We found no evidence from RCTs or non-randomised studies on which to base an assessment of the correct platelet transfusion threshold prior to insertion of a lumbar puncture needle or epidural catheter. There are no ongoing registered RCTs assessing the effects of different platelet transfusion thresholds prior to the insertion of a lumbar puncture or epidural anaesthesia in people with thrombocytopenia. Any future study would need to be very large to detect a difference in the risk of bleeding. A study would need to be designed with at least 47,030 participants to be able to detect an increase in the number of people who had major procedure-related bleeding from 1 in 1000 to 2 in 1000. The use of a central data collection register or routinely collected electronic records (big data) is likely to be the only method to systematically gather data relevant to this population.

A 64-year-old Caucasian man was diagnosed with multiple myeloma in 1998, following radiotherapy for a solitary sternal plasmacytoma 12 months previously. He received nine monthly courses of oral melphalan followed by six courses of oral dexamethasone. In August 1999 he was commenced on oral cyclophosphamide 100 mg ⁄ d, and reported the development of pigmented nails of hands and feet some 5 months later. Cyclophosphamide therapy is documented to rarely cause black pigmentation of the nails after a total dose of between 1AE2 and 12AE3 g. These changes start in the proximal nail beds and progress distally; on withdrawal of cyclophosphamide, resolution proceeds in a similar fashion. The mechanism of nail pigmentation remains unknown, although the initial involvement of the nail bed, the band pattern and distal migration of the band with subsequent disappearance suggests a disturbance of the nail plate.

Antidotes to the ever-growing number of anticoagulants are always desirable in order to placate bleeding in emergencies. In general, the older anticoagulants like coumarins and unfractionated heparin (UFH) have proven reversal agents, whereas the newer ones do not. We studied the in vitro effect of 5 different heparinoids (UFH, Tinzaparin, Enoxaparin, Fondaparinux and Danaparoid) on the calibrated automated thrombogram. The assay uses a fluorogenic substrate that is cleaved by the thrombin formed after the addition of plasma to 5pM tissue factor, 4μM phospholipids and calcium chloride. We investigated all the parameters generated by dedicated software (Thrombinoscope™) ie the lag time (LT), the time to peak (ttpeak), the endogenous thrombin potential (ETP) and the peak thrombin. All the five anticoagulants tested inhibited thrombin generation (TG) in a concentration dependent manner. We subsequently analysed the in vitro effect of different concentrations of six potential reversal agents on correcting TG parameters of maximally inhibited plasma for each anticoagulant. These were protamine sulphate at 2.5, 5 & 8μg/ml, activated FVIIa (Novoseven®) at 5, 10 & 50μg/ml, FEIBA® at 0.5,1 & 2U/ml, Beriplex® at 0.3, 0.6 & 1.2U/ml, Prothromplex® TIM4 at 0.4, 0.8 & 1.8U/ml and fresh frozen plasma (FFP) at 250, 500 & 750μl/ml. The three concentrations reflect the recommended therapeutic doses for each agent together with lower and higher doses than normally used. As predicted, UFH (final concentration 0.527U/ml) was completely reversed with a standard protamine concentration of 5μg/ml. However, the highest dose of protamine gave slightly lower TG, indicating that higher concentrations of protamine sulphate can have a paradoxical ‘anticoagulant’ effect. High doses of FEIBA (2U/ml) and FVIIa (50μg/ml) restored ~50% of thrombin generation parameters. Tinzaparin (at 1antiXaUnit/ml) was also completely neutralised by protamine. However, a higher concentration of 8μg/ml protamine was required. This effect was not seen with Enoxaparin with this higher concentration of protamine reversing only ~40% of the ETP, 21% of the peak thrombin, 71% of ttpeak and 72% of the LT. There was no positive effect of protamine on Fondaparinux (3μg/ml) and Danaparoid (1antiXa U/ml)-treated plasma. Whereas Danaparoid seemed relatively resistant to all six reversal agents, Fondaparinux effect was completely neutralised by FVIIa at concentrations between 10–50μg/ml. This study highlights the differences in neutralisation of different low molecular weight heparins and UFH. In particular, Tinzaparin was much more readily reversed with protamine sulphate than Enoxaparin. It also indicates that high doses of FVIIa could completely reverse Fondaparinux anticoagulation.

There is a need for good laboratory prothrombotic markers to identify individuals at high risk of venous thromboembolism (VTE). Thrombin generation (TG) estimation is an attractive test since thrombin is a vital enzyme in the clotting cascade, influenced by the interplay of nearly all the clotting factors. However, unmodified thrombinography is not sensitive enough to changes in the protein C (PC) pathway including deficiencies of PC, PS and FVLeiden (FVL) and may lack sensitivity to prothrombotic states. So far studies have focused on the addition of exogenous activated PC (APC) or thrombomodulin (TM) to the TG assay to investigate the contribution of the natural anticoagulant pathway. However, TM is still a relatively expensive research reagent and APC bypasses the activation step of endogenous PC and hence may be less sensitive to conditions like PC and PS deficiency. We studied the effect of Protac® on TG. Protac® is a purified snake venom-extract that rapidly activates endogenous PC to APC. We used the CAT™ to measure TG in a group of patients with inherited thrombophilia, their first degree family members with no detectable defect (‘normal’ FM’s) and control subjects. All analyses were done on platelet poor plasma using a tissue factor concentration of 5pM and 4μM phospholipids. The endogenous thrombin potential (ETP; or area under the curve) was calculated using the Thrombinoscope® software. All samples were tested with and without Protac®. The percentage (ETP%) was calculated using the formula: ETP + Protac / ETP − Protac x 100. Protac® has a dose dependent inhibitory effect on the ETP. Initially we selected a concentration of 0.3U/ml Protac® to test a group of normal females and males (n=17 and 20 respectively). Males are more sensitive to Protac® than females (mean ± SEM 11.8±1.5% for males & 33.2±3.7% for females;P<0.0001). Therefore we analysed the thrombophilic cohort using 0.3U/ml Protac® for women and 0.2U/ml for men. We detected a clear difference between female controls (n=13) vs ‘normal’ FMs (n=13;P<0.05), and ‘normal’ FMs vs women with FVL (n=19;P<0.01). The ETP% was higher in ‘normal’ male FMs(mean 19.9%;n=19) when compared to their controls (mean 8.7%;n=7). The differences were significant between male controls and those with FVL (n=18;P <0.001). We observed a wide range in ETP% for both the FVL groups and the ‘normal’ FMs (eg in the male FVL group range = 24.8–76.3% and for their ‘normal’ FMs 2.2–48.6%). We correlated the ETP&ETP% with the different standard thrombophilia tests. The ETP% correlates inversely with PC, PS, APCR and age, whereas there is a positive correlation between the ETP and FVIII, fibrinogen and age. The APCR test only showed a weak correlation with FVIII. Both the ETP% and the APCR tests predicted well for FVL (95%CI 10.4–27.9, n=47 ETP% and CI −1.3 – −0.9, n=43 APCR). We could also detect a weak correlation between FVIII and the ETP + Protac which was lost when the ETP was expressed as a ratio. Unlike the APCR test, the Protac®-TG assay is sensitive to all the constituents of the PC pathway. Our results are consistent with reports showing that a positive family history of VTE is a risk factor for thrombosis despite negative standard thrombophilia tests. It may also help discriminate between individuals with FVL who have a higher prothrombotic risk than others with the same defect. Finally, this new assay is relatively cheap and easy to perform and is ideal for large studies.

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