Platelet storage pool deficiency: diagnosis in patients with prolonged bleeding times and normal platelet aggregation

Expert opinion on the use of platelet secretion assay for the diagnosis of inherited platelet function disorders: Communication from the ISTH SSC Subcommittee on Platelet Physiology

Assessment of platelet secretion is crucial for diagnosing suspected inherited platelet function disorders (IPFD). A previous survey of the SSC on Platelet Physiology of the ISTH and a comprehensive review highlighted that most of the platelet secretion assays (PSAs) lack standardization and validation. The aim of this study was to provide expert consensus guidance on the use of PSAs for IPFD diagnosis. We surveyed 26 experts from 10 different countries using the RAND/UCLA methodology, to attain a consensus on sensitivity, specificity, feasibility, time to readout, and cost of most PSAs. Answers were then graded in three categories: appropriate, uncertain, and inappropriate. Equivocal or misinterpretable statements required a second and third round survey involving 14 of the original 26 experts. We report here the consolidated results of the entire procedure. There was uniform agreement on several general statements, including that PSAs should be performed in hemostasis laboratories as first line diagnostic tests even in patients with normal platelet aggregation, and should include a δ-granule secretion marker. Among the specific assays examined, lumiaggregometry, other luciferin/luciferase-based assays, high-performance liquid chromatography methods, radiolabeled-serotonin based assays, and whole-mount transmission electron microscopy were rated as appropriate for the measurement of δ-granule release, and platelet P-selectin expression by flow cytometry and released proteins by ELISA for α-granule release. For most of the other PSAs, the expert opinions were widely dispersed. Lack of expert consensus on many PSAs clearly indicates an unmet need for rigorous standardization, multicenter comparison of results, and validation of PSAs for clinical laboratory practice.

Circumcision bleeding rates in patients diagnosed with delta-storage pool deficiency later in life

BACKGROUND

Male circumcision is a common procedure, generally performed during the newborn period. Bleeding is an uncommon but feared complication of circumcision. Few reports have evaluated circumcision bleeding rates in patients with bleeding disorders.

OBJECTIVES

To study circumcision bleeding rates in male subjects who were diagnosed later in life with delta-storage pool deficiency (δ-SPD).

METHODS

We retrospectively reviewed the medical records of male subjects (≤18 years of age) who were circumcised without hemostatic prophylaxis prior to δ-SPD diagnosis from 2000 to 2020. Bleeding rates and severity were the main outcomes evaluated. We collected demographic data, bleeding scores using a validated assessment tool, laboratory data, and platelet electron microscopy results. A descriptive analysis was performed.

RESULTS

Twenty-five male subjects were included. The median bleeding score at presentation was 3.5 (range: 2-9). The diagnosis was confirmed using platelet electron microscopy. A value of <2 dense granules/platelet was considered abnormal. Circumcision was performed at a median age of 2 days (range: 1 day to 4 months). None of the subjects had intraoperative or postoperative bleeding. With a bleeding rate of zero, we suggest that newborn males with a family history of δ-SPD may be safely circumcised without hemostatic prophylaxis.

Diagnostic challenges of inherited mild bleeding disorders: a bait for poorly explored clinical and basic research

The best-known inherited mild bleeding disorders (MBDs), i.e. type 1 von Willebrand disease (VWD), platelet function disorders (PFDs), and mild to moderate clotting factor deficiencies, are characterized clinically by mucocutaneous bleeding, and, although they are highly prevalent, still pose difficult diagnostic problems. These include establishing the pathological nature of bleeding, and the uncertainties surrounding the clinical relevance of laboratory results. Furthermore, the high frequency of bleeding symptoms in the normal population and the subjective appraisal of symptoms by patients or parents makes elucidating the pathological nature of bleeding difficult. Standardized bleeding assessment tools and semiquantitative bleeding scores (BSs) help to discriminate normal from abnormal bleeding. However, as most MBDs have similar bleeding patterns, for example, bleeding sites, frequency, and severity, BSs are of little help for diagnosing specific diseases. Global tests of primary hemostasis (bleeding time; PFA-100/200) lack sensitivity and, like BSs, are not disease-specific. Problems with the diagnosis of type 1 VWD and PFD include assay standardization, uncertain definition of von Willebrand factor cut-off levels, and the lack of universal diagnostic criteria for PFD. Regarding clotting factor deficiencies, the bleeding thresholds of some coagulation factors, such as factor VII and FXI, are highly variable, and may lead to misinterpretation of the clinical relevance of mild to moderate deficiencies. Remarkably, a large proportion of MBDs remain undiagnosed even after comprehensive and repeated laboratory testing. These are tentatively considered to represent bleeding of undefined cause, with clinical features indistinguishable from those of classical MBD; the pathogenesis of this is probably multifactorial, and unveiling these mechanisms should constitute a fertile source of translational research.