eMedicine Specialties > Pediatrics: General Medicine > Hematology
Thrombocytopenia-Absent Radius Syndrome: Treatment & Medication
Updated: Sep 17, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Medical Care
In patients with thrombocytopenia absent radius (TAR) syndrome, general thrombocytopenic precautions during times of clinically significant thrombocytopenia with a platelet count <80 X 109/L (usually during the first year of life) should include avoidance of trauma (with use of a soft helmet if needed), avoidance of certain antiplatelet drugs (eg, aspirin, nonsteroidal anti-inflammatory drugs [NSAIDs]), and prolonged pressure on injection sites (especially after intramuscular injections).
- Prehospital care should involve first aid for visible acute hemorrhage.
- Apply firm steady pressure to the site of bleeding.
- Keep the patient warm.
- Elevate the bleeding limb.
- The mainstay of hospital treatment is supportive care. By far, the most important treatment is platelet transfusion.
- The goal of platelet transfusion is to maintain a sufficient volume of platelet to prevent bleeding without adverse effects.
- Prophylactic transfusions with leukocyte-reduced platelet concentrates are used in patients at high risk of clinically significant hemorrhage.
- A transfusion target extrapolated from thrombocytopenia associated with acute leukemia is a platelet count <40 X 109/L. Platelet counts greater than this level are associated with a decreased risk of major vascular bleeding. Melena, epistaxis, hematuria, mucosal bleeding, and hematemesis are controlled in 80% of patients with acute leukemia when a posttransfusion increment of >40 X 109/L is used.
- Potential risks of platelet transfusion include infection, anaphylaxis, and hemolytic reactions.
- Hepatitis viruses (B, C, other) and HIV are the most common infective pathogens potentially transmitted with the transfusion of blood products.
- A further risk with transfusion is human leukocyte antigen (HLA) alloimmunization. However, platelets themselves are not highly immunogenic, and contaminating lymphocytes are most likely to cause HLA alloimmunization. Therefore, leukocyte-reduced platelet concentrates should always be used. Alloimmunization can be delayed by using random single-donor platelets and, ideally, by identifying a limited number of dedicated donors.
- Treatment of conditions refractory or nonresponsive to transfusion is difficult but may include the use of HLA-matched platelets from family members. However, the refractory state can occur even in patients receiving HLA-matched platelets, a finding that suggests a non-HLA, platelet-specific antigen.
- Splenectomy is usually effective for the treatment of thrombocytopenia in adults.
- Hematopoietic stem cell transplantation (HSCT) is an option for patients who remain thrombocytopenic with bleeding despite platelet transfusions.
- Patients with thrombocytopenia have responded to cytokine treatment with erythropoietin and interleukin-6.13,14
Surgical Care
- Splinting of the hands (and legs, if indicated) during infancy improves future function. If surgical correction of the arm deformities is indicated, it should be undertaken after the patient is hemodynamically stable. If surgery is not a feasible option to manage deformities of the upper limb as patients age, adaptive devices to assist with activities of daily living (eg, dressing, toileting, feeding) are helpful. Prostheses are less useful than adaptive devices because the patient often has a weak upper extremity because of poorly developed musculature and because a functional 5-digit hand diminishes the need for a long limb.
- Management of lower-extremity deformities must be individualized given the wide spectrum of anomalies. Intervention can range from no treatment if the deformity is mild (eg, mild varus deformity) and if it causes no functional impairment to the use of a power wheelchair or a motorized cart if the anomaly is severe and if it limits ambulation. Overall, the goal is to improve functioning and enhance independence.
- Splenectomy is usually effective for the treatment of thrombocytopenia in adults.
Consultations
- The patient with suspected TAR syndrome should be examined by a hematologist, orthopedic surgeon, plastic surgeon, and cardiologist, all of whom specialize in treating children.
Diet
- Patients should avoid ingesting cow's milk for the first year of life because cow's milk allergy is associated with TAR and may precipitate thrombocytopenic episodes.
- The frequency of thrombocytopenic episodes and the risk of complications are typically highest during the first 2 years of life, and recurrences decrease as the child ages.
- Bloody diarrhea is reported in 20% of patients. Removal of milk from the diet alleviates this symptom.
Activity
- Careful handling of the patient, with padding his or her crib and with the application of soft helmets, can be used in the first year of life.
- Most patients are adequately hemostatic after the first year of life to allow them to perform normal activities.
- Patients should avoid trauma (eg, contact sports) during periods of thrombocytopenia.
Medication
Antifibrinolytic agents
Antifibrinolytic agents decrease bleeding and transfusion requirements and help establish hemostasis. They are especially useful for controlling bleeding or prolonged oozing from gingival surfaces (eg, during teething in infants).
Aminocaproic acid (Amicar)
Competitively inhibits activation of plasminogen to plasmin.
Adult
30 g/d PO/IV in divided doses q3-6h; not to exceed 30 g/24h
Pediatric
100-200 mg/kg PO/IV loading dose; followed by 200-400 mg/kg/d PO divided q6h for 7-10 d; not to exceed 30 g/d
Coadministration with estrogens may increase clotting factors, leading to hypercoagulable state
Documented hypersensitivity; evidence of active intravascular clotting; disseminated intravascular coagulation (DIC)
Pregnancy
C - Safety for use during pregnancy has not been established.
Precautions
Can be fatal in patients with DIC, so differentiate between hyperfibrinolysis and DIC; decrease dosage to 50 mg/kg/d PO qd in severe renal impairment; use caution in cardiac or hepatic disease
Tranexamic acid (Cyklokapron)
Competitively inhibits activation of plasminogen to plasmin.
Adult
25 mg/kg PO tid/qid
Alternative: 10 mg/kg IV tid/qid in patients unable to take PO form
Pediatric
10-20 mg/kg IV q8-12h loading dose, then 25 mg/kg PO tid/qid for 7-10 d
Coadministration with chlorpromazine may result in cerebral vasospasm and ischemia and possibly reduce cerebral blood flow
Documented hypersensitivity; active intravascular clotting process (eg, DIC); gross hematuria
Pregnancy
B - Usually safe but benefits must outweigh the risks.
Precautions
Caution in renal impairment
Synthetic antidiuretic hormones
Synthetic antidiuretic hormones nonspecifically enhance hemostasis by stimulating the release of von Willebrand factor. Desmopressin stimulates the release of factor VIII, prostaglandins, and plasminogen. However, the mechanism of action is not clear, and it may not be common to all 3 substances. These agents affect vascular walls, increasing platelet adhesion. This local hemostatic action may account for their hemostatic properties.
Desmopressin acetate (DDAVP)
Increases plasma factor VIII levels, promoting platelet aggregation. Intranasal route not recommended because of unproven efficacy in small infants. Only concentrated form (150 mcg/spray) enhances hemostasis.
Adult
Pediatric
0.3 mcg/kg IV over 15-30 min
Coadministration with demeclocycline and lithium decreases effects; fludrocortisone and chlorpropamide increase effects
Documented hypersensitivity; platelet-type von Willebrand disease
Pregnancy
B - Usually safe but benefits must outweigh the risks.
Precautions
May cause tachyphylaxis; efficacy diminished after 2-3 doses; can cause hyponatremia if administered repeatedly, especially with large volumes of IV fluids (eg, perioperatively)
More on Thrombocytopenia-Absent Radius Syndrome |
| Overview: Thrombocytopenia-Absent Radius Syndrome |
| Differential Diagnoses & Workup: Thrombocytopenia-Absent Radius Syndrome |
 Treatment & Medication: Thrombocytopenia-Absent Radius Syndrome |
| Follow-up: Thrombocytopenia-Absent Radius Syndrome |
| Multimedia: Thrombocytopenia-Absent Radius Syndrome |
| References |
| « Previous Page | Next Page » |
References
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MacDonald MR, Schaefer GB, Olney AH, Patton DF. Hypoplasia of the cerebellar vermis and corpus callosum in thrombocytopenia with absent radius syndrome on MRI studies. Am J Med Genet. Mar 1 1994;50(1):46-50. [Medline].
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Further Reading
Keywords
thrombocytopenia-absent radius syndrome, TAR syndrome, tetraphocomelia-thrombocytopenia syndrome, hypomegakaryocytic thrombocytopenia, absent radii, gene, gene, rubella, Roberts syndrome, cow's milk allergy, purpura, petechiae, epistaxis, melena, hemoptysis, hematuria, hematemesis, mental retardation, diarrhea, bilateral radial aplasia, radial club hand, hypoplastic carpals and phalanges, hypoplastic ulnae, humeri, shoulder girdles, syndactyly, clinodactyly, hip dislocation, femoral torsion, tetralogy of Fallot, atrial septal defect, ventricular septal defect, VSD, micrognathia, hypertelorism, Meckel diverticulum, hyperhidrosis, short stature, Fanconi anemia, Blackfan-Diamond syndrome, treatment, diagnosis
