous bleeding (MCB). Normal and abnormal PA tests in 213 patients were reproducible in 93·3% and 90·4% of the cases, respectively. Mean intra‐subject coefficient of variation for PA with strong agonists were <9% and mean intra‐class correlation coefficient for weak agonists were >0·86 (P < 0·0001). Concomitant impaired PA with 10 μmol/l‐adrenaline and 4 μmol/l‐ADP was observed in 13·7% of the controls. This combination was not considered per se a criterion for PFD. PA with adrenaline ≥42% or irreversible aggregation with 4 μmol/l ADP had 93% and 95% Negative Predictive Value for diagnosing PFD, respectively. PA defects were consistently associated with abnormal PS. In contrast, 14·3% of patients with MCB had isolated PS. Thus, standardized PA/PS assays are highly reproducible and concordant in normal and patient populations. Normal PA with adrenaline and low ADP concentration robustly predict a normal PA. Simultaneous PA/PS assays enable the diagnosis of isolated PS defects. This study confirmed that hereditary PA–PS defects are highly prevalent.

Summary Introduction Only ± 50% of patients with type 1 von Willebrand disease (VWD) have recognized molecular defects and diagnosis still rests on demonstrating low plasma von Willebrand factor (VWF) protein/function. However, no generalized consensus exists regarding the type and number of VWF variables that should be considered for diagnosis. Aim To compare the quantitative impact of four different criteria to diagnose type 1 VWD. Methods We tested four laboratory criteria on 4298 laboratory studies during a 5‐year period. The first was the National Heart, Lung, and Blood Institute recommendation, which diagnoses type 1 VWD with plasma VWF antigen (VWF:Ag) and VWF ristocetin cofactor (VWF:RCo) < 30 IU dL−1 and possible VWD/‘low VWF’ with values between 30 and 50 IU dL−1. Second, diagnosis was established when two of three variables, VWF:Ag, VWF:RCo, VWF collagen binding assay (VWF:CB), were ≤ 2.5th percentile. Diagnostic criterion for possible VWD/‘low VWF’ using percentiles was also described. The third criterion (European Group on von Willebrand Disease, EUVWD), uses a plasma level of VWF:RCo (or VWF:CB) ≤ 40 IU dL−1 for diagnosis. Finally, the Zimmerman Program for the Molecular and Clinical Biology of VWD (ZPMCBVWD) diagnoses VWD if VWF:Ag or VWF:RCo are ≤ 40 IU dL−1. Results The three assays had high correlation and excellent agreement at levels < 120 IU dL−1. The National Heart, Lung, and Blood Institute recommendation was followed to diagnose 122 (2.8%) patients with type 1 VWD and 704 (16.4%) with possible VWD/‘low VWF.’ Using percentiles, the diagnosis of type 1 VWD increased to 280 (6.5%) patients; 169 (3.9%) patients had possible VWD and 180 (4.2%) patients had ‘low VWF.’ Diagnoses using EUVWD and ZPMCBVWD criteria increased to 339 (7.9%) and 357 (8.3%) patients, respectively. Discussion Identical data, analyzed using different criteria, led to almost three‐fold difference (2.8–8.3%) in diagnostic rate. This increase is mostly explained by increasing the cut‐off values of VWF measurements from < 30 to ≈ 40 IU dL−1. Further refinement of the laboratory diagnosis of type 1 VWD is a priority.

The purpose of this article is to evaluate the variability and reproducibility of late night salivary cortisol (LNSC) using electrochemiluminescence immunoassay (ECLIA) and compare the accuracy of one or two samples in diagnosis of Cushing's syndrome (CS). We prospectively included 64 healthy volunteers (HV), 35 patients with clinically suspected CS (S), and 26 patients with confirmed CS. Nine patients in the CS group had 24-h urinary free cortisol (UFC) less than two times the upper limit of normal (mild CS). UFC and two consecutive LNSC (LNSC1, LNSC2) were collected at home. All patients in the S group had normal UFC and low-dose dexamethasone suppression test. No differences were found between the HV and S groups in UFC, LNSC1, and LNSC2. Intra-individual variability between the two samples of LNSC was 22% in HV (1.6-91%), 32% in the S group (1.6-144%), and 51% (1.6-156%) in the CS group. Variability was higher in CS patients than those in the HV (P < 0.001) and S groups (P = 0.05). The AUC of LNSC1 was 0.945 (IC 95% 0.880-1.004); when considering the highest LNSC, the AUC was 0.980 (IC 95% 0.954-1.007) (P < 0.01). We found 23% of discordant LNSC in the S group and 11% in the CS group. Three patients with CS had only one elevated LNSC, all of them with mild CS. Our results suggest that LNSC is variable, and reproducibility is affected in both CS and S patients. We found significant improvements in the diagnostic accuracy of the LNSC measurement by obtaining two samples.