Acute bleeding and thrombocytopenia after bone marrow transplantation

The relationship between hemorrhage and low platelet count was first established in patients with acute leukemia, and has been widely applied to thrombocytopenic patients, including BMT patients. Yet, the role of thrombocytopenia in bleeding post BMT has not been systematically studied. We evaluated the risk of bleeding and outcome associated with thrombocytopenia in BMT patients who had prophylactic platelet transfusions at a trigger of 20 x 10(9)/l. Thrombocytopenia was investigated in 321 patients with moderate or severe bleeding (BLD), and in a matched comparison group of 287 patients who did not bleed (NBLD). Profound thrombocytopenia (< or = 10 x 10(9)/l) was found in 8.6% of the BLD patients during the week before the bleeding onset, significantly more frequent than in NBLD patients (2.1% to 4%, P < 0.02), during weeks 2 to 6 post BMT (the period when 75% of the bleeding initiated). On the first day of bleeding, platelet counts < or = 10 x 10(9)/l were found in 13.5%, 11-20 x 10(9)/l in 20.4%, and > 20 x 10(9)/l in 66.1% of all episodes. Overall survival in BLD patients was not associated with the severity of thrombocytopenia before bleeding onset. Severity of thrombocytopenia was significantly associated with reduced survival in NBLD patients. We concluded that bleeding post BMT was significantly associated with thrombocytopenia, but the attributable risk of bleeding from profound thrombocytopenia was not large. Thrombocytopenia may be an important clinical sign in NBLD patients, and should be further explored in relation to acute toxicities other than bleeding.     

Platelet volume analysis in thrombocytopenia in relation to bleeding tendency

It has been shown that large platelets are hemostatically more active than the smaller ones. We therefore studied the relationship between the mean platelet volume and the percentage of micro- and mega-thrombocytes measured by a Coulter counter S plus II, and the bleeding tendency in 57 unselected patients with a platelet count below 50 X 10(9)/l. We found no significant differences for any of these parameters between patients without and those with mild or severe bleeding tendency. This also held true when patients with a possible platelet dysfunction or with coagulation abnormalities were excluded. We conclude that platelet volume analysis in unselected patients with severe thrombocytopenia is not helpful in the prediction of their risk of bleeding.     

Accuracy of platelet counting haematology analysers in severe thrombocytopenia and potential impact on platelet transfusion

Although haematology analysers provide reliable full blood counts, they are known to be inaccurate at enumerating platelets in severe thrombocytopenia. If the thresholds for platelet transfusion, currently set at 10 x 10(9)/l, are to be further reduced, it is vital that the limitations of current analysers are fully understood. The aim of this large multicentre study was to determine the accuracy of haematology analysers in current routine practice for platelet counts below 20 x 10(9)/l. Platelet counts estimated by analysers using optical, impedance and immunological methods were compared with the International Reference Method for platelet counting. The results demonstrated variation in platelet counting between different analysers and even the same type of analyser at different sites. Optical methods for platelet counting on the XE 2100, Advia 120, Cell-Dyn 4000 and H3* were not superior to impedance methods on the XE 2100, LH750 and Pentra analysers. All analysers except one overestimated the platelet count, which would result in under transfusion of platelets. This study highlights the inaccuracies of haematology analysers in platelet counting in severe thrombocytopenia. It re-emphasizes the need for external quality control to improve analyser calibration for samples with low platelet counts, and suggests that the optimal thresholds for prophylactic platelet transfusions should be re-evaluated.     

Hereditary thrombocytopenia with excessively prolonged bleeding time, corrected by infusions of platelet poor plasma

In a family with hereditary thrombocytopenia, transfused normal platelets as well as their own platelets had a shortened survival in the patients' circulation (11). On the other hand, the patients' platelets survived normally when transfused to a normal recipient. Platelet-associated immunoglobulins or circulating platelet antibodies were not detected (immunofluorescence method). About 200 ml platelet poor plasma (PPP) from each of 4 normal donors was infused daily for 5 consecutive d to 1 afflicted family member, causing a rise of platelet count from 65 X 10(9)/l to 163 X 10(9)/l and a decrease of bleeding time from 28 to 11 min 7 d after the PPP was discontinued. The platelet count then gradually decreased and was 65 X 10(9)/l with a bleeding time of 30 min 16 d after the PPP was discontinued. In a repeated PPP infusion experiment a similar response was evoked. It is concluded that the afflicted family members must have a deficiency of some plasma principle necessary to keep platelets fit and circulating.     

Thrombocytopenia in patients with malaria: automated analysis of optical platelet counts and platelet clumps with the Cell Dyn CD4000 analyser

Platelet counts and automated detection of platelet clumps were evaluated by optical analysis with the Abbott CD4000 analyser (Abbott Diagnostics, Santa Clara, CA, USA) in this South African study of 828 samples referred for malaria investigations. Based on microscopy (Micro) and rapid tests (RT) for HRP2 protein and parasite-associated LDH, malaria negative samples (n = 417) were defined as Micro-, RT-. Convalescent cases (n = 64) were Micro-, RT+ and had a recent record of positive microscopy. Malaria positive cases were subdivided into Micro+ (n = 315) and Micro-, RT+, PCR+ (polymerase chain reaction) (n = 32) subgroups. The mean platelet count for Micro+ cases (89.7 x 10(9)/l) was significantly lower than both the malaria negative (mean 212.6 x 10(9)/l) and convalescent malaria (mean 152.8 x 10(9)/l) groups; 89% of microscopy positive cases were thrombocytopenic (< 150 x 10(9)/l) and 30% had severe thrombocytopenia (< 50 x 10(9)/l). For comparison, 32% of the 417 malaria negative samples were thrombocytopenic and 6% of these were severe. Two thirds of samples with parasitaemia above 10% had platelet counts of < 50 x 10(9)/l while the counts were largely independent of parasite numbers when the parasitaemia was below 10%. Thirty percent of samples with microscopically detectable parasites had a PltClmp flag compared to 13% of the malaria negative group but, when the actual platelet count was taken into account, it became apparent that appearance of the flag was primarily associated with thrombocytopenia per se rather than malaria status. In most samples with a PltClmp flag, the CD4000 optical platelet clump 'signature' was indicative of small platelet aggregates and giant platelets. Morphological examination confirmed the presence of varying numbers of small platelet aggregates (3-12 individual platelets), often together with increased giant platelets, in many samples with a PltClmp flag. The observations suggest that while patients with malaria may be predisposed to the development of thrombocytopenia, a reduced platelet count in some patients may also be due in part to pseudo-thrombocytopenia.     

High-dose factor VIIa increases initial thrombin generation and mediates faster platelet activation in thrombocytopenia-like conditions in a cell-based model system

Clinical experience has shown that high doses of recombinant factor VIIa (rFVIIa) may ensure haemostasis in thrombocytopenic patients. We have used a cell-based model system to mimic thrombocytopenia and analyse the effect of rFVIIa. Lowering the platelet density from 200 x 10(9)/l (reflecting normal conditions) to 100, 50, 20 and 10 x 10(9)/l revealed a platelet density-dependent decrease in the maximal rate of thrombin generation, a prolongation in the time to maximal thrombin activity and a lower maximal level of thrombin formed. The platelet activation, measured as the time to half-maximal P-selectin (CD62) exposure, was not significantly dependent on the platelet density in the range of 200 x 10(9)/l to 10 x 10(9)/l, although there was a tendency for slower platelet activation at 20 x 10(9) and 10 x 10(9) platelets/l than at the higher platelet densities. Addition of 50--500 nmol/l rFVIIa to samples with 20 x 10(9) or 10 x 10(9) platelets/l shortened the lag phase of thrombin generation as well as the time to half-maximal platelet activation. Our data indicate that high doses of rFVIIa may help to provide haemostasis in thrombocytopenic patients by increasing the initial thrombin generation, resulting in faster platelet activation and thereby compensating for the lower number of platelets present.     

Problems with platelet counting in thrombocytopenia. A rapid manual method to measure low platelet counts.

Because most automated platelet counters cannot be relied on in thrombocytopenia, clinicians face a problem when decision making is based on platelet counts. Therefore we evaluated a visual platelet counting method from a blood smear with white blood cells (WBCs) as reference (PCW = platelet count based on WBC). Platelet counting for 74 thrombocytopenic (<120 x 10(9)/L) children was performed with PCW and with an automated counter (impedance principle); both methods were compared with evaluation by phase-contrast microscopy as the standard method. The PCW correlated well with the phase-contrast microscopy evaluation (y = -0.38 + 1.01x, r2 = 0.99). For platelet counts <20 x 10(9)/L the maximal deviation was 2 x 10(9)/L. The correlation between automated counts and the standard method was poor. The regression was y = 9.63 + 0.94x, r2 = 0.86. For platelet counts <20 x 10(9)/L the maximal deviation was 37 x 10(9)/L; on average, 7 x 10(9)/L platelets were counted in excess when compared with the standard method. PCW, in contrast to the automated impedance method, discriminated platelets from nonplatelet particles such as debris, fragments of red blood cells (hemolytic-uremic syndrome [HUS]) and of blast cells, and identified platelets of abnormal size. In addition, the appearance ofplatelets, WBCs, and RBCs gave clues to the etiology of thrombocytopenia, such as leukemia, infection, HUS, familial macrothrombocytopenia, and immune thrombocytopenia. PCW is a fast, reliable platelet counting method requiring less experience than the phase-contrast method. Visual evaluation from a stained smear clearly differentiates platelets and nonplatelet particles in contrast to most automated counters. In addition, the original smear can be preserved and reevaluated.     

Vancomycin-dependent antibodies associated with thrombocytopenia and refractoriness to platelet transfusion in patients with leukemia

Two patients with leukemia experienced profound thrombocytopenia and refractoriness to platelet transfusion during vancomycin treatment. In one patient, withdrawal of drug and administration of platelet transfusions restored platelet counts to near normal levels (approximately 100 x 10(9)/L), however, subsequent challenge with vancomycin due to recurring infection again precipitated severe thrombocytopenia (platelets less than 10 x 10(9)/L) and life-threatening hemorrhagic symptoms. Potent vancomycin-dependent antiplatelet antibodies were detected in the serum of both patients during the refractory period using staphylococcal protein A rosette formation. Employing a monoclonal antibody-antigen capture enzyme-linked immunosorbent assay (ELISA), the patients were found to have vancomycin-dependent IgG antibodies that bound specifically to platelet glycoproteins (GP) IIb and/or IIIa. One of these antibodies failed to react with platelets deficient in GPIIb/IIIa obtained from an individual with Glanzmann's thrombasthenia. These findings provide the first major evidence for drug-dependent antibodies in association with severe thrombocytopenia and refractoriness to platelet transfusion in alloimmunized leukemia patients and, further, provide the first demonstration of vancomycin-dependent antibodies reactive with platelets.     

Are white blood cell count, platelet count, erythrocyte sedimentation rate and C-reactive protein useful in the diagnosis of septicaemia and endocarditis?

In 851 predominantly adult patients with septicaemia or endocarditis data regarding white blood cell (WBC) count, platelet count, ESR and C-reactive protein (CRP) obtained within 3 days of admission were analyzed retrospectively. Among 232 patients with complete laboratory data none had the combination of normal ESR, negative CRP and lack of both leukocytosis and thrombocytopenia. CRP was positive (greater than 10 mg/l) in 93%, ESR was elevated (greater than 20 mm/h) in 90%, leukocytosis (WBC greater than 9 X 10(9)/l) was present in 60% and thrombocytopenia (platelets less than 150 X 10(9)/l) in 35% of the patients. Patients with pneumococcal infection had generally higher ESR and CRP values and WBC counts than patients with other infections.     

Graft-v-host disease is associated with autoimmune-like thrombocytopenia [see comments]

Persistent thrombocytopenia after allogeneic marrow transplantation is associated with poor patient survival. To identify the mechanisms of the thrombocytopenia, we studied platelet and fibrinogen kinetics and antiplatelet antibodies in 20 patients between 60 and 649 days (median 90) after transplantation. Seventeen patients had isolated thrombocytopenia (less than 100 X 10(9) platelets/L): the marrow cellularity was normal in five patients and slightly reduced in 12, and there was no discrepancy between thrombopoiesis and myeloerythropoiesis. Three patients had pancytopenia following marrow graft rejection (two) and relapse of leukemia (one). Only three patients had evidence of increased platelet production, indicating that in most cases there is a poor marrow response to thrombocytopenia early after marrow grafting. There was no correlation between platelet count and splenic pooling, suggesting that hypersplenism was an unlikely mechanism of the thrombocytopenia. Although there was a direct relationship between platelet count and platelet survival, the reduction in platelet survival was greater than what could be explained by the fixed platelet removal found in thrombocytopenic patients; this suggests increased platelet destruction. Seven patients had intercurrent infections that reduced both platelet and fibrinogen survivals. In addition, platelet antibodies bound to autologous or marrow donor platelets were present in five of the 12 patients studied. Patients with antiplatelet antibodies had lower platelet counts (30 +/- 10 X 10(9)/L v. 49.1 +/- 28.7 X 10(9)/L, P less than 0.05) and platelet survivals (1.32 +/- 0.92 days v. 3.58 +/- 2.02 days, P less than 0.05) than patients without antiplatelet antibodies. Furthermore, platelet- bound autoantibodies were present in five of six patients with grade II- IV acute or chronic graft-versus-host disease (GVHD), but were not present in six patients free of GVHD (P less than 0.01). We conclude that persistent thrombocytopenia after marrow transplantation is most often secondary to increased platelet destruction mediated by multiple mechanisms and that platelet autoantibodies are found in patients with acute or chronic GVHD.     

Successful treatment with azathioprine for autoimmune thrombocytopenia developing after autologous peripheral blood stem cell transplantation

A 60-year-old man with acute promyelocytic leukemia in complete remission had minimal residual disease (MRD). After two courses of arsenic trioxide treatment, the MRD disappeared. In October 2005, he received an unmanipulated autologous peripheral blood stem cell transplantation (autoPBSCT). Hematologic recovery was prompt; however, after day 21 following the autoPBSCT, platelet counts decreased to below 10 x 10(9)/l. A bone marrow aspirate showed an increased number of immature megakaryocytes, and platelet-associated IgG was elevated to 48.5 ng/10(7) platelets. A diagnosis of autoimmune thrombocytopenia was made. The combination of oral prednisolone (40 mg/day) and bolus immunoglobulin infusion (400 mg/kg, for 5 consecutive days) was ineffective. He was given azathioprine (50 mg/day, orally), and 10 days after the initiation of the treatment, the platelet counts gradually increased and recovered to over 50 x 10(9)/l on day 168, and 100 x 10(9)/l on day 364. To the best of our knowledge, successful treatment of ITP following auto PBSCT with azathioprine has not been previously reported.     

HIV-seropositive thrombocytopenia: the action of zidovudine.

The action of zidovudine when administered to individuals with severe HIV thrombocytopenia was investigated. Four individuals with platelets less than 50 x 10(9)/l and CD4 cells greater than 200 x 10(6)/l were treated with 600 mg zidovudine per day for 6 weeks, no drug for 6 weeks, 1200 mg zidovudine per day for 6 weeks, then no drug for 6 weeks. Glycocalicin, a platelet protein which correlates inversely with platelet survival, was assayed before and after treatment. Glycocalicin indices were also measured in four additional individuals with HIV thrombocytopenia. Platelet counts rose 2.5-fold [95% confidence interval (Cl), 2.0-3.0)] for four subjects who received 600 mg zidovudine per day and 4.9-fold (95% Cl, 4.0-5.8) for three subjects receiving 1200 mg zidovudine per day. Platelet counts declined during drug-free intervals. Plasma glycocalicin indices were elevated in all with untreated HIV thrombocytopenia. Indices fell after zidovudine treatment in six of seven individuals, suggesting that zidovudine prolonged platelet survival. Analysis of 170 HIV-seropositive asymptomatic individuals [mean CD4 count 474 x x 10(6)/l, standard deviation (s.d.) 245 x 10(6)/l] revealed that 14 (8%) had less than 125 x 10(9)/l platelets but only 2 (1%) had less than 50 x 10(9)/l platelets. Platelet counts increased spontaneously in eight individuals with mild HIV thrombocytopenia among the 10 for whom repeat counts were available.     

Acute bleeding complications in patients after bone marrow transplantation

Acute bleeding is a frequent complication that commonly associates with increased morbidity after bone marrow transplantation. Except for diffuse alveolar hemorrhage and cerebral hemorrhage, bleeding is infrequently recorded as a direct cause of death. Yet outcome analyses showed that bleeding from any reviewed site was associated with reduced survival. Reduced survival was correlated with bleeding intensity and the number of bleeding sites. These data point to the need to monitor all manifestations of bleeding, as bleeding may identify patients at risk for bone marrow transplantation toxicity. Until recently, prophylactic platelet transfusions were commonly given at a trigger of 20 x 10(9)/L. Whereas bleeding is more likely to occur when platelet counts drop to low levels, most bleeding episodes were recorded with platelet counts greater than 20 x 10(9)/L, suggesting causes other than profound thrombocytopenia in the pathogenesis of bleeding. Given that a trigger of 10 x 10(9)/L has become accepted for prophylactic platelet transfusions, care should be taken to ensure that parameters other than the incidence of bleeding have not been adversely affected.     

The frequency of bleeding complications in patients with haematological malignancy following the introduction of a stringent prophylactic platelet transfusion policy

Indications for platelet transfusion remain controversial and are frequently based on arbitrary numerical criteria. In October 2000, we introduced a stringent prophylactic-platelet transfusion policy < 10 x 109/l for stable patients and < 20 x 10(9)/l in the presence of major bleeding or additional risk factors. A trigger of < 50 x 10(9)/l was introduced for patients undergoing invasive procedures. A prospective analysis was performed measuring the frequency of minor and major bleeding events, morbidity, mortality and duration of pancytopenia. Blood product usage was assessed and health care savings measured. A total of 98 patients were evaluated on 2147 patient study days and 271 bleeding episodes were recorded. Major bleeding occurred on 1.39% (30/2147) of the study days when platelet counts were < 10 x 10(9)/l and 2.3% (50/2147) of the study days when platelet counts were 10-20 x 10(9)/l. In patients with platelets > 20 x 10(9)/l, there were 117 major bleeding episodes observed on 5.4% of the study days. In patients with no identified additional risk factors present, major haemorrhages were recorded in 0.51% (11/2147) of the study days in patients with platelet counts > or = 10 x 10(9)/l . There was a 36% reduction in platelet units transfused compared with retrospective data when an arbitrary transfusion trigger of 20 x 10(9)/l was in place (P = < 0.02). Of note, a 16% reduction in red cell transfusions was recorded. These data confirm that the introduction of a transfusion trigger of < 10 x 10(9)/l in the absence of fresh bleeding and sepsis (> 38 degrees C) is safe and has a significant impact on overall hospital transfusion costs.     

Difference in kinetics of hematopoietic reconstitution between ALL and ANLL after autologous bone marrow transplantation with marrow treated in vitro with mafosfamide (ASTA Z 7557)

The kinetics of hematopoietic recovery after autologous bone marrow transplantation (ABMT) reflect the hematopoietic capacity of the infused marrow. In vitro treatment of marrow with high doses of mafosfamide (ASTA Z 7557) alters the hematopoietic regenerative capacity of the graft. Thirty-two patients with acute leukemia (12 acute lymphoblastic leukemia (ALL) and 20 acute non-lymphoblastic leukemia (ANLL] with 27 in complete remission and five in partial remission were consolidated with cyclophosphamide (60 mg/kg x 2) and total body irradiation (10 Gy), followed by reinfusion of autologous marrow treated in vitro with mafosfamide. The marrow of each patient had been incubated with the highest tolerable dose of mafosfamide, individually predetermined from a preincubation test. We report here that the kinetics of engraftment are strikingly different in ANLL and ALL patients. In the ANLL group recovery to 0.1% reticulocytes took a median of 20.5 days (range 14-32) versus 15 (11-28) in the ALL group; 33.5 days (18-45) versus 19 (15-30) for leukocytes to reach 1.0 x 10(9)/l; 35 (19-60) versus 20.5 (15-30) for neutrophils to reach 0.5 x 10(9)/l; 110+ (45-480+) versus 50 (23-90) for platelets to reach 50 x 10(9)/l (p less than 0.01 and p less than 0.05). Detection of granulocyte-macrophage progenitors (CFU-GM) regeneration in marrow aspirates post-ABMT was delayed in ANLL (p less than 0.05). Neither the nature of the previous induction therapy, nor the status of the blood or bone marrow at the time of collection (CFU-GM and erythroid burst-forming units/ml) nor the stem cell sensitivity to mafosfamide, nor the doses of progenitor cells infused could explain these differences. We interpreted these observations as suggesting that the engraftment potential has been more severely altered in ANLL than in ALL, which may reflect both the intensity of the in vitro treatment and the intrinsic fragility of the stem cell pool in ANLL.     

Long-term follow-up of chronic autoimmune thrombocytopenic purpura refractory to splenectomy: a prospective analysis

Splenectomy remains the most effective treatment of chronic autoimmune idiopathic thrombocytopenia (ITP) (i.e. of > 6 months duration). Treatment of patients refractory to splenectomy (with absence of response or relapse after initial response) is difficult, and their long-term outcome is not well known. Over a 10-year period, 183 patients with chronic ITP were splenectomized including 158 adults and 25 children ( 100 x 10(9)/l, nine of them without treatment and 27 of them with low-dose steroids or azathioprine; six (13%) remained moderately thrombocytopenic (35 x 10(9)/l to 100 x 10(9)/l platelets); the last five patients, without response to any treatment (up to six regimens), remained severely thrombocytopenic (platelets < 20 x 10(9)/l), and three of them died from bleeding. Twenty-seven (57%) of the 47 refractory cases required at least one hospitalization, in the majority of cases for intravenous immunoglobulin (IVIg) infusions. Seven of the refractory cases occurred in children. Six of them subsequently reached platelet counts > 100 x 10(9)/l, but one died from bleeding. Our findings confirm the overall favourable long-term prognosis of chronic ITP refractory to splenectomy.     

Variable levels of carry over on platelet counts < or = 20 x 10(9)/l with the Bayer Advia 120

Accurate platelet counts are essential for the safe management of severe thrombocytopenia (platelet counts < or = 20 x 10(9)/l). The effect of carry over on platelet counting in severe thrombocytopenia was investigated by performing counts before and after saline rinses on three Bayer Advia 120 automated blood counters. Counts were performed in both primary and manual closed tube system modes on two instruments and in manual open tube mode on a third. A total of 194 samples with platelet counts < or = 20 x 10(9)/l were studied. First counts were significantly higher in all groups. The magnitude of the difference varied both by analyser and counting mode. Carry over was minimal with one analyser in primary mode and second counts were on average only 5.5% lower; on a second analyser in manual closed tube system mode second counts were on average 37.7% lower. A first count of > or = 10 x 10(9)/l fell to <10 x 10(9)/l on the second count in 35 of 145 samples (24.1%). In five such samples, all tested on one analyser, the second count was <50% of the value of the first count. Two of 49 (4.1%) first counts of <10 x 10(9)/l increased to > or = 10 x 10(9)/l on repeat. These results show a variable and often potentially clinically important carry-over effect on severely thrombocytopenic samples using the Advia 120.     

Tranexamic acid therapy in acute myeloid leukemia: possible reduction of platelet transfusions

We studied the clinical efficacy and safety of the antifibrinolytic drug tranexamic acid (TA) in patients undergoing chemotherapy for acute leukemia. 54 newley diagnosed AML patients were treated with 1 g of TA every 6 hours until the platelet count rose to above 20 x 10(9)/l. Platelet transfusions were given, irrespective of the count, only when oral, mucosal or significant skin bleeding manifestations were observed. During induction, the average number of days with thrombocytopenia below 20 x 10(9)/l was 14.4 +/- 7.4 and 4.6 +/- 4.1 transfusions were given in each course. During consolidation, the average number of thrombocytopenic days was 8.4 +/- 8.5 and only 1.7 +/- 1.8 transfusions were administered. In 11.5% of the induction and 32.1% of the consolidation courses, no platelet support was required. TA was tolerated very well and no side effects or thromboembolic complications were observed. Only in 6 of the 78 induction courses did a major bleeding event occur and there were none in any of the 53 consolidation courses. Thus it seems that TA therapy allowed a significant reduction in the use of platelet transfusions without submitting the patients to greater bleeding risks.     

Successful treatment with vincristine for an elderly patient with idiopathic thrombocytopenic purpura]

A 77-year-old female was referred to our hospital in March 1991 because of a severe bleeding tendency. Her blood count on admission was as follows: Hb 7.5 g/dl, WBC 4.6 x 10(9)/l with normal differentiation and platelet 2 x 10(9)/l. One month prior to admission, her blood count was normal. Initially, acute idiopathic thrombocytopenic purpura (ITP) was suspected, because of the acute onset of the bleeding tendency and thrombocytopenia. High dose intravenous immunoglobulin (400 mg/kg/day for 5 days) and bolus methylprednisolone (1 g/day for 3 days then tapered) were administered, starting March 13. Her platelet count had increased immediately on March 20 to 40 x 10(9)/l. However, platelet count decreased to 4 x 10(9)/l in the following two weeks. Her clinical course differed from that of typical acute ITP. Because the treatment with prednisolone was not effective, it was changed to intravenous infusion of vincristine (VCR) at a weekly dose of 1 mg for 6 weeks. The treatment was extremely effective, and her platelet count reached over 200 x 10(9)/l. The treatment was discontinued. Three weeks later, her platelet count decreased to 15 x 10(9)/l, the administration of VCR was resumed, and her platelet count recovered again. Throughout her clinical course, no side effect of VCR was noticed except for mild hypesthesia of the fingertips. VCR therapy was considered to be an useful treatment in elderly patients with ITP.     

Selective decrease in platelet dense granule adenine nucleotides during recovery from acute experimental thrombocytopenia and ensuing thrombocytosis in baboons

Serial measurements of platelet volume, platelet content of adenine nucleotides, beta-thromboglobulin (beta-TG), platelet factor 4 (PF4) and ex vivo platelet aggregation were made in baboons under basal, steady-state conditions of normal platelet production, and during recovery from acute thrombocytopenia induced by the exposure of flowing blood to spherical glass microbeads. The mean basal platelet count of 509 +/- 107 X 10(9)/l (+/- 1 SD; n = 4) fell acutely to 36.8 +/- 12.6 X 10(9)/l after the insertion of glass bead columns and blood filters, placed distally, for 60 min into surgically implanted arteriovenous-shunts in heparinized baboons. After the irreversible removal of up to 90% of the baseline circulating platelet population, recovery from thrombocytopenia was characterized by a constant rate of increase in circulating platelet counts (115 +/- 11 X 10(9)/l/d) and a rebound thrombocytosis to 1.5 times the basal platelet count after 7 d. Steadystate thrombocytopoiesis was achieved by 3-4 weeks after the onset of thrombocytopenia. Platelet dense granule ADP and ATP decreased significantly from 3.89 +/- 0.20 and 2.33 +/- 0.25 mumol/10(11) platelets respectively at baseline to 2.17 +/- 0.37 and 1.68 +/- 0.37 mumol/10(11) platelets respectively after 7 d (P less than 0.001 in both cases) and normalization was achieved only after 4 weeks. By contrast, the mean platelet volume and platelet content of beta-TG and PF4 did not change significantly throughout the course of study (P greater than 0.1 in both cases). Platelet function, assessed by platelet aggregation ex vivo, demonstrated that platelet function was not impaired despite the significant decrease in dense granule ADP. We conclude that a selective, temporal reduction in platelet dense granule adenine nucleotides reflects changes in the thrombocytopoietic control mechanism secondary to induction of acute thrombocytopenia.