Chemotherapy platelet count

Thrombocytopenia is another dose-limiting side effect of chemotherapy. The primary treatment for thrombocytopenia is platelet transfusions. The risk of bleeding is significant when platelet counts are less than 10,000/mm3 (10 x 109/L) ... 

Sequential determination of platelet counts in patients receiving vincristine during early studies unexpectedly occasionally revealed thrombocytosis, which could not be accounted for by systemic response to treatment alone 10,11). Ultimately shown to most likely be the result of increased megakaryocytic endomitosis II), the observation led to the use of vincristine, and later vinblastine, both alone and bound to platelets, in a variety of thrombocytopenic disorders. These include idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura, and chemotherapy-induced microangiopathic hemolytic anemia. 

Platelets, small cell fragments produced from bone marrow cells, work with the cascade of proteins in the formation of blood clots. If platelet counts are low, leaks in blood vessels that would normally be small can lead to the loss of large amoimts of blood. Certain chemotherapy drugs knock out the production of the cells that produce platelets. Oprelvekin (Neumega ), produced in E. coli, stimulates bone marrow to produce that very important type of cell. 

Thrombopoietin is a cytokine that selectively stimulates megakaryocytopoiesis. Thrombopoeitin is not used therapeutically. Theoretical uses include the procurement of platelets for donation and recovery of platelet counts after myelosuppressive chemotherapy. Flowever, a modified recombinant form caused paradoxical reactions, delaying the development of therapeutic thrombopoietin. 

It is started 6-24 hours after completion of chemotherapy and continued for 14-21 days or until the platelet count passes the nadir and rises to more than 50,000 cells/lM.. 

Interleukin-11 is the first growth factor to gain FDA approval for treatment of thrombocytopenia. It is approved for the secondary prevention of thrombocytopenia in patients receiving cytotoxic chemotherapy for treatment of nonmyeloid cancers. Clinical trials show that it reduces the number of platelet transfusions required by patients who experienced severe thrombocytopenia after a previous cycle of chemotherapy. Although IL-11 has broad stimulatory effects on hematopoietic cell lineages in vitro, it does not appear to have significant effects on the leukopenia or neutropenia caused by myelosuppressive chemotherapy. Interleukin-11 is given by subcutaneous injection at a dose of 50 g/kg/d. It is started 6-24 hours after completion of chemotherapy and continued for 14-21 days or until the platelet count passes the nadir and rises to > 50,000 cells/ L. 

Haematological parameters. Full blood count must be analysed prior to administration of FOLFOX chemotherapy to check for persistent bone marrow suppression as previously described. Fow neutrophil or platelet counts (typically neutrophils <1.5 x 109/F or platelets <80 x 109/L) will necessitate a delay in chemotherapy administration, usually by one week. 

The effects of lithium on hemopoiesis have been studied in 100 patients who had developed chronic granulocytopenia after cancer chemotherapy or radiotherapy (240). The mean leukocyte count rose by 46%, but there were no changes in platelet or erythrocyte counts. However, there was a significant increase in platelet count in those whose baseline values were below 150 x 109/1. Lithium was well tolerated (mean serum concentration 0.59 mmol/1). 

The drug is administered at 25-50 /tg/kg/day subcutaneously. Oprelvekin is approved for use in patients undergoing chemotherapy for nonmyeloid malignancies who display severe thrombocytopenia (platelet count <20,000//iL) on a prior cycle of the same chemotherapy and is administered until the platelet count is >100,000//tL. The major complications of therapy are fluid retention and associated cardiac symptoms, such as tachycardia, palpitation, edema, and shortness of breath this is a significant concern in elderly patients and often requires concomitant therapy with diuretics. Fluid retention reverses upon drug discontinuation, but volume status should be carefully monitored in elderly patients, those with a history of heart failure, or those with preexisting pleural or pericardial effusions or ascites. Also reported are blurred vision, injection-site rash or erythema, and paresthesias. 

Fig. 16.3a-c. A 47-year-old woman with locally advanced pancreatic carcinoma and thrombocytopenia, precluding further chemotherapy, was referred for partial splenic embolization. Pre-embolization arteriogram (a) shows normal splenic artery anatomy. The superior splenic artery (b) was selectively catheterized and embolized using particles (range, 300-500 microns). Post-embolization arteriogram (c) shows complete occlusion of the superior splenic artery. One month after embolization, her platelet count was greater than 400,000/mm ... 

Fig. 16.4a,b. A 48-year-old man with pancreatic cancer presented with persistent neutropenia and thrombocytopenia. Patient was referred for partial splenic embolization (PSE) in an attempt to increase white blood ceil and platelet counts prior to additional chemotherapy. Pre-embolization axial CT image of the abdomen (a) shows splenomegaly. CT scan performed 4 months after PSE (b) shows massive necrosis of splenic parenchyma. Within 2 weeks of partial splenic embolization, the platelet count normalized (379,000/mm )... 

In common with most cytotoxic chemotherapy regimens, general side-effects include bone marrow suppression (causing reductions in white cell count, platelets and haemoglobin in particular), nausea and vomiting, diarrhoea, stomatitis and alopecia. 

Hager ED, Dziambor H, Hohmann D, Winkler P, Strama H. Effects of lithium on thrombopoiesis in patients with low platelet cell counts following chemotherapy or radiotherapy. Biol Trace Elem Res 2001 83(2) 139 18. 

Thrombopoietin is an endogenous colony-stimulating factor that increases the number of megakaryocyte colonies in bone marrow and also induces maturation of megakaryocytes (1). Recombinant thrombopoietin is indicated for correction of thrombocytopenia, induced by chemotherapy or radiotherapy (1). It has been tested in subcutaneous doses up to 5 micrograms/kg/day, resulting in increased numbers of platelets at 7 days, with a peak count at 17 days (1). 

MT is a 49-year-old man admitted for his first cycle of chemotherapy for multiple myeloma. He is scheduled to receive VAD therapy (vincristine, doxorubicin [Adriamycin] and dexamethasone). Past medical history includes asthma and diabetes. Admission laboratory values include WBC count 3400 mm platelets 9500 mm (low), Cr 1.8 mg/dL (high), bilirubin 2.4 mg/dL (high). Which of the following factors may lead you to consider dose modification of doxorubicin ... 

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