Thrombocytosis in children with Hemophilus influenzae meningitis

A retrospective study of thrombocytosis in children with Hemophilus influenzae meningitis was performed. Forty-five percent of patients had a platelet count greater than 500 X 10(9)/l during hospitalization. The mean platelet count was 284 X 10(9)/l on admission, and gradually increased to 648 X 10(9)/l on day 11 of hospitalization. These results document that thrombocytosis is common among children with H. influenzae meningitis and suggest that it is probably a recovery phenomenon.     

Thrombocytosis after pneumonia with empyema and other bacterial infections in children

Thrombocytosis is seen in association with many conditions, including infectious diseases. We studied thrombocytosis after severe bacterial infections, particularly pneumonia with empyema in children. A systematic survey of the phenomenon was conducted. Twenty-seven children admitted for pneumonia with empyema were studied. Thrombocytosis (platelet counts greater than 500 x 10(3)/microliters) was present in 92.5%. Platelet counts reached their maximum at 15.1 +/- 3.7 days (range, 7 to 25) and declined to normal after 3 weeks of illness. Compared with a healthy control group, significant thrombocytosis, but of lower incidence, was also noted in children with lobar pneumonia without pleural effusion, bacterial meningitis and osteomyelitis. Platelet functions were examined in seven of the children but no abnormalities were observed. Bone marrow aspiration of three children with pneumonia and empyema showed megakaryocytic hyperplasia. We found no correlation between thrombocytosis, neutrophilia, fever, the clinical course, complications, prognosis or treatment. Neither thromboembolic nor hemorrhagic phenomena were observed.     

Thrombocytosis in childhood

Thrombocytosis is a frequent finding in hemograms obtained from hospitalized and ambulatory children due to the widespread use of automated blood cell counters. Pediatricians are commonly puzzled in cases of thrombocytosis to determine the underlying cause and the need for therapy. The purpose of this review is to assist the general pediatrician into dealing with this common hematological finding in every day clinical practice. Fortunately, primary thrombocytosis or essential thrombocythemia, a clonal disease, is exceedingly rare in childhood, but may be associated with thromboembolic and hemorrhagic complications. On the other hand, secondary or reactive thrombocytosis is very common and is due to a variety of conditions, such as acute and chronic infections, iron deficiency, bleeding, hemolytic anemias, collagen vascular diseases, malignancies, drugs and splenectomy. Treatment of reactive thrombocytosis should be directed to the underlying problem alone. Administration of platelet aggregation inhibitors such as aspirin is unwarranted. Consultation is necessary only for the rare child with extreme thrombocytosis who has clinical and/or laboratory criteria consistent with essential thrombocythemia, or in whom a hemorrhagic or thrombotic complication has developed.     

Thrombocytosis and reduced levels of factor VIII in rheumatoid purpura in children

Thirty three patients with Henoch-Schoenlein purpura were studied at various developmental stages of this disease: specially platelet counts and factors XIII and VIII. During the development phases: 40,6% of the patients have a slight but regressive thrombocytosis (greater than 400 G/l); and 75% a reduced factor XIII, well correlated with the severity of the clinical status (level as low as 60% can be considered as a "gravity threshold"), and corrected during the improvement of the disease. This reduced factor XIII is probably linked to the local inflammation in the vessels. Factor VIII studies (specially VIII A: Ag) were normal.     

Thrombocytosis in pediatric HIV infection

Thrombocytopenia has been extensively reported in association with HIV infection. Twenty-four children (6%) from a cohort of 400 children with platelet counts >500,000/mm(3) were reviewed. All had symptomatic disease and 10 (42%) patients died. In 4 children the platelet count exceeded 700,000/mm(3) and in 1 patient the platelet count was 1.5 million/mm(3). There were no thrombotic complications, and no specific therapy was required for the thrombocytosis. Thus HIV-1 infection, a chronic viral infection, is another etiologic agent for thrombocytosis and is associated with severe disease.     

Thrombocytosis and hyperkalemia revisited

A major concern of physicians caring for patients is the development of hyperkalemia, a potentially life-threatening event requiring accurate determination of its etiology. After metabolic and iatrogenic causes have been excluded, factitious hyperkalemia must be considered, one cause of which may be the method of laboratory determination. Hyperkalemia associated with thrombocytosis has been previously described but is a fact commonly overlooked in the evaluation of a patient with hyperkalemia. We compared the potassium levels in simultaneous serum and plasma samples from patients with normal and elevated platelet counts, since platelet activation during clot formation is associated with release of potassium. We found consistently higher potassium levels in serum (containing products of activated platelets) than in plasma (containing nonactivated platelets). The greatest discrepancy in potassium levels was in patients with thrombocytosis. This preliminary study suggests that if there is no obvious explanation for an elevated serum potassium the plasma potassium level should be measured, particularly in patients with elevated platelet counts.     

Thrombocytosis in Henoch-Sch?nlein purpura

The clinical and laboratory features of acute Henoch-Sch?nlein purpura in 18 patients are presented. Thrombocytosis was noted in 67 per cent of the patients and was significantly associated with the presence of abdominal pain and gastrointestinal bleeding. We found no correlation between increased serum IgA concentrations or elevated sedimentation rates and any of the clinical features of Henoch-Sch?nlein purpura.     

Thrombocytosis and essential thrombocythemia in childhood]

Thrombocytosis is frequently observed in pediatric patients. Among them the secondary thrombocytosis are the most frequent and result from several causes. The rarely primary thrombocytosis can be either constitutive (and often familial) or acquired (essential thrombocythemia). The purpose of this article is to give diagnostic orientation and to suggest which biological tests should be performed.     

Thrombocytosis Associated with Solid Tumors in Children

The association between thrombocytosis and malignant disease was first described by Levin and Conley in 1964¹ but its pathogenesis remains unknown. We have studied the platelet counts in 108 children with solid tumors presenting to this hospital over the last 5 years. Thrombocytosis was defined as a platelet count over 400 × 10⁹/L and was noted in 43 children (40%) at presentation; in the great majority of cases the thrombocytosis could not be ascribed to infection or hemorrhage. The platelet counts in relation to the six commonest diagnoses are shown in Figure 1. The association was particularly marked in the case of hepatic tumors, where 8 out of 10 patients had platelet counts at presentation above 400 × 10⁹/L with a mean of 647 ± 306 (SD) × 10⁹/L (range 294-1310). Thrombocytopenia (platelet count less than 150 × 10⁹/L) was noted in 5 children at presentation; 2 of these had morphological evidence of bone marrow infiltration.     

Thrombocytosis Associated with Solid Tumors in Children

The association between thrombocytosis and malignant disease was first described by Levin and Conley in 1964¹ but its pathogenesis remains unknown. We have studied the platelet counts in 108 children with solid tumors presenting to this hospital over the last 5 years. Thrombocytosis was defined as a platelet count over 400 × 10⁹/L and was noted in 43 children (40%) at presentation; in the great majority of cases the thrombocytosis could not be ascribed to infection or hemorrhage. The platelet counts in relation to the six commonest diagnoses are shown in Figure 1. The association was particularly marked in the case of hepatic tumors, where 8 out of 10 patients had platelet counts at presentation above 400 × 10⁹/L with a mean of 647 ± 306 (SD) × 10⁹/L (range 294-1310). Thrombocytopenia (platelet count less than 150 × 10⁹/L) was noted in 5 children at presentation; 2 of these had morphological evidence of bone marrow infiltration.     

Spontaneous Resolution of Extreme Thrombocytosis in 2 Children

Essential thrombocytosis (ET) is rare in children, sometimes difficult to be distinguished from secondary thrombocytosis. This report concerns 2 children with extreme thrombocytosis of 4100 × 10⁹/L and 1644 × 10⁹/L with partial and complete remission at 3 months and 4 years from diagnosis, with a follow-up of 4 and 17 years, respectively, with no cytoreduction therapy. Diagnosis of ET was suggested according to accepted criteria. However, spontaneous remission of the thrombocytosis argues for the diagnosis of secondary thrombocytosis. These patients highlight the complexity of distinguishing childhood ET from secondary thrombocytosis and the need for cautious personalized decision on cytoreduction therapy.     

Thrombocytosis in an infant with high thrombopoietin concentrations

Patients with essential thrombocythemia (ET) usually have normal thrombopoietin (TPO) concentrations because of negative feedback from thrombocytosis. TPO mutations in familial ET cases result in increased translation efficiency with excessive TPO stimulation and thrombocytosis. The authors describe an infant with a high platelet count (1300 x 103/mm3) and an elevated TPO concentration who was successfully treated with anagrelide. Sequencing of TPO revealed no genetic cause. This case may represent a case of atypical ET in which thrombocytosis results from TPO stimulation rather than clonal proliferation. Measuring TPO concentrations may be warranted for children with unexplained extreme thrombocytosis.     

Thrombocytosis and thrombocytopenia in childhood bacterial meningitis.

To assess factors affecting the development of reactive thrombocytosis during bacterial meningitis, thrombocyte counts of 311 children with cerebrospinal fluid culture-positive bacterial meningitis were followed during hospitalization. Thrombocytosis (platelet counts greater than 500 x 10(9)/liter) was seen in 49% of the patients after the first week of treatment. Thrombocyte counts were higher in infants and in patients with long duration of illness before admission. Subdural effusion and cephalosporin therapy were associated with more pronounced thrombocytosis We found no relation between thrombocytosis and neurologic complications, but the patients who died developed thrombocytopenia instead of thrombocytosis. The difference between the thrombocyte curves of the surviving and dying patients might be utilized in predicting the final outcome in the severest cases of bacterial meningitis. We speculate that inflammatory cytokines, especially interleukin 1-beta, induce reactive thrombocytosis in bacterial meningitis.     

Thrombocytosis in childhood: a survey of 94 patients

The introduction of the newer generation of electronic cell counters allows the routine reporting of platelet numbers when the peripheral blood count is requested. In a 12-month period, 100 episodes of marked thrombocytosis (platelet count more than 900 X 10(9)/L) were found among 94 children. These patients were young (median age 9 months). All but one episode of marked thrombocytosis occurred as a phenomenon secondary to a variety of disease states. Infections, especially those involving the central nervous systems were the commonest cause of an elevated platelet count in this series. Malignant diseases alone were rarely associated with thrombocytosis of this magnitude. The elevated platelet count began to decline at a mean of 3 days after diagnosis, and no thrombotic or hemorrhagic complications were encountered. Marked thrombocytosis is a benign, common phenomenon in young children, but specific treatment is not required.