Chapter 68 Hematologic Manifestations of Childhood Illness
Table 68-1 Normal Hematologic Values in Childhood
aPTT, Activated partial thromboplastin time; Hb, hemoglobin; Hct, hematocrit; MCV, mean corpuscular volume; PT, prothrombin time; RBC, red blood cell.
Data from Rudolph AM, Hoffman JIE, eds: Pediatrics, ed 17, East Norwalk, Conn, Appleton-Century-Crofts, 1982, p 1036, and from Nathan DG, Oski FA, eds: Hematology of infancy and childhood, ed 3, Philadelphia, WB Saunders, 1987, p 1679.
Table 68-2 Preliminary Diagnostic Guidelines for Macrophage Activation Syndrome in Systemic Juvenile Idiopathic Arthritis*
| Laboratory Criteria |
|---|
| Clinical Criteria |
| Histopathologic Criterion |
| Evidence of macrophage hemophagocytosis in the bone marrow aspirate |
| Diagnostic Rule |
| The diagnosis of MAS requires the presence of any two or more laboratory criteria or of ≥2 clinical or laboratory criteria. A bone marrow aspirate for the demonstration of hemophagocytosis may be required only in doubtful cases. |
MAS, Macrophage activation syndrome.
*The suggested criteria are useful only in patients with active systemic-onset juvenile idiopathic arthritis. The laboratory thresholds are examples only and are not specific for the diagnosis.
From Ravelli A, Magni-Manzoni S, Pistorio A, et al: Preliminary diagnostic guidelines for macrophage activation syndrome complicating systemic juvenile idiopathic arthritis. J Pediatr 146:598, 2005.
How to Manage Thromboembolism in the Setting of Pediatric Cancer
When treating thromboembolism in a patient with cancer, LMWH is the preferred choice. Warfarin, although it is less expensive and can be given orally, is difficult to regulate in the setting of multiple chemotherapy agents, frequent invasive procedures, and changing vitamin K stores because of antibiotics and illness.1–3 A randomized clinical trial in adult cancer patients demonstrated that LMWH was more efficacious and as safe as warfarin in preventing recurrent thromboembolism.4 The 2008 ACCP guidelines recommend the use of LMWH in the treatment of cancer-related venous thromboembolism for a minimum of 3 months and until the precipitating factor (e.g., use of asparaginase) has resolved.222 Other practical suggestions have been reported, but none are supported by any systematic observations.2,5,6
• A minimum of two doses of LMWH should be held before lumbar punctures and other invasive procedures.
• For intramuscular asparaginase injections, applying firm pressure and administering the medication at the trough of the anti-Xa level are probably adequate to avoid bleeding.
• Clinicians should maintain platelet counts above 50,000/µL in the first 2 weeks of anticoagulation. After that time period, the LMWH dose should be adjusted according to platelet count (50% dosing for platelet counts 20-50,000/µL; hold doses for platelet counts <20,000/µL).
Asparaginase-Related Thrombosis
• Asparaginase can be resumed when symptoms of thrombosis have resolved and there is evidence of clot stabilization or improvement on repeat imaging, typically after about 4 weeks of anticoagulation.
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Disorders of Phagocyte Function
Inherited Forms of Bone Marrow Failure
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